[top]
000
FXUS63 KABR 220515 AAB
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1215 AM CDT TUE MAY 22 2012
.UPDATE...
AVIATION DISCUSSION UPDATED FOR 06Z TAF ISSUANCE.
THUNDERSTORMS ARE DEVELOPING IN BOTH ND AND NE. THIS LINE...IF IT
FILLS IN WILL AFFECT AREAS WEST OF THE MISSOURI RIVER THIS
EVENING. SHOWERS SHOULD DIMINISH AFTER SUNSET AS INSTABILITY FROM
DAYTIME HEATING DECREASES. NUDGED OVERNIGHT LOWS DOWN IN THE EAST
A COUPLE OF DEGREES BASED ON CURRENT TEMPS AND DEWPOINTS. EVEN
WITH WAA MOVING IN OVERNIGHT SOME QUICK COOLING SHOULD TAKE PLACE
BETWEEN SUNSET AROUND 2Z AND 10Z WHEN BEST WARMING WILL MAKE IT
INTO THE EAST.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...THROUGH THURSDAY MORNING
ACTIVE CONDITIONS ALL THROUGH THE SHORT TERM PERIOD. WILL START
OFF WITH UNSTABLE CONDITIONS OUT WEST THIS AFTERNOON...DESPITE A
RELATIVELY DRY AIR MASS. A WEAK MID LEVEL TR OF HAS ALREADY STARTED
TO INITIATE CONVECTION ACROSS THE HIGHER PORTIONS OF HARDING AND
BUTTE COUNTIES...AND WITH PLENTY OF DAYTIME HEATING AND 500-1000
J/KG CAPE AVAILABLE THROUGH THIS AFTERNOON...THE TRANSITION INTO
WESTERN COUNTIES SEEMS LIKELY. SHEAR IS WEAK...SO SEVERE RISK WILL
BE LIMITED. WITH LOSS OF HEATING AND A LACK OF LOW LEVEL SUPPORT
FARTHER EAST...WOULD EXPECT STORMS WILL DISSIPATE THIS EVENING.
ATTENTION TURNS TO TUESDAY. STRENGTHENING LOW LEVEL FLOW AHEAD OF
DEVELOPING LOW PRESSURE WILL RESULT IN LOW END ADVISORY WINDS
ACROSS THE HIGHER ELEVATIONS OF THE MISSOURI AND SIS SETON
COTE AU...AND IF THE WIND DIRECTION IS RIGHT...DOWN THE JAMES
VALLEY. H85 TEMPERATURES WARM FROM +18C IN THE EAST TO +28C IN THE
WEST UNDER SOUTH/SOUTHWEST LOW LEVEL FLOW. THUS UPPER 80S/LOW 90S
FOR FORECAST HIGHS...HOWEVER MORE IMPORTANTLY H7 TEMPERATURES WORK
UP AROUND +10 TO +12C...WHICH WILL CAP US THROUGH THE DAY. A
COLD FRONT MOVING INTO WESTERN COUNTIES LATE...WITH COOLING
ALOFT...WILL ALLOW FOR CONVECTION TO DEVELOP. CONCERN IS MODEL LOW
LEVEL MOISTURE IS OVERDONE...WHICH IS ALSO INFLUENCING CONVECTIVE
IN DICES. DESPITE THIS...BEST SHEAR/INSTABILITY AND PROBABILITY
FOR CONVECTION TO INITIATE WOULD SUGGEST OUR SEVERE RISK WILL BE
NORTHWEST COUNTIES LATE AFTERNOON/EVENING...AND THEN ACROSS THE
NORTHERN TIER OVERNIGHT.
A SECOND WAVE WILL MOVE SOUTH OF THE CAW FOR THURSDAY MORNING.
LOOKING AT MAINLY MID LEVEL MOISTURE AND WEAK LIFT...ALONG WITH
LIMITED CAPE.
.LONG TERM...THURSDAY THROUGH MONDAY
A BROAD MID LEVEL TROUGH WILL BE OVER THE WESTERN UNITED STATES TO
START THE PERIOD...WITH ENERGY ON THE EAST SIDE OF IT TRACKING
OVER THE NORTHERN PLAINS THURSDAY AND THURSDAY NIGHT. THE TROUGH
THEN KEEPS DIGGING AND RIDGING BUILDS FROM THE SOUTHEASTERN PART
OF THE COUNTRY TO THE NORTHERN PLAINS. THE RIDGE GETS PUSHED EAST
BEGINNING SATURDAY NIGHT WHEN THE WESTERN TROUGH BEGINS TO PUSH
EASTWARD. THE TROUGH ITSELF WEAKENS AS THE MAIN LOW TRACKS OVER
CENTRAL CANADA...WITH JUST WEAK ENERGY MOVING OVER THE AREA SUNDAY
THROUGH MONDAY EVENING.
AT THE SURFACE...AN ELONGATED LOW PRESSURE SYSTEM WILL BE OFF TO
THE EAST AND SOUTH OF THE CAW THURSDAY MORNING...WITH SOME
DIFFERENCES IN THE MODELS AS TO EXACTLY WHERE PRECIPITATION WILL
BE ONGOING. THE EMF IS MUCH MORE AGGRESSIVE WITH PRECIPITATION
THROUGH THE DAY THURSDAY AND INTO THURSDAY EVENING. FRIDAY LOOKS
TO BE DRY AS HIGH PRESSURE DROPS OVER THE NORTHERN PLAINS...THEN
PRECIPITATION RETURNS FRIDAY NIGHT AS ANOTHER LOW PRESSURE SYSTEM
TRACKS ACROSS THE ROCKIES TO THE WEST CENTRAL PLAINS BY SATURDAY
EVENING...THEN NORTHWARD ACROSS THE EASTERN DAKOTAS AND WESTERN
MINNESOTA SATURDAY NIGHT. PRECIPITATION CHANCES LOOK TO BECOME MUCH
LESS ON SUNDAY...BUT WITH THE ENERGY STILL MOVING OVERHEAD...WILL
NOT COMPLETELY REMOVE THE MENTION. MORE CONFIDENT THAT MONDAY WILL
BE DRY AS HIGH PRESSURE DROPS OVER THE NORTHERN PLAINS FROM THE
NORTHWEST.
TEMPERATURES WILL BE A BIT COOL TO START THE PERIOD WITH QUITE A
BIT OF CLOUD COVER AND CHANCES OF PRECIPITATION. HIGHS ON THURSDAY
AND FRIDAY WILL LIKELY NOT REACH 70 DEGREES. WILL SEE A BIT OF A
WARM UP BACK TO NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES DURING
THE LATTER HALF OF THE PERIOD.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
SOUTHERLY WINDS WILL INCREASE BACK INTO THE 20 TO 30 MPH RANGE
WITH HIGHER GUSTS ON TUESDAY MORNING. VFR CONDITIONS ARE EXPECTED
THROUGH TUESDAY AFTERNOON. SOME THUNDERSTORMS ARE POSSIBLE AFTER
00Z WEDNESDAY...MAINLY NEAR THE NORTHERN TIER TAFS OF KATY/KMBG.
THESE TSTORMS MAY BE SEVERE IF THEY DO DEVELOP WITH LARGE HAIL THE
PRIMARY THREAT.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 10 AM THIS MORNING TO 8 PM CDT THIS EVENING
FOR BROWN-BUFFALO-CLARK-CODING TON-DAY-DUEL-EDMUND`S-FOLK-
GRANT-HAMLIN-HAND-HUGHES-HYDE-LYMAN-MARSHALL-MCPHERSON-
POTTER-ROBERTS-SP INK-SULLY.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...CONNELLY
LONG TERM...PARKIN
AVIATION...TDK
WEATHER.GOV/ABERDEEN
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000
FXUS63 KUNR 220450
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1050 PM MDT MON MAY 21 2012
.AVIATION...06Z TAFS
GUSTY SOUTH TO SOUTHWEST WINDS WILL DEVELOP ACROSS THE AREA
TUESDAY MORNING. A COLD FRONT WILL THEN MOVE THROUGH NORTHEAST
WYOMING AND NORTHWEST SOUTH DAKOTA TUESDAY AFTERNOON...AND
THROUGH THE REST OF WESTERN SOUTH DAKOTA TUESDAY EVENING. STRONG
NORTHWEST WINDS WILL SPREAD ACROSS THE AREA BEHIND THE COLD FRONT.
SCATTERED THUNDERSTORMS WILL DEVELOP ACROSS THE AREA TUESDAY
AFTERNOON AND EVENING...WITH THE BEST CHANCE FROM NORTHWEST SOUTH
DAKOTA INTO CENTRAL SOUTH DAKOTA.
&&
.PREV DISCUSSION... /ISSUED 303 PM MDT MON MAY 21 2012/
DISCUSSION...20Z SFC ANALYSIS SHOWS A N/S ORIENTED TROUGH OVER
WESTERN SOUTH DAKOTA WITH A LINE OF CU DEVELOPING ALONG THE TROUGH
LINE. DEWPOINTS ARE IN THE LOWER 50S TO THE EAST OF THE TROUGH AND
IN THE LOWER TO MID 30S TO THE WEST OF THE TROUGH.
LATEST MESO ANALYSIS SHOWS SBCAPE OF 500-1000J/KG EAST OF THE
TROUGH WITH DIMINISHING CIN. EXPECT TO SEE AN ISOLATED
THUNDERSTORM OR TWO DEVELOP LATE THIS AFTERNOON/EARLY
EVENING...AS A WEAK UPPER SHORTWAVE CROSSES THE AREA.
TUESDAY...UPPER TROUGH MOVES INTO THE NORTHERN ROCKIES WITH LEAD
SHORTWAVE ENERGY CREATING A NEW LOW OVER SOUTHEAST MT. TROUGH/DRY-
LINE WILL PUSH INTO SOUTHWEST SD DURING THE DAY WITH GUSTY
SOUTHWEST WINDS BEHIND IT AND VERY DRY RELATIVE HUMIDITIES. AHEAD
OF TROUGH...DEW POINTS IN THE LOWER 50S WILL POOL BRINGING ABOUT
1-2KJ/KG SBCAPE OVER THE FAR EASTERN REACHES OF THE CWA. CAP WILL
BE RATHER STRONG...SO VIGOROUS CONVECTION WILL LIKELY HAVE TO WAIT
UNTIL COLD FRONT THAT FORMS SOUTHWEST OF LOW MOVES INTO WESTERN SD.
SHEAR WILL BE SUFFICIENT FOR SURFACE/ELEVATED SUPERCELLS AND A
COUPLE OF SEVERE THUNDERSTORMS. TEMPERATURES WILL SOAR INTO THE
80S TO LOWER 90S TUESDAY AFTERNOON.
TUESDAY NIGHT/WEDNESDAY...BEHIND THE COLD FRONT COOLER AIR WILL
FILTER INTO THE REGION WITH UPPER TROUGH CLOSING OFF INTO AN UPPER LOW
OVER SOUTHERN SK. CYCLONIC FLOW EXPECTED OVER THE CWA WITH LIMITED
INSTABILITY. RESULT WILL BE GENERIC SHOWERS AND ISOLATED
THUNDERSTORMS OVER MUCH OF THE FORECAST AREA. TEMPERATURES NEAR
GUIDANCE APPEAR REASONABLE GIVEN MODEL FORECAST SOUNDINGS.
EXTENDED...A COUPLE OF UPPER LEVEL LOW PRESSURE SYSTEMS ARE PROGGED
TO PASS WEST AND NORTH OF THE AREA DURING THE LATTER PART OF THE
WEEK AND OVER THE WEEKEND. SOUTHWESTERLY FLOW ALOFT WILL DEVELOP TO
THE SOUTH OF THESE SYSTEMS OVER THE CENTRAL ROCKIES AND INTO THE
CENTRAL AND NORTHERN PLAINS. THIS PATTERN WILL BRING A SERIES OF
UPPER LEVEL DISTURBANCES THROUGH THE AREA...WITH DAILY CHANCES FOR
SHOWERS AND A FEW THUNDERSTORMS THROUGH THE WEEKEND. THE BEST CHANCE
FOR THUNDERSTORMS WILL BE THURSDAY INTO THURSDAY NIGHT AND FRIDAY
NIGHT THROUGH SATURDAY NIGHT. TEMPERATURES WILL GENERALLY BE NEAR OR
SLIGHTLY BELOW AVERAGE LATE THIS WEEK...WITH A WARMUP TO NEAR OR
SLIGHTLY ABOVE AVERAGE TEMPERATURES OVER THE HOLIDAY WEEKEND.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...FIRE WEATHER WATCH FROM 6 AM MDT TUESDAY THROUGH TUESDAY EVENING
FOR SOUTHERN BLACK HILLS-SOUTHWESTERN SOUTH DAKOTA.
WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR TODD-TRIPP.
WY...FIRE WEATHER WATCH FROM 6 AM MDT TUESDAY THROUGH TUESDAY EVENING
FOR LOWER ELEVATIONS OF CROOK AND WESTON COUNTIES-NORTHERN
CAMPBELL-SOUTHERN CAMPBELL.
&&
$$
SHORT TERM...WFO UNR
LONG TERM....WFO UNR
AVIATION...07
[top]
000
FXUS63 KFSD 220404
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1104 PM CDT MON MAY 21 2012
.DISCUSSION.../ISSUED AT 851 PM CDT/
LATEST RAP SHOWS 500-1000 J/KG INSTABILITY DEVELOPING LATE TONIGHT
FOR PARCELS ORIGINATING ABOVE 800 MB. BELOW THAT LAYER THERE IS
FAIRLY STRONG THETA-E ADVECTION TO PRODUCE SOME LIFT. WHAT IS
LACKING IS ANY TYPE OF STRONG FRONT OR EVEN UPPER LEVEL FEATURE TO
ENHANCE LIFT ON THE MESOSCALE. NONETHELESS...WHILE IT IS LIKELY
UNDERDOING THE CONVECTIVE INHIBITION...EXPECT THAT AT LEAST ISOLATED
THUNDERSTORMS WILL BEGIN TO DEVELOP AROUND MIDNIGHT WEST OF THE
JAMES RIVER AND MOVE EAST THROUGH THE NIGHT...REACHING I-29 BY 09Z
AND MOST OF SW MN AND NW IA BY 12Z. DID CONSIDER ADDING A SLIGHT
CHANCE FOR EARLY TOMORROW MORNING EAST OF I-29 BUT WITH CHANCE LESS
THAN 20 PERCENT DECIDED TO FORGO MENTION AT THIS POINT.
OTHERWISE...ONLY OTHER CHANGE WAS TO INCREASE WINDS ALONG AND EAST
OF THE BUFFALO RIDGE. HI-RES WRF-ARW SHOWS WINDS SUSTAINED OVER 20
MPH LATE TONIGHT WITH GUSTS OVER 30 MPH POSSIBLE BY DAWN. THIS WILL
ALSO ALLOW TEMPS TO RISE A COUPLE OF DEGREES LATE TONIGHT SO RAISED
LOWS INTO THE LOWER 60S. UPDATED ZFP/PFM AND GRIDS OUT.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF FORECAST PERIOD.
ELEVATED SHOWERS OR THUNDERSTORMS MAY DEVELOP PRIOR TO 14Z THIS
MORNING...HOWEVER EXPECTED ISOLATED COVERAGE PRECLUDES MENTION IN
TAFS AT THIS TIME. INCREASING SOUTH WINDS WILL CREATE ADDITIONAL
AVIATION CONCERN ON TUESDAY...WITH GUSTS GREATER THAN 25KT LIKELY
AFTER 14Z THROUGH THE END OF THE PERIOD. STRONGEST WINDS SHOULD
DIMINISH BY 23/01Z...THOUGH 45-55KT LOW LEVEL JET ABOVE 1100FT AGL
COULD CREATE LOW LEVEL WIND SHEAR AFTER SUNSET TUESDAY EVENING. WILL
NOT INCLUDE IN TAFS AT THIS TIME...BUT MAY NEED TO BE ADDED IN
FUTURE ISSUANCES.
&&
.PREV DISCUSSION.../ISSUED AT 315 PM CDT/
MID LEVEL CLOUDS ALONG AND EAST OF I29 WILL CONTINUE TO PUSH EAST
THROUGH THIS EVENING WITH PARTLY CLOUDY SKIES EXPECTED MOST OF THE
NIGHT. WILL KEEP A VERY SMALL CHANCE FOR THUNDERSTORMS LATE TONIGHT
AS LOW LEVEL JET INCREASES AHEAD OF ELEVATED INSTABILITY WEST OF I29
AFTER 06Z. NOT ALL THAT CONFIDENT ANYTHING WILL FIRE UP SO ONLY WILL
HAVE 20% POPS AT MOST. SOUTHERLY WINDS WILL ALSO HOLD TEMPERATURES
UP TONIGHT WITH LOWS IN THE MID 50S TO LOWER 60S.
WHILE THERE IS NO MAGIC LINE ON IT AT DAYBREAK...THE CHANCE OF ANY
LINGERING STORMS IN OUR FAR EAST EARLY TUESDAY MORNING SEEMS LOW
ENOUGH TO KEEP MENTION OF OUT FOR TUESDAY...CONSIDERING CHANCE
TONIGHT IS SO SMALL AND THE WARMING AIR SHOULD BE CAPPED. OTHERWISE
A FEW CLOUDS SHOULD BE MOSTLY HIGH AND LEAD TO A MOSTLY SUNNY WARM
AND VERY WINDY DAY. IT HAS BEEN PLAIN FOR THREE DAYS THAT SOUTHERLY
WINDS WILL BE STRONG AND THAT CONTINUES...WITH GUIDANCE AS USUAL
UNDERDOING EXPECTED SURFACE WINDS. WINDS SHOULD MAKE THE 30 MPH
SUSTAINED CRITERIA OR STRONGER OVER ALL OF THE FORECAST AREA SO WILL
GO WITH A WIND ADVISORY 15Z TO 01Z/10 AM TO 8 PM. HIGH TEMPERATURES
GUIDANCE SEEMS ONLY A LITTLE NOT QUITE WARM ENOUGH WITH 80S TO SOME
LOWER 90S WEST.
