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000
FXUS65 KTFX 200439
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1040 PM MDT Wed Jun 19 2013
...UPDATE TO AVIATION...
.UPDATE...Frontal boundary has pushed through the forecast area and
the risk of severe thunderstorms has ended. Have expired the Severe
Thunderstorm Watch and the Flash Flood Watch. Have also cancelled
the High Wind Warning for Norris Hill as winds have diminished in
this area. Updated forecast to remove severe wording. Rain will
continue to fall across north central Montana for another few hours
but should move out of the area around midnight. Only remaining
highlight is an Areal Flood Warning for small streams, creeks and
coulees across much of north central and central Montana. mpj
&&
.AVIATION...
Updated 0440Z.
Surface front has pushed through the forecast area and the risk of
severe weather has ended. Broad area of moderate to heavy stratiform
precipitation will continue over north central Montana overnight
with areas MVFR conditions in low clouds and rain. Gusty westerly
winds with mid level clouds but only isolated to scattered showers
are expected after 15Z Thursday. Winds will diminish after 00Z
Friday. mpj
&&
.PREV DISCUSSION...
/ISSUED 305 PM MDT Wed Jun 19 2013/
Rest of this afternoon through tonight...A fairly vigorous upper
level low centered over the inland Pacific NW this afternoon will
track slowly east into the Northern Rockies tonight, producing
favorable conditions for severe thunderstorm development across much
of the forecast area late this afternoon through this evening.
Diffluent southerly flow ahead of the upper low and an upper level
jet rounding the base of the trough will support large scale lift
while cooling in the mid levels will produce moderate instability.
Thunderstorms have already initiated over the higher terrain in
Beaverhead County as well as the Absorka range in south central MT
with latest visible satellite imagery also indicating convective
cloud development over the Little Belts. Expect this activity to
increase and coverage while tracking north this afternoon with storm
intensification/organization occurring late this afternoon and
evening as it progresses north into the relatively rich moisture
environment over the north central MT plains. Large hail and strong
gusty winds will be the main threat as storms organize late this
afternoon with a transition to more linear organization as the
storms continue northward toward the Canadian border late tonight.
Low level helicity fields would marginally support an isolated
tornado threat if cells can interact with a weak boundary across
north central MT. Threat for severe storms will diminish from south
to north later this evening with rain and high elevation snow
showers continuing through the night in the Glacier Park area where
snow levels will fall to around 7000 feet late tonight as the cold
pool aloft associated with the upper low moves in from the west.
Hoenisch
Winds will likely approach high wind criteria along the Rocky
Mountain Front on Thursday, but am not anticipating a need for
high wind highlights at this time. The Pacific low pressure system
will linger through the day on Friday, keeping a chance of showers
and (likely weak) afternoon/evening thunderstorms over the area,
as temperatures remain about 10 degrees cooler than normal.
Coulston
Friday night through Wednesday...An upper low over the Pacific
Northwest early Friday evening is forecast to weaken as it moves
over the forecast area on Saturday. Models are fairly wet over
southwest and north central Montana on Saturday so have increased
the chances of precipitation especially over north central
Montana. The remnants of the upper low move out by late Saturday
night and by early Sunday morning it appears the only threat for
precipitation will be over north central Montana and possibly the
mountains of the Rocky Mountain Front. On Sunday an upper ridge
will move through the forecast area and expect a mostly dry
period but then southwest flow aloft returns next week. Models
differ on shortwave details and associated precipitation
patterns. Due to these inconsistencies will go with generally a
chance of showers/thunderstorms over the mountains of the Rocky
Mountain Front with a slight chance of showers/thunderstorms
elsewhere. Cool air associated with the upper low will result in
highs on Saturday of only 55 to 65 except over north central
Montana where highs will be closer to 70. Thereafter expect
gradually warming temperatures. Blank
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 50 67 43 65 / 60 20 20 30
CTB 49 63 41 64 / 90 20 20 30
HLN 50 65 43 67 / 50 30 20 30
BZN 45 68 39 68 / 30 30 20 30
WEY 34 60 31 63 / 20 20 10 10
DLN 42 62 37 66 / 50 30 20 20
HVR 56 72 47 70 / 100 20 20 40
LWT 48 68 42 65 / 80 20 30 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
Areal Flood Warning for Small Streams, Creeks and Coulees until 130
PM MDT for Cascade...Chouteau...Judith Basin...Toole...Teton...
Glacier...Pondera...Lewis and Clark.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 200421
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1020 PM MDT Wed Jun 19 2013
.UPDATE...Frontal boundary has pushed through the forecast area and
the risk of severe thunderstorms has ended. Have expired the Severe
Thunderstorm Watch and the Flash Flood Watch. Have also cancelled
the High Wind Warning for Norris Hill as winds have diminished in
this area. Updated forecast to remove severe wording. Rain will
continue to fall across north central Montana for another few hours
but should move out of the area around midnight. Only remaining
highlight is an Areal Flood Warning for small streams, creeks and
coulees across much of north central and central Montana. mpj
&&
.AVIATION...
Updated 2350Z.
Strong to severe thunderstorms will continue to move through
central and north central Montana this evening. A strong surface
cold front has already pushed through portions of southwest
Montana and will continue to move east overnight. Behind the front
a more stable airmass with gusty west winds will move into the
forecast area. VFR conditions should prevail through the period
except for local IFR/MVFR conditions in and around the strongest
storms. Mountain obscurations are expected as well. mpj
&&
.PREV DISCUSSION...
/ISSUED 305 PM MDT Wed Jun 19 2013/
Rest of this afternoon through tonight...A fairly vigorous upper
level low centered over the inland Pacific NW this afternoon will
track slowly east into the Northern Rockies tonight, producing
favorable conditions for severe thunderstorm development across much
of the forecast area late this afternoon through this evening.
Diffluent southerly flow ahead of the upper low and an upper level
jet rounding the base of the trough will support large scale lift
while cooling in the mid levels will produce moderate instability.
Thunderstorms have already initiated over the higher terrain in
Beaverhead County as well as the Absorka range in south central MT
with latest visible satellite imagery also indicating convective
cloud development over the Little Belts. Expect this activity to
increase and coverage while tracking north this afternoon with storm
intensification/organization occurring late this afternoon and
evening as it progresses north into the relatively rich moisture
environment over the north central MT plains. Large hail and strong
gusty winds will be the main threat as storms organize late this
afternoon with a transition to more linear organization as the
storms continue northward toward the Canadian border late tonight.
Low level helicity fields would marginally support an isolated
tornado threat if cells can interact with a weak boundary across
north central MT. Threat for severe storms will diminish from south
to north later this evening with rain and high elevation snow
showers continuing through the night in the Glacier Park area where
snow levels will fall to around 7000 feet late tonight as the cold
pool aloft associated with the upper low moves in from the west.
Hoenisch
Winds will likely approach high wind criteria along the Rocky
Mountain Front on Thursday, but am not anticipating a need for
high wind highlights at this time. The Pacific low pressure system
will linger through the day on Friday, keeping a chance of showers
and (likely weak) afternoon/evening thunderstorms over the area,
as temperatures remain about 10 degrees cooler than normal.
Coulston
Friday night through Wednesday...An upper low over the Pacific
Northwest early Friday evening is forecast to weaken as it moves
over the forecast area on Saturday. Models are fairly wet over
southwest and north central Montana on Saturday so have increased
the chances of precipitation especially over north central
Montana. The remnants of the upper low move out by late Saturday
night and by early Sunday morning it appears the only threat for
precipitation will be over north central Montana and possibly the
mountains of the Rocky Mountain Front. On Sunday an upper ridge
will move through the forecast area and expect a mostly dry
period but then southwest flow aloft returns next week. Models
differ on shortwave details and associated precipitation
patterns. Due to these inconsistencies will go with generally a
chance of showers/thunderstorms over the mountains of the Rocky
Mountain Front with a slight chance of showers/thunderstorms
elsewhere. Cool air associated with the upper low will result in
highs on Saturday of only 55 to 65 except over north central
Montana where highs will be closer to 70. Thereafter expect
gradually warming temperatures. Blank
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 50 67 43 65 / 60 20 20 30
CTB 49 63 41 64 / 90 20 20 30
HLN 50 65 43 67 / 50 30 20 30
BZN 45 68 39 68 / 30 30 20 30
WEY 34 60 31 63 / 20 20 10 10
DLN 42 62 37 66 / 50 30 20 20
HVR 56 72 47 70 / 100 20 20 40
LWT 48 68 42 65 / 80 20 30 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
Areal Flood Warning for Small Streams, Creeks and Coulees until 130
PM MDT for Cascade...Chouteau...Judith Basin...Toole...Teton...
Glacier...Pondera...Lewis and Clark.
&&
$$
weather.gov/greatfalls
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000
FXUS65 KBYZ 200313
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
913 PM MDT WED JUN 19 2013
.UPDATE...
THUNDERSTORM ACTIVITY HAS SHIFTED TO OUR NORTH AND AS OF 03Z IS
LOCATED OVER MUSSELSHELL COUNTY AND SHIFTING SLOWLY EASTWARD ALONG
NOSE OF EASTERLY LOW LEVEL JET. SATELLITE IMAGERY SHOWS VERY
IMPRESSIVE DIFFLUENCE AS DYNAMIC SHORTWAVE LIFTS THRU SOUTH
CENTRAL MT. 700MB TEMPS ON THE ORDER OF 12-14C PROVIDING A VERY
STRONG CAP ACROSS OUR EAST TO THIS POINT...AND SURGE OF DRY WY
AIR ALREADY PREVENTED CONVECTION IN OUR SOUTH INCLUDING THE PRYORS
AND BIG HORNS. CONVECTION CURRENTLY APPROACHING NW ROSEBUD COUNTY
IS MOVING INTO THE CAPPED AIRMASS...BUT AS MID LEVEL TEMPS COOL
AND SFC FRONT PUSHES EAST...CONVECTIVE CHANCES WILL INCREASE
ACROSS OUR NORTH CENTRAL TO NORTHEAST PARTS AS THE NIGHT
PROGRESSES...AND CERTAINLY LOW LEVEL SHEAR/INSTABILITY ARE
FAVORABLE PER EAST WINDS AND DEW PTS IN THE UPPER 50S. WILL KEEP
WITH RISK OF TSTMS MENTIONED ACROSS OUR NORTH INCLUDING
FORSYTH...MILES CITY AND BAKER...THOUGH DO NOT THINK CONVECTION
WILL REACH AS FAR EAST AS FALLON COUNTY UNTIL AFTER 06Z...AND TSTM
COVERAGE WILL BE GREATER TO OUR NORTH. OTHERWISE... SUBSIDENCE
AND STRONG LOW LEVEL DOWNSLOPING ARE ALLOWING FOR WX TO QUIET DOWN
FROM LIVINGSTON TO BILLINGS AND SOUTHWARD. HAVE CLEANED OUT POPS
CONSIDERABLY IN THESE AREAS... AND THERE IS NO MORE RISK OF SEVERE
WX HERE. GUSTY POST FRONTAL W-NW WINDS WILL CONTINUE THROUGH THE
NIGHT AS PACIFIC AIRMASS SURGES INTO THE REGION. JKL
&&
.SHORT TERM...VALID FOR THU AND FRI...
POTENTIAL FOR SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING
WILL BE MORE WIDESPREAD THAN PREVIOUSLY THOUGHT AS DEWPOINTS WERE
IN THE 50S OVER MUCH OF THE AREA. SHEAR WILL INCREASE FROM W TO E
ACROSS THE AREA THIS AFTERNOON AND EVENING. DEWPOINTS IN THE 50S
WERE HELPING TO FEED HIGH CAPES...ESPECIALLY IN THE E. SURFACE
CAPES RANGED FROM 500 TO 2000 J/KG FROM W TO E ACROSS THE AREA AT
19Z. WILL HAVE PLENTY OF LIFT FROM DIFFLUENT FLOW ALOFT...COLD
FRONT MOVING THROUGH W MT...AND STRONG SHORTWAVE SEEN IN WATER
VAPOR IMAGERY...ROTATING AROUND THE BASE OF THE NEGATIVELY TILTED
TROUGH OVER THE PACIFIC NW. A SEVERE THREAT WILL PROGRESS FROM W
TO E ACROSS THE REGION THROUGH THE EVENING AS DYNAMICS MOVE E.
ONLY HINDRANCE TO SEVERE WEATHER WILL BE WHERE THE S TO SW FLOW
WILL ADVECT DRIER AIR INTO THE REGION. GUSTY WINDS WILL BE
POSSIBLE IN THESE AREAS...CURRENTLY EXPECTED FROM KBIL S AND
E...BUT WILL NEED TO WATCH THIS EVOLVING SITUATION CAREFULLY THIS
AFTERNOON. EXPECT SEVERE WEATHER TO EXIT THE AREA AFTER 06Z AS
COLD FRONT MOVES E. BUFKIT SOUNDINGS HAD A STRONG WIND SHIFT
BEHIND THE FRONT WITH WIND SPEEDS WELL INTO THE 30S.
UPPER LOW WILL ROTATE SLOWLY INTO THE REGION THU THROUGH FRI
NIGHT. DOWNSLOPE FLOW WILL COMPETE WITH UPPER DYNAMICS FOR
PRECIPITATION CHANCES ON THU. CONTINUED THE LOW CHANCES OVER AND
NEAR THE MOUNTAINS WITH JUST A SLIGHT MENTION OF THUNDER AS
AIRMASS WILL BE MUCH MORE STABLE THAN TODAY/S AIRMASS. A SECONDARY
COLD FRONT WILL PASS THROUGH THE AREA THU NIGHT WHICH WILL BRING
SCATTERED SHOWERS TO THE AREA. MODELS DIFFERED ON PLACEMENT OF
PRECIPITATION FRI THROUGH FRI NIGHT. DYNAMICS ALOFT AND INVERTED
SURFACE TROUGH OVER THE E WILL BRING A CHANCE OF SHOWERS AND
THUNDERSTORMS TO THE AREA. LEANED ON THE SREF FOR POP FORECAST.
TEMPERATURES WILL BE AROUND SEASONABLE VALUES THU AND FRI. ARTHUR
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
EXTENDED MODELS IN FAIRLY GOOD AGREEMENT SO DID NOT MAKE ANY
SIGNIFICANT CHANGES WITH THIS FORECAST ISSUANCE. LARGE UPPER LOW
CURRENTLY OVER THE PACIFIC NORTHWEST WILL SLOWLY SHIFT EAST ACROSS
THE CANADIAN BORDER SATURDAY AND SATURDAY NIGHT AND BE SITUATED
JUST NORTH OF NORTH DAKOTA DURING THE DAY SUNDAY. AT THE SAME
TIME...A FEW DISTURBANCES WILL GET PULLED NORTHEAST WITH A
SOUTHWEST FLOW ALOFT BRINGING VERY GOOD CHANCES FOR SHOWERS AND
THUNDERSTORMS TO THE ENTIRE FORECAST AREA SATURDAY AND SATURDAY
NIGHT. BEST CHANCES WILL BE NEAR THE DAKOTA BORDERS WHERE CHANCES
HAVE BEEN INCREASED TO LIKELY SATURDAY INTO SATURDAY NIGHT. THE
UPPER LOW SHIFTS FURTHER EAST SUNDAY LEAVING OUR FORECAST AREA IN
A BROAD SOUTHWEST FLOW ALOFT. AT THIS TIME...NO BIG DISTURBANCES
LOOK TO INFLUENCE OUR AREA RESULTING IN MAINLY DRY CONDITIONS WITH
POSSIBLY AN ISOLATED SHOWER/THUNDERSTORM THROUGH THE PERIOD.
TEMPERATURES WILL BE AT OR SLIGHTLY BELOW NORMAL FOR THE WEEKEND
BEFORE WARMING TO ABOVE NORMAL READINGS BY EARLY TO MID NEXT WEEK.
HOOLEY
&&
.AVIATION...
THUNDERSTORM ACTIVITY HAS ENDED AT KLVM AND KBIL...BUT COULD SEE
ISOLD ACTIVITY REACH KMLS AND KBHK LATER TONIGHT. BRIEF MVFR TO
IFR CAN BE EXPECTED IN THE THUNDERSTORMS. OTHERWISE VFR WILL
PREVAIL WITH GUSTY W-NW WINDS ACROSS THE LOWER ELEVATIONS BEHIND A
PACIFIC COLD FRONT. THESE WINDS WILL CONTINUE INTO THURSDAY...WITH
A WEAKENING TREND THROUGH THE AFTERNOON. JKL
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 051/077 052/073 052/069 051/078 054/082 058/082 059/082
11/U 33/T 34/T 41/B 11/B 22/T 21/U
LVM 042/070 041/072 042/067 046/079 046/082 051/081 054/085
23/T 34/T 35/T 40/B 22/T 22/T 21/U
HDN 051/078 052/074 050/072 050/078 052/082 054/083 058/083
10/U 33/T 24/T 41/B 11/B 22/T 21/U
MLS 058/078 055/077 056/076 055/080 056/083 059/083 061/085
20/U 34/T 34/T 42/T 11/B 22/T 21/B
4BQ 055/080 055/076 054/075 053/079 054/084 057/084 059/086
10/U 34/T 46/T 42/T 11/B 22/T 21/U
BHK 059/077 054/078 055/074 054/076 054/084 059/082 062/085
30/U 25/T 56/T 42/T 22/T 22/T 21/U
SHR 048/078 048/075 048/073 047/076 049/081 052/082 053/084
01/U 24/T 34/T 41/B 11/B 22/T 21/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
[top]
000
FXUS65 KGGW 200153
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
753 PM MDT WED JUN 19 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY...
UPDATE...CENTRAL MONTANA CONVECTION CONTINUES TO MOVE NORTH...SOME
CELLS HAVE STARTED IN PETROLEUM COUNTY THIS EVENING. WATER VAPOR
IS SHOWING DIFULENT FLOW ALOFT WITH A WAVE MOVING INTO THE REGION
FROM THE SOUTH. THE HRRR IS DOING OK TONIGHT AND SUPPORTS CURRENT
THINKING AND NATIONAL CENTER THINKING THAT A COMPLEX OF
THUNDERSTORMS IS MOST LIKELY FOR NORTHEAST MONTANA FOR THE LATE
EVENING HOURS INTO THE EARLY OVERNIGHT HOURS. THE LEADING EDGE OF
THIS COULD PRODUCE VERY GUSTY WINDS...AND THEN RAIN HEAVY AT
TIMES. THIS CONTINUES TO SUPPORT THE PHILLIPS COUNTY FLASH FLOOD
WATCH AND ZONE WORDING. DID TWEAK ELEMENTS AROUND TO BEST FIT THE
CURRENT SITUATION. PROTON
A CLOSED UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE PACIFIC
NORTHWEST. SHORTWAVE ENERGY PIVOTING AROUND THIS CLOSED LOW IS
PROPAGATING THROUGH SOUTHWEST FLOW ALOFT AND WILL BE RESPONSIBLE
FOR THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS THIS EVENING.
PLENTY OF CAPE EXISTS BUT WIND SHEAR PROFILES ARE NOT ALL THAT
IMPRESSIVE. THERE IS GOOD DIRECTIONAL SHEAR BUT SPEED SHEAR IS
LACKING. GIVEN CAPE/SHEAR PROFILES...WILL EXPECT DEVELOPING
SUPERCELLS TO FORM INTO LINE SEGMENTS THIS EVENING AS THEY PUSH
FROM THE SOUTHWESTERN ZONES THIS EVENING NORTHEASTWARD THROUGH THE
OVERNIGHT. TEMPERATURES THIS AFTERNOON HAVE BEEN WELL INTO THE
80S...SURFACE DEW POINTS HAVE BEEN HOVERING AROUND 60
DEGREES...AND SO THERE IS PLENTY OF WARM...MOIST...LOW LEVEL AIR.
STEEP MIDLEVEL LAPSE RATES ARE ALSO EVIDENT IN NAM BUFKIT
SOUNDINGS.
CONSIDERING ALL OF THIS...A FEW STORMS MAY BECOME SEVERE WITH
LARGE HAIL AND DAMAGING WINDS. HOWEVER...THE PRIMARY THREAT AT
THIS POINT WILL BE THE HEAVY RAINFALL. NAM BUFKIT SOUNDINGS SHOW
PRECIPITABLE WATER VALUES BETWEEN AN INCH AND AN INCH AND A HALF.
THE LATEST NAM/GFS/ECMWF SHOWS THE POTENTIAL FOR HEAVY RAINFALL
ACROSS THE CWA...WITH THE BEST AGREEMENT IN PHILLIPS AND NORTHERN
VALLEY COUNTIES. THIS IS FURTHER SUPPORTED BY THE SREF. THE HRRR
MODEL HAS ALSO BEEN INSISTING ON DEVELOPING CONVECTION AROUND 00Z
IN THE SOUTHWEST AND HAVING IT FORM INTO A LINE AS IT PUSHES
NORTHEAST OVERNIGHT. THEREFORE...SOME OF THE FAR NORTHEASTERN
ZONES MAY ACTUALLY STAY DRY UNTIL MORNING. GIVEN POTENTIAL FOR
EXCESSIVE RAINFALL RATES TO OCCUR OVER A SHORT DURATION...WILL
HOIST A FLASH FLOOD WATCH FOR PHILLIPS COUNTY. WILL OPT TO LEAVE
OUT NORTHERN VALLEY AT THIS POINT BECAUSE BEST AGREEMENT IS ON
RAINFALL FURTHER WEST BUT THE NEXT SHIFT WILL HAVE TO MONITOR
CLOSELY. A LAKE WIND ADVISORY REMAINS IN EFFECT UNTIL MIDNIGHT AND
GIVEN WINDS ALONG FORT PECK LAKE RECENTLY GUSTING ABOVE 40
MPH...THIS HEADLINE LOOKS GOOD.
SHOWERS AND THUNDERSTORMS MAY LINGER IN THE NORTHEASTERN ZONES ON
THURSDAY. OTHERWISE BEHIND THE COLD FRONTAL PASSAGE EXPECT MUCH
COOLER TEMPERATURES FOR AFTERNOON HIGHS. THE UPPER LOW ACROSS THE
PACIFIC NORTHWEST WILL REMAIN FIRMLY IN PLACE THROUGH FRIDAY
THOUGH AS ADDITIONAL SHORTWAVE ENERGY PUSHES INTO THE FORECAST
REGION. THUS...AFTER A BREAK IN BETWEEN SYSTEMS ON THURSDAY
NIGHT...INCREASED POPS AGAIN ON FRIDAY WITH THE NEXT APPROACHING
SHORTWAVE FEATURE. MALIAWCO
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
GOING FORECAST IN GOOD SHAPE BUT DID TWEAK UP THE POPS/WEATHER FOR
LATE SATURDAY INTO EARLY SUNDAY AS SHOWERS SEEM TO BE A PRETTY GOOD
BET WITH THE UPPER LOW IN PROXIMITY. JAMBA
PREVIOUS DISCUSSION...
LONG TERM FORECAST PERIOD BEGINS AS THE MAIN ENERGY FROM THE
MEANDERING LOW PRESSURE SYSTEM OVER THE PACIFIC NORTHWEST AND
NORTHERN ROCKIES REGIONS FINALLY KICKS OUT THROUGH THE EASTERN
SLOPES OF THE ROCKY MOUNTAINS AND THEN THE NORTHERN HIGH PLAINS
THROUGH THE REMAINDER OF THE WEEKEND.
EXPECT THIS WEEKEND TO BE FAIRLY WET WITH A LITTLE UNCERTAINTY
REGARDING PRECIPITATION AMOUNTS AS THE 00Z RUN OF THE EC HAS YET
TO COME IN. SOME COMPARISONS SHOW SIGNIFICANT DISCREPANCIES TO THE
POINT OF BEING EXACT OPPOSITES. WOULD HAVE TO GIVE IT LESS THAN
AVERAGE FORECAST CONFIDENCE AT BEST. TRIED TO INCREASE POPS IN A
BROAD-BRUSHED AND BLENDED KIND OF WAY WHERE BEST MODEL AGREEMENT
IF ANY WAS TO BE FOUND...THEN REDUCED POPS SIMILARLY WHERE MODELS
AGREED IN THE LACK THEREOF.
THERE SEEMS TO BE A BRIEF SHORT WAVE RIDGE FROM SUNDAY THROUGH
MONDAY MORNING WHICH SHOULD BRING AN END TO THE WET PERIOD FROM
THE WEEKEND.
NORTHEAST MONTANA THEN FINDS ITSELF IN A PERSISTENT ZONAL OR
SLIGHTLY SOUTHWESTERN FLOW ALOFT WITH SOME SMALL SCALE EMBEDDED
DISTURBANCES. ALTHOUGH THE MODELS ARE TRENDING A BIT DRIER TOWARD
THE END OF THE FORECAST PERIOD AS THE GULF OF ALASKA LOW BATTLES
AGAINST THE FOUR CORNERS HIGH. BMICKELSON
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED BUT MVFR CONDITIONS ARE POSSIBLE
STARTING AT GLASGOW THIS EVENING. EVENING SHOWERS AND
THUNDERSTORMS WILL CONTINUE OVERNIGHT...MOST OF THEM ARE EXPECTED
TO IMPACT LOCATIONS ALONG AND NORTH OF HIGHWAY 2 WITH HEAVY RAIN
POSSIBILITIES.
SOUTHEAST WINDS WILL DECREASE TONIGHT AS A COLD FRONT ARRIVES FROM
THE WEST/SOUTHWEST. EXPECT WEST WINDS ON THURSDAY AT ABOUT 10 TO
20 KTS. JAMBA
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 6 AM MDT THURSDAY FOR CENTRAL AND
SOUTHEAST PHILLIPS...NORTHERN PHILLIPS...SOUTHWEST PHILLIPS.
LAKE WIND ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR FORT PECK LAKE
FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 200035
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
635 PM MDT Wed Jun 19 2013
.UPDATE...Strong thunderstorms continue to move across central
Montana but a surface front pushing through southwest Montana is
bringing stable air into the region. Strong and gusty winds have
been reported behind the front and have issued a high wind warning
for Norris Hill in Madison County. As the front continues to push
through the state the strongest storms will move out of my
forecast area. Additional updates are anticipated through the
evening. mpj
&&
.AVIATION...
Updated 2350Z.
Strong to severe thunderstorms will continue to move through
central and north central Montana this evening. A strong surface
cold front has already pushed through portions of southwest
Montana and will continue to move east overnight. Behind the front
a more stable airmass with gusty west winds will move into the
forecast area. VFR conditions should prevail through the period
except for local IFR/MVFR conditions in and around the strongest
storms. Mountain obscurations are expected as well. mpj
&&
.PREV DISCUSSION...
/ISSUED 305 PM MDT Wed Jun 19 2013/
Rest of this afternoon through tonight...A fairly vigorous upper
level low centered over the inland Pacific NW this afternoon will
track slowly east into the Northern Rockies tonight, producing
favorable conditions for severe thunderstorm development across much
of the forecast area late this afternoon through this evening.
Diffluent southerly flow ahead of the upper low and an upper level
jet rounding the base of the trough will support large scale lift
while cooling in the mid levels will produce moderate instability.
Thunderstorms have already initiated over the higher terrain in
Beaverhead County as well as the Absorka range in south central MT
with latest visible satellite imagery also indicating convective
cloud development over the Little Belts. Expect this activity to
increase and coverage while tracking north this afternoon with storm
intensification/organization occurring late this afternoon and
evening as it progresses north into the relatively rich moisture
environment over the north central MT plains. Large hail and strong
gusty winds will be the main threat as storms organize late this
afternoon with a transition to more linear organization as the
storms continue northward toward the Canadian border late tonight.