COLD FRONT ADVANCES INTO FORECAST AREA TUESDAY NIGHT AND WILL KEEP A
CHANCE OF STORMS AS FRONT ADVANCES...LEAVING OUT PART OF NORTHWEST
IA SOUTHEAST OF SUX TO MJQ LINE. THE ADVANCE CONTINUES WEDNESDAY
WITH THE FRONT DEFINITELY SLOWING. WILL TEMPORARILY DECREASE THE
STORM THREAT WEST WEDNESDAY BEFORE PICKING IT UP AGAIN WEDNESDAY
NIGHT AS ANOTHER WAVE APPROACHES...LIKELY POPS LOOK GOOD FOR THE
EAST FOR WEDNESDAY NIGHT. COOLING AND CLOUDS WILL COOL TEMPERATURES
WEDNESDAY FROM TUESDAY EXCEPT IT WILL STILL BE IN THE WARM 80S
SOUTHEAST OF SUX/SPW LINE. WAVE PULLING OUT TO THE NORTHEAST SHOULD
SLOWLY DECREASE THE RAIN THREAT WEDNESDAY NIGHT AND THURSDAY...AND
ON A CLOSE CALL WILL LEAVE MENTION OUT ALTOGETHER FOR FRIDAY GIVEN
SURFACE AND LOW LEVEL RIDGING BEHIND FRONT. TEMPERATURES OF COURSE
WILL BE COOLER DURING THIS TIME.
RIDGING AND ASSOCIATED WARMING SHOULD BRING A THREAT OF STORMS OVER
THE WEEKEND ALONG WITH WARM AND MORE HUMID CONDITIONS. MODELS
ESPECIALLY THE ECMWF ARE FURTHER EAST WITH THE RIDGING THAN THEY
WERE YESTERDAY WHICH WILL MEAN LESS CAPPING AND ALLOWING THE NEXT
SYSTEM TO GET CLOSE. WILL GO WITH THE CURRENT MODEL RUNS AND START
TO DECREASE RAIN CHANCES AGAIN MONDAY ALONG WITH THE RETURN OF
COOLING.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR IAZ001>003-
012>014-020>022-031-032.
MN...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR MNZ071-072-080-
081-089-090-097-098.
NE...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR NEZ013-014.
SD...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR SDZ038>040-050-
052>071.
&&
$$
000
FXUS63 KFSD 220151
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
851 PM CDT MON MAY 21 2012
.DISCUSSION.../ISSUED AT 851 PM CDT/
LATEST RAP SHOWS 500-1000 J/KG INSTABILITY DEVELOPING LATE TONIGHT
FOR PARCELS ORIGINATING ABOVE 800 MB. BELOW THAT LAYER THERE IS
FAIRLY STRONG THETA-E ADVECTION TO PRODUCE SOME LIFT. WHAT IS
LACKING IS ANY TYPE OF STRONG FRONT OR EVEN UPPER LEVEL FEATURE TO
ENHANCE LIFT ON THE MESOSCALE. NONETHELESS...WHILE IT IS LIKELY
UNDERDOING THE CONVECTIVE INHIBITION...EXPECT THAT AT LEAST ISOLATED
THUNDERSTORMS WILL BEGIN TO DEVELOP AROUND MIDNIGHT WEST OF THE
JAMES RIVER AND MOVE EAST THROUGH THE NIGHT...REACHING I-29 BY 09Z
AND MOST OF SW MN AND NW IA BY 12Z. DID CONSIDER ADDING A SLIGHT
CHANCE FOR EARLY TOMORROW MORNING EAST OF I-29 BUT WITH CHANCE LESS
THAN 20 PERCENT DECIDED TO FORGO MENTION AT THIS POINT.
OTHERWISE...ONLY OTHER CHANGE WAS TO INCREASE WINDS ALONG AND EAST
OF THE BUFFALO RIDGE. HI-RES WRF-ARW SHOWS WINDS SUSTAINED OVER 20
MPH LATE TONIGHT WITH GUSTS OVER 30 MPH POSSIBLE BY DAWN. THIS WILL
ALSO ALLOW TEMPS TO RISE A COUPLE OF DEGREES LATE TONIGHT SO RAISED
LOWS INTO THE LOWER 60S. UPDATED ZFP/PFM AND GRIDS OUT.
&&
.AVIATION.../FOR THE 00Z TAF ISSUANCE/
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF FORECAST PERIOD.
ELEVATED SHOWERS OR THUNDERSTORMS MAY DEVELOP AFTER 06Z EAST OF THE
JAMES RIVER VALLEY...HOWEVER EXPECTED ISOLATED COVERAGE PRECLUDES
MENTION IN KFSD/KSUX TAFS AT THIS TIME. INCREASING SOUTH WINDS WILL
CREATE ADDITIONAL AVIATION CONCERN ON TUESDAY...WITH GUSTS GREATER
THAN 25KT LIKELY AFTER 14Z THROUGH THE END OF THE PERIOD.
&&
.PREV DISCUSSION.../ISSUED AT 315 PM CDT/
MID LEVEL CLOUDS ALONG AND EAST OF I29 WILL CONTINUE TO PUSH EAST
THROUGH THIS EVENING WITH PARTLY CLOUDY SKIES EXPECTED MOST OF THE
NIGHT. WILL KEEP A VERY SMALL CHANCE FOR THUNDERSTORMS LATE TONIGHT
AS LOW LEVEL JET INCREASES AHEAD OF ELEVATED INSTABILITY WEST OF I29
AFTER 06Z. NOT ALL THAT CONFIDENT ANYTHING WILL FIRE UP SO ONLY WILL
HAVE 20% POPS AT MOST. SOUTHERLY WINDS WILL ALSO HOLD TEMPERATURES
UP TONIGHT WITH LOWS IN THE MID 50S TO LOWER 60S.
WHILE THERE IS NO MAGIC LINE ON IT AT DAYBREAK...THE CHANCE OF ANY
LINGERING STORMS IN OUR FAR EAST EARLY TUESDAY MORNING SEEMS LOW
ENOUGH TO KEEP MENTION OF OUT FOR TUESDAY...CONSIDERING CHANCE
TONIGHT IS SO SMALL AND THE WARMING AIR SHOULD BE CAPPED. OTHERWISE
A FEW CLOUDS SHOULD BE MOSTLY HIGH AND LEAD TO A MOSTLY SUNNY WARM
AND VERY WINDY DAY. IT HAS BEEN PLAIN FOR THREE DAYS THAT SOUTHERLY
WINDS WILL BE STRONG AND THAT CONTINUES...WITH GUIDANCE AS USUAL
UNDERDOING EXPECTED SURFACE WINDS. WINDS SHOULD MAKE THE 30 MPH
SUSTAINED CRITERIA OR STRONGER OVER ALL OF THE FORECAST AREA SO WILL
GO WITH A WIND ADVISORY 15Z TO 01Z/10 AM TO 8 PM. HIGH TEMPERATURES
GUIDANCE SEEMS ONLY A LITTLE NOT QUITE WARM ENOUGH WITH 80S TO SOME
LOWER 90S WEST.
COLD FRONT ADVANCES INTO FORECAST AREA TUESDAY NIGHT AND WILL KEEP A
CHANCE OF STORMS AS FRONT ADVANCES...LEAVING OUT PART OF NORTHWEST
IA SOUTHEAST OF SUX TO MJQ LINE. THE ADVANCE CONTINUES WEDNESDAY
WITH THE FRONT DEFINITELY SLOWING. WILL TEMPORARILY DECREASE THE
STORM THREAT WEST WEDNESDAY BEFORE PICKING IT UP AGAIN WEDNESDAY
NIGHT AS ANOTHER WAVE APPROACHES...LIKELY POPS LOOK GOOD FOR THE
EAST FOR WEDNESDAY NIGHT. COOLING AND CLOUDS WILL COOL TEMPERATURES
WEDNESDAY FROM TUESDAY EXCEPT IT WILL STILL BE IN THE WARM 80S
SOUTHEAST OF SUX/SPW LINE. WAVE PULLING OUT TO THE NORTHEAST SHOULD
SLOWLY DECREASE THE RAIN THREAT WEDNESDAY NIGHT AND THURSDAY...AND
ON A CLOSE CALL WILL LEAVE MENTION OUT ALTOGETHER FOR FRIDAY GIVEN
SURFACE AND LOW LEVEL RIDGING BEHIND FRONT. TEMPERATURES OF COURSE
WILL BE COOLER DURING THIS TIME.
RIDGING AND ASSOCIATED WARMING SHOULD BRING A THREAT OF STORMS OVER
THE WEEKEND ALONG WITH WARM AND MORE HUMID CONDITIONS. MODELS
ESPECIALLY THE ECMWF ARE FURTHER EAST WITH THE RIDGING THAN THEY
WERE YESTERDAY WHICH WILL MEAN LESS CAPPING AND ALLOWING THE NEXT
SYSTEM TO GET CLOSE. WILL GO WITH THE CURRENT MODEL RUNS AND START
TO DECREASE RAIN CHANCES AGAIN MONDAY ALONG WITH THE RETURN OF
COOLING.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR IAZ001>003-
012>014-020>022-031-032.
MN...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR MNZ071-072-080-
081-089-090-097-098.
NE...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR NEZ013-014.
SD...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR SDZ038>040-050-
052>071.
&&
$$
000
FXUS63 KUNR 212346
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
546 PM MDT MON MAY 21 2012
.AVIATION...00Z TAFS
ISOLATED THUNDERSTORMS POSSIBLE OVER SOUTH CENTRAL SOUTH DAKOTA
THIS EVENING...OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH
TUESDAY AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 303 PM MDT MON MAY 21 2012/
DISCUSSION...20Z SFC ANALYSIS SHOWS A N/S ORIENTED TROUGH OVER
WESTERN SOUTH DAKOTA WITH A LINE OF CU DEVELOPING ALONG THE TROUGH
LINE. DEWPOINTS ARE IN THE LOWER 50S TO THE EAST OF THE TROUGH AND
IN THE LOWER TO MID 30S TO THE WEST OF THE TROUGH.
LATEST MESO ANALYSIS SHOWS SBCAPE OF 500-1000J/KG EAST OF THE
TROUGH WITH DIMINISHING CIN. EXPECT TO SEE AN ISOLATED
THUNDERSTORM OR TWO DEVELOP LATE THIS AFTERNOON/EARLY
EVENING...AS A WEAK UPPER SHORTWAVE CROSSES THE AREA.
TUESDAY...UPPER TROUGH MOVES INTO THE NORTHERN ROCKIES WITH LEAD
SHORTWAVE ENERGY CREATING A NEW LOW OVER SOUTHEAST MT. TROUGH/DRY-
LINE WILL PUSH INTO SOUTHWEST SD DURING THE DAY WITH GUSTY
SOUTHWEST WINDS BEHIND IT AND VERY DRY RELATIVE HUMIDITIES. AHEAD
OF TROUGH...DEW POINTS IN THE LOWER 50S WILL POOL BRINGING ABOUT
1-2KJ/KG SBCAPE OVER THE FAR EASTERN REACHES OF THE CWA. CAP WILL
BE RATHER STRONG...SO VIGOROUS CONVECTION WILL LIKELY HAVE TO WAIT
UNTIL COLD FRONT THAT FORMS SOUTHWEST OF LOW MOVES INTO WESTERN SD.
SHEAR WILL BE SUFFICIENT FOR SURFACE/ELEVATED SUPERCELLS AND A
COUPLE OF SEVERE THUNDERSTORMS. TEMPERATURES WILL SOAR INTO THE
80S TO LOWER 90S TUESDAY AFTERNOON.
TUESDAY NIGHT/WEDNESDAY...BEHIND THE COLD FRONT COOLER AIR WILL
FILTER INTO THE REGION WITH UPPER TROUGH CLOSING OFF INTO AN UPPER LOW
OVER SOUTHERN SK. CYCLONIC FLOW EXPECTED OVER THE CWA WITH LIMITED
INSTABILITY. RESULT WILL BE GENERIC SHOWERS AND ISOLATED
THUNDERSTORMS OVER MUCH OF THE FORECAST AREA. TEMPERATURES NEAR
GUIDANCE APPEAR REASONABLE GIVEN MODEL FORECAST SOUNDINGS.
EXTENDED...A COUPLE OF UPPER LEVEL LOW PRESSURE SYSTEMS ARE PROGGED
TO PASS WEST AND NORTH OF THE AREA DURING THE LATTER PART OF THE
WEEK AND OVER THE WEEKEND. SOUTHWESTERLY FLOW ALOFT WILL DEVELOP TO
THE SOUTH OF THESE SYSTEMS OVER THE CENTRAL ROCKIES AND INTO THE
CENTRAL AND NORTHERN PLAINS. THIS PATTERN WILL BRING A SERIES OF
UPPER LEVEL DISTURBANCES THROUGH THE AREA...WITH DAILY CHANCES FOR
SHOWERS AND A FEW THUNDERSTORMS THROUGH THE WEEKEND. THE BEST CHANCE
FOR THUNDERSTORMS WILL BE THURSDAY INTO THURSDAY NIGHT AND FRIDAY
NIGHT THROUGH SATURDAY NIGHT. TEMPERATURES WILL GENERALLY BE NEAR OR
SLIGHTLY BELOW AVERAGE LATE THIS WEEK...WITH A WARMUP TO NEAR OR
SLIGHTLY ABOVE AVERAGE TEMPERATURES OVER THE HOLIDAY WEEKEND.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...FIRE WEATHER WATCH FROM TUESDAY MORNING THROUGH TUESDAY EVENING
FOR SOUTHERN BLACK HILLS-SOUTHWESTERN SOUTH DAKOTA.
WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR TODD-TRIPP.
WY...FIRE WEATHER WATCH FROM TUESDAY MORNING THROUGH TUESDAY EVENING
FOR LOWER ELEVATIONS OF CROOK AND WESTON COUNTIES-NORTHERN
CAMPBELL-SOUTHERN CAMPBELL.
&&
$$
SHORT TERM...WFO UNR
LONG TERM....WFO UNR
AVIATION...07
000
FXUS63 KFSD 212342
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
642 PM CDT MON MAY 21 2012
.DISCUSSION.../ISSUED AT 315 PM CDT/
MID LEVEL CLOUDS ALONG AND EAST OF I29 WILL CONTINUE TO PUSH EAST
THROUGH THIS EVENING WITH PARTLY CLOUDY SKIES EXPECTED MOST OF THE
NIGHT. WILL KEEP A VERY SMALL CHANCE FOR THUNDERSTORMS LATE TONIGHT
AS LOW LEVEL JET INCREASES AHEAD OF ELEVATED INSTABILITY WEST OF I29
AFTER 06Z. NOT ALL THAT CONFIDENT ANYTHING WILL FIRE UP SO ONLY WILL
HAVE 20% POPS AT MOST. SOUTHERLY WINDS WILL ALSO HOLD TEMPERATURES
UP TONIGHT WITH LOWS IN THE MID 50S TO LOWER 60S.
WHILE THERE IS NO MAGIC LINE ON IT AT DAYBREAK...THE CHANCE OF ANY
LINGERING STORMS IN OUR FAR EAST EARLY TUESDAY MORNING SEEMS LOW
ENOUGH TO KEEP MENTION OF OUT FOR TUESDAY...CONSIDERING CHANCE
TONIGHT IS SO SMALL AND THE WARMING AIR SHOULD BE CAPPED. OTHERWISE
A FEW CLOUDS SHOULD BE MOSTLY HIGH AND LEAD TO A MOSTLY SUNNY WARM
AND VERY WINDY DAY. IT HAS BEEN PLAIN FOR THREE DAYS THAT SOUTHERLY
WINDS WILL BE STRONG AND THAT CONTINUES...WITH GUIDANCE AS USUAL
UNDERDOING EXPECTED SURFACE WINDS. WINDS SHOULD MAKE THE 30 MPH
SUSTAINED CRITERIA OR STRONGER OVER ALL OF THE FORECAST AREA SO WILL
GO WITH A WIND ADVISORY 15Z TO 01Z/10 AM TO 8 PM. HIGH TEMPERATURES
GUIDANCE SEEMS ONLY A LITTLE NOT QUITE WARM ENOUGH WITH 80S TO SOME
LOWER 90S WEST.
COLD FRONT ADVANCES INTO FORECAST AREA TUESDAY NIGHT AND WILL KEEP A
CHANCE OF STORMS AS FRONT ADVANCES...LEAVING OUT PART OF NORTHWEST
IA SOUTHEAST OF SUX TO MJQ LINE. THE ADVANCE CONTINUES WEDNESDAY
WITH THE FRONT DEFINITELY SLOWING. WILL TEMPORARILY DECREASE THE
STORM THREAT WEST WEDNESDAY BEFORE PICKING IT UP AGAIN WEDNESDAY
NIGHT AS ANOTHER WAVE APPROACHES...LIKELY POPS LOOK GOOD FOR THE
EAST FOR WEDNESDAY NIGHT. COOLING AND CLOUDS WILL COOL TEMPERATURES
WEDNESDAY FROM TUESDAY EXCEPT IT WILL STILL BE IN THE WARM 80S
SOUTHEAST OF SUX/SPW LINE. WAVE PULLING OUT TO THE NORTHEAST SHOULD
SLOWLY DECREASE THE RAIN THREAT WEDNESDAY NIGHT AND THURSDAY...AND
ON A CLOSE CALL WILL LEAVE MENTION OUT ALTOGETHER FOR FRIDAY GIVEN
SURFACE AND LOW LEVEL RIDGING BEHIND FRONT. TEMPERATURES OF COURSE
WILL BE COOLER DURING THIS TIME.
RIDGING AND ASSOCIATED WARMING SHOULD BRING A THREAT OF STORMS OVER
THE WEEKEND ALONG WITH WARM AND MORE HUMID CONDITIONS. MODELS
ESPECIALLY THE ECMWF ARE FURTHER EAST WITH THE RIDGING THAN THEY
WERE YESTERDAY WHICH WILL MEAN LESS CAPPING AND ALLOWING THE NEXT
SYSTEM TO GET CLOSE. WILL GO WITH THE CURRENT MODEL RUNS AND START
TO DECREASE RAIN CHANCES AGAIN MONDAY ALONG WITH THE RETURN OF
COOLING.
&&
.AVIATION.../FOR THE 00Z TAF ISSUANCE/
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF FORECAST PERIOD.
ELEVATED SHOWERS OR THUNDERSTORMS MAY DEVELOP AFTER 06Z EAST OF THE
JAMES RIVER VALLEY...HOWEVER EXPECTED ISOLATED COVERAGE PRECLUDES
MENTION IN KFSD/KSUX TAFS AT THIS TIME. INCREASING SOUTH WINDS WILL
CREATE ADDITIONAL AVIATION CONCERN ON TUESDAY...WITH GUSTS GREATER
THAN 25KT LIKELY AFTER 14Z THROUGH THE END OF THE PERIOD.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR IAZ001>003-
012>014-020>022-031-032.
MN...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR MNZ071-072-080-
081-089-090-097-098.
NE...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR NEZ013-014.
SD...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR SDZ038>040-050-
052>071.
&&
$$
000
FXUS63 KABR 212339 AAA
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
639 PM CDT MON MAY 21 2012
.UPDATE...
THUNDERSTORMS ARE DEVELOPING IN BOTH ND AND NE. THIS LINE...IF IT
FILLS IN WILL AFFECT AREAS WEST OF THE MISSOURI RIVER THIS
EVENING. SHOWERS SHOULD DIMINISH AFTER SUNSET AS INSTABILITY FROM
DAYTIME HEATING DECREASES. NUDGED OVERNIGHT LOWS DOWN IN THE EAST
A COUPLE OF DEGREES BASED ON CURRENT TEMPS AND DEWPOINTS. EVEN
WITH WAA MOVING IN OVERNIGHT SOME QUICK COOLING SHOULD TAKE PLACE
BETWEEN SUNSET AROUND 2Z AND 10Z WHEN BEST WARMING WILL MAKE IT
INTO THE EAST.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...THROUGH THURSDAY MORNING
ACTIVE CONDITIONS ALL THROUGH THE SHORT TERM PERIOD. WILL START
OFF WITH UNSTABLE CONDITIONS OUT WEST THIS AFTERNOON...DESPITE A
RELATIVELY DRY AIRMASS. A WEAK MID LEVEL TROF HAS ALREADY STARTED
TO INITIATE CONVECTION ACROSS THE HIGHER PORTIONS OF HARDING AND
BUTTE COUNTIES...AND WITH PLENTY OF DAYTIME HEATING AND 500-1000
J/KG CAPE AVAILABLE THROUGH THIS AFTERNOON...THE TRANSITION INTO
WESTERN COUNTIES SEEMS LIKELY. SHEAR IS WEAK...SO SEVERE RISK WILL
BE LIMITED. WITH LOSS OF HEATING AND A LACK OF LOW LEVEL SUPPORT
FARTHER EAST...WOULD EXPECT STORMS WILL DISSIPATE THIS EVENING.
ATTENTION TURNS TO TUESDAY. STRENGTHENING LOW LEVEL FLOW AHEAD OF
DEVELOPING LOW PRESSURE WILL RESULT IN LOW END ADVISORY WINDS
ACROSS THE HIGHER ELEVATIONS OF THE MISSOURI AND SISSETON
COTEAU...AND IF THE WIND DIRECTION IS RIGHT...DOWN THE JAMES
VALLEY. H85 TEMPERATURES WARM FROM +18C IN THE EAST TO +28C IN THE
WEST UNDER SOUTH/SOUTHWEST LOW LEVEL FLOW. THUS UPPER 80S/LOW 90S
FOR FORECAST HIGHS...HOWEVER MORE IMPORTANTLY H7 TEMPERATURES WORK
UP AROUND +10 TO +12C...WHICH WILL CAP US THROUGH THE DAY. A
COLD FRONT MOVING INTO WESTERN COUNTIES LATE...WITH COOLING
ALOFT...WILL ALLOW FOR CONVECTION TO DEVELOP. CONCERN IS MODEL LOW
LEVEL MOISTURE IS OVERDONE...WHICH IS ALSO INFLUENCING CONVECTIVE
INDICES. DESPITE THIS...BEST SHEAR/INSTABILITY AND PROBABILITY
FOR CONVECTION TO INITIATE WOULD SUGGEST OUR SEVERE RISK WILL BE
NORTHWEST COUNTIES LATE AFTERNOON/EVENING...AND THEN ACROSS THE
NORTHERN TIER OVERNIGHT.
A SECOND WAVE WILL MOVE SOUTH OF THE CWA FOR THURSDAY MORNING.
LOOKING AT MAINLY MID LEVEL MOISTURE AND WEAK LIFT...ALONG WITH
LIMITED CAPE.
.LONG TERM...THURSDAY THROUGH MONDAY
A BROAD MID LEVEL TROUGH WILL BE OVER THE WESTERN UNITED STATES TO
START THE PERIOD...WITH ENERGY ON THE EAST SIDE OF IT TRACKING
OVER THE NORTHERN PLAINS THURSDAY AND THURSDAY NIGHT. THE TROUGH
THEN KEEPS DIGGING AND RIDGING BUILDS FROM THE SOUTHEASTERN PART
OF THE COUNTRY TO THE NORTHERN PLAINS. THE RIDGE GETS PUSHED EAST
BEGINNING SATURDAY NIGHT WHEN THE WESTERN TROUGH BEGINS TO PUSH
EASTWARD. THE TROUGH ITSELF WEAKENS AS THE MAIN LOW TRACKS OVER
CENTRAL CANADA...WITH JUST WEAK ENERGY MOVING OVER THE AREA SUNDAY
THROUGH MONDAY EVENING.
AT THE SURFACE...AN ELONGATED LOW PRESSURE SYSTEM WILL BE OFF TO
THE EAST AND SOUTH OF THE CWA THURSDAY MORNING...WITH SOME
DIFFERENCES IN THE MODELS AS TO EXACTLY WHERE PRECIPITATION WILL
BE ONGOING. THE ECMWF IS MUCH MORE AGGRESSIVE WITH PRECIPITATION
THROUGH THE DAY THURSDAY AND INTO THURSDAY EVENING. FRIDAY LOOKS
TO BE DRY AS HIGH PRESSURE DROPS OVER THE NORTHERN PLAINS...THEN
PRECIPITATION RETURNS FRIDAY NIGHT AS ANOTHER LOW PRESSURE SYSTEM
TRACKS ACROSS THE ROCKIES TO THE WEST CENTRAL PLAINS BY SATURDAY
EVENING...THEN NORTHWARD ACROSS THE EASTERN DAKOTAS AND WESTERN
MINNESOTA SATURDAY NIGHT. PRECIPITATION CHANCES LOOK TO BECOME MUCH
LESS ON SUNDAY...BUT WITH THE ENERGY STILL MOVING OVERHEAD...WILL
NOT COMPLETELY REMOVE THE MENTION. MORE CONFIDENT THAT MONDAY WILL
BE DRY AS HIGH PRESSURE DROPS OVER THE NORTHERN PLAINS FROM THE
NORTHWEST.
TEMPERATURES WILL BE A BIT COOL TO START THE PERIOD WITH QUITE A
BIT OF CLOUD COVER AND CHANCES OF PRECIPITATION. HIGHS ON THURSDAY
AND FRIDAY WILL LIKELY NOT REACH 70 DEGREES. WILL SEE A BIT OF A
WARM UP BACK TO NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES DURING
THE LATTER HALF OF THE PERIOD.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS WILL PREVAIL WITH SOUTHERLY WINDS IN THE 20 TO 30
MPH RANGE UNTIL AFTER SUNSET. WIND SPEEDS WILL DIMINISH SOME DURING THE
OVERNIGHT HOURS...THEN WILL INCREASE BACK INTO THE 15 TO 30 MPH
RANGE OUT OF THE SOUTH ON TUESDAY MORNING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR BROWN-BUFFALO-
CLARK-CODINGTON-DAY-DEUEL-EDMUNDS-FAULK-GRANT-HAMLIN-HAND-
HUGHES-HYDE-LYMAN-MARSHALL-MCPHERSON-POTTER-ROBERTS-SPINK-
SULLY.
MN...NONE.
&&
$$
UPDATE...WISE
SHORT TERM...CONNELLY
LONG TERM...PARKIN
AVIATION...WISE
WEATHER.GOV/ABERDEEN
000
FXUS63 KUNR 212103
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
303 PM MDT MON MAY 21 2012
.DISCUSSION...20Z SFC ANALYSIS SHOWS A N/S ORIENTED TROUGH OVER
WESTERN SOUTH DAKOTA WITH A LINE OF CU DEVELOPING ALONG THE TROUGH
LINE. DEWPOINTS ARE IN THE LOWER 50S TO THE EAST OF THE TROUGHAND
IN THE LOWER TO MID 30S TO THE WEST OF THE TROUGH.
LATEST MESO ANALYSIS SHOWS SBCAPE OF 500-1000J/KG EAST OF THE
TROUGH WITH DIMINISHING CIN. EXPECT TO SEE AN ISOLATED
THUNDERSTORM OR TWO DEVELOP LATE THIS AFTERNOON/EARLY
EVENING...AS A WEAK UPPER SHORTWAVE CROSSES THE AREA.
TUESDAY...UPPER TROUGH MOVES INTO THE NORTHERN ROCKIES WITH LEAD
SHORTWAVE ENERGY CREATING A NEW LOW OVER SOUTHEAST MT. TROUGH/DRY-
LINE WILL PUSH INTO SOUTHWEST SD DURING THE DAY WITH GUSTY
SOUTHWEST WINDS BEHIND IT AND VERY DRY RELATIVE HUMIDITIES. AHEAD
OF TROUGH...DEW POINTS IN THE LOWER 50S WILL POOL BRINGING ABOUT
1-2KJ/KG SBCAPE OVER THE FAR EASTERN REACHES OF THE CWA. CAP WILL
BE RATHER STRONG...SO VIGOROUS CONVECTION WILL LIKELY HAVE TO WAIT
UNTIL COLD FRONT THAT FORMS SOUTHWEST OF LOW MOVES INTO WESTERN SD.
SHEAR WILL BE SUFFICIENT FOR SURFACE/ELEVATED SUPERCELLS AND A
COUPLE OF SEVERE THUNDERSTORMS. TEMPERATURES WILL SOAR INTO THE
80S TO LOWER 90S TUESDAY AFTERNOON.
TUESDAY NIGHT/WEDNESDAY...BEHIND THE COLD FRONT COOLER AIR WILL
FILTER INTO THE REGION WITH UPPER TROUGH CLOSING OFF INTO AN UPPER LOW
OVER SOUTHERN SK. CYCLONIC FLOW EXPECTED OVER THE CWA WITH LIMITED
INSTABILITY. RESULT WILL BE GENERIC SHOWERS AND ISOLATED
THUNDERSTORMS OVER MUCH OF THE FORECAST AREA. TEMPERATURES NEAR
GUIDANCE APPEAR REASONABLE GIVEN MODEL FORECAST SOUNDINGS.
EXTENDED...A COUPLE OF UPPER LEVEL LOW PRESSURE SYSTEMS ARE PROGGED
TO PASS WEST AND NORTH OF THE AREA DURING THE LATTER PART OF THE
WEEK AND OVER THE WEEKEND. SOUTHWESTERLY FLOW ALOFT WILL DEVELOP TO
THE SOUTH OF THESE SYSTEMS OVER THE CENTRAL ROCKIES AND INTO THE
CENTRAL AND NORTHERN PLAINS. THIS PATTERN WILL BRING A SERIES OF
UPPER LEVEL DISTURBANCES THROUGH THE AREA...WITH DAILY CHANCES FOR
SHOWERS AND A FEW THUNDERSTORMS THROUGH THE WEEKEND. THE BEST CHANCE
FOR THUNDERSTORMS WILL BE THURSDAY INTO THURSDAY NIGHT AND FRIDAY
NIGHT THROUGH SATURDAY NIGHT. TEMPERATURES WILL GENERALLY BE NEAR OR
SLIGHTLY BELOW AVERAGE LATE THIS WEEK...WITH A WARMUP TO NEAR OR
SLIGHTLY ABOVE AVERAGE TEMPERATURES OVER THE HOLIDAY WEEKEND.
&&
.AVIATION...18Z TAFS
VFR CONDITIONS ARE EXPECTED TONIGHT...WITH SOUTHERLY WINDS
CONTINUING OVER MUCH OF THE AREA. THERE IS A SLIGHT CHANCE FOR
SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON AND EARLY IN THE
EVENING ACROSS SOME AREAS EAST OF THE BLACK HILLS...ESPECIALLY OVER
SOUTH CENTRAL SD.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR TODD-TRIPP.
WY...NONE.
&&
$$
000
FXUS63 KABR 212023
AFDABR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
323 PM CDT MON MAY 21 2012
.SHORT TERM...THROUGH THURSDAY MORNING
ACTIVE CONDITIONS ALL THROUGH THE SHORT TERM PERIOD. WILL START
OFF WITH UNSTABLE CONDITIONS OUT WEST THIS AFTERNOON...DESPITE A
RELATIVELY DRY AIRMASS. A WEAK MID LEVEL TROF HAS ALREADY STARTED
TO INITIATE CONVECTION ACROSS THE HIGHER PORTIONS OF HARDING AND
BUTTE COUNTIES...AND WITH PLENTY OF DAYTIME HEATING AND 500-1000
J/KG CAPE AVAILABLE THROUGH THIS AFTERNOON...THE TRANSITION INTO
WESTERN COUNTIES SEEMS LIKELY. SHEAR IS WEAK...SO SEVERE RISK WILL
BE LIMITED. WITH LOSS OF HEATING AND A LACK OF LOW LEVEL SUPPORT
FARTHER EAST...WOULD EXPECT STORMS WILL DISSIPATE THIS EVENING.
ATTENTION TURNS TO TUESDAY. STRENGTHENING LOW LEVEL FLOW AHEAD OF
DEVELOPING LOW PRESSURE WILL RESULT IN LOW END ADVISORY WINDS
ACROSS THE HIGHER ELEVATIONS OF THE MISSOURI AND SISSETON
COTEAU...AND IF THE WIND DIRECTION IS RIGHT...DOWN THE JAMES
VALLEY. H85 TEMPERATURES WARM FROM +18C IN THE EAST TO +28C IN THE
WEST UNDER SOUTH/SOUTHWEST LOW LEVEL FLOW. THUS UPPER 80S/LOW 90S
FOR FORECAST HIGHS...HOWEVER MORE IMPORTANTLY H7 TEMPERATURES WORK
UP AROUND +10 TO +12C...WHICH WILL CAP US THROUGH THE DAY. A
COLD FRONT MOVING INTO WESTERN COUNTIES LATE...WITH COOLING
ALOFT...WILL ALLOW FOR CONVECTION TO DEVELOP. CONCERN IS MODEL LOW
LEVEL MOISTURE IS OVERDONE...WHICH IS ALSO INFLUENCING CONVECTIVE
INDICES. DESPITE THIS...BEST SHEAR/INSTABILITY AND PROBABILITY
FOR CONVECTION TO INITIATE WOULD SUGGEST OUR SEVERE RISK WILL BE
NORTHWEST COUNTIES LATE AFTERNOON/EVENING...AND THEN ACROSS THE
NORTHERN TIER OVERNIGHT.
A SECOND WAVE WILL MOVE SOUTH OF THE CWA FOR THURSDAY MORNING.
LOOKING AT MAINLY MID LEVEL MOISTURE AND WEAK LIFT...ALONG WITH
LIMITED CAPE.
.LONG TERM...THURSDAY THROUGH MONDAY
A BROAD MID LEVEL TROUGH WILL BE OVER THE WESTERN UNITED STATES TO
START THE PERIOD...WITH ENERGY ON THE EAST SIDE OF IT TRACKING
OVER THE NORTHERN PLAINS THURSDAY AND THURSDAY NIGHT. THE TROUGH
THEN KEEPS DIGGING AND RIDGING BUILDS FROM THE SOUTHEASTERN PART
OF THE COUNTRY TO THE NORTHERN PLAINS. THE RIDGE GETS PUSHED EAST
BEGINNING SATURDAY NIGHT WHEN THE WESTERN TROUGH BEGINS TO PUSH
EASTWARD. THE TROUGH ITSELF WEAKENS AS THE MAIN LOW TRACKS OVER
CENTRAL CANADA...WITH JUST WEAK ENERGY MOVING OVER THE AREA SUNDAY
THROUGH MONDAY EVENING.