Low level helicity fields would marginally support an isolated
tornado threat if cells can interact with a weak boundary across
north central MT. Threat for severe storms will diminish from south
to north later this evening with rain and high elevation snow
showers continuing through the night in the Glacier Park area where
snow levels will fall to around 7000 feet late tonight as the cold
pool aloft associated with the upper low moves in from the west.
Hoenisch
Winds will likely approach high wind criteria along the Rocky
Mountain Front on Thursday, but am not anticipating a need for
high wind highlights at this time. The Pacific low pressure system
will linger through the day on Friday, keeping a chance of showers
and (likely weak) afternoon/evening thunderstorms over the area,
as temperatures remain about 10 degrees cooler than normal.
Coulston
Friday night through Wednesday...An upper low over the Pacific
Northwest early Friday evening is forecast to weaken as it moves
over the forecast area on Saturday. Models are fairly wet over
southwest and north central Montana on Saturday so have increased
the chances of precipitation especially over north central
Montana. The remnants of the upper low move out by late Saturday
night and by early Sunday morning it appears the only threat for
precipitation will be over north central Montana and possibly the
mountains of the Rocky Mountain Front. On Sunday an upper ridge
will move through the forecast area and expect a mostly dry
period but then southwest flow aloft returns next week. Models
differ on shortwave details and associated precipitation
patterns. Due to these inconsistencies will go with generally a
chance of showers/thunderstorms over the mountains of the Rocky
Mountain Front with a slight chance of showers/thunderstorms
elsewhere. Cool air associated with the upper low will result in
highs on Saturday of only 55 to 65 except over north central
Montana where highs will be closer to 70. Thereafter expect
gradually warming temperatures. Blank
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 50 67 43 65 / 60 20 20 30
CTB 49 63 41 64 / 90 20 20 30
HLN 50 65 43 67 / 50 30 20 30
BZN 45 68 39 68 / 30 30 20 30
WEY 34 60 31 63 / 20 20 10 10
DLN 42 62 37 66 / 50 30 20 20
HVR 56 72 47 70 / 100 20 20 40
LWT 48 68 42 65 / 80 20 30 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
SEVERE THUNDERSTORM WATCH until 10 PM MDT this evening Blaine...
Broadwater...Cascade...Central and Southern Lewis and Clark...
Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...
Fergus...Hill...Jefferson...Judith Basin...Liberty...Meagher...
Northern Rocky Mountain Front...Southern Rocky Mountain Front...
Toole.
FLASH FLOOD WATCH until Midnight MDT tonight Blaine...Cascade...
Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...
Fergus...Hill...Judith Basin...Liberty...Northern Rocky Mountain
Front...Southern Rocky Mountain Front...Toole.
HIGH WIND WARNING until 11 PM MDT this evening For Route 287
over Norris Hill in Madison County.
&&
$$
weather.gov/greatfalls
000
FXUS65 KBYZ 192109
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
309 PM MDT WED JUN 19 2013
.SHORT TERM...VALID FOR THU AND FRI...
POTENTIAL FOR SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING
WILL BE MORE WIDESPREAD THAN PREVIOUSLY THOUGHT AS DEWPOINTS WERE
IN THE 50S OVER MUCH OF THE AREA. SHEAR WILL INCREASE FROM W TO E
ACROSS THE AREA THIS AFTERNOON AND EVENING. DEWPOINTS IN THE 50S
WERE HELPING TO FEED HIGH CAPES...ESPECIALLY IN THE E. SURFACE
CAPES RANGED FROM 500 TO 2000 J/KG FROM W TO E ACROSS THE AREA AT
19Z. WILL HAVE PLENTY OF LIFT FROM DIFLUENT FLOW ALOFT...COLD
FRONT MOVING THROUGH W MT...AND STRONG SHORTWAVE SEEN IN WATER
VAPOR IMAGERY...ROTATING AROUND THE BASE OF THE NEGATIVELY TILTED
TROUGH OVER THE PACIFIC NW. A SEVERE THREAT WILL PROGRESS FROM W
TO E ACROSS THE REGION THROUGH THE EVENING AS DYNAMICS MOVE E.
ONLY HINDRANCE TO SEVERE WEATHER WILL BE WHERE THE S TO SW FLOW
WILL ADVECT DRIER AIR INTO THE REGION. GUSTY WINDS WILL BE
POSSIBLE IN THESE AREAS...CURRENTLY EXPECTED FROM KBIL S AND
E...BUT WILL NEED TO WATCH THIS EVOLVING SITUATION CAREFULLY THIS
AFTERNOON. EXPECT SEVERE WEATHER TO EXIT THE AREA AFTER 06Z AS
COLD FRONT MOVES E. BUFKIT SOUNDINGS HAD A STRONG WIND SHIFT
BEHIND THE FRONT WITH WIND SPEEDS WELL INTO THE 30S.
UPPER LOW WILL ROTATE SLOWLY INTO THE REGION THU THROUGH FRI
NIGHT. DOWNSLOPE FLOW WILL COMPETE WITH UPPER DYNAMICS FOR
PRECIPITATION CHANCES ON THU. CONTINUED THE LOW CHANCES OVER AND
NEAR THE MOUNTAINS WITH JUST A SLIGHT MENTION OF THUNDER AS
AIRMASS WILL BE MUCH MORE STABLE THAN TODAY/S AIRMASS. A SECONDARY
COLD FRONT WILL PASS THROUGH THE AREA THU NIGHT WHICH WILL BRING
SCATTERED SHOWERS TO THE AREA. MODELS DIFFERED ON PLACEMENT OF
PRECIPITATION FRI THROUGH FRI NIGHT. DYNAMICS ALOFT AND INVERTED
SURFACE TROUGH OVER THE E WILL BRING A CHANCE OF SHOWERS AND
THUNDERSTORMS TO THE AREA. LEANED ON THE SREF FOR POP FORECAST.
TEMPERATURES WILL BE AROUND SEASONABLE VALUES THU AND FRI. ARTHUR
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
EXTENDED MODELS IN FAIRLY GOOD AGREEMENT SO DID NOT MAKE ANY
SIGNIFICANT CHANGES WITH THIS FORECAST ISSUANCE. LARGE UPPER LOW
CURRENTLY OVER THE PACIFIC NORTHWEST WILL SLOWLY SHIFT EAST ACROSS
THE CANADIAN BORDER SATURDAY AND SATURDAY NIGHT AND BE SITUATED
JUST NORTH OF NORTH DAKOTA DURING THE DAY SUNDAY. AT THE SAME
TIME...A FEW DISTURBANCES WILL GET PULLED NORTHEAST WITH A
SOUTHWEST FLOW ALOFT BRINGING VERY GOOD CHANCES FOR SHOWERS AND
THUNDERSTORMS TO THE ENTIRE FORECAST AREA SATURDAY AND SATURDAY
NIGHT. BEST CHANCES WILL BE NEAR THE DAKOTA BORDERS WHERE CHANCES
HAVE BEEN INCREASED TO LIKELY SATURDAY INTO SATURDAY NIGHT. THE
UPPER LOW SHIFTS FURTHER EAST SUNDAY LEAVING OUR FORECAST AREA IN
A BROAD SOUTHWEST FLOW ALOFT. AT THIS TIME...NO BIG DISTURBANCES
LOOK TO INFLUENCE OUR AREA RESULTING IN MAINLY DRY CONDITIONS WITH
POSSIBLY AN ISOLATED SHOWER/THUNDERSTORM THROUGH THE PERIOD.
TEMPERATURES WILL BE AT OR SLIGHTLY BELOW NORMAL FOR THE WEEKEND
BEFORE WARMING TO ABOVE NORMAL READINGS BY EARLY TO MID NEXT WEEK.
HOOLEY
&&
.AVIATION...
SCATTERED THUNDERSTORMS WILL DEVELOP ALONG AND WEST OF A KSHR-
KBIL LINE THIS AFTERNOON CONTINUING INTO THE EVENING HOURS. SOME
THUNDERSTORMS MAY BE SEVERE WITH LARGE HAIL AND WIND GUSTS AROUND
55KTS. ELSEWHERE...SKIES WILL REMAIN MOSTLY CLEAR. VFR CONDITIONS
WILL PREVAIL BUT EXPECT IFR TO LIFR CONDITIONS IN AND NEAR
THUNDERSTORM ACTIVITY. A COLD FRONT WILL MOVE ACROSS THE FORECAST
AREA THIS EVENING INTO THE OVERNIGHT HOURS BRINGING GUSTY WESTERLY
WINDS. HOOLEY
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 051/077 052/073 052/069 051/078 054/082 058/082 059/082
31/U 33/T 34/T 41/B 11/B 22/T 21/U
LVM 042/070 041/072 042/067 046/079 046/082 051/081 054/085
33/T 34/T 35/T 40/B 22/T 22/T 21/U
HDN 051/078 052/074 050/072 050/078 052/082 054/083 058/083
20/U 33/T 24/T 41/B 11/B 22/T 21/U
MLS 058/078 055/077 056/076 055/080 056/083 059/083 061/085
20/U 34/T 34/T 42/T 11/B 22/T 21/B
4BQ 055/080 055/076 054/075 053/079 054/084 057/084 059/086
20/U 34/T 46/T 42/T 11/B 22/T 21/U
BHK 059/077 054/078 055/074 054/076 054/084 059/082 062/085
30/U 25/T 56/T 42/T 22/T 22/T 21/U
SHR 048/078 048/075 048/073 047/076 049/081 052/082 053/084
21/U 24/T 34/T 41/B 11/B 22/T 21/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 192105
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
305 PM MDT Wed Jun 19 2013
...SEVERE THUNDERSTORMS LIKELY THIS AFTERNOON AND EVENING...
.DISCUSSION...
Rest of this afternoon through tonight...A fairly vigorous upper
level low centered over the inland Pacific NW this afternoon will
track slowly east into the Northern Rockies tonight, producing
favorable conditions for severe thunderstorm development across much
of the forecast area late this afternoon through this evening.
Diffluent southerly flow ahead of the upper low and an upper level
jet rounding the base of the trough will support large scale lift
while cooling in the mid levels will produce moderate instability.
Thunderstorms have already initiated over the higher terrain in
Beaverhead County as well as the Absorka range in south central MT
with latest visible satellite imagery also indicating convective
cloud development over the Little Belts. Expect this activity to
increase and coverage while tracking north this afternoon with storm
intensification/organization occurring late this afternoon and
evening as it progresses north into the relatively rich moisture
environment over the north central MT plains. Large hail and strong
gusty winds will be the main threat as storms organize late this
afternoon with a transition to more linear organization as the
storms continue northward toward the Canadian border late tonight.
Low level helicity fields would marginally support an isolated
tornado threat if cells can interact with a weak boundary across
north central MT. Threat for severe storms will diminish from south
to north later this evening with rain and high elevation snow
showers continuing through the night in the Glacier Park area where
snow levels will fall to around 7000 feet late tonight as the cold
pool aloft associated with the upper low moves in from the west.
Hoenisch
Winds will likely approach high wind criteria along the Rocky
Mountain Front on Thursday, but am not anticipating a need for
high wind highlights at this time. The Pacific low pressure system
will linger through the day on Friday, keeping a chance of showers
and (likely weak) afternoon/evening thunderstorms over the area,
as temperatures remain about 10 degrees cooler than normal.
Coulston
Friday night through Wednesday...An upper low over the Pacific
Northwest early Friday evening is forecast to weaken as it moves
over the forecast area on Saturday. Models are fairly wet over
southwest and north central Montana on Saturday so have increased
the chances of precipitation especially over north central
Montana. The remnants of the upper low move out by late Saturday
night and by early Sunday morning it appears the only threat for
precipitation will be over north central Montana and possibly the
mountains of the Rocky Mountain Front. On Sunday an upper ridge
will move through the forecast area and expect a mostly dry
period but then southwest flow aloft returns next week. Models
differ on shortwave details and associated precipitation
patterns. Due to these inconsistencies will go with generally a
chance of showers/thunderstorms over the mountains of the Rocky
Mountain Front with a slight chance of showers/thunderstorms
elsewhere. Cool air associated with the upper low will result in
highs on Saturday of only 55 to 65 except over north central
Montana where highs will be closer to 70. Thereafter expect
gradually warming temperatures. Blank
&&
.AVIATION...
Updated 1755Z.
There strong possibility for severe thunderstorms with hail in
excess of one inch in diameter and wind gusts in excess of 50 knots
over Central and North Central Montana...especially in the vicinity
of KHVR...LWT...and to a lesser degree KGTF. Also some of the
thunderstorms will have brief heavy rain with IFR ceilings and
visibilities. Expect thunderstorms to develop over southwest Montana
by mid-afternoon then intensify as they move over the plains. Suk
&&
.HYDROLOGY...
Showers and thunderstorms are expected to develop once again this
afternoon over the Rocky Mountain Front and the adjacent plains
along a surface cold front. These showers and thunderstorms are
then expected to spread east across the plains of north central
and central Montana later this afternoon and continue into this
evening. Forecast models are predicting significant rainfall with
these showers, which is expected to occur in rapid bursts with the
thunderstorms. Some localized flash flooding occurred with storms
along the Rocky Mountain Front Tuesday evening. However, the
greater area of concern is across eastern portions of north
central and central Montana that still have moist soil that would
not be able to absorb much rapid rainfall. Forecast models also
indicate that this area will receive the greatest amount of
rainfall. Taking these factors into consideration, have decided to
issue a Flash Flood Watch from noon MDT today until midnight MDT
tonight for all of north central and central Montana. The greatest
threat for flash flooding for the Rocky Mountain Front and
adjacent plains will be this afternoon, while the greatest threat
in the east will likely be after 5 pm MDT.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 50 67 43 65 / 60 20 20 30
CTB 49 63 41 64 / 90 20 20 30
HLN 50 65 43 67 / 50 30 20 30
BZN 45 68 39 68 / 30 30 20 30
WEY 34 60 31 63 / 20 20 10 10
DLN 42 62 37 66 / 50 30 20 20
HVR 56 72 47 70 / 100 20 20 40
LWT 48 68 42 65 / 80 20 30 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH until Midnight MDT tonight Blaine...Cascade...
Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...
Fergus...Hill...Judith Basin...Liberty...Northern Rocky Mountain
Front...Southern Rocky Mountain Front...Toole.
SEVERE THUNDERSTORM WATCH until 10 PM MDT this evening Blaine...
Broadwater...Cascade...Central and Southern Lewis and Clark...
Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...
Fergus...Hill...Jefferson...Judith Basin...Liberty...Meagher...
Northern Rocky Mountain Front...Southern Rocky Mountain Front...
Toole.
&&
$$
SHORT TERM...
LONG TERM...
AVIATION...
weather.gov/greatfalls
000
FXUS65 KGGW 192102
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
302 PM MDT WED JUN 19 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY...
A CLOSED UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE PACIFIC
NORTHWEST. SHORTWAVE ENERGY PIVOTING AROUND THIS CLOSED LOW IS
PROPAGATING THROUGH SOUTHWEST FLOW ALOFT AND WILL BE RESPONSIBLE
FOR THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS THIS EVENING.
PLENTY OF CAPE EXISTS BUT WIND SHEAR PROFILES ARE NOT ALL THAT
IMPRESSIVE. THERE IS GOOD DIRECTIONAL SHEAR BUT SPEED SHEAR IS
LACKING. GIVEN CAPE/SHEAR PROFILES...WILL EXPECT DEVELOPING
SUPERCELLS TO FORM INTO LINE SEGMENTS THIS EVENING AS THEY PUSH
FROM THE SOUTHWESTERN ZONES THIS EVENING NORTHEASTWARD THROUGH THE
OVERNIGHT. TEMPERATURES THIS AFTERNOON HAVE BEEN WELL INTO THE
80S...SURFACE DEW POINTS HAVE BEEN HOVERING AROUND 60
DEGREES...AND SO THERE IS PLENTY OF WARM...MOIST...LOW LEVEL AIR.
STEEP MIDLEVEL LAPSE RATES ARE ALSO EVIDENT IN NAM BUFKIT
SOUNDINGS.
CONSIDERING ALL OF THIS...A FEW STORMS MAY BECOME SEVERE WITH
LARGE HAIL AND DAMAGING WINDS. HOWEVER...THE PRIMARY THREAT AT
THIS POINT WILL BE THE HEAVY RAINFALL. NAM BUFKIT SOUNDINGS SHOW
PRECIPITABLE WATER VALUES BETWEEN AN INCH AND AN INCH AND A HALF.
THE LATEST NAM/GFS/ECMWF SHOWS THE POTENTIAL FOR HEAVY RAINFALL
ACROSS THE CWA...WITH THE BEST AGREEMENT IN PHILLIPS AND NORTHERN
VALLEY COUNTIES. THIS IS FURTHER SUPPORTED BY THE SREF. THE HRRR
MODEL HAS ALSO BEEN INSISTING ON DEVELOPING CONVECTION AROUND 00Z
IN THE SOUTHWEST AND HAVING IT FORM INTO A LINE AS IT PUSHES
NORTHEAST OVERNIGHT. THEREFORE...SOME OF THE FAR NORTHEASTERN
ZONES MAY ACTUALLY STAY DRY UNTIL MORNING. GIVEN POTENTIAL FOR
EXCESSIVE RAINFALL RATES TO OCCUR OVER A SHORT DURATION...WILL
HOIST A FLASH FLOOD WATCH FOR PHILLIPS COUNTY. WILL OPT TO LEAVE
OUT NORTHERN VALLEY AT THIS POINT BECAUSE BEST AGREEMENT IS ON
RAINFALL FURTHER WEST BUT THE NEXT SHIFT WILL HAVE TO MONITOR
CLOSELY. A LAKE WIND ADVISORY REMAINS IN EFFECT UNTIL MIDNIGHT AND
GIVEN WINDS ALONG FORT PECK LAKE RECENTLY GUSTING ABOVE 40
MPH...THIS HEADLINE LOOKS GOOD.
SHOWERS AND THUNDERSTORMS MAY LINGER IN THE NORTHEASTERN ZONES ON
THURSDAY. OTHERWISE BEHIND THE COLD FRONTAL PASSAGE EXPECT MUCH
COOLER TEMPERATURES FOR AFTERNOON HIGHS. THE UPPER LOW ACROSS THE
PACIFIC NORTHWEST WILL REMAIN FIRMLY IN PLACE THROUGH FRIDAY
THOUGH AS ADDITIONAL SHORTWAVE ENERGY PUSHES INTO THE FORECAST
REGION. THUS...AFTER A BREAK IN BETWEEN SYSTEMS ON THURSDAY
NIGHT...INCREASED POPS AGAIN ON FRIDAY WITH THE NEXT APPROACHING
SHORTWAVE FEATURE. MALIAWCO
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
GOING FORECAST IN GOOD SHAPE BUT DID TWEAK UP THE POPS/WEATHER FOR
LATE SATURDAY INTO EARLY SUNDAY AS SHOWERS SEEM TO BE A PRETTY GOOD
BET WITH THE UPPER LOW IN PROXIMITY. JAMBA
PREVIOUS DISCUSSION...
LONG TERM FORECAST PERIOD BEGINS AS THE MAIN ENERGY FROM THE
MEANDERING LOW PRESSURE SYSTEM OVER THE PACIFIC NORTHWEST AND
NORTHERN ROCKIES REGIONS FINALLY KICKS OUT THROUGH THE EASTERN
SLOPES OF THE ROCKY MOUNTAINS AND THEN THE NORTHERN HIGH PLAINS
THROUGH THE REMAINDER OF THE WEEKEND.
EXPECT THIS WEEKEND TO BE FAIRLY WET WITH A LITTLE UNCERTAINTY
REGARDING PRECIPITATION AMOUNTS AS THE 00Z RUN OF THE EC HAS YET
TO COME IN. SOME COMPARISONS SHOW SIGNIFICANT DISCREPANCIES TO THE
POINT OF BEING EXACT OPPOSITES. WOULD HAVE TO GIVE IT LESS THAN
AVERAGE FORECAST CONFIDENCE AT BEST. TRIED TO INCREASE POPS IN A
BROAD-BRUSHED AND BLENDED KIND OF WAY WHERE BEST MODEL AGREEMENT
IF ANY WAS TO BE FOUND...THEN REDUCED POPS SIMILARLY WHERE MODELS
AGREED IN THE LACK THEREOF.
THERE SEEMS TO BE A BRIEF SHORT WAVE RIDGE FROM SUNDAY THROUGH
MONDAY MORNING WHICH SHOULD BRING AN END TO THE WET PERIOD FROM
THE WEEKEND.
NORTHEAST MONTANA THEN FINDS ITSELF IN A PERSISTENT ZONAL OR
SLIGHTLY SOUTHWESTERN FLOW ALOFT WITH SOME SMALL SCALE EMBEDDED
DISTURBANCES. ALTHOUGH THE MODELS ARE TRENDING A BIT DRIER TOWARD
THE END OF THE FORECAST PERIOD AS THE GULF OF ALASKA LOW BATTLES
AGAINST THE FOUR CORNERS HIGH. BMICKELSON
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED BUT MVFR CONDITIONS ARE POSSIBLE
STARTING AT GLASGOW THIS EVENING. EVENING SHOWERS AND
THUNDERSTORMS WILL CONTINUE OVERNIGHT...MOST OF THEM ARE EXPECTED
TO IMPACT LOCATIONS ALONG AND NORTH OF HIGHWAY 2 WITH HEAVY RAIN
POSSIBILITIES.
SOUTHEAST WINDS WILL DECREASE TONIGHT AS A COLD FRONT ARRIVES FROM
THE WEST/SOUTHWEST. EXPECT WEST WINDS ON THURSDAY AT ABOUT 10 TO
20 KTS. JAMBA
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR CENTRAL AND SOUTHEAST
PHILLIPS...NORTHERN PHILLIPS...SOUTHWEST PHILLIPS.
LAKE WIND ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR FORT PECK LAKE
FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
[top]
000
FXUS65 KMSO 192044
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
244 PM MDT Wed Jun 19 2013
...SIGNIFICANT PRECIPITATION THROUGH THURSDAY MORNING...
...LIGHT SNOW ACCUMULATION ABOVE 6000 FEET TONIGHT...
.DISCUSSION...A low pressure system currently located in central
Washington and Oregon will continue to slowly move eastward into
western Montana and north central Idaho tonight. This feature has
abundant moisture and energy associated with it which will lead to
an active period for the next 24-36 hours. Below is a summary of
the main impacts:
Thunderstorms: General thunderstorms are expected this afternoon
and evening across western Montana. A few storms could briefly
become strong this afternoon, mainly across southwest Montana and
along the Continental Divide through Powell County. While the
stronger storms should be fairly isolated and short lived, a few
could produce gusty winds, small hail and very heavy rain.
Heavy rain: Moderate to heavy rain will continue this afternoon
and overnight. The heaviest amounts are expected through north
central Idaho up into northwest Montana. Some locations along the
Idaho/Montana border have already received up to an inch of rain
fall, with another 0.50-1.00 inch of rain possible by the end of
Thursday. Flooding is not expected to be an overall issue although
small streams and rivers will likely begin to rise. Additionally,
some ponding of water on the roadways and in urban areas is possible.
Snow: Snow levels are expected to drop by Thursday morning to
about 6000 feet. This will allow for some accumulating snow in the
higher terrain as well as high elevation passes, such as Lost
Trail. Those planning to be in the high backcountry should be
prepared for wet, raw weather conditions.
The upper level low pressure system will slowly move through
the region, continuing a wet and cool pattern through Saturday.
A brief break in precipitation is expected Saturday evening into
Sunday morning as a ridge of high pressure builds into the region.
This will be short lived however as the ridge quickly moves
eastward leaving western Montana and north central Idaho in a
moist southwest flow through mid week. Although temperatures will
warm back towards normal, showers and thunderstorms will continue
to be a possibility.
&&
.AVIATION...
A broad storm system will exist over the Northern Rockies during
the next 24 hours. Each of the four air terminals will experience
occasional vicinity thunderstorms through 20/0600Z, with only
rain showers present at times thereafter. Widespread rainfall will
exist for much of the next 24 hours for KGPI and KMSO, lowering
ceilings and visibilities at times. Terrain obscurations will be
commonplace during this time as well. KSMN and KBTM should
experience improved flying conditions after 20/0600Z.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
Kitsmiller/Zumpfe
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000
FXUS65 KTFX 191754
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1155 AM MDT Wed Jun 19 2013
...UPDATE TO AVIATION...
...STRONG TO POSSIBLY SEVERE THUNDERSTORMS THIS AFTERNOON INTO
THIS EVENING...
.UPDATE...
Satellite imagery this morning shows a fairly vigorous upper level
low centered over eastern OR, poised to track east into the
Northern Rockies tonight. As the upper low tracks east today, flow
aloft will increase from the south and southeast with surface low
development occurring over central MT late this afternoon and
evening. SE flow in the low levels will hold relatively high
dewpoint airmass at the surface over north central MT which will
lead to moderate instability late this afternoon and evening. only
question remaining with respect to Thunderstorm strength is the
impact of cloud cloud-cover currently over the central and western
MT. Latest satellite trends do show some of this cloud field
beginning to break up with with lesser cloud-cover upstream in S to
SE flow aloft which should allow for the necessary surface heating
for moderate instability to be realized. Expect initial storms to
develop after noon over the higher terrain of western and SW MT
with these storms moving north and intensifying/organizing late
this afternoon and evening as they encounter richer low level
moisture and more favorable shear. Large hail and damaging winds
still appear to be the main threat with storms this
afternoon/evening and cannot rule out a small (5%) threat for
Tornadoes as weak low level helicity values look to briefly reach
marginal levels across portions of north central MT. Current
gridded forecast covers the situation well with only minor updates
required this morning. Hoenisch
&&
.AVIATION...
Updated 1755Z.
There strong possibility for severe thunderstorms with hail in
excess of one inch in diameter and wind gusts in excess of 50 knots
over Central and North Central Montana...especially in the vicinity
of KHVR...LWT...and to a lesser degree KGTF. Also some of the
thunderstorms will have brief heavy rain with IFR ceilings and
visibilities. Expect thunderstorms to develop over southwest Montana
by mid-afternoon then intensify as they move over the plains. Suk
&&
.HYDROLOGY...
Showers and thunderstorms are expected to develop once again this
afternoon over the Rocky Mountain Front and the adjacent plains
along a surface cold front. These showers and thunderstorms are
then expected to spread east across the plains of north central
and central Montana later this afternoon and continue into this
evening. Forecast models are predicting significant rainfall with
these showers, which is expected to occur in rapid bursts with the
thunderstorms. Some localized flash flooding occurred with storms
along the Rocky Mountain Front Tuesday evening. However, the
greater area of concern is across eastern portions of north
central and central Montana that still have moist soil that would
not be able to absorb much rapid rainfall. Forecast models also
indicate that this area will receive the greatest amount of
rainfall. Taking these factors into consideration, have decided to
issue a Flash Flood Watch from noon MDT today until midnight MDT
tonight for all of north central and central Montana. The greatest
threat for flash flooding for the Rocky Mountain Front and
adjacent plains will be this afternoon, while the greatest threat
in the east will likely be after 5 pm MDT.
&&
.PREV DISCUSSION...