AT THE SURFACE...AN ELONGATED LOW PRESSURE SYSTEM WILL BE OFF TO
THE EAST AND SOUTH OF THE CWA THURSDAY MORNING...WITH SOME
DIFFERENCES IN THE MODELS AS TO EXACTLY WHERE PRECIPITATION WILL
BE ONGOING. THE ECMWF IS MUCH MORE AGGRESSIVE WITH PRECIPITATION
THROUGH THE DAY THURSDAY AND INTO THURSDAY EVENING. FRIDAY LOOKS
TO BE DRY AS HIGH PRESSURE DROPS OVER THE NORTHERN PLAINS...THEN
PRECIPITATION RETURNS FRIDAY NIGHT AS ANOTHER LOW PRESSURE SYSTEM
TRACKS ACROSS THE ROCKIES TO THE WEST CENTRAL PLAINS BY SATURDAY
EVENING...THEN NORTHWARD ACROSS THE EASTERN DAKOTAS AND WESTERN
MINNESOTA SATURDAY NIGHT. PRECIPITATION CHANCES LOOK TO BECOME MUCH
LESS ON SUNDAY...BUT WITH THE ENERGY STILL MOVING OVERHEAD...WILL
NOT COMPLETELY REMOVE THE MENTION. MORE CONFIDENT THAT MONDAY WILL
BE DRY AS HIGH PRESSURE DROPS OVER THE NORTHERN PLAINS FROM THE
NORTHWEST.
TEMPERATURES WILL BE A BIT COOL TO START THE PERIOD WITH QUITE A
BIT OF CLOUD COVER AND CHANCES OF PRECIPITATION. HIGHS ON THURSDAY
AND FRIDAY WILL LIKELY NOT REACH 70 DEGREES. WILL SEE A BIT OF A
WARM UP BACK TO NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES DURING
THE LATTER HALF OF THE PERIOD.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A LINE OF LIGHT SHOWERS WILL TRACK ACROSS THE FAR EASTERN PORTION
OF THE CWA DURING THE AFTERNOON HOURS...BUT WILL NOT AFFECT ANY OF
THE TAF SITES. VFR CONDITIONS WILL PREVAIL WITH SOUTHERLY WINDS IN
THE 20 TO 30 MPH RANGE. WIND SPEEDS WILL DIMINISH SOME DURING THE
OVERNIGHT HOURS...THEN WILL INCREASE BACK INTO THE 15 TO 30 MPH
RANGE OUT OF THE SOUTH TO SOUTHEAST ON TUESDAY MORNING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR BROWN-BUFFALO-
CLARK-CODINGTON-DAY-DEUEL-EDMUNDS-FAULK-GRANT-HAMLIN-HAND-
HUGHES-HYDE-LYMAN-MARSHALL-MCPHERSON-POTTER-ROBERTS-SPINK-
SULLY.
MN...NONE.
&&
$$
SHORT TERM...CONNELLY
LONG TERM...PARKIN
AVIATION...PARKIN
WEATHER.GOV/ABERDEEN
000
FXUS63 KFSD 212014
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
315 PM CDT MON MAY 21 2012
.DISCUSSION.../ISSUED AT 315 PM CDT/
MID LEVEL CLOUDS ALONG AND EAST OF I29 WILL CONTINUE TO PUSH EAST
THROUGH THIS EVENING WITH PARTLY CLOUDY SKIES EXPECTED MOST OF THE
NIGHT. WILL KEEP A VERY SMALL CHANCE FOR THUNDERSTORMS LATE TONIGHT
AS LOW LEVEL JET INCREASES AHEAD OF ELEVATED INSTABILITY WEST OF I29
AFTER 06Z. NOT ALL THAT CONFIDENT ANYTHING WILL FIRE UP SO ONLY WILL
HAVE 20% POPS AT MOST. SOUTHERLY WINDS WILL ALSO HOLD TEMPERATURES
UP TONIGHT WITH LOWS IN THE MID 50S TO LOWER 60S.
WHILE THERE IS NO MAGIC LINE ON IT AT DAYBREAK...THE CHANCE OF ANY
LINGERING STORMS IN OUR FAR EAST EARLY TUESDAY MORNING SEEMS LOW
ENOUGH TO KEEP MENTION OF OUT FOR TUESDAY...CONSIDERING CHANCE
TONIGHT IS SO SMALL AND THE WARMING AIR SHOULD BE CAPPED. OTHERWISE
A FEW CLOUDS SHOULD BE MOSTLY HIGH AND LEAD TO A MOSTLY SUNNY WARM
AND VERY WINDY DAY. IT HAS BEEN PLAIN FOR THREE DAYS THAT SOUTHERLY
WINDS WILL BE STRONG AND THAT CONTINUES...WITH GUIDANCE AS USUAL
UNDERDOING EXPECTED SURFACE WINDS. WINDS SHOULD MAKE THE 30 MPH
SUSTAINED CRITERIA OR STRONGER OVER ALL OF THE FORECAST AREA SO WILL
GO WITH A WIND ADVISORY 15Z TO 01Z/10 AM TO 8 PM. HIGH TEMPERATURES
GUIDANCE SEEMS ONLY A LITTLE NOT QUITE WARM ENOUGH WITH 80S TO SOME
LOWER 90S WEST.
COLD FRONT ADVANCES INTO FORECAST AREA TUESDAY NIGHT AND WILL KEEP A
CHANCE OF STORMS AS FRONT ADVANCES...LEAVING OUT PART OF NORTHWEST
IA SOUTHEAST OF SUX TO MJQ LINE. THE ADVANCE CONTINUES WEDNESDAY
WITH THE FRONT DEFINITELY SLOWING. WILL TEMPORARILY DECREASE THE
STORM THREAT WEST WEDNESDAY BEFORE PICKING IT UP AGAIN WEDNESDAY
NIGHT AS ANOTHER WAVE APPROACHES...LIKELY POPS LOOK GOOD FOR THE
EAST FOR WEDNESDAY NIGHT. COOLING AND CLOUDS WILL COOL TEMPERATURES
WEDNESDAY FROM TUESDAY EXCEPT IT WILL STILL BE IN THE WARM 80S
SOUTHEAST OF SUX/SPW LINE. WAVE PULLING OUT TO THE NORTHEAST SHOULD
SLOWLY DECREASE THE RAIN THREAT WEDNESDAY NIGHT AND THURSDAY...AND
ON A CLOSE CALL WILL LEAVE MENTION OUT ALTOGETHER FOR FRIDAY GIVEN
SURFACE AND LOW LEVEL RIDGING BEHIND FRONT. TEMPERATURES OF COURSE
WILL BE COOLER DURING THIS TIME.
RIDGING AND ASSOCIATED WARMING SHOULD BRING A THREAT OF STORMS OVER
THE WEEKEND ALONG WITH WARM AND MORE HUMID CONDITIONS. MODELS
ESPECIALLY THE ECMWF ARE FURTHER EAST WITH THE RIDGING THAN THEY
WERE YESTERDAY WHICH WILL MEAN LESS CAPPING AND ALLOWING THE NEXT
SYSTEM TO GET CLOSE. WILL GO WITH THE CURRENT MODEL RUNS AND START
TO DECREASE RAIN CHANCES AGAIN MONDAY ALONG WITH THE RETURN OF
COOLING.
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF FORECAST PERIOD.
ISOLATED THUNDERSTORMS MAY DEVELOP AFTER 06Z ALONG AND WEST OF I29.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR IAZ001>003-
012>014-020>022-031-032.
MN...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR MNZ071-072-080-
081-089-090-097-098.
NE...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR NEZ013-014.
SD...WIND ADVISORY FROM 10 AM TO 8 PM CDT TUESDAY FOR SDZ038>040-050-
052>071.
&&
$$
000
FXUS63 KABR 211736 AAC
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1236 PM CDT MON MAY 21 2012
.UPDATE...
SEE UPDATED AVIATION DISCUSSION BELOW.
A QUICK UPDATE TO EXPAND SHOWER MENTION ACROSS THE REST OF THE
CWA. LINE OF WEAK SHOWERS PUSHING EAST OF THE AREA ENOUGH TO GET
THE PAVEMENT WET AT THE OFFICE...BUT FAILED TO MEASURE...AND ONLY
LASTED 10 MINUTES. ANTICIPATE THESE CONDITIONS WILL CONTINUE AS
THE LINE TREKS EAST THROUGH THE MID/LATE MORNING HOURS.
LOOKING BACK WEST FOR THIS AFTERNOON...ATMOSPHERE WILL BECOME
UNSTABLE...WITH BETWEEN 500-1500 J/KG MUCAPE. ANY BOUNDARY OR
POCKET OF HIGHER MOISTURE LEFT FROM THIS MORNINGS SPRINKLE COULD
SET STAGE FOR AN ISOLATED STORM TO FIRE.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH WEDNESDAY
THE POTENTIAL FOR SEVERE STORMS TUESDAY NIGHT WILL BE THE MAIN
FORECAST CHALLENGE.
AS OF 8Z...WAA IS ONGOING ACROSS THE WESTERN DAKOTAS VIA WEAK
SOUTHERLY FLOW. SOMEWHAT SURPRISINGLY ACCAS HAS DEVELOPED OVER THE
WESTERN CWA DESPITE THE DRY AIRMASS IN PLACE. HI-RES MODELS
SUGGEST THIS ACCAS FIELD WILL TRACK ACROSS THE REGION TODAY WITH
SCT SPRINKLES POSSIBLE. HOWEVER WITH DRY AIR IN THE LOWER
LEVELS...WILL MAINTAIN A DRY FORECAST FOR TODAY. THE MAIN ISSUE
FOR TODAY WILL BE GUSTY SOUTHERLY WINDS AS THE REGION WILL BE
SANDWICH BETWEEN A DEPARTING HIGH PRESSURE TO THE EAST...AND AN
APPROACHING LOW PRESSURE SYSTEM FROM WEST. WINDS SHOULD REMAIN
BELOW ADVISORY CRITERIA.
A STRONG LLJ DEVELOPS TONIGHT ACROSS THE EASTERN DAKOTAS AND
WESTERN MINNESOTA. WHILE THE NOSE OF THE LLJ IS POINTED INTO
NE NORTH DAKOTA...A SE STORM MOTION...ALONG WITH A WEAK MID LEVEL
IMPULSE MAY RESULT IN CONVECTION IN THE NORTHEASTERN CWA.
STRONGER SOUTHERLY WINDS ARE EXPECTED ON TUESDAY AS A STRENGTHENING
LOW PRESSURE SYSTEM WILL BE LOCATED OVER THE WESTERN DAKOTAS.
MOMENTUM TRANSFER IN BUFKIT...ALONG H925 WINDS SUGGEST A WIND
ADVISORY WILL LIKELY BE NEEDED TUESDAY AFTERNOON FOR THE EASTERN
CWA. A HEALTHY MID LEVEL CAP WILL BE IN PLACE ACROSS THE WARM
SECTOR OF THE LOW PRESSURE SYSTEM WITH TEMPS AT H7 +10 TO +12C.
CONVECTIVE TEMPERATURES ARE EASILY IN THE 90S TO NEAR 100 DEGREES.
CONVECTION WILL LIKELY BE HELD OFF UNTIL AFTER 0Z WEDNESDAY WHEN A
COLD FRONT MOVES ACROSS THE CWA. THE BEST LIFT AND INSTABILITY IS
STILL LOCATED NORTHEAST OF SOUTH DAKOTA THUS WILL MAINTAIN THE HIGHEST
POPS IN THE NE CWA...WITH LOWER POPS IN THE SW.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
THE LONG TERM MODELS SEEM TO BE CONVERGING ON A SOLUTION FOR THE
EXTENDED FORECAST. EARLY IN THE PERIOD A BROAD MID LEVEL TROF
SHOULD BE CARVING OUT ACROSS THE WESTERN CONUS. THE LEADING PIECE
OF ENERGY ASSOCIATED WITH THIS PATTERN AMPLIFICATION SHOULD BE
LIFTING NORTHEAST ACROSS THE CENTRAL/NORTHERN PLAINS WITH A GOOD
CHANCE OF RAIN FOR MUCH OF THE CWA WEDNESDAY NIGHT AND THURSDAY.
THEN THERE SHOULD BE A BIT OF LULL IN THE ACTIVITY AS THE MID
LEVEL RIDGE REBOUNDS AHEAD OF NEXT SYSTEM DIGGING INTO THE
SOUTHWEST CONUS. THAT ENERGY/TROF LIFTS OUT ACROSS THE NORTHERN
PLAINS IN FULL FORCE ON SATURDAY AND SATURDAY NIGHT. CAPPING DUE
TO FAIRLY WARM MID LEVEL TEMPS MAY PRECLUDE DEEP CONVECTION AT
LEAST INITIALLY...BUT SUSPECT COMBINATION OF ADVANCING SFC/H85
WARM FRONT LATE SATURDAY OR SATURDAY NIGHT WILL BE ENOUGH TO BREAK
THE CAP AND ALLOW FOR DEEP CONVECTION. FORECASTER CONFIDENCE IS
ABOUT AVERAGE THAT THIS SCENARIO WILL PLAY OUT ACCORDING TO PLAN.
MEANWHILE TEMPERATURES WILL AVERAGE OUT BELOW NORMAL FOR THE FIRST
COUPLE OF DAYS IN POST FRONTAL ENVIRONMENT...BUT THEN TREND TO
ABOVE NORMAL FOR THE WEEKEND AS WARM AND MOIST AIRMASS INFILTRATES
THE REGION.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A LINE OF LIGHT SHOWERS WILL TRACK ACROSS THE FAR EASTERN PORTION
OF THE CWA DURING THE AFTERNOON HOURS...BUT WILL NOT AFFECT ANY OF
THE TAF SITES. VFR CONDITIONS WILL PREVAIL WITH SOUTHERLY WINDS IN
THE 20 TO 30 MPH RANGE. WIND SPEEDS WILL DIMINISH SOME DURING THE
OVERNIGHT HOURS...THEN WILL INCREASE BACK INTO THE 15 TO 30 MPH
RANGE OUT OF THE SOUTH TO SOUTHEAST ON TUESDAY MORNING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...CONNELLY
SHORT TERM...SD
LONG TERM...TDK
AVIATION...PARKIN
WEATHER.GOV/ABERDEEN
000
FXUS63 KFSD 211709
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1210 PM CDT MON MAY 21 2012
.DISCUSSION.../ISSUED AT 845 AM CDT/
HAVE UPDATED FORECAST TO INCREASE MID LEVEL CLOUDS ASSOCIATED WITH
MID LEVEL WARM AIR ADVECTION ACROSS CWA TODAY. WILL GENERALLY BE
PARTLY TO MOSTLY CLOUDY THIS AFTERNOON. DID LOWER TEMPERATURES A
DEGREE OR TWO DUE TO THE CLOUDS. ALSO ADDED A FEW SPRIKNLES ACROSS
WESTERN CWA THIS MORNING.
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF FORECAST PERIOD.
ISOLATED THUNDERSTORMS MAY DEVELOP AFTER 06Z ALONG AND WEST OF I29.
&&
.DISCUSSION.../ISSUED AT 316 AM CDT/
SHOULD BE A QUIET DAY WITH MODERATING TEMPERATURES AS A SOUTHERLY
WIND DEVELOPS. HIGH LAPSE RATES ALOFT THIS MORNING MAY SUPPORT SOME
ACCAS IN CENTRAL SOUTH DAKOTA BUT BETTER LAPSE RATES REMAIN WEST OF
THE CWA TODAY SO EXPECT DRY AIR BELOW 750MB TO KEEP ANY BRIEF RAIN
THREAT AT BAY. OTHERWISE...PARTLY CLOUDY CONDITIONS WITH WINDS
BECOMING BREEZY IN CENTRAL SOUTH DAKOTA. HIGHS SHOULD MAINLY BE IN
THE 70S WITH A FEW LOWER 80S IN SOUTH CENTRAL SOUTH DAKOTA.
WILL MAINTAIN A LOW POP FOR TONIGHT AS LAPSE RATES AND INSTABILITY
INCREASE A BIT...POSSIBLY ENOUGH TO SPARK OFF A SHOWER OR
THUNDERSTORM...NOTHING SEVERE. WITH A STRONGLY INCREASING SOUTHERLY
BREEZE DID GO AHEAD AND RAISE LOWS A COUPLE OF DEGREES...SOMETHING
CLOSER TO THE CONSRAW OUTPUT WHICH DOES BETTER UNDER STRONG FLOW
REGIMES. THIS MEANS LOWS FROM THE UPPER 50S TO MID 60S.
THIS WILL LEAD INTO A VERY WARM TUESDAY WITH VERY STRONG SOUTHERLY
WINDS. WILL NOT ISSUE A WIND ADVISORY AT THIS TIME BUT WILL LIKELY
NEED TO ISSUE ONE THIS AFTERNOON. EXPECT SOUTH WINDS OF 20 TO 40 MPH
THROUGH MOST OF THE DAY. DECENT MIXING SHOULD ALSO SUPPORT HIGHS
FROM THE MID 80S TO LOWER 90S...AND WOULD NOT BE SURPRISED IF WE CAN
WARM A COUPLE MORE DEGREES BEYOND THIS.
WILL SEE A CHANCE FOR THUNDERSTORMS OVER MAINLY THE NORTHERN AND
WESTERN CWA ON TUESDAY NIGHT...BUT SEVERE WEATHER IS NOT EXPECTED.
LOOKS LIKE THE BETTER INSTABILITY WILL REMAIN BOTTLED UP TO THE
WEST. VERY STRONG SOUTH WINDS WILL CONTINUE WHICH SHOULD YIELD LOWS
IN THE MID 60S FOR MOST LOCATIONS.
THE BEST CHANCE FOR THUNDERSTORMS WILL COME LATE WEDNESDAY AFTERNOON
INTO WEDNESDAY NIGHT AS A BOUNDARY SETS UP OVER THE SOUTHEAST CWA. A
FAIRLY STRONG MID LEVEL WAVE WILL SPREAD ACROSS THE AREA ON
WEDNESDAY NIGHT SO A VERY GOOD CHANCE FOR RAIN AND THUNDERSTORMS.
EXPECT CAPE VALUES OF 1500 TO 2000 J/KG OVER NORTHWEST IOWA ON
WEDNESDAY NIGHT AND WITH DECENT DEEP 40 KNOT OR SO BULK SHEAR VALUES
SOME SEVERE WEATHER WILL BE A THREAT. ALSO SOME POTENTIAL FOR HEAVY
RAIN WITH THE BOUNDARY SETTING UP PARALLEL TO THE UPPER LEVEL FLOW
AND PWAT VALUES LIKELY AROUND AN INCH AND A HALF OR A LITTLE
HIGHER.