/ISSUED 555 AM MDT Wed Jun 19 2013/
Today through Friday...Thunderstorms from overnight have exited
the area, but another round of potentially severe weather is on
tap for today. The Pacific low pressure system that brought
thunderstorms to the western portion of the forecast area
yesterday will slowly move into the Pacific Northwest today. The
moist, unstable, and diffluent southerly flow ahead of the system
will combine with a strong embedded disturbance and the associated
cold front over the area for more widespread thunderstorm
development than yesterday. Therefore, the Storm Prediction Center
has all of north central/central Montana under a Slight Risk for
severe thunderstorms today. While some storms over the western
plains of north central/central Montana may see marginally severe
thunderstorms (wind gusts around 60 mph, hail around 1 inch in
diameter), the greater focus will be on the eastern plains.
Surface winds there will be breezy and out of the east ahead of
the cold front, which will advect moist air (dewpoints in the
upper 50s to lower 60s) into the area and enhance the instability.
The surface winds will also combine with the stronger winds aloft
to provide strong wind shear (with regard to both speed and
direction) to that area as well. The enhanced instability and
shear will focus the potential for significantly strong
thunderstorms (hail possibly 2+ inches in diameter, wind gusts in
excess of 70 mph) on the eastern TFX plains. Wind shear may even
be strong enough to possibly generate an isolated tornado.
However, all of these ingredients seem to come together later this
afternoon, which means that thunderstorm development there may not
occur until after 4 or 5 pm MDT, while storms farther west will
develop after 1 pm MDT. Forecast models are also indicating that
these storms may produce heavy rainfall, so have issued a Flash
Flood Watch for the area as well (please see Hydrology section for
details). While storms will generate over the higher terrain of
southwest Montana, the potential for severe storms there is low.
Overall, storms will exit the area to the east with the passage of
the cold front this evening. Westerly downslope winds will help
limit overnight precipitation to the western mountains. A much
cooler airmass will also move into the area, possibly bringing
light measurable snow to the mountain peaks. Winds will likely
approach high wind criteria along the Rocky Mountain Front on
Thursday, but am not anticipating a need for high wind highlights
at this time. The Pacific low pressure system will linger through
the day on Friday, keeping a chance of showers and (likely weak)
afternoon/evening thunderstorms over the area, as temperatures
remain about 10 degrees cooler than normal. Coulston
Friday night through Wednesday...An upper low over the Pacific
Northwest early Friday evening is forecast to weaken as it moves
over the forecast area on Saturday. Models are fairly wet over
southwest and north central Montana on Saturday so have increased
the chances of precipitation especially over north central
Montana. The remnants of the upper low move out by late Saturday
night and by early Sunday morning it appears the only threat for
precipitation will be over north central Montana and possibly the
mountains of the Rocky Mountain Front. On Sunday an upper ridge
will move through the forecast area and expect a mostly dry
period but then southwest flow aloft returns next week. Models
differ on shortwave details and associated precipitation
patterns. Due to these inconsistencies will go with generally a
chance of showers/thunderstorms over the mountains of the Rocky
Mountain Front with a slight chance of showers/thunderstorms
elsewhere. Cool air associated with the upper low will result in
highs on Saturday of only 55 to 65 except over north central
Montana where highs will be closer to 70. Thereafter expect
gradually warming temperatures. Blank
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 76 47 67 43 / 80 40 20 20
CTB 74 45 63 41 / 90 70 20 20
HLN 75 46 65 43 / 70 40 30 20
BZN 81 42 68 39 / 40 30 30 20
WEY 69 32 60 31 / 30 30 20 10
DLN 72 39 62 37 / 50 50 30 20
HVR 88 52 72 47 / 60 100 20 20
LWT 83 45 68 42 / 50 80 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH through this evening Blaine...Cascade...
Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...
Fergus...Hill...Judith Basin...Liberty...Northern Rocky Mountain
Front...Southern Rocky Mountain Front...Toole.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 191701
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1101 AM MDT Wed Jun 19 2013
...STRONG TO POSSIBLY SEVERE THUNDERSTORMS THIS AFTERNOON INTO
THIS EVENING...
.UPDATE...
Satellite imagery this morning shows a fairly vigorous upper level
low centered over eastern OR, poised to track east into the
Northern Rockies tonight. As the upper low tracks east today, flow
aloft will increase from the south and southeast with surface low
development occurring over central MT late this afternoon and
evening. SE flow in the low levels will hold relatively high
dewpoint airmass at the surface over north central MT which will
lead to moderate instability late this afternoon and evening. only
question remaining with respect to Thunderstorm strength is the
impact of cloud cloud-cover currently over the central and western
MT. Latest satellite trends do show some of this cloud field
begining to break up with with lesser cloud-cover upstream in S to
SE flow aloft which should allow for the necessary surface heating
for moderate instability to be realized. Expect initial storms to
develop after noon over the higher terrain of western and SW MT
with these storms moving north and intensifying/organizing late
this afternoon and evening as they encounter richer low level
moisture and more favorable shear. Large hail and damaging winds
still appear to be the main threat with storms this
afternoon/evening and cannot rule out a small (5%) threat for
Tornadoes as weak low level helicity values look to briefly reach
marginal levels across portions of north central MT. Current
gridded forecast covers the situation well with only minor updates
required this morning. Hoenisch
&&
.AVIATION...
Updated 1155Z.
The main message today will be the possibility for severe
thunderstorms with hail in excess of one inch in diameter and wind
gusts in excess of 50 knots. Also some of the thunderstorms will
have brief heavy rain with IFR ceilings and visibilities. Expect
thunderstorms to develop over southwest Montana by mid-afternoon
then intensify as they move over the plains. Feel fairly confident
of the timing mentioned in the tafs for the showers/thunderstorms.
One forecast parameter with little confidence is wind. Confidence is
especially low with forecast wind directions. Actually confidence in
wind directions increases tonight as the cold front moves through
and winds shift to the southwest. Blank
&&
.HYDROLOGY...
Showers and thunderstorms are expected to develop once again this
afternoon over the Rocky Mountain Front and the adjacent plains
along a surface cold front. These showers and thunderstorms are
then expected to spread east across the plains of north central
and central Montana later this afternoon and continue into this
evening. Forecast models are predicting significant rainfall with
these showers, which is expected to occur in rapid bursts with the
thunderstorms. Some localized flash flooding occurred with storms
along the Rocky Mountain Front Tuesday evening. However, the
greater area of concern is across eastern portions of north
central and central Montana that still have moist soil that would
not be able to absorb much rapid rainfall. Forecast models also
indicate that this area will receive the greatest amount of
rainfall. Taking these factors into consideration, have decided to
issue a Flash Flood Watch from noon MDT today until midnight MDT
tonight for all of north central and central Montana. The greatest
threat for flash flooding for the Rocky Mountain Front and
adjacent plains will be this afternoon, while the greatest threat
in the east will likely be after 5 pm MDT.
&&
.PREV DISCUSSION...
/ISSUED 555 AM MDT Wed Jun 19 2013/
Today through Friday...Thunderstorms from overnight have exited
the area, but another round of potentially severe weather is on
tap for today. The Pacific low pressure system that brought
thunderstorms to the western portion of the forecast area
yesterday will slowly move into the Pacific Northwest today. The
moist, unstable, and diffluent southerly flow ahead of the system
will combine with a strong embedded disturbance and the associated
cold front over the area for more widespread thunderstorm
development than yesterday. Therefore, the Storm Prediction Center
has all of north central/central Montana under a Slight Risk for
severe thunderstorms today. While some storms over the western
plains of north central/central Montana may see marginally severe
thunderstorms (wind gusts around 60 mph, hail around 1 inch in
diameter), the greater focus will be on the eastern plains.
Surface winds there will be breezy and out of the east ahead of
the cold front, which will advect moist air (dewpoints in the
upper 50s to lower 60s) into the area and enhance the instability.
The surface winds will also combine with the stronger winds aloft
to provide strong wind shear (with regard to both speed and
direction) to that area as well. The enhanced instability and
shear will focus the potential for significantly strong
thunderstorms (hail possibly 2+ inches in diameter, wind gusts in
excess of 70 mph) on the eastern TFX plains. Wind shear may even
be strong enough to possibly generate an isolated tornado.
However, all of these ingredients seem to come together later this
afternoon, which means that thunderstorm development there may not
occur until after 4 or 5 pm MDT, while storms farther west will
develop after 1 pm MDT. Forecast models are also indicating that
these storms may produce heavy rainfall, so have issued a Flash
Flood Watch for the area as well (please see Hydrology section for
details). While storms will generate over the higher terrain of
southwest Montana, the potential for severe storms there is low.
Overall, storms will exit the area to the east with the passage of
the cold front this evening. Westerly downslope winds will help
limit overnight precipitation to the western mountains. A much
cooler airmass will also move into the area, possibly bringing
light measurable snow to the mountain peaks. Winds will likely
approach high wind criteria along the Rocky Mountain Front on
Thursday, but am not anticipating a need for high wind highlights
at this time. The Pacific low pressure system will linger through
the day on Friday, keeping a chance of showers and (likely weak)
afternoon/evening thunderstorms over the area, as temperatures
remain about 10 degrees cooler than normal. Coulston
Friday night through Wednesday...An upper low over the Pacific
Northwest early Friday evening is forecast to weaken as it moves
over the forecast area on Saturday. Models are fairly wet over
southwest and north central Montana on Saturday so have increased
the chances of precipitation especially over north central
Montana. The remnants of the upper low move out by late Saturday
night and by early Sunday morning it appears the only threat for
precipitation will be over north central Montana and possibly the
mountains of the Rocky Mountain Front. On Sunday an upper ridge
will move through the forecast area and expect a mostly dry
period but then southwest flow aloft returns next week. Models
differ on shortwave details and associated precipitation
patterns. Due to these inconsistencies will go with generally a
chance of showers/thunderstorms over the mountains of the Rocky
Mountain Front with a slight chance of showers/thunderstorms
elsewhere. Cool air associated with the upper low will result in
highs on Saturday of only 55 to 65 except over north central
Montana where highs will be closer to 70. Thereafter expect
gradually warming temperatures. Blank
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 76 47 67 43 / 80 40 20 20
CTB 74 45 63 41 / 90 70 20 20
HLN 75 46 65 43 / 70 40 30 20
BZN 81 42 68 39 / 40 30 30 20
WEY 69 32 60 31 / 30 30 20 10
DLN 72 39 62 37 / 50 50 30 20
HVR 88 52 72 47 / 60 100 20 20
LWT 83 45 68 42 / 50 80 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH through this evening Blaine...Cascade...
Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...
Fergus...Hill...Judith Basin...Liberty...Northern Rocky Mountain
Front...Southern Rocky Mountain Front...Toole.
&&
$$
weather.gov/greatfalls
000
FXUS65 KGGW 191540
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
940 AM MDT WED JUN 19 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH FRIDAY...
UPDATE...ONLY MINOR TWEAKS WERE MADE TO THE GRIDS THIS MORNING AS
THE GOING FORECAST LOOKS TO BE IN PRETTY DECENT SHAPE. STILL
EXPECTING THUNDERSTORMS TO DEVELOP AND MOVE ACROSS THE AREA THIS
EVENING INTO TONIGHT. A FEW STORMS MAY BECOME SEVERE WITH LARGE
HAIL AND GUSTY WINDS. PHILLIPS...PETROLEUM...AND WESTERN GARFIELD
COUNTIES WOULD PROBABLY OFFER THE BEST CHANCES FOR THAT AS STORMS
WILL NOT PUSH FURTHER EAST UNTIL LATE EVENING AT WHICH TIME THERE
WILL BE A LOSS OF DAYTIME HEATING. STORMS MAY BEGIN TO WEAKEN AT
THAT TIME. NEVERTHELESS...GIVEN UNCERTAINTY KEPT SEVERE MENTION IN
THE GRIDS ACROSS THE ENTIRE CWA FOR THIS EVENING. HEAVY RAINFALL
ALSO APPEARS TO BE A CONCERN. THE 12Z NAM IS SHOWING THE POTENTIAL
FOR OVER THREE QUARTERS OF AN INCH OF QPF WITHIN A THREE HOUR PERIOD
THIS EVENING ACROSS PARTS OF PHILLIPS COUNTY. IN ADDITION...BOTH
THE LATEST GFS AND ECMWF SHOW BETWEEN A HALF OF AN INCH AND AN
INCH OF QPF WITHIN A SIX HOUR PERIOD IN ABOUT THE SAME AREA. MODEL
FORECAST SOUNDINGS INDICATE PRECIPITABLE WATER VALUES OF WELL OVER
AN INCH. GIVEN THE POTENTIAL FOR STORMS TO DROP COPIUS AMOUNTS OF
RAINFALL IN A SHORT PERIOD OF TIME...FLASH FLOODING MAY BECOME AN
IMPACT. WILL TAKE A LOOK AT THE LATEST GUIDANCE BUT A FLASH FLOOD
WATCH MAY NEED TO BE CONSIDERED FOR PARTS OF THE CWA. RIGHT NOW
WOULD BE INCLINED TO INCLUDE ONLY PHILLIPS COUNTY. WILL MAKE A
FINAL DECISION WITH THE AFTERNOON PACKAGE. MALIAWCO
PREVIOUS SHORT TERM DISCUSSION...
STAGE STILL SET FOR THUNDERSTORMS...INCLUDING SEVERE THREAT...FOR
TODAY. LOW LEVEL FLOW STRENGTHENS WITH 30KT 850 WINDS BRINGING
GULF MOISTURE NORTHWARD. DRYLINE FEATURE DEVELOPING OVER SOUTHERN
MONTANA WITH DRY AIR PUSHING OUT OF THE GREAT BASIN.
EXPECT STORMS TO FIRE THIS AFTERNOON ACROSS CENTRAL MONTANA...
FARTHER TO THE EAST THEN THE PAST FEW DAYS WITH EASTWARD SHIFT OF
THE UPPER LOW. STORM MOTION EXPECTED TO STILL BE MAINLY NORTH TO
NORTHEAST...ALTHOUGH DEVELOPMENT WILL BE EASTWARD WITH THE
MOVEMENT OF THE COLD FRONT/CONVERGENCE LINE/WIND SHIFT DURING THE
EVENING.
WEDGE OF DRY AIR WRAPS INTO THE SYSTEM FOR DRY COOL WEATHER ON
THURSDAY ALONG WITH WESTERLY DOWNSLOPE FLOW. THIS DRY PERIOD WILL
BE SHORT LIVED WITH THE UPPER LOW LINGERING OVER THE NORTHERN
ROCKIES. MOISTURE AND SHORTWAVE ACTIVITY INCREASE BY THURSDAY
NIGHT FOR BETTER CHANCES OF THUNDERSTORMS INTO FRIDAY. EBERT
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
LONG TERM FORECAST PERIOD BEGINS AS THE MAIN ENERGY FROM THE
MEANDERING LOW PRESSURE SYSTEM OVER THE PACIFIC NORTHWEST AND
NORTHERN ROCKIES REGIONS FINALLY KICKS OUT THROUGH THE EASTERN
SLOPES OF THE ROCKY MOUNTAINS AND THEN THE NORTHERN HIGH PLAINS
THROUGH THE REMAINDER OF THE WEEKEND.
EXPECT THIS WEEKEND TO BE FAIRLY WET WITH A LITTLE UNCERTAINTY
REGARDING PRECIPITATION AMOUNTS AS THE 00Z RUN OF THE EC HAS YET
TO COME IN. SOME COMPARISONS SHOW SIGNIFICANT DISCREPANCIES TO THE
POINT OF BEING EXACT OPPOSITES. WOULD HAVE TO GIVE IT LESS THAN
AVERAGE FORECAST CONFIDENCE AT BEST. TRIED TO INCREASE POPS IN A
BROAD-BRUSHED AND BLENDED KIND OF WAY WHERE BEST MODEL AGREEMENT
IF ANY WAS TO BE FOUND...THEN REDUCED POPS SIMILARLY WHERE MODELS
AGREED IN THE LACK THEREOF.
THERE SEEMS TO BE A BRIEF SHORT WAVE RIDGE FROM SUNDAY THROUGH
MONDAY MORNING WHICH SHOULD BRING AN END TO THE WET PERIOD FROM
THE WEEKEND.
NORTHEAST MONTANA THEN FINDS ITSELF IN A PERSISTENT ZONAL OR
SLIGHTLY SOUTHWESTERN FLOW ALOFT WITH SOME SMALL SCALE EMBEDDED
DISTURBANCES. ALTHOUGH THE MODELS ARE TRENDING A BIT DRIER TOWARD
THE END OF THE FORECAST PERIOD AS THE GULF OF ALASKA LOW BATTLES
AGAINST THE FOUR CORNERS HIGH. BMICKELSON
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED INTO THE AFTERNOON BUT MVFR IS A
POSSIBILITY STARTING AT GLASGOW THIS EVENING. AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS WILL DEVELOP...MOST OF THEM ARE
EXPECTED TO IMPACT LOCATIONS ALONG AND NORTH OF HIGHWAY 2 WITH
HEAVY RAIN POSSIBILITIES.
WIDESPREAD SUSTAINED WINDS OF 20 TO 30 MPH WILL LIKELY RAISE
CROSSWIND CONCERNS FROM THE EAST AND SOUTHEAST...GUSTING UP TO 45
MPH DURING PEAK HEATING. A COLD FRONT ARRIVES FROM THE SOUTHWEST
JUST BEYOND THE END OF THIS TAF CYCLE.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR FORT PECK LAKE
FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 191513
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
913 AM MDT WED JUN 19 2013
.UPDATE...
SEVERE THUNDERSTORMS WILL BE POSSIBLE N OF A KLVM TO KBIL LINE
THIS AFTERNOON AND EVENING. IF CONVECTION INHIBITION CAN BE
OVERCOME OVER SE MT...SEVERE WEATHER WILL BE POSSIBLE THERE TOO.
PLENTY OF FACTORS WILL CONTRIBUTE TO LIFT OVER THE AREA THROUGH
TONIGHT. DIFLUENT FLOW WAS EVIDENT ON WATER VAPOR IMAGERY THIS
MORNING. UPPER LOW WAS ALSO SEEN ON IMAGERY NEGATIVELY TILTING
INTO THE PACIFIC NW. A STRONG 500 MB FLOW W OF THE AREA AT 12Z
WILL MOVE E DURING THE DAY BRINGING INCREASING SHEAR. SHORTWAVE
ENERGY WILL ROTATE INTO THE AREA TODAY THROUGH TONIGHT...BRINGING
Q-VECTOR CONVERGENCE. A LOW-LEVEL JET WILL STRENGTHEN OVER THE
EASTERN ZONES TODAY AS WELL. MORE LIFT WILL BE PROVIDED BY STRONG
JET DIVERGENCE OVER THE WESTERN ZONES TONIGHT.
THERE WILL NOT BE A LOT OF MOISTURE TO WORK WITH THROUGH THIS
EVENING AS MOISTURE TRANSPORT VECTORS SHOWED THE BEST MOISTURE
BEING TRANSPORTED FROM THE CENTRAL PLAINS INTO THE NE PART OF MT.
REMAINDER OF THE AREA WILL RECEIVE MOISTURE FROM WY/SE ID/UT WHERE
PRECIPITABLE WATERS WERE AROUND /0.30/ INCHES WHICH WAS DRY AIR.
AS FOR INSTABILITY...HIGH CAPES AND HELICITIES WILL BE E OF KBIL
THIS AFTERNOON AND EVENING SO STORMS THAT DO FORM WILL NEED TO
MONITORED CLOSELY FOR SEVERE POTENTIAL. STORMS THAT FORM ALONG
THE NORTHERN TIER WILL BE IN A HIGH CAPE/INCREASING SHEAR
ENVIRONMENT AND WILL NEED TO BE WATCHED AS WELL. THE AREAS WHERE
SEVERE STORMS AND DRY THUNDERSTORMS WERE MENTIONED WERE IN GOOD
SHAPE PER THE ABOVE.
NOTE THAT THE 12Z HRRR HAS NOTHING DEVELOPING UNTIL 22Z THIS
AFTERNOON. SEE NO NEED TO CHANGE GOING FORECAST. THE SYSTEM/S COLD
FRONT WILL MOVE INTO THE WESTERN ZONES BY 00Z TONIGHT AND CROSS
THE AREA OVERNIGHT. SPC SSEO FROM 00Z LAST NIGHT SHOWED ACTIVE
WEATHER EXITING THE AREA BETWEEN 06-09Z TONIGHT.
ONLY TEMPERATURE ADJUSTMENT WAS TO LOWER READINGS INTO THE 80S IN
FAR SE MT WHERE MIXING WILL BE JUST ABOVE 850 MB. ARTHUR
&&
.SHORT TERM...VALID FOR TDY AND THU...
...TODAY...
AN APPROACHING UPPER LEVEL LOW WILL PIVOT A NEGATIVELY
TILTED SHORTWAVE ACROSS WESTERN MONTANA THIS AFTERNOON. THIS WILL
PUSH A SURFACE LOW...CURRENTLY POSITIONED ACROSS SOUTHEAST
IDAHO...ACROSS THE FORECAST AREA INTO EASTERN MONTANA BY TONIGHT.
THE ACCOMPANYING SURGE OF SOUTHWESTERLY WIND BEHIND THE LOW WILL
PUSH VERY DRY AIR ACROSS THE SOUTHERN PORTIONS OF THE FORECAST
AREA BY THIS AFTERNOON...WITH THE MOIST GULF MOISTURE TAP WRAPPING
AROUND THE NORTHERN SIDE OF THE LOW INTO THE GGW AND TFX FORECAST
AREAS. EXPECT TO SEE DEW POINTS CRASH INTO THE 30S AND 40S ACROSS
SOUTHERN PORTIONS OF THE FORECAST AREA AS MIXING BECOMES
ESTABLISHED IN THE LATE MORNING. OUR NORTHERN TIER OF COUNTIES
WILL REMAIN ON THE GRADIENT BETWEEN THE DRY AIR AND MUCH MORE
MOIST AIR AND SHOULD RETAIN DEW POINTS IN THE 50S. THESE HIGHER
DEW POINTS WILL SUPPORT THE BETTER POTENTIAL FOR CONVECTION AND
EVEN SOME SEVERE WEATHER IN THE FORM OF HAIL AND STRONG WINDS.
HOWEVER...FARTHER SOUTH TOWARD BILLINGS THE LCLS WILL BE ALMOST
15K FEET WITH ALL THE CAPE EXTREMELY ELEVATED. CURRENT THINKING IS
THAT THE BEST CHANCE OF STRONG TO SEVERE THUNDERSTORMS WILL
PROGRESS FROM THE CRAZY MOUNTAINS TO HARLOWTON TO ROUNDUP TO
NORTHERN ROSEBUD COUNTY BY THIS EVENING. HOWEVER FOR THE SOUTHERN
TIER OF THE FORECAST AREA...EXPECT ONLY ISOLATED DRY THUNDERSTORMS
WHICH COULD PRODUCE SOME GUSTY WINDS. EXPECT THE CONVECTIVE THREAT
WILL END ACROSS THE FORECAST AREA BY 03 TO 06Z AS THE THREAT
SHIFTS NORTH.
...TONIGHT AND THURSDAY...
THE SURFACE COLD FRONT WILL PROGRESS ACROSS THE FORECAST AREA
FROM THE LATE AFTERNOON IN THE WEST TO AFTER MIDNIGHT IN THE EAST.
COOLER AIR WILL PUSH IN BEHIND THE FRONT BRINGING ALLOWING
TEMPERATURES TO BE COOLER THAN LAST NIGHT IN CENTRAL AND WESTERN
ZONES. WINDS WILL STAY UP OVERNIGHT IN THE EAST KEEPING OVERNIGHT
LOWS IN THE MID TO UPPER 50S. TEMPERATURES WILL BE COOLER TOMORROW
IN THE POST FRONTAL ENVIRONMENT WITH 700MB TEMPERATURES CRASHING
AROUND +13C TO DOWN TO AROUND +5C. THUS EXPECT HIGH TEMPERATURES
TO STAY MAINLY IN THE 70S THURSDAY. THE UPPER LEVEL LOW WILL STILL
BE POSITIONED TO OUR WEST ON THURSDAY AND A NEW SURFACE LOW WILL
DEVELOP OVER NORTHERN WYOMING GOING INTO THURSDAY EVENING. THIS
ALLOWS EASTERLY LOW LEVEL WINDS TO INCREASE THE MOISTURE OVER
SOUTHEAST MONTANA. THIS COMBINED WITH THE INVERTED SURFACE TROUGH
ACROSS EASTERN MONTANA...EXPECT TO SEE AN INCREASED CHANCE OF
DEVELOPING SOME SHOWERS BY THURSDAY EVENING.
CHURCH
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
SLOWING TREND OF TRANSIT OF THE UPPER LOW THROUGH THE AREA IS
BRINGING INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS SATURDAY
AND SUNDAY BUT HELPING MAKE LATER PERIODS DRIER. FRIDAY WILL STILL
BE SEEING LOW LEVEL MOISTURE RECOVERING SO THERE IS A THREAT OF
CONVECTION BUT PRECIP AMOUNTS WILL BE LIGHT.
FRIDAY NIGHT THE UPPER LOW DIGS INTO SOUTHWESTERN MONTANA AND
REALLY GIVES A CHANCE FOR MOISTURE TO DEEPEN ACROSS CENTRAL AND
EASTERN MONTANA AT THE LOWER LEVELS DESPITE SOUTHWESTERLY FLOW
ALOFT STILL TRYING TO ADVECT IN DRIER AIR. WITH STRONG DIFFLUENCE
AND PLAINS MOISTURE WRAPPING BACK INTO THE YELLOWSTONE VALLEY
LOOKS LIKE A GOOD CHANCE TO GET WET. SATURDAY IN PARTICULAR WILL
HAVE TO BE WATCHED FOR THE STRENGTH OF STORMS WITH FAVORABLE SHEAR
BUT INSTABILITY MAY BE LIMITED DUE TO COOL BOUNDARY LAYER
TEMPERATURES.
SUNDAY THE UPPER LOW EJECTS INTO EASTERN MONTANA AND WRAP AROUND
MOISTURE CONTINUES TO BRING A THREAT OF SHOWERS AND THUNDERSTORMS
TO MAINLY THE EASTERN HALF OF THE AREA. TEMPERATURES ON FRIDAY
THROUGH SUNDAY COULD RUN 10 DEGREES BELOW NORMAL ESPECIALLY IF
CLOUDS DOMINATE AND ENOUGH DYNAMIC COOLING OCCURS.
MONDAY AND BEYOND IS DRYING AS FLOW BECOMES WESTERLY AND NEXT
UPSTREAM SYSTEM IS PROGGED TO EJECT TO THE NORTH AND WEST OF
MONTANA. BORSUM
&&
.AVIATION...
ISOLATED THUNDERSTORMS WILL DEVELOP OVER THE MOUNTAINS BY EARLY
THIS AFTERNOON WITH A FEW THUNDERSTORMS MOVING ONTO THE PLAINS
WEST OF BILLINGS BY MID AFTERNOON. THE MAJORITY OF THE
THUNDERSTORM ACTIVITY IS EXPECTED TO BE NORTH AND WEST OF KBIL.
STRONG GUSTY WINDS WILL BE THE MAIN THREAT WITH ANY THUNDERSTORM.