WILL SEE SOME THREAT FOR RAIN AND THUNDERSTORMS LINGER INTO THURSDAY
BUT NOT LOOKING LIKE A MAJOR THREAT. EXPECT COOLER TEMPERATURES WITH
HIGHS FROM THE UPPER 60S TO MID 70S.
IN THE LATTER PERIODS(FRI/SUN)...SOME AGREEMENT DURING THIS TIME
WITH THE BETTER AGREEMENT BETWEEN THE ECMWF AND GEM. THE MAIN
FEATURE WILL BE A DIGGING TROUGH OF LOW PRESSURE OVER THE WESTERN
UNITED STATES AND A STRENGTHENING RIDGE OVER THE EASTERN UNITED
STATES. FRIDAY NIGHT INTO SATURDAY MORNING THE BIGGEST DIFFERENCE
WITH THE GFS QUITE A BIT COOLER THAN THE EC/GEM. WILL SIDE A BIT
TOWARDS THE WARMER MODELS BUT HAVE TO TEMPER THAT BACK A BIT WITH
SOME LACK OF CONFIDENCE. WILL BE A DECENT THREAT FOR PRECIPITATION
THROUGH THIS ENTIRE PERIOD...AND MAY AT SOME POINT IN TIME NEED TO
INCREASE POPS FOR FRIDAY NIGHT IF MODELS CONTINUE TO TREND IN THE
CURRENT DIRECTION. BASICALLY LOOKING AT 70S ON FRIDAY WITH BOUNDARY
TO THE SOUTH...THEN 80S SAT AND SUN AS THE BOUNDARY SHOOTS
NORTHWARD. THE EC/GEM SUPPORT 90 TO 95 DEGREES ON SATURDAY IN MY
SOUTHERN CWA SO WILL NEED TO WATCH FOR THE TRENDS IN THE MODELS AND
MAY NEED TO GO WARMER ON SATURDAY. /08
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KUNR 211639
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1039 AM MDT MON MAY 21 2012
.UPDATE...16Z SFC ANALYSIS SHOWS HIGH PRESSURE OVER EASTERN
KANSAS WITH LOW PRESSURE CENTERED OVER SOUTHERN ALBERTA AND A
TROUGH EXTENDING SOUTHWARD FROM THE LOW INTO EASTERN WYOMING. THE
RESULTING PRESSURE GRADIENT WAS PRODUCING BREEZY TO WINDY
CONDITIONS OVER WESTERN SOUTH DAKOTA AND LIGHT WINDS NEAR THE
TROUGH IN EASTERN WYOMING. THE SFC TROUGH WILL CONTINUE TO SLIDE
SLOWLY EASTWARD TODAY. THERE MAY BE ENOUGH INSTABILITY AHEAD OF
THE TROUGH FOR A FEW THUNDERSTORMS TO DEVELOP EAST OF THE TROUGH
LINE OVER SOUTH CENTRAL SOUTH DAKOTA LATE THIS AFTERNOON OR EARLY
THIS EVENING.
&&
.AVIATION...18Z TAF FORECASTS
VFR CONDITIONS ARE EXPECTED TODAY AND
TONIGHT...WITH SOUTHERLY WINDS CONTINUING OVER MUCH OF THE AREA.
THERE IS A SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS LATE THIS
AFTERNOON AND EARLY IN THE EVENING ACROSS SOME AREAS EAST OF THE
BLACK HILLS...ESPECIALLY OVER SOUTH CENTRAL SD.
&&
.PREV DISCUSSION... /ISSUED 239 AM MDT MON MAY 21 2012/
DISCUSSION...08Z SURFACE ANALYSIS HAD WEAK LOW OVER SOUTHEAST MT
WITH TROUGH INTO INTO SOUTH CENTRAL WY. LOW LEVEL JET CREATING
SOME ACCAS OVER CENTRAL SD/NE...BUT ACTIVITY SHOULD BE ON THE
WANE/OUT OF THE CWA BY 12Z. WATER VAPOUR SHOWED UPPER RIDGE
CONTINUED TO BUILD OVER THE NORTHERN PLAINS.
TODAY/TONIGHT...UPPER RIDGE BUILDS INTO THE REGION WITH THERMAL
RIDGE AMPLIFYING. TEMPERATURES WELL INTO THE 80S EXPECTED TODAY.
WEAK TROUGH WILL SHIFT ONTO THE SD PLAINS LATE TODAY/TONIGHT AND
MAY BE THE FOCUS FOR ISOLATED -TSRA ACTIVITY WITH ABOUT 1KJ/KG
SBCAPE AVAILABLE. CAP WILL BE INCREASING...SO THREAT WILL BE LOW.
TUESDAY...UPPER TROUGH MOVES INTO THE NORTHERN ROCKIES WITH LEAD
SHORTWAVE ENERGY CREATING A NEW LOW OVER SOUTHEAST MT. TROUGH/DRY-
LINE WILL PUSH INTO SOUTHWEST SD DURING THE DAY WITH GUSTY
SOUTHWEST WINDS BEHIND IT AND VERY DRY RELATIVE HUMIDITIES. AHEAD
OF TROUGH...DEW POINTS IN THE LOWER 50S WILL POOL BRINGING ABOUT
1-2KJ/KG SBCAPE OVER THE FAR EASTERN REACHES OF THE CWA. CAP WILL
BE RATHER STRONG...SO VIGOROUS CONVECTION WILL LIKELY HAVE TO WAIT
UNTIL COLD FRONT THAT FORMS SOUTHWEST OF LOW MOVES THROUGH ONTO
THE SD PLAINS. SHEAR WILL BE SUFFICIENT FOR SURFACE/ELEVATED
SUPERCELLS AND THUS EXPECTED A COUPLE OF SEVERE THUNDERSTORMS.
TEMPERATURES WILL SOAR INTO THE 80S TO LOWER 90S TUESDAY AFTERNOON.
TUESDAY NIGHT/WEDNESDAY...BEHIND COLD FRONT COOLER AIR WILL FILTER
INTO THE CWA WITH UPPER TROUGH CLOSING OFF INTO AN UPPER LOW OVER
SOUTHERN SK. CYCLONIC FLOW EXPECTED OVER THE CWA WITH LIMITED
INSTABILITY. RESULT WILL BE GENERIC POPS OVER MUCH OF THE CWA.
TEMPERATURES NEAR GUIDANCE APPEAR REASONABLE GIVEN FORECAST
SOUNDINGS.
EXTENDED...A COUPLE OF UPPER LEVEL LOW PRESSURE SYSTEMS ARE PROGGED
TO PASS WEST AND NORTH OF THE AREA DURING THE LATTER PART OF THE
WEEK AND OVER THE WEEKEND. SOUTHWESTERLY FLOW ALOFT WILL DEVELOP TO
THE SOUTH OF THESE SYSTEMS OVER THE CENTRAL ROCKIES AND INTO THE
CENTRAL AND NORTHERN PLAINS. THIS PATTERN WILL BRING A SERIES OF
UPPER LEVEL DISTURBANCES ACROSS THE AREA...WITH DAILY CHANCES FOR
SHOWERS AND A FEW THUNDERSTORMS FROM THURSDAY THROUGH THE WEEKEND.
THE BETTER CHANCES FOR THUNDERSTORMS WILL BE OVER THE WEEKEND AS
MOISTURE AND INSTABILITY INCREASE OVER THE AREA. TIMING OF THESE
WAVES ARE UNCERTAIN...BUT THE BETTER CHANCES FOR PCPN AT THIS TIME
LOOK TO BE THURSDAY INTO THURSDAY NIGHT AND FRIDAY NIGHT THROUGH
SATURDAY NIGHT. TEMPERATURES WILL GENERALLY BE NEAR OR SLIGHTLY
BELOW AVERAGE LATE THIS WEEK...WITH A WARMUP TO NEAR OR SLIGHTLY
ABOVE AVERAGE TEMPERATURES OVER THE WEEKEND.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
000
FXUS63 KABR 211524
AFDABR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
1024 AM CDT MON MAY 21 2012
.UPDATE...
A QUICK UPDATE TO EXPAND SHOWER MENTION ACROSS THE REST OF THE
CWA. LINE OF WEAK SHOWERS PUSHING EAST OF THE AREA ENOUGH TO GET
THE PAVEMENT WET AT THE OFFICE...BUT FAILED TO MEASURE...AND ONLY
LASTED 10 MINUTES. ANTICIPATE THESE CONDITIONS WILL CONTINUE AS
THE LINE TREKS EAST THROUGH THE MID/LATE MORNING HOURS.
LOOKING BACK WEST FOR THIS AFTERNOON...ATMOSPHERE WILL BECOME
UNSTABLE...WITH BETWEEN 500-1500 J/KG MUCAPE. ANY BOUNDARY OR
POCKET OF HIGHER MOISTURE LEFT FROM THIS MORNINGS SPRINKLE COULD
SET STAGE FOR AN ISOLATED STORM TO FIRE.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH WEDNESDAY
THE POTENTIAL FOR SEVERE STORMS TUESDAY NIGHT WILL BE THE MAIN
FORECAST CHALLENGE.
AS OF 8Z...WAA IS ONGOING ACROSS THE WESTERN DAKOTAS VIA WEAK
SOUTHERLY FLOW. SOMEWHAT SURPRISINGLY ACCAS HAS DEVELOPED OVER THE
WESTERN CWA DESPITE THE DRY AIRMASS IN PLACE. HI-RES MODELS
SUGGEST THIS ACCAS FIELD WILL TRACK ACROSS THE REGION TODAY WITH
SCT SPRINKLES POSSIBLE. HOWEVER WITH DRY AIR IN THE LOWER
LEVELS...WILL MAINTAIN A DRY FORECAST FOR TODAY. THE MAIN ISSUE
FOR TODAY WILL BE GUSTY SOUTHERLY WINDS AS THE REGION WILL BE
SANDWICH BETWEEN A DEPARTING HIGH PRESSURE TO THE EAST...AND AN
APPROACHING LOW PRESSURE SYSTEM FROM WEST. WINDS SHOULD REMAIN
BELOW ADVISORY CRITERIA.
A STRONG LLJ DEVELOPS TONIGHT ACROSS THE EASTERN DAKOTAS AND
WESTERN MINNESOTA. WHILE THE NOSE OF THE LLJ IS POINTED INTO
NE NORTH DAKOTA...A SE STORM MOTION...ALONG WITH A WEAK MID LEVEL
IMPULSE MAY RESULT IN CONVECTION IN THE NORTHEASTERN CWA.
STRONGER SOUTHERLY WINDS ARE EXPECTED ON TUESDAY AS A STRENGTHENING
LOW PRESSURE SYSTEM WILL BE LOCATED OVER THE WESTERN DAKOTAS.
MOMENTUM TRANSFER IN BUFKIT...ALONG H925 WINDS SUGGEST A WIND
ADVISORY WILL LIKELY BE NEEDED TUESDAY AFTERNOON FOR THE EASTERN
CWA. A HEALTHY MID LEVEL CAP WILL BE IN PLACE ACROSS THE WARM
SECTOR OF THE LOW PRESSURE SYSTEM WITH TEMPS AT H7 +10 TO +12C.
CONVECTIVE TEMPERATURES ARE EASILY IN THE 90S TO NEAR 100 DEGREES.
CONVECTION WILL LIKELY BE HELD OFF UNTIL AFTER 0Z WEDNESDAY WHEN A
COLD FRONT MOVES ACROSS THE CWA. THE BEST LIFT AND INSTABILITY IS
STILL LOCATED NORTHEAST OF SOUTH DAKOTA THUS WILL MAINTAIN THE HIGHEST
POPS IN THE NE CWA...WITH LOWER POPS IN THE SW.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
THE LONG TERM MODELS SEEM TO BE CONVERGING ON A SOLUTION FOR THE
EXTENDED FORECAST. EARLY IN THE PERIOD A BROAD MID LEVEL TROF
SHOULD BE CARVING OUT ACROSS THE WESTERN CONUS. THE LEADING PIECE
OF ENERGY ASSOCIATED WITH THIS PATTERN AMPLIFICATION SHOULD BE
LIFTING NORTHEAST ACROSS THE CENTRAL/NORTHERN PLAINS WITH A GOOD
CHANCE OF RAIN FOR MUCH OF THE CWA WEDNESDAY NIGHT AND THURSDAY.
THEN THERE SHOULD BE A BIT OF LULL IN THE ACTIVITY AS THE MID
LEVEL RIDGE REBOUNDS AHEAD OF NEXT SYSTEM DIGGING INTO THE
SOUTHWEST CONUS. THAT ENERGY/TROF LIFTS OUT ACROSS THE NORTHERN
PLAINS IN FULL FORCE ON SATURDAY AND SATURDAY NIGHT. CAPPING DUE
TO FAIRLY WARM MID LEVEL TEMPS MAY PRECLUDE DEEP CONVECTION AT
LEAST INITIALLY...BUT SUSPECT COMBINATION OF ADVANCING SFC/H85
WARM FRONT LATE SATURDAY OR SATURDAY NIGHT WILL BE ENOUGH TO BREAK
THE CAP AND ALLOW FOR DEEP CONVECTION. FORECASTER CONFIDENCE IS
ABOUT AVERAGE THAT THIS SCENARIO WILL PLAY OUT ACCORDING TO PLAN.
MEANWHILE TEMPERATURES WILL AVERAGE OUT BELOW NORMAL FOR THE FIRST
COUPLE OF DAYS IN POST FRONTAL ENVIRONMENT...BUT THEN TREND TO
ABOVE NORMAL FOR THE WEEKEND AS WARM AND MOIST AIRMASS INFILTRATES
THE REGION.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS ARE EXPECTED THROUGH TODAY...BUT WINDS WILL
INCREASE INTO THE 15 TO 30 MPH RANGE BY AFTERNOON...WITH THE
GUSTIER WINDS LIKE AT KPIR/KMBG. AN ADVECTING DECK OF ACCAS MAY
PROVIDE FOR A SPRINKLE OR TWO ACROSS THE REGION THIS MORNING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...CONNELLY
SHORT TERM...SD
LONG TERM...TDK
AVIATION...TDK
WEATHER.GOV/ABERDEEN
000
FXUS63 KFSD 211346
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
845 AM CDT MON MAY 21 2012
.DISCUSSION...
HAVE UPDATED FORECAST TO INCREASE MID LEVEL CLOUDS ASSOCIATED WITH
MID LEVEL WARM AIR ADVECTION ACROSS CWA TODAY. WILL GENERALLY BE
PARTLY TO MOSTLY CLOUDY THIS AFTERNOON. DID LOWER TEMPERATURES A
DEGREE OR TWO DUE TO THE CLOUDS. ALSO ADDED A FEW SPRIKNLES ACROSS
WESTERN CWA THIS MORNING.
&&
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF FORECAST PERIOD. A
FEW ACCAS SHOWERS HAVE DEVELOPED WEST RIVER BUT AS THEY`RE MOVING
EAST...THEY HAVE WEAKENED QUITE A BIT. SO MAY SEE A FEW MID LEVEL
CLOUDS DRIFTING OVER TAF LOCATIONS AS A RESULT. SOUTH WINDS WILL BE
INCREASING AFTER 20Z AS GRADIENT BEGINS TO TIGHT AND HIGH PUSHES OFF
TO THE EAST.
&&
.DISCUSSION.../ISSUED AT 316 AM CDT/
SHOULD BE A QUIET DAY WITH MODERATING TEMPERATURES AS A SOUTHERLY
WIND DEVELOPS. HIGH LAPSE RATES ALOFT THIS MORNING MAY SUPPORT SOME
ACCAS IN CENTRAL SOUTH DAKOTA BUT BETTER LAPSE RATES REMAIN WEST OF
THE CWA TODAY SO EXPECT DRY AIR BELOW 750MB TO KEEP ANY BRIEF RAIN
THREAT AT BAY. OTHERWISE...PARTLY CLOUDY CONDITIONS WITH WINDS
BECOMING BREEZY IN CENTRAL SOUTH DAKOTA. HIGHS SHOULD MAINLY BE IN
THE 70S WITH A FEW LOWER 80S IN SOUTH CENTRAL SOUTH DAKOTA.
WILL MAINTAIN A LOW POP FOR TONIGHT AS LAPSE RATES AND INSTABILITY
INCREASE A BIT...POSSIBLY ENOUGH TO SPARK OFF A SHOWER OR
THUNDERSTORM...NOTHING SEVERE. WITH A STRONGLY INCREASING SOUTHERLY
BREEZE DID GO AHEAD AND RAISE LOWS A COUPLE OF DEGREES...SOMETHING
CLOSER TO THE CONSRAW OUTPUT WHICH DOES BETTER UNDER STRONG FLOW
REGIMES. THIS MEANS LOWS FROM THE UPPER 50S TO MID 60S.
THIS WILL LEAD INTO A VERY WARM TUESDAY WITH VERY STRONG SOUTHERLY
WINDS. WILL NOT ISSUE A WIND ADVISORY AT THIS TIME BUT WILL LIKELY
NEED TO ISSUE ONE THIS AFTERNOON. EXPECT SOUTH WINDS OF 20 TO 40 MPH
THROUGH MOST OF THE DAY. DECENT MIXING SHOULD ALSO SUPPORT HIGHS
FROM THE MID 80S TO LOWER 90S...AND WOULD NOT BE SURPRISED IF WE CAN
WARM A COUPLE MORE DEGREES BEYOND THIS.
WILL SEE A CHANCE FOR THUNDERSTORMS OVER MAINLY THE NORTHERN AND
WESTERN CWA ON TUESDAY NIGHT...BUT SEVERE WEATHER IS NOT EXPECTED.
LOOKS LIKE THE BETTER INSTABILITY WILL REMAIN BOTTLED UP TO THE
WEST. VERY STRONG SOUTH WINDS WILL CONTINUE WHICH SHOULD YIELD LOWS
IN THE MID 60S FOR MOST LOCATIONS.
THE BEST CHANCE FOR THUNDERSTORMS WILL COME LATE WEDNESDAY AFTERNOON
INTO WEDNESDAY NIGHT AS A BOUNDARY SETS UP OVER THE SOUTHEAST CWA. A
FAIRLY STRONG MID LEVEL WAVE WILL SPREAD ACROSS THE AREA ON
WEDNESDAY NIGHT SO A VERY GOOD CHANCE FOR RAIN AND THUNDERSTORMS.
EXPECT CAPE VALUES OF 1500 TO 2000 J/KG OVER NORTHWEST IOWA ON
WEDNESDAY NIGHT AND WITH DECENT DEEP 40 KNOT OR SO BULK SHEAR VALUES
SOME SEVERE WEATHER WILL BE A THREAT. ALSO SOME POTENTIAL FOR HEAVY
RAIN WITH THE BOUNDARY SETTING UP PARALLEL TO THE UPPER LEVEL FLOW
AND PWAT VALUES LIKELY AROUND AN INCH AND A HALF OR A LITTLE
HIGHER.
WILL SEE SOME THREAT FOR RAIN AND THUNDERSTORMS LINGER INTO THURSDAY
BUT NOT LOOKING LIKE A MAJOR THREAT. EXPECT COOLER TEMPERATURES WITH
HIGHS FROM THE UPPER 60S TO MID 70S.
IN THE LATTER PERIODS(FRI/SUN)...SOME AGREEMENT DURING THIS TIME
WITH THE BETTER AGREEMENT BETWEEN THE ECMWF AND GEM. THE MAIN
FEATURE WILL BE A DIGGING TROUGH OF LOW PRESSURE OVER THE WESTERN
UNITED STATES AND A STRENGTHENING RIDGE OVER THE EASTERN UNITED
STATES. FRIDAY NIGHT INTO SATURDAY MORNING THE BIGGEST DIFFERENCE
WITH THE GFS QUITE A BIT COOLER THAN THE EC/GEM. WILL SIDE A BIT
TOWARDS THE WARMER MODELS BUT HAVE TO TEMPER THAT BACK A BIT WITH
SOME LACK OF CONFIDENCE. WILL BE A DECENT THREAT FOR PRECIPITATION
THROUGH THIS ENTIRE PERIOD...AND MAY AT SOME POINT IN TIME NEED TO
INCREASE POPS FOR FRIDAY NIGHT IF MODELS CONTINUE TO TREND IN THE
CURRENT DIRECTION. BASICALLY LOOKING AT 70S ON FRIDAY WITH BOUNDARY
TO THE SOUTH...THEN 80S SAT AND SUN AS THE BOUNDARY SHOOTS
NORTHWARD. THE EC/GEM SUPPORT 90 TO 95 DEGREES ON SATURDAY IN MY
SOUTHERN CWA SO WILL NEED TO WATCH FOR THE TRENDS IN THE MODELS AND
MAY NEED TO GO WARMER ON SATURDAY. /08
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KABR 211133 AAA
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
633 AM CDT MON MAY 21 2012
.UPDATE...
AVIATION DISCUSSION UPDATED FOR 12Z TAFS.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH WEDNESDAY
THE POTENTIAL FOR SEVERE STORMS TUESDAY NIGHT WILL BE THE MAIN
FORECAST CHALLENGE.
AS OF 8Z...WAA IS ONGOING ACROSS THE WESTERN DAKOTAS VIA WEAK
SOUTHERLY FLOW. SOMEWHAT SURPRISINGLY ACCAS HAS DEVELOPED OVER THE
WESTERN CWA DESPITE THE DRY AIRMASS IN PLACE. HI-RES MODELS
SUGGEST THIS ACCAS FIELD WILL TRACK ACROSS THE REGION TODAY WITH
SCT SPRINKLES POSSIBLE. HOWEVER WITH DRY AIR IN THE LOWER
LEVELS...WILL MAINTAIN A DRY FORECAST FOR TODAY. THE MAIN ISSUE
FOR TODAY WILL BE GUSTY SOUTHERLY WINDS AS THE REGION WILL BE
SANDWICH BETWEEN A DEPARTING HIGH PRESSURE TO THE EAST...AND AN
APPROACHING LOW PRESSURE SYSTEM FROM WEST. WINDS SHOULD REMAIN
BELOW ADVISORY CRITERIA.
A STRONG LLJ DEVELOPS TONIGHT ACROSS THE EASTERN DAKOTAS AND
WESTERN MINNESOTA. WHILE THE NOSE OF THE LLJ IS POINTED INTO
NE NORTH DAKOTA...A SE STORM MOTION...ALONG WITH A WEAK MID LEVEL
IMPULSE MAY RESULT IN CONVECTION IN THE NORTHEASTERN CWA.
STRONGER SOUTHERLY WINDS ARE EXPECTED ON TUESDAY AS A STRENGTHENING
LOW PRESSURE SYSTEM WILL BE LOCATED OVER THE WESTERN DAKOTAS.
MOMENTUM TRANSFER IN BUFKIT...ALONG H925 WINDS SUGGEST A WIND
ADVISORY WILL LIKELY BE NEEDED TUESDAY AFTERNOON FOR THE EASTERN
CWA. A HEALTHY MID LEVEL CAP WILL BE IN PLACE ACROSS THE WARM
SECTOR OF THE LOW PRESSURE SYSTEM WITH TEMPS AT H7 +10 TO +12C.
CONVECTIVE TEMPERATURES ARE EASILY IN THE 90S TO NEAR 100 DEGREES.
CONVECTION WILL LIKELY BE HELD OFF UNTIL AFTER 0Z WEDNESDAY WHEN A
COLD FRONT MOVES ACROSS THE CWA. THE BEST LIFT AND INSTABILITY IS
STILL LOCATED NORTHEAST OF SOUTH DAKOTA THUS WILL MAINTAIN THE HIGHEST
POPS IN THE NE CWA...WITH LOWER POPS IN THE SW.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
THE LONG TERM MODELS SEEM TO BE CONVERGING ON A SOLUTION FOR THE
EXTENDED FORECAST. EARLY IN THE PERIOD A BROAD MID LEVEL TROF
SHOULD BE CARVING OUT ACROSS THE WESTERN CONUS. THE LEADING PIECE
OF ENERGY ASSOCIATED WITH THIS PATTERN AMPLIFICATION SHOULD BE
LIFTING NORTHEAST ACROSS THE CENTRAL/NORTHERN PLAINS WITH A GOOD
CHANCE OF RAIN FOR MUCH OF THE CWA WEDNESDAY NIGHT AND THURSDAY.
THEN THERE SHOULD BE A BIT OF LULL IN THE ACTIVITY AS THE MID
LEVEL RIDGE REBOUNDS AHEAD OF NEXT SYSTEM DIGGING INTO THE
SOUTHWEST CONUS. THAT ENERGY/TROF LIFTS OUT ACROSS THE NORTHERN
PLAINS IN FULL FORCE ON SATURDAY AND SATURDAY NIGHT. CAPPING DUE
TO FAIRLY WARM MID LEVEL TEMPS MAY PRECLUDE DEEP CONVECTION AT
LEAST INITIALLY...BUT SUSPECT COMBINATION OF ADVANCING SFC/H85
WARM FRONT LATE SATURDAY OR SATURDAY NIGHT WILL BE ENOUGH TO BREAK
THE CAP AND ALLOW FOR DEEP CONVECTION. FORECASTER CONFIDENCE IS
ABOUT AVERAGE THAT THIS SCENARIO WILL PLAY OUT ACCORDING TO PLAN.
MEANWHILE TEMPERATURES WILL AVERAGE OUT BELOW NORMAL FOR THE FIRST
COUPLE OF DAYS IN POST FRONTAL ENVIRONMENT...BUT THEN TREND TO ABOVE
NORMAL FOR THE WEEKEND AS WARM AND MOIST AIRMASS INFILTRATES THE
REGION.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS ARE EXPECTED THROUGH TODAY...BUT WINDS WILL
INCREASE INTO THE 15 TO 30 MPH RANGE BY AFTERNOON...WITH THE
GUSTIER WINDS LIKE AT KPIR/KMBG. AN ADVECTING DECK OF ACCAS MAY
PROVIDE FOR A SPRINKLE OR TWO ACROSS THE REGION THIS MORNING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...SD
LONG TERM...TDK
AVIATION...TDK
WEATHER.GOV/ABERDEEN
000
FXUS63 KFSD 211130
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
630 AM CDT MON MAY 21 2012
.DISCUSSION.../ISSUED AT 316 AM CDT/
SHOULD BE A QUIET DAY WITH MODERATING TEMPERATURES AS A SOUTHERLY
WIND DEVELOPS. HIGH LAPSE RATES ALOFT THIS MORNING MAY SUPPORT SOME
ACCAS IN CENTRAL SOUTH DAKOTA BUT BETTER LAPSE RATES REMAIN WEST OF
THE CWA TODAY SO EXPECT DRY AIR BELOW 750MB TO KEEP ANY BRIEF RAIN
THREAT AT BAY. OTHERWISE...PARTLY CLOUDY CONDITIONS WITH WINDS
BECOMING BREEZY IN CENTRAL SOUTH DAKOTA. HIGHS SHOULD MAINLY BE IN
THE 70S WITH A FEW LOWER 80S IN SOUTH CENTRAL SOUTH DAKOTA.
WILL MAINTAIN A LOW POP FOR TONIGHT AS LAPSE RATES AND INSTABILITY
INCREASE A BIT...POSSIBLY ENOUGH TO SPARK OFF A SHOWER R
THUNDERSTORM...NOTHING SEVERE. WITH A STRONGLY INCREASING SOUTHERLY
BREEZE DID GO AHEAD AND RAISE LOWS A COUPLE OF DEGREES...SOMETHING
CLOSER TO THE CONSRAW OUTPUT WHICH DOES BETTER UNDER STRONG FLOW
REGIMES. THIS MEANS LOWS FROM THE UPPER 50S TO MID 60S.
THIS WILL LEAD INTO A VERY WARM TUESDAY WITH VERY STRONG SOUTHERLY
WINDS. WILL NOT ISSUE A WIND ADVISORY AT THIS TIME BUT WILL LIKELY
NEED TO ISSUE ONE THIS AFTERNOON. EXPECT SOUTH WINDS OF 20 TO 40 MPH
THROUGH MOST OF THE DAY. DECENT MIXING SHOULD ALSO SUPPORT HIGHS
FROM THE MID 80S TO LOWER 90S...AND WOULD NOT BE SURPRISED IF WE CAN
WARM A COUPLE MORE DEGREES BEYOND THIS.
WILL SEE A CHANCE FOR THUNDERSTORMS OVER MAINLY THE NORTHERN AND
WESTERN CWA ON TUESDAY NIGHT...BUT SEVERE WEATHER IS NOT EXPECTED.
LOOKS LIKE THE BETTER INSTABILITY WILL REMAIN BOTTLED UP TO THE
WEST. VERY STRONG SOUTH WINDS WILL CONTINUE WHICH SHOULD YIELD LOWS
IN THE MID 0S FOR MOST LOCATIONS.
THE BEST CHANCE FOR THUNDERSTORMS WILL COME LATE WEDNESDAY AFTERNOON
INTO WEDNESDAY NIGHT AS A BOUNDARY SETS UP OVER THE SOUTHEAST CWA. A
FAIRLY STRONG MID LEVEL WAVE WILL SPREAD ACROSS THE AREA ON
WEDNESDAY NIGHT SO A VERY GOOD CHANCE FOR RAIN AND THUNDERSTORMS.
EXPECT CAPE VALUES OF 1500 TO 200 J/KG OVER NORTHWEST IOWA ON
WEDNESDAY NIGHT AND WITH DECENT DEEP 40 KNOT OR SO BULK SHEAR VALUES
SOME SEVERE WEATHER WILL BE A THREAT. ALSO SOME POTENTIAL FOR HEAVY
RAIN WITH THE BOUNDARY SETTING UP PARALLEL TO THE UPPER LEVEL FLOW
AND PWAT VALUES LIKELY AROUND AN INCH AND A HALF OR A LITTLE
HIGHER.
WILL SEE SOME THREAT FOR RAIN AND THUNDERSTORMS LINGER INTO THURSDAY
BUT NOT LOOKING LIKE A MAJOR THREAT. EXPECT COOLER TEMPERATURES WITH
HIGHS FROM THE UPPER 60S TO MID 70S.
IN THE LATTER PERIODS(FRI/SUN)...SOME AGREEMENT DURING THIS TIME
WITH THE BETTER AGREEMENT BETWEEN THE ECMWF AND GEM. THE MAIN
FEATURE WILL BE A DIGGING TROUGH OF LOW PRESSURE OVER THE WESTERN
UNITED STATES AND A STRENGTHENING RIDGE OVER THE EASTERN UNITED
STATES. FRIDAY NIGHT INTO SATURDAY MORNING THE BIGGEST DIFFERENCE
WITH THE GFS QUITE A BIT COOLER THAN THE EC/GEM. WILL SIDE A BIT
TOWARDS THE WARMER MODELS BUT HAVE TO TEMPER THAT BACK A BIT WITH
SOME LACK OF CONFIDENCE. WILL BE A DECENT THREAT FOR PRECIPITATION
THROUGH THIS ENTIRE PERIOD...AND MAY AT SOME POINT IN TIME NEED TO
INCREASE POPS FOR FRIDAY NIGHT IF MODELS CONTINUE TO TREND IN THE
CURRENT DIRECTION. BASICALLY LOOKING AT 70S ON FRIDAY WITH BOUNDARY
TO THE SOUTH...THEN 80S SAT AND SUN AS THE BOUNDARY SHOOTS
NORTHWARD. THE EC/GEM SUPPORT 90 TO 95 DEGREES ON SATURDAY IN MY
SOUTHERN CWA SO WILL NEED TO WATCH FOR THE TRENDS IN THE MODELS AND
MAY NEED TO GO WARMER ON SATURDAY. /08
&&
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF FORECAST PERIOD. A
FEW ACCAS SHOWERS HAVE DEVELOPED WEST RIVER BUT AS THEY`RE MOVING
EAST...THEY HAVE WEAKENED QUITE A BIT. SO MAY SEE A FEW MID LEVEL
CLOUDS DRIFTING OVER TAF LOCATIONS AS A RESULT. SOUTH WINDS WILL BE
INCREASING AFTER 20Z AS GRADIENT BEGINS TO TIGHT AND HIGH PUSHES OFF
TO THE EAST.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KUNR 210839
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
239 AM MDT MON MAY 21 2012
.DISCUSSION...08Z SURFACE ANALYSIS HAD WEAK LOW OVER SOUTHEAST MT
WITH TROUGH INTO INTO SOUTH CENTRAL WY. LOW LEVEL JET CREATING
SOME ACCAS OVER CENTRAL SD/NE...BUT ACTIVITY SHOULD BE ON THE
WANE/OUT OF THE CWA BY 12Z. WATER VAPOUR SHOWED UPPER RIDGE
CONTINUED TO BUILD OVER THE NORTHERN PLAINS.
TODAY/TONIGHT...UPPER RIDGE BUILDS INTO THE REGION WITH THERMAL
RIDGE AMPLIFYING. TEMPERATURES WELL INTO THE 80S EXPECTED TODAY.
WEAK TROUGH WILL SHIFT ONTO THE SD PLAINS LATE TODAY/TONIGHT AND
MAY BE THE FOCUS FOR ISOLATED -TSRA ACTIVITY WITH ABOUT 1KJ/KG
SBCAPE AVAILABLE. CAP WILL BE INCREASING...SO THREAT WILL BE LOW.
TUESDAY...UPPER TROUGH MOVES INTO THE NORTHERN ROCKIES WITH LEAD
SHORTWAVE ENERGY CREATING A NEW LOW OVER SOUTHEAST MT. TROUGH/DRY-
LINE WILL PUSH INTO SOUTHWEST SD DURING THE DAY WITH GUSTY
SOUTHWEST WINDS BEHIND IT AND VERY DRY RELATIVE HUMIDITIES. AHEAD
OF TROUGH...DEW POINTS IN THE LOWER 50S WILL POOL BRINGING ABOUT
1-2KJ/KG SBCAPE OVER THE FAR EASTERN REACHES OF THE CWA. CAP WILL
BE RATHER STRONG...SO VIGOROUS CONVECTION WILL LIKELY HAVE TO WAIT
UNTIL COLD FRONT THAT FORMS SOUTHWEST OF LOW MOVES THROUGH ONTO
THE SD PLAINS. SHEAR WILL BE SUFFICIENT FOR SURFACE/ELEVATED
SUPERCELLS AND THUS EXPECTED A COUPLE OF SEVERE THUNDERSTORMS.
TEMPERATURES WILL SOAR INTO THE 80S TO LOWER 90S TUESDAY AFTERNOON.
TUESDAY NIGHT/WEDNESDAY...BEHIND COLD FRONT COOLER AIR WILL FILTER
INTO THE CWA WITH UPPER TROUGH CLOSING OFF INTO AN UPPER LOW OVER
SOUTHERN SK. CYCLONIC FLOW EXPECTED OVER THE CWA WITH LIMITED
INSTABILITY. RESULT WILL BE GENERIC POPS OVER MUCH OF THE CWA.
TEMPERATURES NEAR GUIDANCE APPEAR REASONABLE GIVEN FORECAST
SOUNDINGS.