A COLD FRONT WILL MOVE ACROSS THE FORECAST AREA THIS EVENING INTO
THE OVERNIGHT HOURS. HOOLEY
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 093 052/077 052/072 052/069 051/078 054/082 056/082
1/T 11/B 23/T 34/T 41/B 11/B 22/T
LVM 085 043/072 041/069 042/067 046/079 046/082 049/081
3/T 22/T 23/T 35/T 50/B 02/T 22/T
HDN 095 053/078 052/074 050/072 050/078 052/082 052/083
1/T 11/B 32/T 34/T 41/B 11/B 22/T
MLS 096 058/081 055/076 056/076 055/080 056/083 057/083
1/N 21/B 44/T 34/T 43/T 11/B 11/B
4BQ 095 054/081 055/076 054/075 053/079 054/084 055/084
1/N 11/B 44/T 34/T 52/T 11/B 22/T
BHK 087 057/080 054/076 055/074 054/076 054/080 057/082
1/N 21/B 36/T 55/T 53/T 11/B 22/T
SHR 090 048/078 050/073 048/073 047/076 049/081 050/082
1/T 11/B 32/T 24/T 41/B 11/B 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 191156
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
555 AM MDT Wed Jun 19 2013
UPDATED AVIATION SECTION
...STRONG TO POSSIBLY SEVERE THUNDERSTORMS THIS AFTERNOON INTO
THIS EVENING...
.DISCUSSION...
Today through Friday...Thunderstorms from overnight have exited
the area, but another round of potentially severe weather is on
tap for today. The Pacific low pressure system that brought
thunderstorms to the western portion of the forecast area
yesterday will slowly move into the Pacific Northwest today. The
moist, unstable, and diffluent southerly flow ahead of the system
will combine with a strong embedded disturbance and the associated
cold front over the area for more widespread thunderstorm
development than yesterday. Therefore, the Storm Prediction Center
has all of north central/central Montana under a Slight Risk for
severe thunderstorms today. While some storms over the western
plains of north central/central Montana may see marginally severe
thunderstorms (wind gusts around 60 mph, hail around 1 inch in
diameter), the greater focus will be on the eastern plains.
Surface winds there will be breezy and out of the east ahead of
the cold front, which will advect moist air (dewpoints in the
upper 50s to lower 60s) into the area and enhance the instability.
The surface winds will also combine with the stronger winds aloft
to provide strong wind shear (with regard to both speed and
direction) to that area as well. The enhanced instability and
shear will focus the potential for significantly strong
thunderstorms (hail possibly 2+ inches in diameter, wind gusts in
excess of 70 mph) on the eastern TFX plains. Wind shear may even
be strong enough to possibly generate an isolated tornado.
However, all of these ingredients seem to come together later this
afternoon, which means that thunderstorm development there may not
occur until after 4 or 5 pm MDT, while storms farther west will
develop after 1 pm MDT. Forecast models are also indicating that
these storms may produce heavy rainfall, so have issued a Flash
Flood Watch for the area as well (please see Hydrology section for
details). While storms will generate over the higher terrain of
southwest Montana, the potential for severe storms there is low.
Overall, storms will exit the area to the east with the passage of
the cold front this evening. Westerly downslope winds will help
limit overnight precipitation to the western mountains. A much
cooler airmass will also move into the area, possibly bringing
light measurable snow to the mountain peaks. Winds will likely
approach high wind criteria along the Rocky Mountain Front on
Thursday, but am not anticipating a need for high wind highlights
at this time. The Pacific low pressure system will linger through
the day on Friday, keeping a chance of showers and (likely weak)
afternoon/evening thunderstorms over the area, as temperatures
remain about 10 degrees cooler than normal. Coulston
Friday night through Wednesday...An upper low over the Pacific
Northwest early Friday evening is forecast to weaken as it moves
over the forecast area on Saturday. Models are fairly wet over
southwest and north central Montana on Saturday so have increased
the chances of precipitation especially over north central
Montana. The remnants of the upper low move out by late Saturday
night and by early Sunday morning it appears the only threat for
precipitation will be over north central Montana and possibly the
mountains of the Rocky Mountain Front. On Sunday an upper ridge
will move through the forecast area and expect a mostly dry
period but then southwest flow aloft returns next week. Models
differ on shortwave details and associated precipitation
patterns. Due to these inconsistencies will go with generally a
chance of showers/thunderstorms over the mountains of the Rocky
Mountain Front with a slight chance of showers/thunderstorms
elsewhere. Cool air associated with the upper low will result in
highs on Saturday of only 55 to 65 except over north central
Montana where highs will be closer to 70. Thereafter expect
gradually warming temperatures. Blank
&&
.AVIATION...
Updated 1155Z.
The main message today will be the possibility for severe
thunderstorms with hail in excess of one inch in diameter and wind
gusts in excess of 50 knots. Also some of the thunderstorms will
have brief heavy rain with IFR ceilings and visibilities. Expect
thunderstorms to develop over southwest Montana by mid-afternoon
then intensify as they move over the plains. Feel fairly confident
of the timing mentioned in the tafs for the showers/thunderstorms.
One forecast parameter with little confidence is wind. Confidence is
especially low with forecast wind directions. Actually confidence in
wind directions increases tonight as the cold front moves through
and winds shift to the southwest. Blank
&&
.HYDROLOGY...
Showers and thunderstorms are expected to develop once again this
afternoon over the Rocky Mountain Front and the adjacent plains
along a surface cold front. These showers and thunderstorms are
then expected to spread east across the plains of north central
and central Montana later this afternoon and continue into this
evening. Forecast models are predicting significant rainfall with
these showers, which is expected to occur in rapid bursts with the
thunderstorms. Some localized flash flooding occurred with storms
along the Rocky Mountain Front Tuesday evening. However, the
greater area of concern is across eastern portions of north
central and central Montana that still have moist soil that would
not be able to absorb much rapid rainfall. Forecast models also
indicate that this area will receive the greatest amount of
rainfall. Taking these factors into consideration, have decided to
issue a Flash Flood Watch from noon MDT today until midnight MDT
tonight for all of north central and central Montana. The greatest
threat for flash flooding for the Rocky Mountain Front and
adjacent plains will be this afternoon, while the greatest threat
in the east will likely be after 5 pm MDT.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 76 47 67 43 / 90 40 20 20
CTB 74 45 63 41 / 100 70 20 20
HLN 75 46 65 43 / 70 40 30 20
BZN 81 42 68 39 / 40 30 30 20
WEY 69 32 60 31 / 40 30 20 10
DLN 72 39 62 37 / 60 50 30 20
HVR 88 52 72 47 / 60 100 20 20
LWT 83 45 68 42 / 60 80 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH from Noon MDT today through this evening
Blaine...Cascade...Chouteau...Eastern Glacier...Eastern
Pondera...Eastern Teton...Fergus...Hill...Judith Basin...
Liberty...Northern Rocky Mountain Front...Southern Rocky
Mountain Front...Toole.
&&
$$
SHORT TERM...COULSTON
LONG TERM...BLANK
AVIATION...mpj
weather.gov/greatfalls
000
FXUS65 KTFX 191048
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
448 AM MDT Wed Jun 19 2013
...Strong to possibly severe thunderstorms today into this
evening...
.DISCUSSION...
Today through Friday...Thunderstorms from overnight have exited
the area, but another round of potentially severe weather is on
tap for today. The Pacific low pressure system that brought
thunderstorms to the western portion of the forecast area
yesterday will slowly move into the Pacific Northwest today. The
moist, unstable, and diffluent southerly flow ahead of the system
will combine with a strong embedded disturbance and the associated
cold front over the area for more widespread thunderstorm
development than yesterday. Therefore, the Storm Prediction Center
has all of north central/central Montana under a Slight Risk for
severe thunderstorms today. While some storms over the western
plains of north central/central Montana may see marginally severe
thunderstorms (wind gusts around 60 mph, hail around 1 inch in
diameter), the greater focus will be on the eastern plains.
Surface winds there will be breezy and out of the east ahead of
the cold front, which will advect moist air (dewpoints in the
upper 50s to lower 60s) into the area and enhance the instability.
The surface winds will also combine with the stronger winds aloft
to provide strong wind shear (with regard to both speed and
direction) to that area as well. The enhanced instability and
shear will focus the potential for significantly strong
thunderstorms (hail possibly 2+ inches in diameter, wind gusts in
excess of 70 mph) on the eastern TFX plains. Wind shear may even
be strong enough to possibly generate an isolated tornado.
However, all of these ingredients seem to come together later this
afternoon, which means that thunderstorm development there may not
occur until after 4 or 5 pm MDT, while storms farther west will
develop after 1 pm MDT. Forecast models are also indicating that
these storms may produce heavy rainfall, so have issued a Flash
Flood Watch for the area as well (please see Hydrology section for
details). While storms will generate over the higher terrain of
southwest Montana, the potential for severe storms there is low.
Overall, storms will exit the area to the east with the passage of
the cold front this evening. Westerly downslope winds will help
limit overnight precipitation to the western mountains. A much
cooler airmass will also move into the area, possibly bringing
light measurable snow to the mountain peaks. Winds will likely
approach high wind criteria along the Rocky Mountain Front on
Thursday, but am not anticipating a need for high wind highlights
at this time. The Pacific low pressure system will linger through
the day on Friday, keeping a chance of showers and (likely weak)
afternoon/evening thunderstorms over the area, as temperatures
remain about 10 degrees cooler than normal. Coulston
Friday night through Wednesday...An upper low over the Pacific
Northwest early Friday evening is forecast to weaken as it moves
over the forecast area on Saturday. Models are fairly wet over
southwest and north central Montana on Saturday so have increased
the chances of precipitation especially over north central
Montana. The remnants of the upper low move out by late Saturday
night and by early Sunday morning it appears the only threat for
precipitation will be over north central Montana and possibly the
mountains of the Rocky Mountain Front. On Sunday an upper ridge
will move through the forecast area and expect a mostly dry
period but then southwest flow aloft returns next week. Models
differ on shortwave details and associated precipitation
patterns. Due to these inconsistencies will go with generally a
chance of showers/thunderstorms over the mountains of the Rocky
Mountain Front with a slight chance of showers/thunderstorms
elsewhere. Cool air associated with the upper low will result in
highs on Saturday of only 55 to 65 except over north central
Montana where highs will be closer to 70. Thereafter expect
gradually warming temperatures. Blank
&&
.AVIATION...
Updated 0450Z.
Widespread showers and thunderstorms will continue to move
through western portions of north central Montana through 10Z.
During this time, areas of MVFR conditions in heavy rain remain
possible along with mountain obscurations. A surface cold front
will push east of the continental divide Wednesday afternoon then
moves into eastern Montana after 03Z. Another round of strong to
severe thunderstorms will develop ahead of the frontal boundary
but clearing skies and calmer weather will move in behind the
front. mpj
&&
.HYDROLOGY...
Showers and thunderstorms are expected to develop once again this
afternoon over the Rocky Mountain Front and the adjacent plains
along a surface cold front. These showers and thunderstorms are
then expected to spread east across the plains of north central
and central Montana later this afternoon and continue into this
evening. Forecast models are predicting significant rainfall with
these showers, which is expected to occur in rapid bursts with the
thunderstorms. Some localized flash flooding occurred with storms
along the Rocky Mountain Front Tuesday evening. However, the
greater area of concern is across eastern portions of north
central and central Montana that still have moist soil that would
not be able to absorb much rapid rainfall. Forecast models also
indicate that this area will receive the greatest amount of
rainfall. Taking these factors into consideration, have decided to
issue a Flash Flood Watch from noon MDT today until midnight MDT
tonight for all of north central and central Montana. The greatest
threat for flash flooding for the Rocky Mountain Front and
adjacent plains will be this afternoon, while the greatest threat
in the east will likely be after 5 pm MDT.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 76 47 67 43 / 90 40 20 20
CTB 74 45 63 41 / 100 70 20 20
HLN 75 46 65 43 / 70 40 30 20
BZN 81 42 68 39 / 40 30 30 20
WEY 69 32 60 31 / 40 30 20 10
DLN 72 39 62 37 / 60 50 30 20
HVR 88 52 72 47 / 60 100 20 20
LWT 83 45 68 42 / 60 80 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH from Noon MDT today through this evening
Blaine...Cascade...Chouteau...Eastern Glacier...Eastern
Pondera...Eastern Teton...Fergus...Hill...Judith Basin...
Liberty...Northern Rocky Mountain Front...Southern Rocky
Mountain Front...Toole.
&&
$$
SHORT TERM...COULSTON
LONG TERM...BLANK
AVIATION...mpj
weather.gov/greatfalls
000
FXUS65 KBYZ 191023
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
423 AM MDT WED JUN 19 2013
.SHORT TERM...VALID FOR TDY AND THU...
...TODAY...
AN APPROACHING UPPER LEVEL LOW WILL PIVOT A NEGATIVELY
TILTED SHORTWAVE ACROSS WESTERN MONTANA THIS AFTERNOON. THIS WILL
PUSH A SURFACE LOW...CURRENTLY POSITIONED ACROSS SOUTHEAST
IDAHO...ACROSS THE FORECAST AREA INTO EASTERN MONTANA BY TONIGHT.
THE ACCOMPANYING SURGE OF SOUTHWESTERLY WIND BEHIND THE LOW WILL
PUSH VERY DRY AIR ACROSS THE SOUTHERN PORTIONS OF THE FORECAST
AREA BY THIS AFTERNOON...WITH THE MOIST GULF MOISTURE TAP WRAPPING
AROUND THE NORTHERN SIDE OF THE LOW INTO THE GGW AND TFX FORECAST
AREAS. EXPECT TO SEE DEW POINTS CRASH INTO THE 30S AND 40S ACROSS
SOUTHERN PORTIONS OF THE FORECAST AREA AS MIXING BECOMES
ESTABLISHED IN THE LATE MORNING. OUR NORTHERN TIER OF COUNTIES
WILL REMAIN ON THE GRADIENT BETWEEN THE DRY AIR AND MUCH MORE
MOIST AIR AND SHOULD RETAIN DEW POINTS IN THE 50S. THESE HIGHER
DEW POINTS WILL SUPPORT THE BETTER POTENTIAL FOR CONVECTION AND
EVEN SOME SEVERE WEATHER IN THE FORM OF HAIL AND STRONG WINDS.
HOWEVER...FARTHER SOUTH TOWARD BILLINGS THE LCLS WILL BE ALMOST
15K FEET WITH ALL THE CAPE EXTREMELY ELEVATED. CURRENT THINKING IS
THAT THE BEST CHANCE OF STRONG TO SEVERE THUNDERSTORMS WILL
PROGRESS FROM THE CRAZY MOUNTAINS TO HARLOWTON TO ROUNDUP TO
NORTHERN ROSEBUD COUNTY BY THIS EVENING. HOWEVER FOR THE SOUTHERN
TIER OF THE FORECAST AREA...EXPECT ONLY ISOLATED DRY THUNDERSTORMS
WHICH COULD PRODUCE SOME GUSTY WINDS. EXPECT THE CONVECTIVE THREAT
WILL END ACROSS THE FORECAST AREA BY 03 TO 06Z AS THE THREAT
SHIFTS NORTH.
...TONIGHT AND THURSDAY...
THE SURFACE COLD FRONT WILL PROGRESS ACROSS THE FORECAST AREA
FROM THE LATE AFTERNOON IN THE WEST TO AFTER MIDNIGHT IN THE EAST.
COOLER AIR WILL PUSH IN BEHIND THE FRONT BRINGING ALLOWING
TEMPERATURES TO BE COOLER THAN LAST NIGHT IN CENTRAL AND WESTERN
ZONES. WINDS WILL STAY UP OVERNIGHT IN THE EAST KEEPING OVERNIGHT
LOWS IN THE MID TO UPPER 50S. TEMPERATURES WILL BE COOLER TOMORROW
IN THE POST FRONTAL ENVIRONMENT WITH 700MB TEMPERATURES CRASHING
AROUND +13C TO DOWN TO AROUND +5C. THUS EXPECT HIGH TEMPERATURES
TO STAY MAINLY IN THE 70S THURSDAY. THE UPPER LEVEL LOW WILL STILL
BE POSITIONED TO OUR WEST ON THURSDAY AND A NEW SURFACE LOW WILL
DEVELOP OVER NORTHERN WYOMING GOING INTO THURSDAY EVENING. THIS
ALLOWS EASTERLY LOW LEVEL WINDS TO INCREASE THE MOISTURE OVER
SOUTHEAST MONTANA. THIS COMBINED WITH THE INVERTED SURFACE TROUGH
ACROSS EASTERN MONTANA...EXPECT TO SEE AN INCREASED CHANCE OF
DEVELOPING SOME SHOWERS BY THURSDAY EVENING.
CHURCH
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
SLOWING TREND OF TRANSIT OF THE UPPER LOW THROUGH THE AREA IS
BRINGING INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS SATURDAY
AND SUNDAY BUT HELPING MAKE LATER PERIODS DRIER. FRIDAY WILL STILL
BE SEEING LOW LEVEL MOISTURE RECOVERING SO THERE IS A THREAT OF
CONVECTION BUT PRECIP AMOUNTS WILL BE LIGHT.
FRIDAY NIGHT THE UPPER LOW DIGS INTO SOUTHWESTERN MONTANA AND
REALLY GIVES A CHANCE FOR MOISTURE TO DEEPEN ACROSS CENTRAL AND
EASTERN MONTANA AT THE LOWER LEVELS DESPITE SOUTHWESTERLY FLOW
ALOFT STILL TRYING TO ADVECT IN DRIER AIR. WITH STRONG DIFFLUENCE
AND PLAINS MOISTURE WRAPPING BACK INTO THE YELLOWSTONE VALLEY
LOOKS LIKE A GOOD CHANCE TO GET WET. SATURDAY IN PARTICULAR WILL
HAVE TO BE WATCHED FOR THE STRENGTH OF STORMS WITH FAVORABLE SHEAR
BUT INSTABILITY MAY BE LIMITED DUE TO COOL BOUNDARY LAYER
TEMPERATURES.
SUNDAY THE UPPER LOW EJECTS INTO EASTERN MONTANA AND WRAP AROUND
MOISTURE CONTINUES TO BRING A THREAT OF SHOWERS AND THUNDERSTORMS
TO MAINLY THE EASTERN HALF OF THE AREA. TEMPERATURES ON FRIDAY
THROUGH SUNDAY COULD RUN 10 DEGREES BELOW NORMAL ESPECIALLY IF
CLOUDS DOMINATE AND ENOUGH DYNAMIC COOLING OCCURS.
MONDAY AND BEYOND IS DRYING AS FLOW BECOMES WESTERLY AND NEXT
UPSTREAM SYSTEM IS PROGGED TO EJECT TO THE NORTH AND WEST OF
MONTANA. BORSUM
&&
.AVIATION...
EXPECT DRY CONDITIONS UNTIL MIDDAY. ISOLATED THUNDERSTORMS WILL
DEVELOP OVER THE MOUNTAINS IN THE AFTERNOON AND MOVE INTO WESTERN
LOWER ELEVATIONS INCLUDING KLVM BUT ACTIVITY WILL REMAIN WEST OF
KBIL. BIGGEST THREAT WILL BE GUSTY WINDS FROM STORMS. A FRONT WILL
MOVE THROUGH THE AREA AFTER 00Z BRINGING STRONG GUSTY WEST WINDS.
BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 093 052/077 052/072 052/069 051/078 054/082 056/082
1/T 11/B 23/T 34/T 41/B 11/B 22/T
LVM 085 043/072 041/069 042/067 046/079 046/082 049/081
3/T 22/T 23/T 35/T 50/B 02/T 22/T
HDN 095 053/078 052/074 050/072 050/078 052/082 052/083
1/T 11/B 32/T 34/T 41/B 11/B 22/T
MLS 096 058/081 055/076 056/076 055/080 056/083 057/083
1/N 21/B 44/T 34/T 43/T 11/B 11/B
4BQ 095 054/081 055/076 054/075 053/079 054/084 055/084
1/N 11/B 44/T 34/T 52/T 11/B 22/T
BHK 091 057/080 054/076 055/074 054/076 054/080 057/082
1/N 21/B 36/T 55/T 53/T 11/B 22/T
SHR 090 048/078 050/073 048/073 047/076 049/081 050/082
1/T 11/B 32/T 24/T 41/B 11/B 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 191016
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
416 AM MDT WED JUN 19 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH FRIDAY...
STAGE STILL SET FOR THUNDERSTORMS...INCLUDING SEVERE THREAT...FOR
TODAY. LOW LEVEL FLOW STRENGTHENS WITH 30KT 850 WINDS BRINGING
GULF MOISTURE NORTHWARD. DRYLINE FEATURE DEVELOPING OVER SOUTHERN
MONTANA WITH DRY AIR PUSHING OUT OF THE GREAT BASIN.
EXPECT STORMS TO FIRE THIS AFTERNOON ACROSS CENTRAL MONTANA...
FARTHER TO THE EAST THEN THE PAST FEW DAYS WITH EASTWARD SHIFT OF
THE UPPER LOW. STORM MOTION EXPECTED TO STILL BE MAINLY NORTH TO
NORTHEAST...ALTHOUGH DEVELOPMENT WILL BE EASTWARD WITH THE
MOVEMENT OF THE COLD FRONT/CONVERGENCE LINE/WIND SHIFT DURING THE
EVENING.
WEDGE OF DRY AIR WRAPS INTO THE SYSTEM FOR DRY COOL WEATHER ON
THURSDAY ALONG WITH WESTERLY DOWNSLOPE FLOW. THIS DRY PERIOD WILL
BE SHORT LIVED WITH THE UPPER LOW LINGERING OVER THE NORTHERN
ROCKIES. MOISTURE AND SHORTWAVE ACTIVITY INCREASE BY THURSDAY
NIGHT FOR BETTER CHANCES OF THUNDERSTORMS INTO FRIDAY. EBERT
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
LONG TERM FORECAST PERIOD BEGINS AS THE MAIN ENERGY FROM THE
MEANDERING LOW PRESSURE SYSTEM OVER THE PACIFIC NORTHWEST AND
NORTHERN ROCKIES REGIONS FINALLY KICKS OUT THROUGH THE EASTERN
SLOPES OF THE ROCKY MOUNTAINS AND THEN THE NORTHERN HIGH PLAINS
THROUGH THE REMAINDER OF THE WEEKEND.
EXPECT THIS WEEKEND TO BE FAIRLY WET WITH A LITTLE UNCERTAINTY
REGARDING PRECIPITATION AMOUNTS AS THE 00Z RUN OF THE EC HAS YET
TO COME IN. SOME COMPARISONS SHOW SIGNIFICANT DISCREPANCIES TO THE
POINT OF BEING EXACT OPPOSITES. WOULD HAVE TO GIVE IT LESS THAN
AVERAGE FORECAST CONFIDENCE AT BEST. TRIED TO INCREASE POPS IN A
BROAD-BRUSHED AND BLENDED KIND OF WAY WHERE BEST MODEL AGREEMENT
IF ANY WAS TO BE FOUND...THEN REDUCED POPS SIMILARLY WHERE MODELS
AGREED IN THE LACK THEREOF.
THERE SEEMS TO BE A BRIEF SHORT WAVE RIDGE FROM SUNDAY THROUGH
MONDAY MORNING WHICH SHOULD BRING AN END TO THE WET PERIOD FROM
THE WEEKEND.
NORTHEAST MONTANA THEN FINDS ITSELF IN A PERSISTENT ZONAL OR
SLIGHTLY SOUTHWESTERN FLOW ALOFT WITH SOME SMALL SCALE EMBEDDED
DISTURBANCES. ALTHOUGH THE MODELS ARE TRENDING A BIT DRIER TOWARD
THE END OF THE FORECAST PERIOD AS THE GULF OF ALASKA LOW BATTLES
AGAINST THE FOUR CORNERS HIGH. BMICKELSON
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED TO PREVAIL FOR ALL TAF SITES THROUGHOUT
MOST OF THE TAF PERIOD. ALTHOUGH AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS WILL DEVELOP...MOST OF THEM ARE EXPECTED TO IMPACT
LOCATIONS ALONG AND NORTH OF HIGHWAY 2 WITH STRONG TO SEVERE
STORMS POSSIBLE. WIDESPREAD SUSTAINED WINDS OF 20 TO 30 MPH WILL
LIKELY RAISE CROSSWIND CONCERNS FROM THE EAST AND
SOUTHEAST...GUSTING UP TO 45 MPH DURING PEAK HEATING. A COLD
FRONT ARRIVES FROM THE WEST JUST BEYOND THE END OF THIS TAF CYCLE.
MALIAWCO/MICKELSON
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR FORT PECK LAKE
FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KMSO 190923
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
323 AM MDT Wed Jun 19 2013
...MOUNTAIN SNOW TO IMPACT MARIAS, LOGAN, LOST TRAIL PASSES
THURSDAY MORNING...
.DISCUSSION...The upper low pressure system will slowly enter the
region today, setting up for a very wet and cool day. Heavy rain
has already been falling in the Clearwater Mountains overnight and
this morning, and is expected to continue through most of the day.
This region and the Idaho Panhandle, including northwestern
Montana will likely to pick up the heaviest rain today, with 1" to
2" inches possible. Heavy rain will likely cause local streams and
rivers to rise, however flooding is not anticipated at this time.
Elsewhere in western Montana, showers and thunderstorms are
expected to develop ahead of the main shield of precipitation this
afternoon. These storms are not expected to be as strong as we saw
yesterday, though they could produce very heavy rain, gusty winds,
and small hail. Later this afternoon and evening, heavy rain is
expected to finally make in and around the Glacier National Park
area. An additional 1.00" to 1.50" inches of rain is possible, and
with already saturated ground, runoff from the rain could
potential cause small rock and mudslides. Keep apprised to any
changes to the forecast, and those spending anytime outdoors today
should keep an eye to the sky.
Wednesday night into Thursday morning snow levels will fall to
around 6000 feet as the coldest part the upper level low moves
east across the northern Rockies. The heaviest precipitation will
be on the leading edge of the system, and should fall as rain.
However, snow is expected to affect Logan Pass and Glacier
National Park Thursday morning, and higher elevations in the park
throughout the day. Marias and Lost Trail passes will also be
affected by light snow accumulations Thursday morning around 1 to
2 inches. Accumulation on roadways is possible, so early morning
travelers should be prepared for winter driving conditions over
the passes.
Friday and Saturday will remain cool and showery as the system
slowly progresses east. Sunday afternoon into have the potential
to be nice with a weak ridge building ahead of the next system.
However, moist southwest flow from a digging trough off the
Washington coast may also cause thunderstorms. Generally, the
unsettled weather will continue well into next week.
&&
.AVIATION...An upper level low over Washington State continues to
meander east over the northern Rockies today. Expect increasing
mountain obscurations and thunderstorms embedded in a broader
area of increasing clouds. Main threat from thunder storms is
heavy rain, but especially KMSO and KGPI will be affected.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
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https://www.facebook.com/US.NationalWeatherService.Missoula.gov
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000
FXUS65 KTFX 190451
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1050 PM MDT Tue Jun 18 2013
...UPDATE TO AVIATION...
.UPDATE...
A few strong thunderstorms continue to push northward through the
region. The thunderstorm watch will continue a bit longer where it
is currently in effect in case a severe storm develops. The flash
flood warnings will continue a bit longer as well. Expect a few
thunderstorms to continue after midnight. Otherwise current
forecast is on track. Brusda
&&
.AVIATION...
Updated 0450Z.
Widespread showers and thunderstorms will continue to move through
western portions of north central Montana through 10Z. During this
time, areas of MVFR conditions in heavy rain remain possible along
with mountain obscurations. A surface cold front will push east of
the continental divide Wednesday afternoon then moves into eastern
Montana after 03Z. Another round of strong to severe thunderstorms
will develop ahead of the frontal boundary but clearing skies and
calmer weather will move in behind the front. mpj
&&
.HYDROLOGY...
More widespread showers and thunderstorms are possible along the
Rocky Mountain Front and adjacent plains this afternoon and
evening and over most of the plains of North Central/Central
Montana on Wednesday. Some of these storms may produce brief heavy
rainfall. These periods will need to be monitored for possible
areal flood/flash flood highlights. The greater area of concern is
across eastern portions of north central and central Montana for
Wednesday that still have moist soil that would not be able to
absorb much rapid rainfall. If rainfall from storms today are
significant along the Rocky Mountain Front additional rainfall on
Wednesday will increase the flooding threat there as well.
&&
.PREV DISCUSSION...
/ISSUED 555 PM MDT Tue Jun 18 2013/
Today through Thursday...A low pressure system moving over the
Pacific Northwest coast today will bring increased moisture and
instability to Montana. These factors will help generate showers and
thunderstorms over terrain this afternoon. A frontal boundary
associated with this system will also move into Western Montana
today providing a good forcing mechanism for storm development. As a
result the Storm Prediction Center continues to keep Western and
Central Montana under a Slight Risk for severe thunderstorms. Storms
decrease overnight, but another round of potentially severe weather
is expected for Wednesday as the main system continues to move east
across the Northern Rockies. The most unstable conditions will also
shift northeast into Central and Eastern Montana, where the Storm
Prediction Center has a Slight Risk for Wednesday as well. The
potential for the strongest storms will be along and east of a
Havre-to-Stanford line as wind shear and instability are strongest
there. Precipitation from storms may be heavy adding the potential
for flash flooding. The system will lift northeast across the area
later Wednesday night into Thursday keeping high POPs in the
mountains. Westerly down-slope winds will hinder shower/thunderstorm
development Thursday though. Winds strengthen along the Rocky
Mountain Front Thursday making high wind highlights possible.
Temperatures cool Wednesday as the main front moves through the area.
Thursday night through Tuesday...No significant changes made to
the medium range forecast. An unsettled pattern will persist
through Saturday as a closed upper low will remain quasi-
stationary over northwest Montana. Short wave energy will
continue to rotate out from the base of the low and help initiate
shower and thunderstorm development each day. The strength of
these storms will depend on availability of low level moisture
and the strength of the divergent flow aloft. The models also
continue to differ on the upper low`s position which, in turn,
will affect where and how strong thunderstorms will be. Because
of these differences, have continued to broad-brush the pops
through Saturday. By late Saturday, the models move the low to
northeast Montana and lift it out as an upper ridge begins
building over the Pacific Northwest. The ridge breaks down on
Sunday as short wave energy ripples across the area within the
westerly flow aloft. Isolated thunderstorms will remain a
possibility Sunday and Monday. By Tuesday, weak upper ridging
returns though isolated showers will persist over the southwest
mountains. Temperatures will remain below seasonal averages to
start the period due to cloud cover and periodic cold advection
from transient shortwaves. Temperatures should rise above
seasonal averages to start the week.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 54 76 46 67 / 40 80 80 20
CTB 52 73 45 64 / 100 100 90 30
HLN 53 75 46 67 / 50 70 60 30
BZN 48 79 42 69 / 20 50 40 20
WEY 38 70 32 61 / 10 30 20 20
DLN 48 71 39 65 / 20 60 50 20
HVR 59 84 51 73 / 20 80 90 20
LWT 53 80 44 69 / 20 60 80 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 190305
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
905 PM MDT Tue Jun 18 2013
.UPDATE...
A few strong thunderstorms continue to push northward through the
region. The thunderstorm watch will continue a bit longer where it
is currently in effect in case a severe storm develops. The flash
flood warnings will continue a bit longer as well. Expect a few
thunderstorms to continue after midnight. Otherwise current
forecast is on track. Brusda
&&
.AVIATION...
Updated 2355Z.
Widespread thunderstorm activity, mainly west of I-15 and north of
KBTM, will continue into the evening hours. Some storms are
producing large hail and very heavy rain. Less than VFR conditions
can be expected in heavy precipitation. Convective activity
diminishes after 06Z but another round of thunderstorms will develop
Wednesday. mpj
&&
.HYDROLOGY...
More widespread showers and thunderstorms are possible along the
Rocky Mountain Front and adjacent plains this afternoon and
evening and over most of the plains of North Central/Central
Montana on Wednesday. Some of these storms may produce brief heavy
rainfall. These periods will need to be monitored for possible
areal flood/flash flood highlights. The greater area of concern is
across eastern portions of north central and central Montana for
Wednesday that still have moist soil that would not be able to
absorb much rapid rainfall. If rainfall from storms today are
significant along the Rocky Mountain Front additional rainfall on
Wednesday will increase the flooding threat there as well.
&&
.PREV DISCUSSION...
/ISSUED 555 PM MDT Tue Jun 18 2013/
Today through Thursday...A low pressure system moving over the
Pacific Northwest coast today will bring increased moisture and
instability to Montana. These factors will help generate showers and
thunderstorms over terrain this afternoon. A frontal boundary
associated with this system will also move into Western Montana
today providing a good forcing mechanism for storm development. As a
result the Storm Prediction Center continues to keep Western and
Central Montana under a Slight Risk for severe thunderstorms. Storms
decrease overnight, but another round of potentially severe weather
is expected for Wednesday as the main system continues to move east
across the Northern Rockies. The most unstable conditions will also
shift northeast into Central and Eastern Montana, where the Storm
Prediction Center has a Slight Risk for Wednesday as well. The
potential for the strongest storms will be along and east of a
Havre-to-Stanford line as wind shear and instability are strongest
there. Precipitation from storms may be heavy adding the potential
for flash flooding. The system will lift northeast across the area
later Wednesday night into Thursday keeping high POPs in the
mountains. Westerly down-slope winds will hinder shower/thunderstorm
development Thursday though. Winds strengthen along the Rocky
Mountain Front Thursday making high wind highlights possible.
Temperatures cool Wednesday as the main front moves through the area.
Thursday night through Tuesday...No significant changes made to
the medium range forecast. An unsettled pattern will persist
through Saturday as a closed upper low will remain quasi-
stationary over northwest Montana. Short wave energy will
continue to rotate out from the base of the low and help initiate
shower and thunderstorm development each day. The strength of
these storms will depend on availability of low level moisture
and the strength of the divergent flow aloft. The models also
continue to differ on the upper low`s position which, in turn,
will affect where and how strong thunderstorms will be. Because
of these differences, have continued to broad-brush the pops
through Saturday. By late Saturday, the models move the low to
northeast Montana and lift it out as an upper ridge begins
building over the Pacific Northwest. The ridge breaks down on
Sunday as short wave energy ripples across the area within the
westerly flow aloft. Isolated thunderstorms will remain a
possibility Sunday and Monday. By Tuesday, weak upper ridging
returns though isolated showers will persist over the southwest
mountains. Temperatures will remain below seasonal averages to
start the period due to cloud cover and periodic cold advection
from transient shortwaves. Temperatures should rise above
seasonal averages to start the week.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 54 76 46 67 / 40 80 80 20
CTB 52 73 45 64 / 100 100 90 30
HLN 53 75 46 67 / 50 70 60 30
BZN 48 79 42 69 / 20 50 40 20
WEY 38 70 32 61 / 10 30 20 20
DLN 48 71 39 65 / 20 60 50 20
HVR 59 84 51 73 / 20 80 90 20
LWT 53 80 44 69 / 20 60 80 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
SEVERE THUNDERSTORM WATCH until 10 PM MDT this evening Eastern
Glacier...Eastern Pondera...Eastern Teton...Liberty...Northern
Rocky Mountain Front...Southern Rocky Mountain Front...Toole.
&&
$$
weather.gov/greatfalls
000
FXUS65 KBYZ 190259
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
859 PM MDT TUE JUN 18 2013
.UPDATE...
UPDATE TO FORECAST THIS EVENING. UPPER RIDGE OF HIGH PRESSURE
MOVING SLOWLY EASTWARD ACROSS THE FORECAST AREA THIS EVENING AS AN
UPPER TROUGH OF LOW PRESSURE MOVES ON TO THE PACIFIC WEST COAST.
ISOLATED THUNDERSTORMS DID DEVELOP OVER THE HIGHER TERRAIN THIS
AFTERNOON AND EVENING BUT DID NOT MOVE VERY FAR AWAY FROM THE
MOUNTAINS DUE TO VERY LIGHT MID-LEVEL STEERING WINDS. A FEW STORMS
DID PRODUCE HEAVY RAINFALL AS THEY WERE ABLE TO TAP INTO A SHALLOW
MOIST BOUNDARY LAYER. BULK WIND SHEAR WAS NON-EXISTENT AND NO
SEVRE WEATHER DEVELOPED. FOR TONIGHT...HAVE LOWERED POPS TO
ISOLATED FOR THE REST OF THE EVENING WITH A DRY FORECAST AFTER
06Z. DID BUMP OVERNIGHT LOWS UP A FEW DEGREES ACROSS THE CENTRAL
ZONES AS THERMAL RIDGE WILL REMAIN OVER THESE AREAS TONIGHT. REST
OF THE FORECAST ON TRACK. RICHMOND
&&
.SHORT TERM...VALID FOR WED AND THU...
CONVECTION WAS OCCURRING OVER SOUTHERN PARTS OF THE AREA PER
RADAR IMAGERY THIS AFTERNOON. LATEST RAP ANALYSIS SHOWED SURFACE
CAPES OF 1500-2500 J/KG OVER SE MT. ELSEWHERE...CAPES WERE IN THE
700 TO 2000 J/KG RANGE...PRETTY VARIABLE ACROSS THE FORECAST AREA.
SHEAR WAS GENERALLY WEAK...HOWEVER VALUES WERE 30 TO 35 KT OVER SE
MT...SO BEST CHANCES OF ANY STRONG TO SEVERE STORMS WILL BE OVER
THE SE. WILL CONTINUE TO MENTION SMALL HAIL/GUSTY WINDS ACROSS THE
AREA DUE TO THE CAPES AND INVERTED-V SOUNDINGS. HAD POPS ACROSS
THE AREA THIS EVENING...THEN ACTIVITY SHOULD DISSIPATE AFTER
MIDNIGHT MDT WITH LOSS OF HEATING.
JET ENERGY WILL ROTATE AROUND THE UPPER LOW OVER THE PACIFIC
NW...CAUSING IT TO PROGRESS E WITH TIME. WILL HAVE INCREASING
Q-VECTOR CONVERGENCE OVER THE AREA STARTING ON WED...AS SHORTWAVES
CONTINUE MOVING INTO THE REGION. UPPER DIFLUENCE WILL CONTINUE TO
CONTRIBUTE TO LIFT ON WED. BOTH THE GFS AND WRF HAD LARGE CAPES
2000-3000 J/KG OVER THE FAR EASTERN AND NORTHERN PARTS OF THE
AREA WED AND WED EVENING...AS WELL AS INCREASING SHEAR OVER THE
AREA FROM W TO E. HOWEVER...DRY AIR OVER THE FOUR CORNERS REGION
THIS AFTERNOON WILL ADVECT N INTO THE FORECAST AREA ON
WED...KEEPING THE E DRY THROUGH THE DAY. WILL KEEP A CHANCE OF
THUNDERSTORMS OVER THE NW HALF OF THE REGION FROM KBIL N AND W...AND
WILL CONTINUE TO MENTION POSSIBLE SEVERE OVER THE N. COLD FRONT
MOVES THROUGH WED NIGHT BRINGING A CHANCE OF THUNDERSTORMS TO MOST
OF THE AREA.
UPPER LOW WILL ROTATE OVER ID THU AND THU NIGHT. CAPES WILL BE VERY
LOW ON THU. HAD LOW POPS ACROSS THE AREA. A SECONDARY COLD FRONT
WITH FRONTOGENESIS WILL MOVE THROUGH THE REGION THU
NIGHT...BRINGING A BETTER CHANCE OF PRECIPITATION.
WILL HAVE A WARM NIGHT TONIGHT AS 850 MB THERMAL RIDGE MOVES INTO
THE AREA AND LOW-LEVEL JET STRENGTHENS OVER THE E. WED WILL BE HOT
WITH 700 MB TEMPERATURES AROUND +14 DEGREES C AHEAD OF THE COLD
FRONT. ARTHUR
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
PAC NW UPPER LOW WILL KICK SLOWLY THROUGH THE REGION FRI/SAT...AND
ALL MODELS HAVE TRENDED SIMILARLY WITH REGARD TO STRENGTH AND
TIMING OF THIS FEATURE. WITH CONFIDENCE HAVE RAISED POPS ACROSS
THE REGION ON THESE DAYS. ACTIVITY IN THE WEST SHOULD BE NON-
SEVERE THOUGH WITH LOW WET BULB TEMPS SOME SMALL HAIL IS POSSIBLE
WITH ANY STRONGER CELLS. GFS SHOWS DEEPER MOISTURE AND INSTABILITY
MAY SURGE FROM THE DAKOTAS INTO OUR EAST AHEAD OF THE UPPER
LOW...SO CANNOT RULE OUT THE POTENTIAL FOR SEVERE STORMS IN OUR
EAST ON THESE DAYS...ALONG WITH HEAVY RAIN. SYSTEM WILL EXIT TO
OUR EAST EITHER SATURDAY NIGHT OR EARLY SUNDAY. TEMPS FRIDAY AND
SATURDAY WILL COOL TO SLIGHTLY BELOW NORMAL.
DRIER CONDITIONS SHOULD EMERGE BY SUNDAY IN OUR WEST...WITH A
PERIOD OF DRY WX PERHAPS EXTENDING INTO MONDAY UNDER SHORTWAVE
RIDGING. MODELS DIVERGE A BIT IN THE HANDLING OF THE PACIFIC FLOW
HERE. WILL ADVERTISE A DRY PERIOD SUNDAY INTO MONDAY...THEN SLIGHT
POPS MONDAY AFTERNOON THROUGH TUESDAY AS WE MAY BE IMPACTED BY
PACIFIC SHORTWAVE ENERGY BY THEN. TEMPS SHOULD RETURN BACK TO A
LITTLE ABOVE NORMAL BY DAYS 6/7.
LOOKING FURTHER AHEAD...LATEST GFS/ECMWF SHOW STRONGER RIDGING
WITH NEAR 590DAM HEIGHTS BY WED/THU OF NEXT WEEK. WILL NEED TO
KEEP WATCH OF THIS TREND.
JKL
&&
.AVIATION...
AN ISOLATED THUNDERSTORM MAY PERSIST UNTIL 06Z FROM NORTHERN
WYOMING INTO SOUTHEAST MONTANA WITH LOCAL MVFR VISIBILITY IN HEAVY
RAINFALL. OTHERWISE VFR CONDITIONS EXPECTED THROUGH MID DAY
WEDNESDAY. ANOTHER ROUND OF ISOLATED TO SCATTERED THUNDERSTORMS IS
EXPECTED WEDNESDAY AFTERNOON AND EVENING. WIND GUSTS WITH THESE
STORMS WILL BE STRONG AT TIMES. CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
WED THU FRI SAT SUN MON TUE
-----------------------------------------------------------
BIL 061/089 052/077 052/072 052/069 051/078 054/082 056/082
22/T 22/T 33/T 34/T 41/B 12/T 22/T
LVM 051/084 043/072 041/069 042/067 046/079 046/082 049/081
33/T 23/T 33/T 34/T 40/B 02/T 22/T
HDN 061/091 053/078 052/074 050/072 050/078 052/082 052/083
21/U 22/T 32/T 34/T 41/B 12/T 22/T
MLS 061/096 058/081 055/076 056/076 055/080 056/083 057/083
21/N 22/T 44/T 34/T 43/T 22/T 22/T
4BQ 061/095 054/081 055/076 054/075 053/079 054/084 055/084
21/N 22/T 44/T 34/T 42/T 12/T 22/T
BHK 057/090 057/080 054/076 055/074 054/076 054/080 057/082
21/N 22/T 36/T 54/T 43/T 22/T 22/T
SHR 054/090 048/078 050/073 048/073 047/076 049/081 050/082
31/U 22/T 32/T 23/T 31/B 12/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KMSO 190223 AAA
AFDMSO
Area Forecast Discussion...UPDATED
National Weather Service Missoula MT
823 PM MDT Tue Jun 18 2013
.UPDATE...Cancelled the Severe Thunderstorm Watch for Flathead
County, Montana.
&&
.DISCUSSION...Storm development has subsided across western
Montana this evening, but isolated, weaker storms may continue
through the night. As a result, the Severe Thunderstorm Watch has
been cancelled for Flathead County.
&&
.AVIATION...Isolated, weak storms continue across much of
northwestern Montana this evening, but the threat for severe storms
has ended. A second wave of thunderstorms is expected to form
overnight and will affect mostly north central Idaho into
northwest Montana, although at the time, this convection should miss
the TAF terminals. Late tonight into tomorrow morning, heavy rain
will develop across the region and produce low ceilings, which
will obscure the higher terrain and periodically lower visibility.
&&
.PREV DISCUSSION... /ISSUED 742 PM MDT Tue Jun 18 2013/
UPDATE...The severe thunderstorm watch has been cancelled for all
counties except Flathead County.
DISCUSSION...The main focus of thunderstorms has shifted north
into Flathead County this evening. The threat for severe
thunderstorms in Flathead County will remain for at least another
hour or two. The main threats will be heavy rain, gusty winds and
isolated hail. Further south in southwest and west central
Montana, the favorable environment for strong thunderstorms has
waned. Although showers and isolated thunderstorms remain, they
are no longer expected to be severe. Another round of
thunderstorms is possible late this evening and overnight, and
should be mostly focus across north central Idaho into northwest
Montana. The main threat with these storms will be for very heavy
rain, although small hail and gusty winds cannot be ruled out.
PREV DISCUSSION... /ISSUED 215 PM MDT Tue Jun 18 2013/
DISCUSSION...An active weather scenario is setting up for the
next 24-48 hours as a low pressure system begins to approach and move
through western Montana and north central Idaho. Below are listed
the main impacts with this system:
***Strong Thunderstorms***: Thunderstorms are already beginning to
form this afternoon under good surface heating and lots of energy
and moisture aloft, a favorable pattern for strong to severe
thunderstorms exists. The storms are expected to come in two main waves.
The first wave is expected to form across southwest Montana this
afternoon and move northward into west central and northwest
Montana (generally east of a line from Hamilton to Missoula to
Kalispell) this afternoon and evening. A second wave of
thunderstorms will develop tonight over north central Idaho and
move into northwest Montana (generally west of a line from Lost
Trail Pass to Lowell to Plains to Eureka) overnight.
Thunderstorms will have the potential to produce very heavy rain
(which could affect flood prone basins and recent burn areas in
Idaho county), hail potentially over 1 inch in diameter and
strong winds greater than 50 mph. Those with outdoor activities
today and tonight should keep an eye to the sky.
***Heavy rain***: As the upper low pressure system moves into the
region tonight and Wednesday, a scenario for very heavy rain is
developing. The heaviest rain is expected across the Clearwater
mountains into the Idaho panhandle and across northwest Montana.
1" to 2" of rain are possible in these areas tonight through
Wednesday night. River and stream levels will likely rise
although flooding is not anticipated at this time. There could be
localized issues with ponding of water on roadways in urban
areas. Elsewhere, most all of the region should see a wetting
rain however amounts will be lower as you head into southwest
Montana and Lemhi County. Another wave of moisture and energy
associated with the upper low pressure system will impact
northern Idaho and western Montana Wednesday afternoon. This
could mean an additional 0.25 to 0.75 inch of rain, with the
higher amounts in the higher terrain of northwest Montana.
***High terrain and mountain pass snow***: As the upper low
pressure system approaches late Wednesday, much cooler air will
rush into northern Idaho and western Montana. Snow levels should
be between 6000 to 7000 feet with some slushy snow/road impacts
possible over higher mountain passes such as Lost Trail Pass by
Thursday morning. However, by the time the cooler air arrives,
the heaviest precipitation should shift north into Canada and
well east of the Divide. The upper low pressure system will
continue to direct surges of moisture and a very cool air mass
over the northern Rockies Friday and Saturday. Higher terrain
areas should continue to see some additional snow.
In the longer term, the very cool and moist low pressure system
should exit to the east late Saturday. However, it appears a moist
westerly flow may set up over the northern Rockies late Sunday,
Monday and Tuesday with additional showers.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
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https://www.facebook.com/US.NationalWeatherService.Missoula.gov
https://www.twitter.com/NWSMissoula
000
FXUS65 KMSO 190142
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
742 PM MDT Tue Jun 18 2013
.UPDATE...The severe thunderstorm watch has been cancelled for all
counties except Flathead County.
&&
.DISCUSSION...The main focus of thunderstorms has shifted north
into Flathead County this evening. The threat for severe
thunderstorms in Flathead County will remain for at least another
hour or two. The main threats will be heavy rain, gusty winds and
isolated hail. Further south in southwest and west central
Montana, the favorable environment for strong thunderstorms has
waned. Although showers and isolated thunderstorms remain, they
are no longer expected to be severe. Another round of
thunderstorms is possible late this evening and overnight, and
should be mostly focus across north central Idaho into northwest
Montana. The main threat with these storms will be for very heavy
rain, although small hail and gusty winds cannot be ruled out.
&&
.AVIATION...Scattered thunderstorms have already developed across
southwest Montana this afternoon. These storms are expected to
track northward through the afternoon and early evening and could
impact airfields KBTM between 18/2000z and 18/2300z, KMSO between
18/2200z and 19/0100z and KGPI between 18/2300z and 19/0300z. Some
thunderstorms could become quite strong with wind gusts over 45
kts, hail and very heavy rain reducing visibility at times. A
second wave of thunderstorms is expected to form late this evening
and will affect mostly north central Idaho into northwest Montana
although at the time this convection should miss the TAF
terminals. Late tonight into tomorrow morning, heavy rain will
develop across the region producing low ceilings which will
obscure the higher terrain and periodically lower visibility.
&&
.PREV DISCUSSION... /ISSUED 215 PM MDT Tue Jun 18 2013/
DISCUSSION...An active weather scenario is setting up for the
next 24-48 hours as a low pressure system begins to approach and move
through western Montana and north central Idaho. Below are listed
the main impacts with this system:
***Strong Thunderstorms***: Thunderstorms are already beginning to
form this afternoon under good surface heating and lots of energy
and moisture aloft, a favorable pattern for strong to severe
thunderstorms exists. The storms are expected to come in two main waves.
The first wave is expected to form across southwest Montana this
afternoon and move northward into west central and northwest
Montana (generally east of a line from Hamilton to Missoula to
Kalispell) this afternoon and evening. A second wave of
thunderstorms will develop tonight over north central Idaho and
move into northwest Montana (generally west of a line from Lost
Trail Pass to Lowell to Plains to Eureka) overnight.
Thunderstorms will have the potential to produce very heavy rain
(which could affect flood prone basins and recent burn areas in
Idaho county), hail potentially over 1 inch in diameter and
strong winds greater than 50 mph. Those with outdoor activities
today and tonight should keep an eye to the sky.
***Heavy rain***: As the upper low pressure system moves into the
region tonight and Wednesday, a scenario for very heavy rain is
developing. The heaviest rain is expected across the Clearwater
mountains into the Idaho panhandle and across northwest Montana.
1" to 2" of rain are possible in these areas tonight through
Wednesday night. River and stream levels will likely rise
although flooding is not anticipated at this time. There could be
localized issues with ponding of water on roadways in urban
areas. Elsewhere, most all of the region should see a wetting
rain however amounts will be lower as you head into southwest
Montana and Lemhi County. Another wave of moisture and energy
associated with the upper low pressure system will impact
northern Idaho and western Montana Wednesday afternoon. This
could mean an additional 0.25 to 0.75 inch of rain, with the
higher amounts in the higher terrain of northwest Montana.
***High terrain and mountain pass snow***: As the upper low
pressure system approaches late Wednesday, much cooler air will
rush into northern Idaho and western Montana. Snow levels should
be between 6000 to 7000 feet with some slushy snow/road impacts
possible over higher mountain passes such as Lost Trail Pass by
Thursday morning. However, by the time the cooler air arrives,
the heaviest precipitation should shift north into Canada and
well east of the Divide. The upper low pressure system will
continue to direct surges of moisture and a very cool air mass
over the northern Rockies Friday and Saturday. Higher terrain
areas should continue to see some additional snow.
In the longer term, the very cool and moist low pressure system
should exit to the east late Saturday. However, it appears a moist
westerly flow may set up over the northern Rockies late Sunday,
Monday and Tuesday with additional showers.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
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https://www.facebook.com/US.NationalWeatherService.Missoula.gov
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000
FXUS65 KTFX 190053
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
653 PM MDT Tue Jun 18 2013
.UPDATE...Strong to severe thunderstorms will continue to affect my
northwest zones through the evening hours. Have updated the
forecast to increase pops across this area for the remainder of
tonight. There is some concern that widespread heavy rains in this
area may cause flooding concerns. This potential will continue to
be monitored through the night. mpj
&&
.AVIATION...
Updated 2355Z.
Widespread thunderstorm activity, mainly west of I-15 and north of
KBTM, will continue into the evening hours. Some storms are
producing large hail and very heavy rain. Less than VFR conditions
can be expected in heavy precipitation. Convective activity
diminishes after 06Z but another round of thunderstorms will develop
Wednesday. mpj
&&
.HYDROLOGY...
More widespread showers and thunderstorms are possible along the
Rocky Mountain Front and adjacent plains this afternoon and
evening and over most of the plains of North Central/Central
Montana on Wednesday. Some of these storms may produce brief heavy
rainfall. These periods will need to be monitored for possible
areal flood/flash flood highlights. The greater area of concern is
across eastern portions of north central and central Montana for
Wednesday that still have moist soil that would not be able to
absorb much rapid rainfall. If rainfall from storms today are
significant along the Rocky Mountain Front additional rainfall on
Wednesday will increase the flooding threat there as well.
&&
.PREV DISCUSSION...
/ISSUED 555 PM MDT Tue Jun 18 2013/
Today through Thursday...A low pressure system moving over the
Pacific Northwest coast today will bring increased moisture and
instability to Montana. These factors will help generate showers and
thunderstorms over terrain this afternoon. A frontal boundary
associated with this system will also move into Western Montana
today providing a good forcing mechanism for storm development. As a
result the Storm Prediction Center continues to keep Western and
Central Montana under a Slight Risk for severe thunderstorms. Storms
decrease overnight, but another round of potentially severe weather
is expected for Wednesday as the main system continues to move east
across the Northern Rockies. The most unstable conditions will also
shift northeast into Central and Eastern Montana, where the Storm
Prediction Center has a Slight Risk for Wednesday as well. The
potential for the strongest storms will be along and east of a
Havre-to-Stanford line as wind shear and instability are strongest
there. Precipitation from storms may be heavy adding the potential
for flash flooding. The system will lift northeast across the area
later Wednesday night into Thursday keeping high POPs in the
mountains. Westerly down-slope winds will hinder shower/thunderstorm
development Thursday though. Winds strengthen along the Rocky
Mountain Front Thursday making high wind highlights possible.
Temperatures cool Wednesday as the main front moves through the area.