EXTENDED...A COUPLE OF UPPER LEVEL LOW PRESSURE SYSTEMS ARE PROGGED
TO PASS WEST AND NORTH OF THE AREA DURING THE LATTER PART OF THE
WEEK AND OVER THE WEEKEND. SOUTHWESTERLY FLOW ALOFT WILL DEVELOP TO
THE SOUTH OF THESE SYSTEMS OVER THE CENTRAL ROCKIES AND INTO THE
CENTRAL AND NORTHERN PLAINS. THIS PATTERN WILL BRING A SERIES OF
UPPER LEVEL DISTURBANCES ACROSS THE AREA...WITH DAILY CHANCES FOR
SHOWERS AND A FEW THUNDERSTORMS FROM THURSDAY THROUGH THE WEEKEND.
THE BETTER CHANCES FOR THUNDERSTORMS WILL BE OVER THE WEEKEND AS
MOISTURE AND INSTABILITY INCREASE OVER THE AREA. TIMING OF THESE
WAVES ARE UNCERTAIN...BUT THE BETTER CHANCES FOR PCPN AT THIS TIME
LOOK TO BE THURSDAY INTO THURSDAY NIGHT AND FRIDAY NIGHT THROUGH
SATURDAY NIGHT. TEMPERATURES WILL GENERALLY BE NEAR OR SLIGHTLY
BELOW AVERAGE LATE THIS WEEK...WITH A WARMUP TO NEAR OR SLIGHTLY
ABOVE AVERAGE TEMPERATURES OVER THE WEEKEND.
&&
.AVIATION...12Z TAFS
VFR CONDITIONS ARE EXPECTED THROUGH THIS EVENING...WITH SOUTH TO
SOUTHWEST WINDS CONTINUING OVER MUCH OF THE AREA. THERE IS A SLIGHT
CHANCE FOR SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON AND EVENING
ACROSS SOME AREAS EAST OF THE BLACK HILLS...ESPECIALLY OVER SOUTH
CENTRAL SD.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...HELGESON
LONG TERM....26
AVIATION...26
000
FXUS63 KFSD 210816
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
316 AM CDT MON MAY 21 2012
.DISCUSSION.../ISSUED AT 316 AM CDT/
SHOULD BE A QUIET DAY WITH MODERATING TEMPERATURES AS A SOUTHERLY
WIND DEVELOPS. HIGH LAPSE RATES ALOFT THIS MORNING MAY SUPPORT SOME
ACCAS IN CENTRAL SOUTH DAKOTA BUT BETTER LAPSE RATES REMAIN WEST OF
THE CWA TODAY SO EXPECT DRY AIR BELOW 750MB TO KEEP ANY BRIEF RAIN
THREAT AT BAY. OTHERWISE...PARTLY CLOUDY CONDITIONS WITH WINDS
BECOMING BREEZY IN CENTRAL SOUTH DAKOTA. HIGHS SHOULD MAINLY BE IN
THE 70S WITH A FEW LOWER 80S IN SOUTH CENTRAL SOUTH DAKOTA.
WILL MAINTAIN A LOW POP FOR TONIGHT AS LAPSE RATES AND INSTABILITY
INCREASE A BIT...POSSIBLY ENOUGH TO SPARK OFF A SHOWER R
THUNDERSTORM...NOTHING SEVERE. WITH A STRONGLY INCREASING SOUTHERLY
BREEZE DID GO AHEAD AND RAISE LOWS A COUPLE OF DEGREES...SOMETHING
CLOSER TO THE CONSRAW OUTPUT WHICH DOES BETTER UNDER STRONG FLOW
REGIMES. THIS MEANS LOWS FROM THE UPPER 50S TO MID 60S.
THIS WILL LEAD INTO A VERY WARM TUESDAY WITH VERY STRONG SOUTHERLY
WINDS. WILL NOT ISSUE A WIND ADVISORY AT THIS TIME BUT WILL LIKELY
NEED TO ISSUE ONE THIS AFTERNOON. EXPECT SOUTH WINDS OF 20 TO 40 MPH
THROUGH MOST OF THE DAY. DECENT MIXING SHOULD ALSO SUPPORT HIGHS
FROM THE MID 80S TO LOWER 90S...AND WOULD NOT BE SURPRISED IF WE CAN
WARM A COUPLE MORE DEGREES BEYOND THIS.
WILL SEE A CHANCE FOR THUNDERSTORMS OVER MAINLY THE NORTHERN AND
WESTERN CWA ON TUESDAY NIGHT...BUT SEVERE WEATHER IS NOT EXPECTED.
LOOKS LIKE THE BETTER INSTABILITY WILL REMAIN BOTTLED UP TO THE
WEST. VERY STRONG SOUTH WINDS WILL CONTINUE WHICH SHOULD YIELD LOWS
IN THE MID 0S FOR MOST LOCATIONS.
THE BEST CHANCE FOR THUNDERSTORMS WILL COME LATE WEDNESDAY AFTERNOON
INTO WEDNESDAY NIGHT AS A BOUNDARY SETS UP OVER THE SOUTHEAST CWA. A
FAIRLY STRONG MID LEVEL WAVE WILL SPREAD ACROSS THE AREA ON
WEDNESDAY NIGHT SO A VERY GOOD CHANCE FOR RAIN AND THUNDERSTORMS.
EXPECT CAPE VALUES OF 1500 TO 200 J/KG OVER NORTHWEST IOWA ON
WEDNESDAY NIGHT AND WITH DECENT DEEP 40 KNOT OR SO BULK SHEAR VALUES
SOME SEVERE WEATHER WILL BE A THREAT. ALSO SOME POTENTIAL FOR HEAVY
RAIN WITH THE BOUNDARY SETTING UP PARALLEL TO THE UPPER LEVEL FLOW
AND PWAT VALUES LIKELY AROUND AN INCH AND A HALF OR A LITTLE
HIGHER.
WILL SEE SOME THREAT FOR RAIN AND THUNDERSTORMS LINGER INTO THURSDAY
BUT NOT LOOKING LIKE A MAJOR THREAT. EXPECT COOLER TEMPERATURES WITH
HIGHS FROM THE UPPER 60S TO MID 70S.
IN THE LATTER PERIODS(FRI/SUN)...SOME AGREEMENT DURING THIS TIME
WITH THE BETTER AGREEMENT BETWEEN THE ECMWF AND GEM. THE MAIN
FEATURE WILL BE A DIGGING TROUGH OF LOW PRESSURE OVER THE WESTERN
UNITED STATES AND A STRENGTHENING RIDGE OVER THE EASTERN UNITED
STATES. FRIDAY NIGHT INTO SATURDAY MORNING THE BIGGEST DIFFERENCE
WITH THE GFS QUITE A BIT COOLER THAN THE EC/GEM. WILL SIDE A BIT
TOWARDS THE WARMER MODELS BUT HAVE TO TEMPER THAT BACK A BIT WITH
SOME LACK OF CONFIDENCE. WILL BE A DECENT THREAT FOR PRECIPITATION
THROUGH THIS ENTIRE PERIOD...AND MAY AT SOME POINT IN TIME NEED TO
INCREASE POPS FOR FRIDAY NIGHT IF MODELS CONTINUE TO TREND IN THE
CURRENT DIRECTION. BASICALLY LOOKING AT 70S ON FRIDAY WITH BOUNDARY
TO THE SOUTH...THEN 80S SAT AND SUN AS THE BOUNDARY SHOOTS
NORTHWARD. THE EC/GEM SUPPORT 90 TO 95 DEGREES ON SATURDAY IN MY
SOUTHERN CWA SO WILL NEED TO WATCH FOR THE TRENDS IN THE MODELS AND
MAY NEED TO GO WARMER ON SATURDAY. /08
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
VFR CONDITIONS THROUGH THE TAF PERIOD. LIGHT AND VARIABLE WINDS
OVERNIGHT...WITH INCREASING SOUTH-SOUTHEAST WINDS SPREADING EAST
ACROSS THE AREA AFTER 21/12Z AS HIGH PRESSURE MOVES EAST INTO
MINNESOTA/IOWA. SOUTHERLY WIND GUSTS OVER 25KTS BECOMING LIKELY
ALONG/WEST OF THE JAMES RIVER BY 18Z MONDAY. STRONGEST GUSTS SHOULD
SUBSIDE TOWARD SUNSET AFTER 22/01Z MONDAY EVENING...HOWEVER BREEZY
CONDITIONS WILL PERSIST WEST OF I-29 THROUGH THE END OF THE PERIOD.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KABR 210524 AAB
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1224 AM CDT MON MAY 21 2012
.UPDATE...
AVIATION DISCUSSION HAS BEEN UPDATED FOR 06Z TAF ISSUANCE.
NO MAJOR CHANGES MADE TO THE FORECAST AT THIS TIME. JUST A FEW
MINOR TWEAKS MADE TO HOURLY TEMPS AND WINDS. SEE UPDATED AVIATION
DISCUSSION BELOW.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
HIGH PRESSURE WILL REMAIN OVER THE AREA TONIGHT AND INTO THE
MORNING MONDAY...THEN GETS PUSHED EAST AHEAD OF AN APPROACHING
LOW PRESSURE SYSTEM. MAY BE A BIT BREEZY MONDAY AFTERNOON AS THE
PRESSURE GRADIENT TIGHTENS UP BETWEEN THE TWO SYSTEMS. THE LOW
CENTER AND ASSOCIATED FRONTAL BOUNDARY DO NOT MOVE ACROSS THE CWA
UNTIL THE TUESDAY EVENING AND OVERNIGHT HOURS. MODELS CURRENTLY
SHOWING FAIRLY DECENT INSTABILITY AND MOISTURE WITH THE
FRONT...BUT ALSO SHOW H7 TEMPERATURES RISING INTO THE +11 TO +13
DEGREE RANGE...SO MAY BE TOO MUCH OF A CAP IN PLACE TO GET MUCH
GOING IN THE WAY OF CONVECTION. HOWEVER...IF ANY CONVECTION WERE
TO GET GOING IN SPITE OF THE CAP...THEN CONDITIONS WOULD BE
FAVORABLE FOR SEVERE POTENTIAL. WILL STICK WITH CHANCE POPS ACROSS
THE EASTERN CWA TUESDAY NIGHT WHERE THE BEST CONDITIONS WILL BE IN
PLACE...WITH LOWER POPS TO THE WEST.
WILL SEE WAA KICK IN ON MONDAY WITH HIGH TEMPERATURES EXPECTED TO
REACH THE MID 70S TO LOWER 80S. WITH STRONGER SOUTHERLY FLOW ON
TUESDAY AND CONTINUED WAA...HIGHS IN THE MID 80S TO LOWER 90S
SHOULD BE ACHIEVED. COOLEST LOW TEMPERATURES WILL BE TONIGHT WITH
40S EXPECTED MOST AREAS...THEN WARMER LOWS IN THE 50S MONDAY NIGHT
AND IN THE MID 50S TO LOWER 60S TUESDAY NIGHT.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
DECENT AGREEMENT BETWEEN DETERMINISTIC GUIDANCE IN THIS
TIME FRAME...THOUGH MINOR VARIATIONS IN MID AND UPPER FLOW WILL
HAVE DRASTIC CONSEQUENCES ON WHAT IS RAPIDLY BECOMING A FORECAST
DOMINATED BY THE DAILY CHANCE FOR THUNDERSTORMS. START THE PERIOD
OF WITH A DEPARTING SHORTWAVE IN SOUTHWEST FLOW...WITH DECREASING
HEIGHTS AND MUCH COOLER MID LEVEL TEMPERATURES...PROFILES SUPPORT
DAYTIME DRIVEN CONVECTION. A SECOND WAVE DEVELOPS IN THE LEE OF
THE ROCKIES FOR EARLY THURSDAY AND LIFTS NORTHEAST...SOUTH OF THE
CWA...WITH SOME WRAP AROUND STRATIFORM PRECIPITATION FRIDAY AS
WELL. A NOTE OF INTEREST FOR THE END OF THE PERIOD...SOUTHERLY MID
LEVEL FLOW HAS H7/H85 TEMPERATURES WARM UPWARDS OF +14C/+26C
RESPECTIVELY BASED ON A MORE CONSISTENT ECMWF SOLUTION...WHICH
WOULD BE A SIGNIFICANT CLIMATOLOGICAL DEVIATION FOR SPRING.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
HIGH PRESSURE OVER WESTERN SOUTH DAKOTA WILL TRANSITION EAST
OVERNIGHT...WITH WINDS DROPPING TO LIGHT/VARIABLE UNTIL HIGH
PRESSURE MOVES EAST. WINDS WILL BE PRIMARILY OUT OF THE SOUTH TO
SOUTHEAST FOR MOST OF THE DAY MONDAY AND STRONG AT 15 TO 25 KTS
SUSTAINED WITH HIGHER GUSTS. VFR CONDITIONS EXPECTED TO PREVAIL
THROUGH THE PERIOD.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...PARKIN
LONG TERM...CONNELLY
AVIATION...TDK
WEATHER.GOV/ABERDEEN
000
FXUS63 KFSD 210333
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1033 PM CDT SUN MAY 20 2012
.DISCUSSION.../ISSUED AT 915 PM CDT/
THE HOURLY TEMPERATURES AT 9 PM WERE IN REALLY GOOD SHAPE IN THE
GRIDDED FORECAST...WHICH STRONGLY SUGGESTS THAT OUR GOING LOWS
TONIGHT DO NOT NEED ALTERING. WINDS HAVE COME AROUND TO THE
SOUTHEAST IN OUR WESTERN ZONES AS THE SURFACE RIDGE SLIDES OFF TO
THE EAST. CURRENT THOUGHTS REMAIN THAT ANY LATE NIGHT ELEVATED
CONVECTION WILL REMAIN JUST TO THE WEST OF GREGORY COUNTY COINCIDING
WITH THE STRONGEST LOW LEVEL JET AND THETA E ADVECTION. /MJF
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
VFR CONDITIONS THROUGH THE TAF PERIOD. LIGHT AND VARIABLE WINDS
OVERNIGHT...WITH INCREASING SOUTH-SOUTHEAST WINDS SPREADING EAST
ACROSS THE AREA AFTER 21/12Z AS HIGH PRESSURE MOVES EAST INTO
MINNESOTA/IOWA. SOUTHERLY WIND GUSTS OVER 25KTS BECOMING LIKELY
ALONG/WEST OF THE JAMES RIVER BY 18Z MONDAY. STRONGEST GUSTS SHOULD
SUBSIDE TOWARD SUNSET AFTER 22/01Z MONDAY EVENING...HOWEVER BREEZY
CONDITIONS WILL PERSIST WEST OF I-29 THROUGH THE END OF THE PERIOD.
&&
.PREV DISCUSSION.../ISSUED AT 320 PM CDT/
HIGH PRESSURE WILL BUILD INTO THE AREA THIS EVENING. WINDS WILL NOT
DROP OFF REAL QUICKLY IN THE EARLY EVENING AS A WELL MIXED
ATMOSPHERE WILL CONTINUE TO MIX DOWN WINDS OF 10 TO 20 MPH THROUGH
AT LEAST 00Z. ONCE TEMPERATURES COOL 3 TO 5 DEGREES THEN WINDS WILL
QUICKLY DROP OFF TO LIGHT AND VARIABLE. WINDS WILL SLOWLY INCREASE
OUT OF THE SOUTHEAST AFTER MIDNIGHT WEST OF THE JAMES RIVER AS HIGH
PRESSURE MOVES EAST. OTHERWISE...CU DEVELOPING ACROSS THE AREA WILL
QUICKLY DISSIPATE BY EARLY TO MID EVENING LEAVING CLEAR SKIES. THERE
COULD BE A FEW HIGH CLOUDS RETURNING LATE EVENING BUT THIS WILL NOT
AFFECT COOLING OVERNIGHT. WITH DRY AND COOL AIR IN PLACE...EXPECT
LOWS TO FALL INTO THE LOWER TO MID 40S WITH WARMEST READING TOWARD
CHAMBERLAIN AND GREGORY COUNTY DUE TO INCREASING WINDS. DID ALSO
CONSIDER ADDING PATCHY FOG INTO SW MN AND NW IA...BUT AT THIS
POINT...IT APPEARS ENOUGH MIXING WILL OCCUR THIS AFTERNOON TO REMOVE
THE NEAR SURFACE MOISTURE FROM LAST NIGHTS RAIN. WHILE SOME SHALLOW
RIVER VALLEY FOG IS STILL POSSIBLE...IT DOES NOT APPEAR LIKE IT WILL
BE WIDESPREAD ENOUGH TO WARRANT MENTIONING AT THIS TIME.
SUNSHINE SHOULD BE PREVALENT MONDAY WITH JUST A FEW CLOUDS
ASSOCIATED WITH WEAK SHORT WAVE COMING OVER RIDGE TO THE WEST. WITH
THIS WAVE WILL COME A BAND OF WARM ADVECTION AND INSTABILITY. WIND
FIELDS DO NOT LOOK TOO FAVORABLE BUT WILL LEAVE IN A SLIGHT CHANCE
OF THUNDERSTORMS SOUTH AND EAST MONDAY NIGHT. GUIDANCE LOOKS GOOD
FOR TEMPERATURES MONDAY AND MONDAY NIGHT.
WARMER TEMPERATURES...STRONG SOUTHERLY WINDS...AND CAPPING KEEPING A
LID ON STORM CHANCE STILL LOOKS LIKE THE STORY FOR TUESDAY. WINDS
SHOULD BE UP IN THE WIND ADVISORY CATEGORY BUT WILL HOLD OFF ON THIS
HIGHLIGHT ONE MORE FORECAST FOR DETAIL REFINEMENT. TEMPERATURE
GETTING TO THE 80S LOOKS GOOD WITH 90 POSSIBLE SOUTHWEST.
APPROACH AND PASSAGE OF NEXT COLD FRONT TUESDAY NIGHT AND WEDNESDAY
WILL BRING A THREAT OF STORMS. LIKE YESTERDAYS SYSTEM...