Thursday night through Tuesday...No significant changes made to
the medium range forecast. An unsettled pattern will persist
through Saturday as a closed upper low will remain quasi-
stationary over northwest Montana. Short wave energy will
continue to rotate out from the base of the low and help initiate
shower and thunderstorm development each day. The strength of
these storms will depend on availability of low level moisture
and the strength of the divergent flow aloft. The models also
continue to differ on the upper low`s position which, in turn,
will affect where and how strong thunderstorms will be. Because
of these differences, have continued to broad-brush the pops
through Saturday. By late Saturday, the models move the low to
northeast Montana and lift it out as an upper ridge begins
building over the Pacific Northwest. The ridge breaks down on
Sunday as short wave energy ripples across the area within the
westerly flow aloft. Isolated thunderstorms will remain a
possibility Sunday and Monday. By Tuesday, weak upper ridging
returns though isolated showers will persist over the southwest
mountains. Temperatures will remain below seasonal averages to
start the period due to cloud cover and periodic cold advection
from transient shortwaves. Temperatures should rise above
seasonal averages to start the week.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 54 76 46 67 / 40 80 80 20
CTB 52 73 45 64 / 100 100 90 30
HLN 53 75 46 67 / 50 70 60 30
BZN 48 79 42 69 / 30 50 40 20
WEY 38 70 32 61 / 20 30 20 20
DLN 48 71 39 65 / 20 60 50 20
HVR 59 84 51 73 / 20 80 90 20
LWT 53 80 44 69 / 20 60 80 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
SEVERE THUNDERSTORM WATCH until 10 PM MDT this evening
Broadwater...Cascade...Central and Southern Lewis and Clark...
Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...
Hill...Jefferson...Judith Basin...Liberty...Meagher...Northern
Rocky Mountain Front...Southern Rocky Mountain Front...Toole.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 182352
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
555 PM MDT Tue Jun 18 2013
...UPDATE TO AVIATION...
.DISCUSSION...
Today through Thursday...A low pressure system moving over the
Pacific Northwest coast today will bring increased moisture and
instability to Montana. These factors will help generate showers and
thunderstorms over terrain this afternoon. A frontal boundary
associated with this system will also move into Western Montana
today providing a good forcing mechanism for storm development. As a
result the Storm Prediction Center continues to keep Western and
Central Montana under a Slight Risk for severe thunderstorms. Storms
decrease overnight, but another round of potentially severe weather
is expected for Wednesday as the main system continues to move east
across the Northern Rockies. The most unstable conditions will also
shift northeast into Central and Eastern Montana, where the Storm
Prediction Center has a Slight Risk for Wednesday as well. The
potential for the strongest storms will be along and east of a
Havre-to-Stanford line as wind shear and instability are strongest
there. Precipitation from storms may be heavy adding the potential
for flash flooding. The system will lift northeast across the area
later Wednesday night into Thursday keeping high POPs in the
mountains. Westerly down-slope winds will hinder shower/thunderstorm
development Thursday though. Winds strengthen along the Rocky
Mountain Front Thursday making high wind highlights possible.
Temperatures cool Wednesday as the main front moves through the area.
Thursday night through Tuesday...No significant changes made to
the medium range forecast. An unsettled pattern will persist
through Saturday as a closed upper low will remain quasi-
stationary over northwest Montana. Short wave energy will
continue to rotate out from the base of the low and help initiate
shower and thunderstorm development each day. The strength of
these storms will depend on availability of low level moisture
and the strength of the divergent flow aloft. The models also
continue to differ on the upper low`s position which, in turn,
will affect where and how strong thunderstorms will be. Because
of these differences, have continued to broad-brush the pops
through Saturday. By late Saturday, the models move the low to
northeast Montana and lift it out as an upper ridge begins
building over the Pacific Northwest. The ridge breaks down on
Sunday as short wave energy ripples across the area within the
westerly flow aloft. Isolated thunderstorms will remain a
possibility Sunday and Monday. By Tuesday, weak upper ridging
returns though isolated showers will persist over the southwest
mountains. Temperatures will remain below seasonal averages to
start the period due to cloud cover and periodic cold advection
from transient shortwaves. Temperatures should rise above
seasonal averages to start the week.
&&
.AVIATION...
Updated 2355Z.
Widespread thunderstorm activity, mainly west of I-15 and north of
KBTM, will continue into the evening hours. Some storms are
producing large hail and very heavy rain. Less than VFR conditions
can be expected in heavy precipitation. Convective activity
diminishes after 06Z but another round of thunderstorms will develop
Wednesday. mpj
&&
.HYDROLOGY...
More widespread showers and thunderstorms are possible along the
Rocky Mountain Front and adjacent plains this afternoon and
evening and over most of the plains of North Central/Central
Montana on Wednesday. Some of these storms may produce brief heavy
rainfall. These periods will need to be monitored for possible
areal flood/flash flood highlights. The greater area of concern is
across eastern portions of north central and central Montana for
Wednesday that still have moist soil that would not be able to
absorb much rapid rainfall. If rainfall from storms today are
significant along the Rocky Mountain Front additional rainfall on
Wednesday will increase the flooding threat there as well.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 54 76 46 67 / 60 80 80 20
CTB 52 73 45 64 / 70 100 90 30
HLN 53 75 46 67 / 50 70 60 30
BZN 48 79 42 69 / 30 50 40 20
WEY 38 70 32 61 / 20 30 20 20
DLN 48 71 39 65 / 40 60 50 20
HVR 59 84 51 73 / 50 80 90 20
LWT 53 80 44 69 / 40 60 80 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
SEVERE THUNDERSTORM WATCH until 10 PM MDT this evening
Broadwater...Cascade...Central and Southern Lewis and Clark...
Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...
Hill...Jefferson...Judith Basin...Liberty...Meagher...Northern
Rocky Mountain Front...Southern Rocky Mountain Front...Toole.
&&
$$
weather.gov/greatfalls
000
FXUS65 KBYZ 182100
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
300 PM MDT TUE JUN 18 2013
.SHORT TERM...VALID FOR WED AND THU...
CONVECTION WAS OCCURRING OVER SOUTHERN PARTS OF THE AREA PER
RADAR IMAGERY THIS AFTERNOON. LATEST RAP ANALYSIS SHOWED SURFACE
CAPES OF 1500-2500 J/KG OVER SE MT. ELSEWHERE...CAPES WERE IN THE
700 TO 2000 J/KG RANGE...PRETTY VARIABLE ACROSS THE FORECAST AREA.
SHEAR WAS GENERALLY WEAK...HOWEVER VALUES WERE 30 TO 35 KT OVER SE
MT...SO BEST CHANCES OF ANY STRONG TO SEVERE STORMS WILL BE OVER
THE SE. WILL CONTINUE TO MENTION SMALL HAIL/GUSTY WINDS ACROSS THE
AREA DUE TO THE CAPES AND INVERTED-V SOUNDINGS. HAD POPS ACROSS
THE AREA THIS EVENING...THEN ACTIVITY SHOULD DISSIPATE AFTER
MIDNIGHT MDT WITH LOSS OF HEATING.
JET ENERGY WILL ROTATE AROUND THE UPPER LOW OVER THE PACIFIC
NW...CAUSING IT TO PROGRESS E WITH TIME. WILL HAVE INCREASING
Q-VECTOR CONVERGENCE OVER THE AREA STARTING ON WED...AS SHORTWAVES
CONTINUE MOVING INTO THE REGION. UPPER DIFLUENCE WILL CONTINUE TO
CONTRIBUTE TO LIFT ON WED. BOTH THE GFS AND WRF HAD LARGE CAPES
2000-3000 J/KG OVER THE FAR EASTERN AND NORTHERN PARTS OF THE
AREA WED AND WED EVENING...AS WELL AS INCREASING SHEAR OVER THE
AREA FROM W TO E. HOWEVER...DRY AIR OVER THE FOUR CORNERS REGION
THIS AFTERNOON WILL ADVECT N INTO THE FORECAST AREA ON
WED...KEEPING THE E DRY THROUGH THE DAY. WILL KEEP A CHANCE OF
THUNDERSTORMS OVER THE NW HALF OF THE REGION FROM KBIL N AND W...AND
WILL CONTINUE TO MENTION POSSIBLE SEVERE OVER THE N. COLD FRONT
MOVES THROUGH WED NIGHT BRINGING A CHANCE OF THUNDERSTORMS TO MOST
OF THE AREA.
UPPER LOW WILL ROTATE OVER ID THU AND THU NIGHT. CAPES WILL BE VERY
LOW ON THU. HAD LOW POPS ACROSS THE AREA. A SECONDARY COLD FRONT
WITH FRONTOGENESIS WILL MOVE THROUGH THE REGION THU
NIGHT...BRINGING A BETTER CHANCE OF PRECIPITATION.
WILL HAVE A WARM NIGHT TONIGHT AS 850 MB THERMAL RIDGE MOVES INTO
THE AREA AND LOW-LEVEL JET STRENGTHENS OVER THE E. WED WILL BE HOT
WITH 700 MB TEMPERATURES AROUND +14 DEGREES C AHEAD OF THE COLD
FRONT. ARTHUR
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
PAC NW UPPER LOW WILL KICK SLOWLY THROUGH THE REGION FRI/SAT...AND
ALL MODELS HAVE TRENDED SIMILARLY WITH REGARD TO STRENGTH AND
TIMING OF THIS FEATURE. WITH CONFIDENCE HAVE RAISED POPS ACROSS
THE REGION ON THESE DAYS. ACTIVITY IN THE WEST SHOULD BE NON-
SEVERE THOUGH WITH LOW WET BULB TEMPS SOME SMALL HAIL IS POSSIBLE
WITH ANY STRONGER CELLS. GFS SHOWS DEEPER MOISTURE AND INSTABILITY
MAY SURGE FROM THE DAKOTAS INTO OUR EAST AHEAD OF THE UPPER
LOW...SO CANNOT RULE OUT THE POTENTIAL FOR SEVERE STORMS IN OUR
EAST ON THESE DAYS...ALONG WITH HEAVY RAIN. SYSTEM WILL EXIT TO
OUR EAST EITHER SATURDAY NIGHT OR EARLY SUNDAY. TEMPS FRIDAY AND
SATURDAY WILL COOL TO SLIGHTLY BELOW NORMAL.
DRIER CONDITIONS SHOULD EMERGE BY SUNDAY IN OUR WEST...WITH A
PERIOD OF DRY WX PERHAPS EXTENDING INTO MONDAY UNDER SHORTWAVE
RIDGING. MODELS DIVERGE A BIT IN THE HANDLING OF THE PACIFIC FLOW
HERE. WILL ADVERTISE A DRY PERIOD SUNDAY INTO MONDAY...THEN SLIGHT
POPS MONDAY AFTERNOON THROUGH TUESDAY AS WE MAY BE IMPACTED BY
PACIFIC SHORTWAVE ENERGY BY THEN. TEMPS SHOULD RETURN BACK TO A
LITTLE ABOVE NORMAL BY DAYS 6/7.
LOOKING FURTHER AHEAD...LATEST GFS/ECMWF SHOW STRONGER RIDGING
WITH NEAR 590DAM HEIGHTS BY WED/THU OF NEXT WEEK. WILL NEED TO
KEEP WATCH OF THIS TREND.
JKL
&&
.AVIATION...
A WEAK DISTURBANCE WILL BRING ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH GREATEST COVERAGE
NEAR THE MTNS AND FOOTHILLS...POSSIBLY IMPACTING KLVM AND KSHR AT
TIMES. VFR WILL PREVAIL BUT LOCAL MVFR IS POSSIBLE IN ANY STRONGER
STORMS...AND MOUNTAINS WILL BE OCCASIONALLY OBSCURED. THIS
ACTIVITY WILL DIMINISH AFTER SUNSET. ON WEDNESDAY...AN APPROACHING
COLD FRONT WILL BRING ANOTHER CHANCE OF THUNDERSTORMS ALONG WITH
GUSTIER WINDS. JKL
&&
.PRELIMINARY POINT TEMP/POPS...
WED THU FRI SAT SUN MON TUE
-----------------------------------------------------------
BIL 060/089 052/077 052/072 052/069 051/078 054/082 056/082
22/T 22/T 33/T 34/T 41/B 12/T 22/T
LVM 050/084 043/072 041/069 042/067 046/079 046/082 049/081
33/T 23/T 33/T 34/T 40/B 02/T 22/T
HDN 059/091 053/078 052/074 050/072 050/078 052/082 052/083
21/U 22/T 32/T 34/T 41/B 12/T 22/T
MLS 061/096 058/081 055/076 056/076 055/080 056/083 057/083
21/N 22/T 44/T 34/T 43/T 22/T 22/T
4BQ 061/095 054/081 055/076 054/075 053/079 054/084 055/084
31/N 22/T 44/T 34/T 42/T 12/T 22/T
BHK 057/090 057/080 054/076 055/074 054/076 054/080 057/082
31/N 22/T 36/T 54/T 43/T 22/T 22/T
SHR 054/090 048/078 050/073 048/073 047/076 049/081 050/082
31/U 22/T 32/T 23/T 31/B 12/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 182100
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
300 PM MDT TUE JUN 18 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY...
STORMS ARE BEGINNING TO FIRE UP ALONG THE CENTRAL MONTANA
MOUNTAINS THIS AFTERNOON. THESE STORMS WILL PUSH TO THE NORTH AND
NORTHEAST AND COULD MOVE INTO NORTHEAST MONTANA THIS EVENING AND
OVERNIGHT. THUS KEPT MENTION OF ISOLATED SHOWERS IN FOR THE
AFTERNOON AND EVENING. BRISK SOUTHEAST WINDS WILL CONTINUE
OVERNIGHT IN RESPONSE TO A DEVELOPING SURFACE LOW OVER CENTRAL
MONTANA. WITH SOUTHEAST WINDS CONTINUING INTO WEDNESDAY
EVENING...THE LAKE WIND ADVISORY LOOKS ON TRACK THROUGH MIDNIGHT
WEDNESDAY NIGHT. A NOCTURNAL STORM OR TWO CAN NOT BE RULED OUT
THANKS TO WEAK QG FORCING AND MIDLEVEL INSTABILITY OVER THE NORTH
AND WEST.
WEDNESDAY GUSTY LOW LEVEL SOUTHEAST FLOW WILL CONTINUE TO ADVECT
IN GULF MOISTURE OUT OF THE GREAT PLAINS...ADDING TO THE ALREADY
EXCELLENT SURFACE BASED INSTABILITY OF 3000 J/KG WEDNESDAY
AFTERNOON. WITH THAT SAID...SHEAR LOOKS A BIT MARGINAL OVER THE
EASTERN 2/3RDS OF NORTHEAST MONTANA...AND MAY WELL HELP LIMIT THE
THREAT FOR SEVERE STORMS.
STILL THINKING STORMS WILL FIRE WEDNESDAY AFTERNOON OVER THE CENTRAL
MONTANA MOUNTAINS...DRIFTING NORTHEASTWARD INTO THE AREA THROUGH
THE AFTERNOON AND EVENING HOURS. A CONVECTIVE COMPLEX WILL LIKELY
DEVELOP...IMPACTING THE NORTH WITH HEAVY RAINFALL THROUGH THE
OVERNIGHT HOURS WEDNESDAY NIGHT/THURSDAY MORNING. GUSTY SOUTHEAST
WINDS WILL SWITCH TO THE WEST BEHIND THE ASSOCIATED SURFACE FRONT
LATE WEDNESDAY NIGHT.
BY MIDDAY THURSDAY THE COMPLEX WILL HAVE EXITED THE AREA...BUT
WITH THE UPPER TROUGH OVERHEAD AND LINGERING LOW LEVEL MOISTURE
CAN NOT RULE OUT AN ISOLATED SHOWER OR THUNDERSTORM. TEMPERATURES
WILL BE COOLER...IN THE MID 70S TO LOW 80S. GILCHRIST
.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
ONLY MINOR TWEAKS WERE MADE TO THE EXTENDED FORECAST. THE LONG
RANGE FORECAST REMAINS ON TRACK WITH AN UPPER CLOSED LOW ACROSS
THE PACIFIC NORTHWEST AND NORTHEAST MONTANA UNDER SOUTHWEST FLOW
ALOFT BEGINNING ON THURSDAY NIGHT. PULSES OF SHORTWAVE ENERGY
PROPAGATING AROUND THIS UPPER LOW WILL LEAD TO POSSIBLE SHOWERS
AND THUNDERSTORMS EACH DAY THROUGH THE WEEKEND. BOTH THE 12Z
ECMWF AND GFS SOLUTIONS CARRY A COUPLE OF PARTICULARLY VIGOROUS
SHORTWAVES THROUGH THE AREA DURING THE WEEKEND. THERE SHOULD BE
PLENTY OF AVAILABLE MOISTURE WITH LOW LEVEL SOUTHEASTERLY FLOW IN
PLACE AND SO RAISED POPS FROM THE FRIDAY NIGHT THROUGH SUNDAY TIME
PERIOD...AND THEN TAPERED DOWN PRECIPITATION CHANCES FROM WEST TO
EAST AS THE UPPER LEVEL ENERGY PULLS OUT OF THE FORECAST REGION BY
SUNDAY NIGHT.
MONDAY AND BEYOND...KEPT SLIGHT CHANCE POPS IN THE GRIDS FOR
NOW...BUT MODEL GUIDANCE INDICATES THAT SOUTHWEST FLOW ALOFT
ACROSS THE CWA SHOULD TRANSITION INTO MORE OF A RIDGING PATTERN
SOMETIME DURING THE MIDDLE PORTION OF THE WEEK. THIS SHOULD
PROMOTE LARGE SCALE SUBSIDENCE AND A DRYING PATTERN.
ADDITIONALLY...THIS MAY ALLOW FOR A MODERATION IN TEMPERATURES AND
SO TRENDED TEMPERATURES WARMER TOWARD THE MIDDLE OF THE WEEK. MALIAWCO
PREVIOUS LONG TERM DISCUSSION...
SYNOPTIC SET UP... LONG TERM BEGINS WITH A DOME OF HEAT OVER THE
DESERT SOUTHWEST AND A RIDGE SPURRING OFF ACROSS COLORADO... THE
CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY. A LARGE TROUGH HAS
EMBEDDED ITSELF INTO THE PACIFIC NORTHWEST. NORTHEAST MONTANA IS
WEDGED BETWEEN THESE TWO AIRMASSES IN SOUTHWEST FLOW ALOFT. A WEAK
RIDGE ALSO RUNS FROM SOUTHERN SASKATCHEWAN THROUGH NORTHERN
ALBERTA AND INTO NORTHER ALASKA.
THURSDAY NIGHT THROUGH SATURDAY NIGHT... THE CORE OF THE CLOSED LOW
TO THE WEST IS EXPECTED TO DRIFT ONTO THE HIGH PLAINS AND WILL
COOL TEMPERATURES DOWN FOR AWHILE ALLOWING FOR A CHANCE OF SHOWERS
AND THUNDERSTORMS EACH AFTERNOON AND EVENING.
SUNDAY ONWARD... MODELS ARE HAVING PROBLEMS DECIDED WHAT TO TO DO
WITH THIS LOW ONCE ITS OVER THE HIGH PLAINS. CONSISTENCY FROM RUN
TO RUN AND MODEL TO MODEL SEEMS FAIRLY POOR... DECREASING CONFIDENCE.
CURRENTLY MODELS POINT TOWARD THE CLOSED LOW KICKING OFF TOWARD
ONTARIO AND A NEW RIDGE ESTABLISHING ITSELF RIGHT BEHIND OVER
WESTERN MONTANA ON MONDAY. THIS RIDGE SHOULD BECOME A GREATER
INFLUENCE WITH WARMING TEMPERATURES AND DECREASING CHANCES FOR
THUNDER THROUGH MID WEEK.
&&
.AVIATION...
AN ISOLATED SHOWER OR THUNDERSTORM REMAINS POSSIBLE THROUGH
TONIGHT BUT VFR CONDITIONS WILL CONTINUE TO PREVAIL AT THE
TERMINALS. MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO DEVELOP WEDNESDAY AND WEDNESDAY EVENING. THIS MAY RESULT IN
REDUCED CEILINGS AND VISIBILITIES. MVFR IS THEREFORE POSSIBLE IN
SOME OF THE HEAVIER THUNDERSTORMS. WINDS ARE ANTICIPATED TO BE FROM THE
SOUTHEAST THROUGH WEDNESDAY FROM 10 TO 20 KTS WITH GUSTS AS HIGH
AS 30 KTS. MALIAWCO
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL MIDNIGHT MDT WEDNESDAY NIGHT FOR FORT
PECK LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND
SOUTHERN VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 182043
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
243 PM MDT Tue Jun 18 2013
.DISCUSSION...
Today through Thursday...A low pressure system moving over the
Pacific Northwest coast today will bring increased moisture and
instability to Montana. These factors will help generate showers and
thunderstorms over terrain this afternoon. A frontal boundary
associated with this system will also move into Western Montana
today providing a good forcing mechanism for storm development. As a
result the Storm Prediction Center continues to keep Western and
Central Montana under a Slight Risk for severe thunderstorms. Storms
decrease overnight, but another round of potentially severe weather
is expected for Wednesday as the main system continues to move east
across the Northern Rockies. The most unstable conditions will also
shift northeast into Central and Eastern Montana, where the Storm
Prediction Center has a Slight Risk for Wednesday as well. The
potential for the strongest storms will be along and east of a
Havre-to-Stanford line as wind shear and instability are strongest
there. Precipitation from storms may be heavy adding the potential
for flash flooding. The system will lift northeast across the area
later Wednesday night into Thursday keeping high POPs in the
mountains. Westerly down-slope winds will hinder shower/thunderstorm
development Thursday though. Winds strengthen along the Rocky
Mountain Front Thursday making high wind highlights possible.
Temperatures cool Wednesday as the main front moves through the area.
Thursday night through Tuesday...No significant changes made to
the medium range forecast. An unsettled pattern will persist
through Saturday as a closed upper low will remain quasi-
stationary over northwest Montana. Short wave energy will
continue to rotate out from the base of the low and help initiate
shower and thunderstorm development each day. The strength of
these storms will depend on availability of low level moisture
and the strength of the divergent flow aloft. The models also
continue to differ on the upper low`s position which, in turn,
will affect where and how strong thunderstorms will be. Because
of these differences, have continued to broad-brush the pops
through Saturday. By late Saturday, the models move the low to
northeast Montana and lift it out as an upper ridge begins
building over the Pacific Northwest. The ridge breaks down on
Sunday as short wave energy ripples across the area within the
westerly flow aloft. Isolated thunderstorms will remain a
possibility Sunday and Monday. By Tuesday, weak upper ridging
returns though isolated showers will persist over the southwest
mountains. Temperatures will remain below seasonal averages to
start the period due to cloud cover and periodic cold advection
from transient shortwaves. Temperatures should rise above
seasonal averages to start the week.
&&
.AVIATION...
Updated 1725Z.
A trof over the Pacific Northwest will continue to influence the
weather across the area through 18Z Wednesday. Thunderstorms will
initially develop over the mountains early this afternoon and begin
to push into the plains late in the afternoon. The most widespread
thunderstorms activity will be in the KCTB area where a cold front
will approach this evening. Some of the storms cloud contain large
hail and strong wind gusts to 50 knots...mainly north and west of a
KBTM to KGTF to KHVR line. Less than VFR conditions can be expected
with some of the heavier storms. The threat for storms will be lower
in KLWT and KBZN area where lack of lift and/or drier air will limit
thunderstorm coverage. Langlieb
&&
.HYDROLOGY...
More widespread showers and thunderstorms are possible along the
Rocky Mountain Front and adjacent plains this afternoon and
evening and over most of the plains of North Central/Central
Montana on Wednesday. Some of these storms may produce brief heavy
rainfall. These periods will need to be monitored for possible
areal flood/flash flood highlights. The greater area of concern is
across eastern portions of north central and central Montana for
Wednesday that still have moist soil that would not be able to
absorb much rapid rainfall. If rainfall from storms today are
significant along the Rocky Mountain Front additional rainfall on
Wednesday will increase the flooding threat there as well.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 54 76 46 67 / 60 80 80 20
CTB 52 73 45 64 / 70 100 90 30
HLN 53 75 46 67 / 50 70 60 30
BZN 48 79 42 69 / 30 50 40 20
WEY 38 70 32 61 / 20 30 20 20
DLN 48 71 39 65 / 40 60 50 20
HVR 59 84 51 73 / 50 80 90 20
LWT 53 80 44 69 / 40 60 80 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
SEVERE THUNDERSTORM WATCH until 10 PM MDT this evening
Broadwater...Cascade...Central and Southern Lewis and Clark...
Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...
Hill...Jefferson...Judith Basin...Liberty...Meagher...Northern
Rocky Mountain Front...Southern Rocky Mountain Front...Toole.
&&
$$
weather.gov/greatfalls
000
FXUS65 KMSO 182015
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
215 PM MDT Tue Jun 18 2013
.DISCUSSION...An active weather scenario is setting up for the
next 24-48 hours as a low pressure system begins to approach and move
through western Montana and north central Idaho. Below are listed
the main impacts with this system:
***Strong Thunderstorms***: Thunderstorms are already beginning to
form this afternoon under good surface heating and lots of energy
and moisture aloft, a favorable pattern for strong to severe
thunderstorms exists. The storms are expected to come in two main waves.
The first wave is expected to form across southwest Montana this
afternoon and move northward into west central and northwest
Montana (generally east of a line from Hamilton to Missoula to
Kalispell) this afternoon and evening. A second wave of
thunderstorms will develop tonight over north central Idaho and
move into northwest Montana (generally west of a line from Lost
Trail Pass to Lowell to Plains to Eureka) overnight.
Thunderstorms will have the potential to produce very heavy rain
(which could affect flood prone basins and recent burn areas in
Idaho county), hail potentially over 1 inch in diameter and
strong winds greater than 50 mph. Those with outdoor activities
today and tonight should keep an eye to the sky.
***Heavy rain***: As the upper low pressure system moves into the
region tonight and Wednesday, a scenario for very heavy rain is
developing. The heaviest rain is expected across the Clearwater
mountains into the Idaho panhandle and across northwest Montana.
1" to 2" of rain are possible in these areas tonight through
Wednesday night. River and stream levels will likely rise
although flooding is not anticipated at this time. There could be
localized issues with ponding of water on roadways in urban
areas. Elsewhere, most all of the region should see a wetting
rain however amounts will be lower as you head into southwest
Montana and Lemhi County. Another wave of moisture and energy
associated with the upper low pressure system will impact
northern Idaho and western Montana Wednesday afternoon. This
could mean an additional 0.25 to 0.75 inch of rain, with the
higher amounts in the higher terrain of northwest Montana.
***High terrain and mountain pass snow***: As the upper low
pressure system approaches late Wednesday, much cooler air will
rush into northern Idaho and western Montana. Snow levels should
be between 6000 to 7000 feet with some slushy snow/road impacts
possible over higher mountain passes such as Lost Trail Pass by
Thursday morning. However, by the time the cooler air arrives,
the heaviest precipitation should shift north into Canada and
well east of the Divide. The upper low pressure system will
continue to direct surges of moisture and a very cool air mass
over the northern Rockies Friday and Saturday. Higher terrain
areas should continue to see some additional snow.
In the longer term, the very cool and moist low pressure system
should exit to the east late Saturday. However, it appears a moist
westerly flow may set up over the northern Rockies late Sunday,
Monday and Tuesday with additional showers.
&&
.AVIATION...Scattered thunderstorms have already developed across
southwest Montana this afternoon. These storms are expected to
track northward through the afternoon and early evening and could
impact airfields KBTM between 18/2000z and 18/2300z, KMSO between
18/2200z and 19/0100z and KGPI between 18/2300z and 19/0300z. Some
thunderstorms could become quite strong with wind gusts over 45
kts, hail and very heavy rain reducing visibility at times. A
second wave of thunderstorms is expected for form late this
evening and will affect mostly north central Idaho into northwest
Montana although at the time this convection should miss the TAF
terminals. Late tonight into tomorrow morning, heavy rain will
develop across the region producing low ceilings which will
obscure the higher terrain and periodically lower visibility.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
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000
FXUS65 KTFX 181724
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1125 AM MDT Tue Jun 18 2013
UPDATED AVIATION SECTION
.UPDATE...
Minor updates to the forecast this morning. Adjusted POP a bit
based on current model data. Still expecting convective activity
with best chances developing over terrain this afternoon.
&&
.AVIATION...
Updated 1725Z.
A trof over the Pacific Northwest will continue to influence the
weather across the area through 18Z Wednesday. Thunderstorms will
initially develop over the mountains early this afternoon and begin
to push into the plains late in the afternoon. The most widespread
thunderstorms activity will be in the KCTB area where a cold front
will approach this evening. Some of the storms cloud contain large
hail and strong wind gusts to 50 knots...mainly north and west of a
KBTM to KGTF to KHVR line. Less than VFR conditions can be expected
with some of the heavier storms. The threat for storms will be lower
in KLWT and KBZN area where lack of lift and/or drier air will limit
thunderstorm coverage. Langlieb
&&
.HYDROLOGY...
More widespread showers and thunderstorms are possible along the
Rocky Mountain Front and adjacent plains today and over most of
the plains of north central/central Montana on Wednesday. Some of
these storms may produce brief heavy rainfall. These periods will
need to be monitored for possible areal flood/flash flood
highlights. The greater area of concern is across eastern portions
of north central and central Montana for Wednesday that still
have moist soil that would not be able to absorb much rapid
rainfall. However, if the rainfall from storms today are
significant along the Rocky Mountain Front, the additional rainfall
on Wednesday will increase the flooding threat there as well.
&&
.PREV DISCUSSION...
/ISSUED 555 AM MDT Tue Jun 18 2013/
Today through Thursday...Forecast models continue to indicate that
strong to possibly severe thunderstorms are possible both today
and Wednesday. As the Pacific low pressure system moves onto the
Pacific Northwest coast today, the flow aloft over western and
central Montana will become more moist, unstable, and
southwesterly. Temperatures will also warm to around 10 degrees
above normal. These factors will help generate showers and
thunderstorms over the higher terrain of these areas. The frontal
boundary associated with this system will also move into western
Montana today to provide a good focusing mechanism for storm
development. The flow aloft will also become more diffluent, which
should enhance vertical development of storms. These factors,
along with strong wind shear (both speed and directional) and
significant instability (CAPE values of 1500 to 2500 J/kg), the
Storm Prediction Center (SPC) has put portions of western and
central Montana under a Slight Risk for severe thunderstorms, and
we have subsequently added mention of damaging winds, large hail,
and heavy rainfall for this area. This area is generally northwest
of a Havre-to- Butte line. Thunderstorms will decrease overnight,
but another round of potentially severe weather is expected for
Wednesday as the system continues to move east across the Pacific
Northwest. The most unstable portion of the flow aloft and the
surface frontal boundary will also shift east into central and
eastern Montana, where SPC has the Slight Risk for Wednesday. Am
thinking that the potential for the strongest storms will be along
and east of a Havre-to-Stanford line, as that appears to be the
favored area for wind shear and instability due to the position of
the frontal boundary. However, isolated severe storms are possible
west of this line as well, though they may be more marginally
severe. Have therefore continued the damaging wind/large
hail/heavy rainfall wording for these areas. Precipitation from
these storms may be exceptionally heavy in the aforementioned
eastern areas, adding the potential for flash flooding as well
(please see Hydrology section for details). The system will lift
northeast across the area later Wednesday night and into Thursday.
This will shift the flow aloft more westerly, but it will remain
moist, so have kept high POPs in the mountains. However, the
resulting strong westerly down-slope winds will hinder
shower/thunderstorm development over the plains. Winds aloft
become marginally strong along the Rocky Mountain Front on
Thursday, so will need to monitor this for possible high wind
highlights there. Temperatures will begin to cool closer to
normal from the west on Wednesday as the frontal boundary moves
through the area and showers become more widespread. In the wake
of the front, temperatures will cool to around 10 degrees below
normal by Thursday, which may cause snow to fall at elevations
above 6500 feet. Coulston
Thursday night through Tuesday...No significant changes made to
the medium range forecast. An unsettled pattern will persist
through Saturday as a closed upper low will remain quasi-
stationary over northwest Montana. Short wave energy will
continue to rotate out from the base of the low and help initiate
shower and thunderstorm development each day. The strength of
these storms will depend on availability of low level moisture
and the strength of the divergent flow aloft. The models also
continue to differ on the upper low`s position which, in turn,
will affect where and how strong thunderstorms will be. Because
of these differences, have continued to broad-brush the pops
through Saturday. By late Saturday, the models move the low to
northeast Montana and lift it out as an upper ridge begins
building over the Pacific Northwest. The ridge breaks down on
Sunday as short wave energy ripples across the area within the
westerly flow aloft. Isolated thunderstorms will remain a
possibility Sunday and Monday. By Tuesday, weak upper ridging
returns though isolated showers will persist over the southwest
mountains. Temperatures will remain below seasonal averages to
start the period due to cloud cover and periodic cold advection
from transient shortwaves. Temperatures should rise above
seasonal averages to start the week.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 85 54 76 46 / 60 60 80 80
CTB 83 51 73 45 / 70 70 100 90
HLN 86 52 75 46 / 60 50 70 60
BZN 86 47 79 42 / 30 30 50 40
WEY 78 37 70 32 / 20 20 30 20
DLN 84 48 71 39 / 40 40 60 50
HVR 86 59 83 51 / 20 50 80 90
LWT 83 53 79 44 / 30 40 60 80
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 181620
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1020 AM MDT Tue Jun 18 2013
.UPDATE...
Minor updates to the forecast this morning. Adjusted POP a bit
based on current model data. Still expecting convective activity
with best chances developing over terrain this afternoon.
&&
.AVIATION...
Updated 1155Z.
Moist and unstable southwest flow aloft will continue. The air-mass
is unstable and will further destabilize after 17z. Strong
thunderstorms will develop after 20z and continue beyond 00z. Some
storms may become severe. VFR conditions prevail with MVFR
conditions possible in the vicinity of thunderstorms. Mountains and
higher terrain may be obscured at times after 20z.
&&
.HYDROLOGY...
More widespread showers and thunderstorms are possible along the
Rocky Mountain Front and adjacent plains today and over most of
the plains of north central/central Montana on Wednesday. Some of
these storms may produce brief heavy rainfall. These periods will
need to be monitored for possible areal flood/flash flood
highlights. The greater area of concern is across eastern portions
of north central and central Montana for Wednesday that still
have moist soil that would not be able to absorb much rapid
rainfall. However, if the rainfall from storms today are
significant along the Rocky Mountain Front, the additional rainfall
on Wednesday will increase the flooding threat there as well.
&&
.PREV DISCUSSION...
/ISSUED 555 AM MDT Tue Jun 18 2013/
Today through Thursday...Forecast models continue to indicate that
strong to possibly severe thunderstorms are possible both today
and Wednesday. As the Pacific low pressure system moves onto the
Pacific Northwest coast today, the flow aloft over western and
central Montana will become more moist, unstable, and
southwesterly. Temperatures will also warm to around 10 degrees
above normal. These factors will help generate showers and
thunderstorms over the higher terrain of these areas. The frontal
boundary associated with this system will also move into western
Montana today to provide a good focusing mechanism for storm
development. The flow aloft will also become more diffluent, which
should enhance vertical development of storms. These factors,
along with strong wind shear (both speed and directional) and
significant instability (CAPE values of 1500 to 2500 J/kg), the
Storm Prediction Center (SPC) has put portions of western and
central Montana under a Slight Risk for severe thunderstorms, and
we have subsequently added mention of damaging winds, large hail,
and heavy rainfall for this area. This area is generally northwest
of a Havre-to- Butte line. Thunderstorms will decrease overnight,
but another round of potentially severe weather is expected for
Wednesday as the system continues to move east across the Pacific
Northwest. The most unstable portion of the flow aloft and the
surface frontal boundary will also shift east into central and
eastern Montana, where SPC has the Slight Risk for Wednesday. Am
thinking that the potential for the strongest storms will be along
and east of a Havre-to-Stanford line, as that appears to be the
favored area for wind shear and instability due to the position of
the frontal boundary. However, isolated severe storms are possible
west of this line as well, though they may be more marginally
severe. Have therefore continued the damaging wind/large
hail/heavy rainfall wording for these areas. Precipitation from
these storms may be exceptionally heavy in the aforementioned
eastern areas, adding the potential for flash flooding as well
(please see Hydrology section for details). The system will lift
northeast across the area later Wednesday night and into Thursday.
This will shift the flow aloft more westerly, but it will remain
moist, so have kept high POPs in the mountains. However, the
resulting strong westerly down-slope winds will hinder
shower/thunderstorm development over the plains. Winds aloft
become marginally strong along the Rocky Mountain Front on
Thursday, so will need to monitor this for possible high wind
highlights there. Temperatures will begin to cool closer to
normal from the west on Wednesday as the frontal boundary moves
through the area and showers become more widespread. In the wake
of the front, temperatures will cool to around 10 degrees below
normal by Thursday, which may cause snow to fall at elevations
above 6500 feet. Coulston
Thursday night through Tuesday...No significant changes made to
the medium range forecast. An unsettled pattern will persist
through Saturday as a closed upper low will remain quasi-
stationary over northwest Montana. Short wave energy will
continue to rotate out from the base of the low and help initiate
shower and thunderstorm development each day. The strength of
these storms will depend on availability of low level moisture
and the strength of the divergent flow aloft. The models also
continue to differ on the upper low`s position which, in turn,
will affect where and how strong thunderstorms will be. Because
of these differences, have continued to broad-brush the pops
through Saturday. By late Saturday, the models move the low to
northeast Montana and lift it out as an upper ridge begins
building over the Pacific Northwest. The ridge breaks down on
Sunday as short wave energy ripples across the area within the
westerly flow aloft. Isolated thunderstorms will remain a
possibility Sunday and Monday. By Tuesday, weak upper ridging
returns though isolated showers will persist over the southwest
mountains. Temperatures will remain below seasonal averages to
start the period due to cloud cover and periodic cold advection
from transient shortwaves. Temperatures should rise above
seasonal averages to start the week.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 85 54 76 46 / 60 60 80 80
CTB 83 51 73 45 / 70 70 100 90
HLN 86 52 75 46 / 60 50 70 60
BZN 86 47 79 42 / 30 30 50 40
WEY 78 37 70 32 / 20 20 30 20
DLN 84 48 71 39 / 40 40 60 50
HVR 86 59 83 51 / 20 50 80 90
LWT 83 53 79 44 / 30 40 60 80
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
weather.gov/greatfalls
000
FXUS65 KGGW 181553
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
953 AM MDT TUE JUN 18 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY...
UPDATE...ONLY MINOR TWEAKS WERE MADE WITH THE MORNING UPDATE.
ADJUSTED SKY COVER TO BETTER REFLECT THE SMALL CUMULUS DECK OVER
THE CENTRAL PART OF THE FORECAST AREA. ALSO ISSUED A LAKE WIND
ADVISORY AS SOUTHEAST WINDS HAVE ALREADY REACHED 20 MPH ON THE
LAKE AND ARE EXPECTED TO REMAIN NEAR 20 MPH INTO WEDNESDAY NIGHT.
GILCHRIST
PREVIOUS DISCUSSION...UPPER RIDGE AXIS SLIDING INTO EASTERN
MONTANA AS UPPER LOW CONTINUES TO SPIN TOWARD THE PACIFIC
NORTHWEST. THUNDERSTORMS DEVELOPED ALONG THE FRONT RANGE LAST
EVENING...WEAKENING AS THEY ENCOUNTER THE MORE STABLE AIRMASS
UNDER THE RIDGE THIS MORNING.
AS SYSTEM CONTINUE TO EVOLVE TODAY...SOUTHEAST WINDS WILL BE
INCREASING...PULLING MOISTURE NORTHWARD ACROSS THE PLAINS. WINDS
EXPECTED TO REMAIN BELOW LAKE WIND CRITERIA TODAY WITH WARM AIR
ADVECTION BUT TIGHTENING PRESSURE GRADIENT COULD OVERCOME THE LACK
OF SUBSIDENCE MIXING.
EXPECT ADDITIONAL STORMS TO FIRE ALONG THE FRONT RANGE TODAY THAT
COULD DRIFT INTO NORTHEAST MONTANA ALTHOUGH INCREASINGLY SOUTHERLY
MID AND UPPER LEVEL FLOW COULD PUSH THE STORMS NORTH TOWARD CANADA.
BY WEDNESDAY CONDITIONS BECOME MUCH MORE FAVORABLE FOR STRONG TO
SEVERE THUNDERSTORMS. UPPER LOW MOVES INTO THE NORTHERN ROCKIES
WITH NOSE OF JET PUSHING INTO MONTANA. SOUTHEAST LOW LEVEL FLOW
CONTINUE TO PUMP IN GULF MOISTURE. COLD FRONT SLOWLY MOVING ACROSS
THE STATE WILL PROVIDE MAIN FOCUS FOR STORM DEVELOPMENT AS IT
MOVES FROM CENTRAL MONTANA IN THE AFTERNOON THEN ACROSS EASTERN
MONTANA DURING THE EVENING.
DRIER AND COOLER AIRMASS MOVES INTO THE REGION BEHIND THE COLD
FRONT BY THURSDAY MORNING. UPPER LOW OVER WESTERN MONTANA LIFTING
INTO SOUTHERN ALBERTA...BUT COOL CYCLONIC FLOW COULD PRODUCE A FEW
SHOWERS OR THUNDERSTORMS. EBERT
.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
SYNOPTIC SET UP... LONG TERM BEGINS WITH A DOME OF HEAT OVER THE
DESERT SOUTHWEST AND A RIDGE SPURRING OFF ACROSS COLORADO... THE
CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY. A LARGE TROUGH HAS
EMBEDDED ITSELF INTO THE PACIFIC NORTHWEST. NORTHEAST MONTANA IS
WEDGED BETWEEN THESE TWO AIRMASSES IN SOUTHWEST FLOW ALOFT. A WEAK
RIDGE ALSO RUNS FROM SOUTHERN SASKATCHEWAN THROUGH NORTHERN
ALBERTA AND INTO NORTHER ALASKA.
THURSDAY NIGHT THROUGH SATURDAY NIGHT... THE CORE OF THE CLOSED LOW
TO THE WEST IS EXPECTED TO DRIFT ONTO THE HIGH PLAINS AND WILL
COOL TEMPERATURES DOWN FOR AWHILE ALLOWING FOR A CHANCE OF SHOWERS
AND THUNDERSTORMS EACH AFTERNOON AND EVENING.
SUNDAY ONWARD... MODELS ARE HAVING PROBLEMS DECIDED WHAT TO TO DO
WITH THIS LOW ONCE ITS OVER THE HIGH PLAINS. CONSISTENCY FROM RUN
TO RUN AND MODEL TO MODEL SEEMS FAIRLY POOR... DECREASING CONFIDENCE.
CURRENTLY MODELS POINT TOWARD THE CLOSED LOW KICKING OFF TOWARD
ONTARIO AND A NEW RIDGE ESTABLISHING ITSELF RIGHT BEHIND OVER
WESTERN MONTANA ON MONDAY. THIS RIDGE SHOULD BECOME A GREATER
INFLUENCE WITH WARMING TEMPERATURES AND DECREASING CHANCES FOR
THUNDER THROUGH MID WEEK.
&&
.AVIATION...
AN ISOLATED SHOWER OR THUNDERSTORM MAY DEVELOP THIS AFTERNOON BUT
CONFIDENCE IS LOW. OTHERWISE...VFR CEILINGS AND VISIBILITIES ARE
EXPECTED TO PREVAIL THROUGH THE TAF PERIOD.
SOUTHEAST WINDS WILL BE DIRECTED FROM THE SOUTHEAST TODAY FROM 10
TO 20 KTS. MALIAWCO
&&
.HYDROLOGY...
A FLOOD WARNING REMAINS IN EFFECT FOR THE MILK RIVER NEAR GLASGOW.
THE LATEST GUIDANCE FROM THE RIVER FORECAST CENTER SUGGESTS THE
MILK RIVER NEAR GLASGOW WILL POSSIBLY GO BELOW FLOOD STAGE BY
FRIDAY.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL MIDNIGHT MDT WEDNESDAY NIGHT FOR FORT
PECK LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND
SOUTHERN VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 181543
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
943 AM MDT TUE JUN 18 2013
.UPDATE...
JUST A FEW POP ADJUSTMENTS FOR THE AFTERNOON TO GO CLOSER TO THE
SREF SOLUTION WHICH WAS HANDLING THE MORNING PRECIPITATION IN THE
NE BIG HORNS WELL. UPPER LOW OFF THE PACIFIC NW COAST WILL EJECT
SHORTWAVE ENERGY INTO THE FORECAST AREA THIS AFTERNOON IN SW FLOW.
PRECIPITABLE WATERS WILL BE AROUND /0.75/ INCHES TODAY WITH CAPES
1000 J/KG OR LESS. SOUNDINGS HAD A BIT OF AN INVERTED-V
APPEARANCE WHICH WOULD SUPPORT GUSTY WINDS WITH ANY THUNDERSTORMS.
THE CAPES WILL SUPPORT SMALL HAIL...SO CONTINUED THE MENTION OF
GUSTY WINDS/SMALL HAIL IN THE FORECAST. SHEAR VALUES WERE NOT
IMPRESSIVE THIS AFTERNOON. THE BEST SHEAR WILL BE OVER THE EASTERN
ZONES AROUND 00Z WED...BUT WILL STILL NOT BE VERY STRONG.
TEMPERATURE FORECAST WAS IN GOOD SHAPE AND REFLECTED MIXDOWN
VALUES. ARTHUR
&&
.SHORT TERM...VALID FOR TDY AND WED...
YESTERDAY AFTERNOON SAW SOME ISOLATED SHOWERS AND THUNDERSTORMS
OVER MOUNTAIN LOCATIONS...BUT THOSE FAILED TO MOVE OFF INTO THE
LOWER ELEVATIONS. ENVIRONMENTAL CONDITIONS TODAY WILL BE SIMILAR
TO YESTERDAY. DEW POINTS ARE EXPECTED TO BE IN THE MID 40S TO LOWER
50S ESPECIALLY FOR CENTRAL AND WESTERN ZONES. THIS LOW-LEVEL
MOISTURE IS MARGINALLY ENOUGH TO CONSIDER THE THREAT OF
THUNDERSTORMS MOVING OFF THE MOUNTAINS AND INTO THE PLAINS ACROSS
WESTERN ZONES. HOWEVER...THE AMOUNT OF MOISTURE IS ALSO LIMITING
IN THE SENSE THAT LFCS ARE VERY HIGH...ON THE ORDER OF 10K FEET.
ALTHOUGH TEMPERATURES ARE EXPECTED TO RISE TO THE UPPER 80S TO
NEAR 90...WHICH IS CLOSE TO THE CONVECTIVE TEMPERATURE...SUCH
ELEVATED CAPE WILL BE HARD TO REALIZE...MAKING THUNDERSTORM
FORMATION DIFFICULT TO ACHIEVE. THE CAVEAT HERE IS A WEAK
SHORTWAVE PROVIDING ADDITIONAL FORCING OVER THE MOUNTAINS IN
ADDITION TO THE DIURNAL HEATING. THUS EXPECT SHOWERS AND
THUNDERSTORMS TO DEVELOP OVER THE MOUNTAINS IN THE EARLY
AFTERNOON...AND REMAIN MOSTLY ANCHORED OVER THE MOUNTAINS WITH THE
EXCEPTION OF A COUPLE STORMS WHICH COULD IMPACT NEARBY LOWER
ELEVATIONS.
ANOTHER AREA OF INTEREST FOR CONVECTION TOMORROW AFTERNOON AND
EARLY EVENING WILL BE ACROSS FAR SOUTHEASTERN MONTANA. SOUTHERN
POWDER RIVER AND CARTER COUNTIES LIE JUST OUTSIDE THE NORTHERN
FRINGE OF A SLIGHT RISK OF SEVERE WEATHER FROM SPC. THE
SOUTHEASTERLY FLOW WILL CONTINUE TO BRING 50 DEGREE DEW POINT AIR
INTO THE SOUTHEAST CORNER OF THE STATE NEAR THE NOSE OF THE LOW-
LEVEL JET. THE BETTER INGREDIENTS FOR CONVECTION CERTAINLY APPEAR
FARTHER SOUTH WHERE THE TEMPERATURES ARE WARMER. SOUTHEAST MONTANA
WILL HAVE A PROBLEM WITH CAPPING AROUND 700MB ABOVE THE SLIGHTLY
COOLER SOUTHEASTERLY LOW-LEVEL FLOW. HOWEVER...FORECAST SOUNDINGS
FOR BROADUS SHOW A WEAKER CAP THAN AT MLS OR BHK. WITH MODELS
MOVING PRECIPITATION OVER LOCATIONS SOUTH OF BROADUS ALONG THE
NORTHEAST WYOMING BORDER...CERTAINLY CANNOT RULE OUT THE CHANCE OF
THUNDERSTORMS IN THIS SECTION OF THE FORECAST AREA.
THE THERMAL RIDGE WILL REMAIN OVER THE FORECAST AREA
OVERNIGHT...ALONG WITH SOUTHEASTERLY WINDS AHEAD OF THE SURFACE
TROUGH AND MID TO HIGH CLOUD COVER LINGERING FROM THE DAYS
CONVECTION. THIS WILL COMBINE TO PRODUCE WARM OVERNIGHT LOW
TEMPERATURES.
WEDNESDAY IS ANOTHER COMPLEX DAY FOR CONVECTION ACROSS THE
FORECAST AREA. THE APPROACHING PACIFIC THROUGH WILL INTRODUCE SOME
STRONGER QG FORCING OVER WESTERN ZONES BY TOMORROW AFTERNOON. THE
POSITION OF THE LOW FAVORS TAPPING INTO DRY AIR OVER THE GREAT
BASIN AND PULLING IT OVER THE FORECAST AREA. MEANWHILE THE BETTER
LOW LEVEL MOISTURE IS PUSHED NORTH AROUND THE LOW THROUGH THE
GLASGOW FORECAST AREA INTO GREAT FALLS FORECAST AREA. WITH THE
BETTER FORCING AND MOISTURE POSITIONED MAINLY NORTH AND WEST OF
THE FORECAST AREA...EXPECT WE WILL WATCH THE STRONGEST
THUNDERSTORMS MOVE BY TO OUR NORTH BY WEDNESDAY EVENING.
HOWEVER...SINCE NORTHERN AND WESTERN PORTIONS OF THE FORECAST AREA
WILL REMAIN ON THE FRINGES OF THESE BETTER INGREDIENTS HAVE CHOSEN
KEEP 50 POPS AND MENTION OF SEVERE IN THESE AREAS. TAPERED BACK
POPS FOR THE MORE SOUTHERN AND EASTERN LOCATIONS AND REMOVED THE
SEVERE WORDING.
TEMPERATURES ON WEDNESDAY WILL BE IN THE MID TO UPPER 80S FOR MOST
OF THE FORECAST AREA AS THE THERMAL RIDGE MOVES FARTHER EAST. ALSO
EXPECT THE SURFACE FRONT TO PUSH ACROSS THE FORECAST AREA FROM
WEST TO EAST BY LATE WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING.
EXPECT THE PRE FRONTAL WARMING WILL ALSO CONTRIBUTE TO WARMER HIGH
TEMPERATURES. CHURCH
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
PACIFIC LOW OVER THE NORTHWEST ON THURSDAY SHOULD HAVE SHUNTED
THE BEST LOW LEVEL MOISTURE NORTHEAST OF THE AREA BUT IT CLEARLY
IS SLOWER AND DEEPER KEEPING MORE CYCLONIC FLOW OVER THE AREA.
THIS SHOULD MAKE MOUNTAIN THUNDERSTORMS POSSIBLE MOVING OVER THE
PLAINS BUT WOULD EXPECT LACK OF DEEP MOISTURE TO LIMIT STORM
INTENSITY. BIG STORY ON THURSDAY IS THAT TEMPERATURES WILL BE
NEARLY 15 DEGREES COOLER THAN WEDNESDAY.
FRIDAY LOOKS SIMILAR TO THURSDAY THOUGH THE ECMWF HINTS A BIT OF
LOW LEVEL AIRMASS RECOVERY COMPARED TO THURSDAY BUT STILL DOES NOT
LOOK LIKE MORE THAN ISOLATED THUNDERSTORMS. SATURDAY THE UPPER LOW
EJECTS INTO SOUTHERN CANADA AND A TROUGH AXIS CROSSES MONTANA.
CONFLUENT FLOW ALOFT SHOULD HAVE A GOOD CHANCE AT SURPRESSING MOST
CONVECTION ACROSS THE WESTERN HALF OF THE AREA WHILE A COLD FRONT
MOVING THROUGH EASTERN MONTANA MAY TRY AND TRIGGER SOME MORE
CONVECTION.
HEIGHTS REMAIN SURPRESSED IN THE SUNDAY AND MONDAY TIME FRAME WITH
WEAK IMPULSES MOVING THROUGH THE AREA IN WEST SOUTHWESTERLY FLOW
ALOFT. TEMPERATURES WILL BE NEAR NORMAL AND WHILE THUNDER CANNOT
BE RULED OUT THE PATTERN DOES NOT FAVOR ANYTHING MORE THAN GENERIC
STORMS. BORSUM
&&
.AVIATION...
A WEAK DISTURBANCE WILL BRING ISOLD -SHRA NEAR KSHR THIS MORNING.
LOOK FOR ISOLD TO SCT SHOWERS/TSTMS THIS AFTERNOON AND EVENING...
WITH GREATEST COVERAGE NEAR THE MTNS AND FOOTHILLS...PERHAPS
IMPACTING KLVM AND KSHR. VFR WILL PREVAIL BUT LOCAL MVFR IS
POSSIBLE IN ANY STRONGER STORMS. JKL
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 088 062/088 053/077 050/073 050/075 051/076 051/079
2/T 22/T 22/T 22/T 22/T 22/T 22/T
LVM 089 050/089 047/072 040/070 042/071 047/078 046/081
3/T 33/T 23/T 22/T 23/T 32/T 22/T
HDN 090 059/090 053/078 053/074 050/076 051/077 051/079
1/B 22/T 22/T 33/T 23/T 32/T 22/T
MLS 086 060/090 058/081 055/074 055/077 055/079 055/080
1/B 22/T 42/T 33/T 33/T 33/T 22/T
4BQ 086 059/092 055/081 055/075 052/077 052/079 051/080
3/T 21/B 22/T 33/T 33/T 33/T 22/T
BHK 081 057/086 057/080 054/075 053/074 052/076 052/076
1/U 22/T 32/T 45/T 54/T 33/T 32/T
SHR 083 052/088 050/078 050/073 048/075 047/076 048/078
3/T 22/T 22/T 33/T 22/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 181156
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
555 AM MDT Tue Jun 18 2013
UPDATED AVIATION SECTION
...Strong to possibly severe thunderstorms today and Wednesday...
.DISCUSSION...
Today through Thursday...Forecast models continue to indicate that
strong to possibly severe thunderstorms are possible both today
and Wednesday. As the Pacific low pressure system moves onto the
Pacific Northwest coast today, the flow aloft over western and
central Montana will become more moist, unstable, and
southwesterly. Temperatures will also warm to around 10 degrees
above normal. These factors will help generate showers and
thunderstorms over the higher terrain of these areas. The frontal
boundary associated with this system will also move into western
Montana today to provide a good focusing mechanism for storm
development. The flow aloft will also become more diffluent, which
should enhance vertical development of storms. These factors,
along with strong wind shear (both speed and directional) and
significant instability (CAPE values of 1500 to 2500 J/kg), the
Storm Prediction Center (SPC) has put portions of western and
central Montana under a Slight Risk for severe thunderstorms, and
we have subsequently added mention of damaging winds, large hail,
and heavy rainfall for this area. This area is generally northwest
of a Havre-to- Butte line. Thunderstorms will decrease overnight,
but another round of potentially severe weather is expected for
Wednesday as the system continues to move east across the Pacific
Northwest. The most unstable portion of the flow aloft and the
surface frontal boundary will also shift east into central and
eastern Montana, where SPC has the Slight Risk for Wednesday. Am
thinking that the potential for the strongest storms will be along
and east of a Havre-to-Stanford line, as that appears to be the
favored area for wind shear and instability due to the position of
the frontal boundary. However, isolated severe storms are possible
west of this line as well, though they may be more marginally
severe. Have therefore continued the damaging wind/large
hail/heavy rainfall wording for these areas. Precipitation from
these storms may be exceptionally heavy in the aforementioned
eastern areas, adding the potential for flash flooding as well
(please see Hydrology section for details). The system will lift
northeast across the area later Wednesday night and into Thursday.
This will shift the flow aloft more westerly, but it will remain
moist, so have kept high POPs in the mountains. However, the
resulting strong westerly downslope winds will hinder
shower/thunderstorm development over the plains. Winds aloft
become marginally strong along the Rocky Mountain Front on
Thursday, so will need to monitor this for possible high wind
highlights there. Temperatures will begin to cool closer to
normal from the west on Wednesday as the frontal boundary moves
through the area and showers become more widespread. In the wake
of the front, temperatures will cool to around 10 degrees below
normal by Thursday, which may cause snow to fall at elevations
above 6500 feet. Coulston
Thursday night through Tuesday...No significant changes made to
the medium range forecast. An unsettled pattern will persist
through Saturday as a closed upper low will remain quasi-
stationary over northwest Montana. Short wave energy will
continue to rotate out from the base of the low and help initiate
shower and thunderstorm development each day. The strength of
these storms will depend on availability of low level moisture
and the strength of the divergent flow aloft. The models also
continue to differ on the upper low`s position which, in turn,
will affect where and how strong thunderstorms will be. Because
of these differences, have continued to broadbrush the pops
through Saturday. By late Saturday, the models move the low to
northeast Montana and lift it out as an upper ridge begins
building over the Pacific Northwest. The ridge breaks down on
Sunday as short wave energy ripples across the area within the
westerly flow aloft. Isolated thunderstorms will remain a
possibility Sunday and Monday. By Tuesday, weak upper ridging
returns though isolated showers will persist over the southwest
mountains. Temperatures will remain below seasonal averages to
start the period due to cloud cover and periodic cold advection
from transient shortwaves. Temperatures should rise above
seasonal averages to start the week.
&&
.AVIATION...
Updated 1155Z.
Moist and unstable southwest flow aloft will continue. The airmass
is unstable and will further destabilize after 17z. Strong
thunderstorms will develop after 20z and continue beyond 00z. Some
storms may become severe. VFR conditions prevail with MVFR
conditions possible in the vicinity of thunderstorms. Mountains and
higher terrain may be obscured at times after 20z.
&&
.HYDROLOGY...
More widespread showers and thunderstorms are possible along the
Rocky Mountain Front and adjacent plains today and over most of
the plains of north central/central Montana on Wednesday. Some of
these storms may produce brief heavy rainfall. These periods will
need to be monitored for possible areal flood/flash flood
highlights. The greater area of concern is across eastern portions
of north central and central Montana for Wednesday that still
have moist soil that would not be able to absorb much rapid
rainfall. However, if the rainfall from storms today are
significant along the Rocky Mountain Front, the additional rainfall
on Wednesday will increase the flooding threat there as well.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 85 54 76 46 / 60 60 80 80
CTB 83 51 73 45 / 70 70 100 90
HLN 86 52 75 46 / 60 50 70 60
BZN 86 47 79 42 / 40 30 50 40
WEY 78 37 70 32 / 30 20 30 20
DLN 84 48 71 39 / 40 40 60 50
HVR 86 59 83 51 / 20 50 80 90
LWT 82 53 79 44 / 40 40 60 80
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COULSTON
LONG TERM...EMANUEL
AVIATION...EMANUEL
weather.gov/greatfalls
000
FXUS65 KTFX 181042
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
442 AM MDT Tue Jun 18 2013
...Strong to possibly severe thunderstorms today and Wednesday...
.DISCUSSION...
Today through Thursday...Forecast models continue to indicate that
strong to possibly severe thunderstorms are possible both today
and Wednesday. As the Pacific low pressure system moves onto the
Pacific Northwest coast today, the flow aloft over western and
central Montana will become more moist, unstable, and
southwesterly. Temperatures will also warm to around 10 degrees
above normal. These factors will help generate showers and
thunderstorms over the higher terrain of these areas. The frontal
boundary associated with this system will also move into western
Montana today to provide a good focusing mechanism for storm
development. The flow aloft will also become more diffluent, which
should enhance vertical development of storms. These factors,
along with strong wind shear (both speed and directional) and
significant instability (CAPE values of 1500 to 2500 J/kg), the
Storm Prediction Center (SPC) has put portions of western and
central Montana under a Slight Risk for severe thunderstorms, and
we have subsequently added mention of damaging winds, large hail,
and heavy rainfall for this area. This area is generally northwest
of a Havre-to- Butte line. Thunderstorms will decrease overnight,
but another round of potentially severe weather is expected for
Wednesday as the system continues to move east across the Pacific
Northwest. The most unstable portion of the flow aloft and the
surface frontal boundary will also shift east into central and
eastern Montana, where SPC has the Slight Risk for Wednesday. Am
thinking that the potential for the strongest storms will be along
and east of a Havre-to-Stanford line, as that appears to be the
favored area for wind shear and instability due to the position of
the frontal boundary. However, isolated severe storms are possible
west of this line as well, though they may be more marginally
severe. Have therefore continued the damaging wind/large
hail/heavy rainfall wording for these areas. Precipitation from
these storms may be exceptionally heavy in the aforementioned
eastern areas, adding the potential for flash flooding as well
(please see Hydrology section for details). The system will lift
northeast across the area later Wednesday night and into Thursday.
This will shift the flow aloft more westerly, but it will remain
moist, so have kept high POPs in the mountains. However, the
resulting strong westerly downslope winds will hinder
shower/thunderstorm development over the plains. Winds aloft
become marginally strong along the Rocky Mountain Front on
Thursday, so will need to monitor this for possible high wind
highlights there. Temperatures will begin to cool closer to
normal from the west on Wednesday as the frontal boundary moves
through the area and showers become more widespread. In the wake
of the front, temperatures will cool to around 10 degrees below
normal by Thursday, which may cause snow to fall at elevations
above 6500 feet. Coulston
Thursday night through Tuesday...No significant changes made to
the medium range forecast. An unsettled pattern will persist
through Saturday as a closed upper low will remain quasi-
stationary over northwest Montana. Short wave energy will
continue to rotate out from the base of the low and help initiate
shower and thunderstorm development each day. The strength of
these storms will depend on availability of low level moisture
and the strength of the divergent flow aloft. The models also
continue to differ on the upper low`s position which, in turn,
will affect where and how strong thunderstorms will be. Because
of these differences, have continued to broadbrush the pops
through Saturday. By late Saturday, the models move the low to
northeast Montana and lift it out as an upper ridge begins
building over the Pacific Northwest. The ridge breaks down on
Sunday as short wave energy ripples across the area within the
westerly flow aloft. Isolated thunderstorms will remain a
possibility Sunday and Monday. By Tuesday, weak upper ridging
returns though isolated showers will persist over the southwest
mountains. Temperatures will remain below seasonal averages to
start the period due to cloud cover and periodic cold advection
from transient shortwaves. Temperatures should rise above
seasonal averages to start the week.
&&
.AVIATION...
Updated 0455Z.
Scattered showers and thunderstorms will continue to move across
central Montana through 09Z with the KHLN and KLWT areas most likely
to see convective activity. Skies will clear out by 12Z but another
round of strong and possibly severe thunderstorms will develop after
20Z and continue into the late evening. VFR conditions will prevail
but conditions may deteriorate to MVFR in heavy rainfall associated
with the strongest storms. mpj
&&
.HYDROLOGY...
More widespread showers and thunderstorms are possible along the
Rocky Mountain Front and adjacent plains today and over most of
the plains of north central/central Montana on Wednesday. Some of
these storms may produce brief heavy rainfall. These periods will
need to be monitored for possible areal flood/flash flood
highlights. The greater area of concern is across eastern portions
of north central and central Montana for Wednesday that still
have moist soil that would not be able to absorb much rapid
rainfall. However, if the rainfall from storms today are
significant along the Rocky Mountain Front, the additional
rainfall on Wednesday will increase the flooding threat there.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 85 54 76 46 / 60 60 80 80
CTB 83 51 73 45 / 70 70 100 90
HLN 86 52 75 46 / 60 50 70 60
BZN 86 47 79 42 / 40 30 50 40
WEY 78 37 70 32 / 30 20 30 20
DLN 84 48 71 39 / 40 40 60 50
HVR 86 59 83 51 / 20 50 80 90
LWT 82 53 79 44 / 40 40 60 80
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COULSTON
LONG TERM...EMANUEL
AVIATION...mpj
weather.gov/greatfalls
000
FXUS65 KBYZ 181016
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
416 AM MDT TUE JUN 18 2013
.SHORT TERM...VALID FOR TDY AND WED...
YESTERDAY AFTERNOON SAW SOME ISOLATED SHOWERS AND THUNDERSTORMS
OVER MOUNTAIN LOCATIONS...BUT THOSE FAILED TO MOVE OFF INTO THE
LOWER ELEVATIONS. ENVIRONMENTAL CONDITIONS TODAY WILL BE SIMILAR
TO YESTERDAY. DEW POINTS ARE EXPECTED TO BE IN THE MID 40S TO LOWER
50S ESPECIALLY FOR CENTRAL AND WESTERN ZONES. THIS LOW-LEVEL
MOISTURE IS MARGINALLY ENOUGH TO CONSIDER THE THREAT OF
THUNDERSTORMS MOVING OFF THE MOUNTAINS AND INTO THE PLAINS ACROSS
WESTERN ZONES. HOWEVER...THE AMOUNT OF MOISTURE IS ALSO LIMITING
IN THE SENSE THAT LFCS ARE VERY HIGH...ON THE ORDER OF 10K FEET.
ALTHOUGH TEMPERATURES ARE EXPECTED TO RISE TO THE UPPER 80S TO
NEAR 90...WHICH IS CLOSE TO THE CONVECTIVE TEMPERATURE...SUCH
ELEVATED CAPE WILL BE HARD TO REALIZE...MAKING THUNDERSTORM
FORMATION DIFFICULT TO ACHIEVE. THE CAVEAT HERE IS A WEAK
SHORTWAVE PROVIDING ADDITIONAL FORCING OVER THE MOUNTAINS IN
ADDITION TO THE DIURNAL HEATING. THUS EXPECT SHOWERS AND
THUNDERSTORMS TO DEVELOP OVER THE MOUNTAINS IN THE EARLY
AFTERNOON...AND REMAIN MOSTLY ANCHORED OVER THE MOUNTAINS WITH THE
EXCEPTION OF A COUPLE STORMS WHICH COULD IMPACT NEARBY LOWER
ELEVATIONS.
ANOTHER AREA OF INTEREST FOR CONVECTION TOMORROW AFTERNOON AND
EARLY EVENING WILL BE ACROSS FAR SOUTHEASTERN MONTANA. SOUTHERN
POWDER RIVER AND CARTER COUNTIES LIE JUST OUTSIDE THE NORTHERN
FRINGE OF A SLIGHT RISK OF SEVERE WEATHER FROM SPC. THE
SOUTHEASTERLY FLOW WILL CONTINUE TO BRING 50 DEGREE DEW POINT AIR
INTO THE SOUTHEAST CORNER OF THE STATE NEAR THE NOSE OF THE LOW-
LEVEL JET. THE BETTER INGREDIENTS FOR CONVECTION CERTAINLY APPEAR
FARTHER SOUTH WHERE THE TEMPERATURES ARE WARMER. SOUTHEAST MONTANA
WILL HAVE A PROBLEM WITH CAPPING AROUND 700MB ABOVE THE SLIGHTLY
COOLER SOUTHEASTERLY LOW-LEVEL FLOW. HOWEVER...FORECAST SOUNDINGS
FOR BROADUS SHOW A WEAKER CAP THAN AT MLS OR BHK. WITH MODELS
MOVING PRECIPITATION OVER LOCATIONS SOUTH OF BROADUS ALONG THE
NORTHEAST WYOMING BORDER...CERTAINLY CANNOT RULE OUT THE CHANCE OF
THUNDERSTORMS IN THIS SECTION OF THE FORECAST AREA.
THE THERMAL RIDGE WILL REMAIN OVER THE FORECAST AREA
OVERNIGHT...ALONG WITH SOUTHEASTERLY WINDS AHEAD OF THE SURFACE
TROUGH AND MID TO HIGH CLOUD COVER LINGERING FROM THE DAYS
CONVECTION. THIS WILL COMBINE TO PRODUCE WARM OVERNIGHT LOW
TEMPERATURES.
WEDNESDAY IS ANOTHER COMPLEX DAY FOR CONVECTION ACROSS THE
FORECAST AREA. THE APPROACHING PACIFIC THROUGH WILL INTRODUCE SOME
STRONGER QG FORCING OVER WESTERN ZONES BY TOMORROW AFTERNOON. THE
POSITION OF THE LOW FAVORS TAPPING INTO DRY AIR OVER THE GREAT
BASIN AND PULLING IT OVER THE FORECAST AREA. MEANWHILE THE BETTER
LOW LEVEL MOISTURE IS PUSHED NORTH AROUND THE LOW THROUGH THE
GLASGOW FORECAST AREA INTO GREAT FALLS FORECAST AREA. WITH THE
BETTER FORCING AND MOISTURE POSITIONED MAINLY NORTH AND WEST OF
THE FORECAST AREA...EXPECT WE WILL WATCH THE STRONGEST
THUNDERSTORMS MOVE BY TO OUR NORTH BY WEDNESDAY EVENING.
HOWEVER...SINCE NORTHERN AND WESTERN PORTIONS OF THE FORECAST AREA
WILL REMAIN ON THE FRINGES OF THESE BETTER INGREDIENTS HAVE CHOSEN
KEEP 50 POPS AND MENTION OF SEVERE IN THESE AREAS. TAPERED BACK
POPS FOR THE MORE SOUTHERN AND EASTERN LOCATIONS AND REMOVED THE
SEVERE WORDING.
TEMPERATURES ON WEDNESDAY WILL BE IN THE MID TO UPPER 80S FOR MOST
OF THE FORECAST AREA AS THE THERMAL RIDGE MOVES FARTHER EAST. ALSO
EXPECT THE SURFACE FRONT TO PUSH ACROSS THE FORECAST AREA FROM
WEST TO EAST BY LATE WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING.
EXPECT THE PRE FRONTAL WARMING WILL ALSO CONTRIBUTE TO WARMER HIGH
TEMPERATURES. CHURCH
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
PACIFIC LOW OVER THE NORTHWEST ON THURSDAY SHOULD HAVE SHUNTED
THE BEST LOW LEVEL MOISTURE NORTHEAST OF THE AREA BUT IT CLEARLY
IS SLOWER AND DEEPER KEEPING MORE CYCLONIC FLOW OVER THE AREA.
THIS SHOULD MAKE MOUNTAIN THUNDERSTORMS POSSIBLE MOVING OVER THE
PLAINS BUT WOULD EXPECT LACK OF DEEP MOISTURE TO LIMIT STORM
INTENSITY. BIG STORY ON THURSDAY IS THAT TEMPERATURES WILL BE
NEARLY 15 DEGREES COOLER THAN WEDNESDAY.
FRIDAY LOOKS SIMILAR TO THURSDAY THOUGH THE ECMWF HINTS A BIT OF
LOW LEVEL AIRMASS RECOVERY COMPARED TO THURSDAY BUT STILL DOES NOT
LOOK LIKE MORE THAN ISOLATED THUNDERSTORMS. SATURDAY THE UPPER LOW
EJECTS INTO SOUTHERN CANADA AND A TROUGH AXIS CROSSES MONTANA.
CONFLUENT FLOW ALOFT SHOULD HAVE A GOOD CHANCE AT SURPRESSING MOST
CONVECTION ACROSS THE WESTERN HALF OF THE AREA WHILE A COLD FRONT
MOVING THROUGH EASTERN MONTANA MAY TRY AND TRIGGER SOME MORE
CONVECTION.
HEIGHTS REMAIN SURPRESSED IN THE SUNDAY AND MONDAY TIME FRAME WITH
WEAK IMPULSES MOVING THROUGH THE AREA IN WEST SOUTHWESTERLY FLOW
ALOFT. TEMPERATURES WILL BE NEAR NORMAL AND WHILE THUNDER CANNOT
BE RULED OUT THE PATTERN DOES NOT FAVOR ANYTHING MORE THAN GENERIC
STORMS. BORSUM
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL WITH MAINLY MOUNTAIN THUNDERSTORMS IN
THE AFTERNOON AND EVENING. IMPACTS ON TERMINAL SITES WILL BE
LIMITED BUT A STORM MOVING OFF FO THE MOUNTAINS AND IMPACT KLVM
CANNOT BE RULES OUT. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 088 062/088 053/077 050/073 050/075 051/076 051/079
2/T 22/T 22/T 22/T 22/T 22/T 22/T
LVM 089 050/089 047/072 040/070 042/071 047/078 046/081
4/T 33/T 23/T 22/T 23/T 32/T 22/T
HDN 090 059/090 053/078 053/074 050/076 051/077 051/079
2/T 22/T 22/T 33/T 23/T 32/T 22/T
MLS 086 060/090 058/081 055/074 055/077 055/079 055/080
1/U 22/T 42/T 33/T 33/T 33/T 22/T
4BQ 086 059/092 055/081 055/075 052/077 052/079 051/080
1/B 21/B 22/T 33/T 33/T 33/T 22/T
BHK 081 057/086 057/080 054/075 053/074 052/076 052/076
1/U 22/T 32/T 45/T 54/T 33/T 32/T
SHR 083 052/088 050/078 050/073 048/075 047/076 048/078
3/T 22/T 22/T 33/T 22/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KMSO 181012
AFDMSO
Area Forecast Discussion
National Weather Service Missoula MT
412 AM MDT Tue Jun 18 2013
...STRONG POSSIBLY SEVERE THUNDERSTORMS TODAY AND TONIGHT...
.DISCUSSION...A southwesterly flow will bring another warm day
across the region this afternoon. The atmosphere will become
increasingly unstable throughout the day, producing strong and
possibly severe thunderstorms into the evening hours.
*Timing: The storms are still expected to develop just after mid
day along the terrain in southwestern Montana and along the MT/ID
border in central Idaho. Storms will likely track north-north
east and intensify as they move into west-central Montana around
1400-1500 MDT. Storms should hold together and have new
development when a surface boundary, currently in eastern WA,
enters northwestern Montana in the evening. Another round of
storms have the potential to re-develop in the same areas of the
earlier storms and continue to move north through western Montana
into early Wednesday morning.
*Impacts: Large hail, up to 1 inch and possibly larger, could
cause some property damage, especially to vehicles that are not
in a covered area. Brief wind gusts greater than 50mph could
cause tree damage and localized power outages. Brief heavy rain
could pose a threat due to flash flooding in flood-prone
locations such as burn scars and poor drainage areas. Glacier
National Park, more importantly, The Going-To-The-Sun-Road,
stands to pick up the greatest amount of rain, that could create
issues to rock and mudslides.
Wednesday...There will once again be another chance for strong
thunderstorms to develop, however not expected to be as strong or
severe than what we should see today. Though, heavy rain at times
is expected with a cold front associated with the upper-level low
pressure that will track closer to western Montana. The heaviest
rain is anticipated to be Wednesday evening and in northwestern
Montana, possibly as far south as the central Bitterroot Valley.
Expected rain amounts from Tuesday through Wednesday:
Mountains including Lookout Pass and Glacier National Park:
1.00-1.50 inches.
Valleys north of I-90 including Kalispell, Libby, Polson, Eureka,
and Seeley/Swan region: 0.75-1.25 inches.
Valleys south of I-90 and central Idaho including Missoula,
Hamilton, Salmon, and Grangeville: 0.35-0.75 inches
Thursday, there is once again the potential for snow to affect
mountain passes. Some models are showing snow levels in northwest
Montana as low as 6000 feet Thursday morning. Main areas that
would be impacted include Logan Pass, Marias Pass, and potentially
McDonald Pass. Snow amounts of 2 inches or less would be all that
is expected at pass level, however, 3 to 4 inches is possible
above 7000 feet.
Friday and Saturday will be cooler than average and moist as the
upper level low slowly exits the region.
Forecast confidence beyond Saturday is below average due to large
run to run and model to model variations in the pattern for
Monday. Some forecasts have Monday as a very nice day with a ridge
ahead of another low pressure system developing off the west
coast. Others have a quicker and cooler transition. The only thing
that models agree on well is the development of the low off the
west coast, which is a good setup to pump Pacific moisture into
the northern Rockies. So the generally unsettled weather continues
into next week.
&&
.AVIATION...Cloud coverage will be on the increase this afternoon,
with strong to severe thunderstorms beginning to develop after the
noon hour today. Storms will first impact locations in central
Idaho and southwestern Montana just after the noon hour and track
north into central Montana and KMSO. Later in the afternoon, after
18/2200Z KGPI should be impacted by the rain and thunderstorms.
Strong gusty winds greater than 50mph and large hail greater than
1 inch could briefly impact all air terminals. Scattered showers
and thunderstorms are expected to continue into Wednesday morning
for western Montana and central Idaho.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
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000
FXUS65 KGGW 180943
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
343 AM MDT TUE JUN 18 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH THURSDAY...
UPPER RIDGE AXIS SLIDING INTO EASTERN MONTANA AS UPPER LOW
CONTINUES TO SPIN TOWARD THE PACIFIC NORTHWEST. THUNDERSTORMS
DEVELOPED ALONG THE FRONT RANGE LAST EVENING...WEAKENING AS THEY
ENCOUNTER THE MORE STABLE AIRMASS UNDER THE RIDGE THIS MORNING.
AS SYSTEM CONTINUE TO EVOLVE TODAY...SOUTHEAST WINDS WILL BE
INCREASING...PULLING MOISTURE NORTHWARD ACROSS THE PLAINS. WINDS
EXPECTED TO REMAIN BELOW LAKE WIND CRITERIA TODAY WITH WARM AIR
ADVECTION BUT TIGHTENING PRESSURE GRADIENT COULD OVERCOME THE LACK
OF SUBSIDENCE MIXING.
EXPECT ADDITIONAL STORMS TO FIRE ALONG THE FRONT RANGE TODAY THAT
COULD DRIFT INTO NORTHEAST MONTANA ALTHOUGH INCREASINGLY SOUTHERLY
MID AND UPPER LEVEL FLOW COULD PUSH THE STORMS NORTH TOWARD CANADA.
BY WEDNESDAY CONDITIONS BECOME MUCH MORE FAVORABLE FOR STRONG TO
SEVERE THUNDERSTORMS. UPPER LOW MOVES INTO THE NORTHERN ROCKIES
WITH NOSE OF JET PUSHING INTO MONTANA. SOUTHEAST LOW LEVEL FLOW
CONTINUE TO PUMP IN GULF MOISTURE. COLD FRONT SLOWLY MOVING ACROSS
THE STATE WILL PROVIDE MAIN FOCUS FOR STORM DEVELOPMENT AS IT
MOVES FROM CENTRAL MONTANA IN THE AFTERNOON THEN ACROSS EASTERN
MONTANA DURING THE EVENING.
DRIER AND COOLER AIRMASS MOVES INTO THE REGION BEHIND THE COLD
FRONT BY THURSDAY MORNING. UPPER LOW OVER WESTERN MONTANA LIFTING
INTO SOUTHERN ALBERTA...BUT COOL CYCLONIC FLOW COULD PRODUCE A FEW
SHOWERS OR THUNDERSTORMS. EBERT
.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
SYNOPTIC SET UP... LONG TERM BEGINS WITH A DOME OF HEAT OVER THE
DESERT SOUTHWEST AND A RIDGE SPURRING OFF ACROSS COLORADO... THE
CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY. A LARGE TROUGH HAS
EMBEDDED ITSELF INTO THE PACIFIC NORTHWEST. NORTHEAST MONTANA IS
WEDGED BETWEEN THESE TWO AIRMASSES IN SOUTHWEST FLOW ALOFT. A WEAK
RIDGE ALSO RUNS FROM SOUTHERN SASKATCHEWAN THROUGH NORTHERN
ALBERTA AND INTO NORTHER ALASKA.
THURSDAY NIGHT THROUGH SATURDAY NIGHT... THE CORE OF THE CLOSED LOW
TO THE WEST IS EXPECTED TO DRIFT ONTO THE HIGH PLAINS AND WILL
COOL TEMPERATURES DOWN FOR AWHILE ALLOWING FOR A CHANCE OF SHOWERS
AND THUNDERSTORMS EACH AFTERNOON AND EVENING.
SUNDAY ONWARD... MODELS ARE HAVING PROBLEMS DECIDED WHAT TO TO DO
WITH THIS LOW ONCE ITS OVER THE HIGH PLAINS. CONSISTENCY FROM RUN
TO RUN AND MODEL TO MODEL SEEMS FAIRLY POOR... DECREASING CONFIDENCE.
CURRENTLY MODELS POINT TOWARD THE CLOSED LOW KICKING OFF TOWARD
ONTARIO AND A NEW RIDGE ESTABLISHING ITSELF RIGHT BEHIND OVER
WESTERN MONTANA ON MONDAY. THIS RIDGE SHOULD BECOME A GREATER
INFLUENCE WITH WARMING TEMPERATURES AND DECREASING CHANCES FOR
THUNDER THROUGH MID WEEK.
&&
.AVIATION...
VFR.
AN ISOLATED THUNDERSTORM IS POSSIBLE DURING THE LATE AFTERNOON AND
EVENING FOR KGGW OR KGDV BUT IS CURRENTLY BELOW MENTION IN TAFS.
LIGHTS SOUTHEAST WINDS TONIGHT INCREASING TO 10 TO 20 KTS
SUSTAINED AFTER SUNRISE THROUGH TOMORROW EVENING. GAH
&&
.HYDROLOGY...
A FLOOD WARNING REMAINS IN EFFECT FOR THE MILK RIVER NEAR GLASGOW.
THE LATEST GUIDANCE FROM THE RIVER FORECAST CENTER SUGGESTS THE
MILK RIVER NEAR GLASGOW WILL POSSIBLY GO BELOW FLOOD STAGE BY
FRIDAY.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
|