PRECIPITATION SEEMS LIKELY TO LEAN TO BEING POSTFRONTAL. THIS IS
MORE TRUE GIVEN THAT THIS FRONT IS LIKELY TO SLOW AS IT GETS INTO
AREA AND UPPER SUPPORT LAGS. AS FRONT CONTINUES TO POKE
THROUGH...THUNDERSTORM CHANCES WILL LINGER...SO WILL KEEP STORM
CHANCE IN FORECAST THROUGH AT LEAST FRIDAY GIVEN TROUGH TO THE WEST
AND MOISTURE AND INSTABILITY INCREASING FROM THE SOUTH.
MODELS CONTINUE TO AGREE ON STRONG UPPER RIDGING TOWARD THE WEEKEND
WITH THE ECMWF BEING VERY STRONG ON THIS. WARMING FROM THIS RIDGING
SHOULD PUSH TEMPERATURES BACK TO SUMMER LEVELS BY THE WEEKEND AFTER
THE MIDWEEK COOLING. THIS TIME THE SUMMER HEAT SHOULD BE ACCOMPANIED
BY GREATER HUMIDITY. GUIDANCE SEEMS TO BE TOO POKEY ON THIS WARMING
EVEN IF THE MORE MODE MODEST GFS RIDGING IS ACCEPTED.
THE OTHER EFFECT OF THIS RIDGING COULD BE CAPPING AND A TREND TO ANY
STORMS MOVING NORTH OF AREA FOR NEXT WEEKEND. IN CASE THE RIDGING
FORECAST IS OVERDONE...WILL KEEP A SLIGHT CHANCE IN THE WEST AND
NORTH WITH NO MENTION IN MOST OF NORTHWEST IA.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KUNR 210228
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
828 PM MDT SUN MAY 20 2012
.DISCUSSION...CURRENT SURFACE MAP SHOWS HIGH PRESSURE ACROSS THE
EASTERN DAKOTAS. A FEW CU/ACCAS ACROSS NORTHEAST WYOMING AND THE BLACK
HILLS IN AREA OF WEAK INSTABILITY/THETA-E ADVECTION. THREAT OF
THUNDERSTORMS DIMINISHING. FORECAST UPDATED TO REMOVE
THUNDERSTORMS FOR THE REMAINDER OF THE NIGHT.
&&
.AVIATION...00Z TAFS
VFR CONDITIONS EXPECTED THROUGH MONDAY EVENING.
ISOLATED THUNDERSTORMS ARE POSSIBLE ACROSS SOUTH CENTRAL SOUTH
DAKOTA LATE MONDAY AFTERNOON AND EVENING.
&&
.PREV DISCUSSION... /ISSUED 242 PM MDT SUN MAY 20 2012/
DISCUSSION...20Z SURFACE ANALYSIS SHOWED HIGH PRESSURE OVER THE
GREAT PLAINS. SOUTHERLY WINDS HAVE DEVELOPED TO THE WEST OF THE
HIGH...OVER NORTHEASTERN WYOMING AND WESTERN SOUTH DAKOTA. CUMULUS
WERE NOTED DEVELOPING OVER NORTHEASTERN WYOMING AND THE BLACK
HILLS THIS AFTERNOON WHERE SBCAPE HAS RISEN TO 250-500J/KG.
TONIGHT...THE UPPER RIDGE BUILDING OVER MONTANA AND WYOMING WILL
PROVIDE LARGE SCALE DESCENT OVER THE REGION SO ANY THUNDERSTORMS
WILL HAVE TO OVERCOME THAT AND SHOULD THEREFORE BE ISOLATED AND SHORT-LIVED.
LOW LEVEL JET DEVELOPS OVER CENTRAL SOUTH DAKOTA LATE
TONIGHT...WHICH MAY PROVIDE ENOUGH MID LEVEL INSTABILITY FOR
ISOLATED THUNDERSTORMS TO DEVELOP OVER SOUTH CENTRAL SOUTH DAKOTA
LATE TONIGHT/EARLY MONDAY.
MONDAY/MONDAY NIGHT...UPPER/THERMAL RIDGE BUILDS OVER THE FORECAST
AREA. SOUTHERLY LOW LEVEL JET UP TO 40KTS WILL SHIFT FROM WESTERN
SD INTO EASTERN SD...AND THEN REDEVELOP OVER NORTHEAST WY/WESTERN
SD MONDAY NIGHT. CAPPING BECOMES MORE PRONOUNCED...BUT NARROW AXIS
OF 1KJ/KG SBCAPE MAY BE ENOUGH FOR A FEW -TSRA OVER SOUTH CENTRAL
SD DURING PEAK HEATING LATE MONDAY AFTERNOON/EARLY EVENING.
TEMPERATURES WILL BE NOTICEABLY WARMER.
TUESDAY/TUESDAY NIGHT...UPPER RIDGE SHIFTS EAST AS UPPER TROUGH
SHIFTS INTO THE NORTHERN PLAINS WITH UPPER LOW OVER SOUTHERN SK.
SEVERAL SHORTWAVES WILL CROSS THE NORTHERN PLAINS. COOL FRONT MOVES
THROUGH LATE. INSTABILITY/SHEAR ALONG FRONT WILL LIKELY BE
SUFFICIENT FOR A FEW SEVERE STORMS...MAINLY OVER EASTERN PORTIONS
OF THE CWA. BEHIND FRONT...MODERATE BAND OF 850-700MB
FRONTOGENESIS WILL BRING BETTER CHANCES FOR POST FRONTAL
PRECIPITATION. TUESDAY SHOULD BE THE WARMEST DAY WITH 700MB
THERMAL RIDGE PEAKING AROUND 12C.
EXTENDED...AN UPPER LEVEL SYSTEM WILL PASS NORTH OF THE AREA DURING
THE MIDDLE AND LATTER PART OF THE WEEK. SOUTHWESTERLY FLOW ALOFT
WILL DEVELOP TO THE SOUTH OF THE SYSTEM OVER THE ROCKIES AND INTO
THE PLAINS. THIS PATTERN WILL LIKELY BRING A SERIES OF UPPER LEVEL
DISTURBANCES ACROSS THE AREA...WITH DAILY CHANCES FOR SHOWERS AND A
FEW STORMS FROM WEDNESDAY THROUGH THE END OF THE WEEK. TEMPERATURES
WILL GENERALLY BE NEAR OR SLIGHTLY BELOW AVERAGE LATE THIS WEEK...
WITH A WARMUP LIKELY OVER THE WEEKEND.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...07
LONG TERM....WFO UNR
AVIATION...07
000
FXUS63 KFSD 210216
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
915 PM CDT SUN MAY 20 2012
.DISCUSSION.../ISSUED AT 915 PM CDT/
THE HOURLY TEMPERATURES AT 9 PM WERE IN REALLY GOOD SHAPE IN THE
GRIDDED FORECAST...WHICH STRONGLY SUGGESTS THAT OUR GOING LOWS
TONIGHT DO NOT NEED ALTERING. WINDS HAVE COME AROUND TO THE
SOUTHEAST IN OUR WESTERN ZONES AS THE SURFACE RIDGE SLIDES OFF TO
THE EAST. CURRENT THOUGHTS REMAIN THAT ANY LATE NIGHT ELEVATED
CONVECTION WILL REMAIN JUST TO THE WEST OF GREGORY COUNTY COINCIDING
WITH THE STRONGEST LOW LEVEL JET AND THETA E ADVECTION. /MJF
&&
.AVIATION.../FOR THE 00Z TAF ISSUANCE/
VFR CONDITIONS THROUGH THE TAF PERIOD. LINGERING GUSTY WINDS EAST OF
US HIGHWAY 59 AT 20/23Z WILL QUICKLY BECOME LIGHT AND VARIABLE BY
SUNSET. INCREASING SOUTH-SOUTHEAST WINDS WILL SPREAD EAST ACROSS THE
AREA AFTER 21/12Z AS HIGH PRESSURE MOVES EAST INTO MINNESOTA/IOWA.
SOUTHERLY WIND GUSTS OVER 25KTS BECOMING LIKELY ALONG/WEST OF THE
JAMES RIVER BY 18Z MONDAY.
&&
.PREV DISCUSSION.../ISSUED AT 320 PM CDT/
HIGH PRESSURE WILL BUILD INTO THE AREA THIS EVENING. WINDS WILL NOT
DROP OFF REAL QUICKLY IN THE EARLY EVENING AS A WELL MIXED
ATMOSPHERE WILL CONTINUE TO MIX DOWN WINDS OF 10 TO 20 MPH THROUGH
AT LEAST 00Z. ONCE TEMPERATURES COOL 3 TO 5 DEGREES THEN WINDS WILL
QUICKLY DROP OFF TO LIGHT AND VARIABLE. WINDS WILL SLOWLY INCREASE
OUT OF THE SOUTHEAST AFTER MIDNIGHT WEST OF THE JAMES RIVER AS HIGH
PRESSURE MOVES EAST. OTHERWISE...CU DEVELOPING ACROSS THE AREA WILL
QUICKLY DISSIPATE BY EARLY TO MID EVENING LEAVING CLEAR SKIES. THERE
COULD BE A FEW HIGH CLOUDS RETURNING LATE EVENING BUT THIS WILL NOT
AFFECT COOLING OVERNIGHT. WITH DRY AND COOL AIR IN PLACE...EXPECT
LOWS TO FALL INTO THE LOWER TO MID 40S WITH WARMEST READING TOWARD
CHAMBERLAIN AND GREGORY COUNTY DUE TO INCREASING WINDS. DID ALSO
CONSIDER ADDING PATCHY FOG INTO SW MN AND NW IA...BUT AT THIS
POINT...IT APPEARS ENOUGH MIXING WILL OCCUR THIS AFTERNOON TO REMOVE
THE NEAR SURFACE MOISTURE FROM LAST NIGHTS RAIN. WHILE SOME SHALLOW
RIVER VALLEY FOG IS STILL POSSIBLE...IT DOES NOT APPEAR LIKE IT WILL
BE WIDESPREAD ENOUGH TO WARRANT MENTIONING AT THIS TIME.
SUNSHINE SHOULD BE PREVALENT MONDAY WITH JUST A FEW CLOUDS
ASSOCIATED WITH WEAK SHORT WAVE COMING OVER RIDGE TO THE WEST. WITH
THIS WAVE WILL COME A BAND OF WARM ADVECTION AND INSTABILITY. WIND
FIELDS DO NOT LOOK TOO FAVORABLE BUT WILL LEAVE IN A SLIGHT CHANCE
OF THUNDERSTORMS SOUTH AND EAST MONDAY NIGHT. GUIDANCE LOOKS GOOD
FOR TEMPERATURES MONDAY AND MONDAY NIGHT.
WARMER TEMPERATURES...STRONG SOUTHERLY WINDS...AND CAPPING KEEPING A
LID ON STORM CHANCE STILL LOOKS LIKE THE STORY FOR TUESDAY. WINDS
SHOULD BE UP IN THE WIND ADVISORY CATEGORY BUT WILL HOLD OFF ON THIS
HIGHLIGHT ONE MORE FORECAST FOR DETAIL REFINEMENT. TEMPERATURE
GETTING TO THE 80S LOOKS GOOD WITH 90 POSSIBLE SOUTHWEST.
APPROACH AND PASSAGE OF NEXT COLD FRONT TUESDAY NIGHT AND WEDNESDAY
WILL BRING A THREAT OF STORMS. LIKE YESTERDAYS SYSTEM...
PRECIPITATION SEEMS LIKELY TO LEAN TO BEING POSTFRONTAL. THIS IS
MORE TRUE GIVEN THAT THIS FRONT IS LIKELY TO SLOW AS IT GETS INTO
AREA AND UPPER SUPPORT LAGS. AS FRONT CONTINUES TO POKE
THROUGH...THUNDERSTORM CHANCES WILL LINGER...SO WILL KEEP STORM
CHANCE IN FORECAST THROUGH AT LEAST FRIDAY GIVEN TROUGH TO THE WEST
AND MOISTURE AND INSTABILITY INCREASING FROM THE SOUTH.
MODELS CONTINUE TO AGREE ON STRONG UPPER RIDGING TOWARD THE WEEKEND
WITH THE ECMWF BEING VERY STRONG ON THIS. WARMING FROM THIS RIDGING
SHOULD PUSH TEMPERATURES BACK TO SUMMER LEVELS BY THE WEEKEND AFTER
THE MIDWEEK COOLING. THIS TIME THE SUMMER HEAT SHOULD BE ACCOMPANIED
BY GREATER HUMIDITY. GUIDANCE SEEMS TO BE TOO POKEY ON THIS WARMING
EVEN IF THE MORE MODE MODEST GFS RIDGING IS ACCEPTED.
THE OTHER EFFECT OF THIS RIDGING COULD BE CAPPING AND A TREND TO ANY
STORMS MOVING NORTH OF AREA FOR NEXT WEEKEND. IN CASE THE RIDGING
FORECAST IS OVERDONE...WILL KEEP A SLIGHT CHANCE IN THE WEST AND
NORTH WITH NO MENTION IN MOST OF NORTHWEST IA.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KABR 202327 AAA
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
627 PM CDT SUN MAY 20 2012
.UPDATE...
NO MAJOR CHANGES MADE TO THE FORECAST AT THIS TIME. JUST A FEW
MINOR TWEAKS MADE TO HOURLY TEMPS AND WINDS. SEE UPDATED AVIATION
DISCUSSION BELOW.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
HIGH PRESSURE WILL REMAIN OVER THE AREA TONIGHT AND INTO THE
MORNING MONDAY...THEN GETS PUSHED EAST AHEAD OF AN APPROACHING
LOW PRESSURE SYSTEM. MAY BE A BIT BREEZY MONDAY AFTERNOON AS THE
PRESSURE GRADIENT TIGHTENS UP BETWEEN THE TWO SYSTEMS. THE LOW
CENTER AND ASSOCIATED FRONTAL BOUNDARY DO NOT MOVE ACROSS THE CWA
UNTIL THE TUESDAY EVENING AND OVERNIGHT HOURS. MODELS CURRENTLY
SHOWING FAIRLY DECENT INSTABILITY AND MOISTURE WITH THE
FRONT...BUT ALSO SHOW H7 TEMPERATURES RISING INTO THE +11 TO +13
DEGREE RANGE...SO MAY BE TOO MUCH OF A CAP IN PLACE TO GET MUCH
GOING IN THE WAY OF CONVECTION. HOWEVER...IF ANY CONVECTION WERE
TO GET GOING IN SPITE OF THE CAP...THEN CONDITIONS WOULD BE
FAVORABLE FOR SEVERE POTENTIAL. WILL STICK WITH CHANCE POPS ACROSS
THE EASTERN CWA TUESDAY NIGHT WHERE THE BEST CONDITIONS WILL BE IN
PLACE...WITH LOWER POPS TO THE WEST.
WILL SEE WAA KICK IN ON MONDAY WITH HIGH TEMPERATURES EXPECTED TO
REACH THE MID 70S TO LOWER 80S. WITH STRONGER SOUTHERLY FLOW ON
TUESDAY AND CONTINUED WAA...HIGHS IN THE MID 80S TO LOWER 90S
SHOULD BE ACHIEVED. COOLEST LOW TEMPERATURES WILL BE TONIGHT WITH
40S EXPECTED MOST AREAS...THEN WARMER LOWS IN THE 50S MONDAY NIGHT
AND IN THE MID 50S TO LOWER 60S TUESDAY NIGHT.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
DECENT AGREEMENT BETWEEN DETERMINISTIC GUIDANCE IN THIS
TIMEFRAME...THOUGH MINOR VARIATIONS IN MID AND UPPER FLOW WILL
HAVE DRASTIC CONSEQUENCES ON WHAT IS RAPIDLY BECOMING A FORECAST
DOMINATED BY THE DAILY CHANCE FOR THUNDERSTORMS. START THE PERIOD
OF WITH A DEPARTING SHORTWAVE IN SOUTHWEST FLOW...WITH DECREASING
HEIGHTS AND MUCH COOLER MID LEVEL TEMPERATURES...PROFILES SUPPORT
DAYTIME DRIVEN CONVECTION. A SECOND WAVE DEVELOPS IN THE LEE OF
THE ROCKIES FOR EARLY THURSDAY AND LIFTS NORTHEAST...SOUTH OF THE
CWA...WITH SOME WRAP AROUND STRATIFORM PRECIPITATION FRIDAY AS
WELL. A NOTE OF INTEREST FOR THE END OF THE PERIOD...SOUTHERLY MID
LEVEL FLOW HAS H7/H85 TEMPERATURES WARM UPWARDS OF +14C/+26C
RESPECTIVELY BASED ON A MORE CONSISTENT ECMWF SOLUTION...WHICH
WOULD BE A SIGNIFICANT CLIMATOLOGICAL DEVIATION FOR SPRING.
&&
.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
HIGH PRESSURE OVER WESTERN SOUTH DAKOTA WILL TRANSITION EAST
OVERNIGHT...WITH WINDS DROPPING TO LIGHT/VARIABLE UNTIL HIGH
PRESSURE MOVES EAST. WINDS WILL BE PRIMARILY OUT OF THE SOUTH FOR
MOST OF THE DAY MONDAY AND STRONG AT 15 TO 25 KTS SUSTAINED WITH
HIGHER GUSTS. VFR CONDITIONS EXPECTED TO PREVAIL THROUGH THE PERIOD.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...WISE
SHORT TERM...PARKIN
LONG TERM...CONNELLY
AVIATION...WISE
WEATHER.GOV/ABERDEEN
000
FXUS63 KFSD 202324
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
624 PM CDT SUN MAY 20 2012
.DISCUSSION.../ISSUED AT 320 PM CDT/
HIGH PRESSURE WILL BUILD INTO THE AREA THIS EVENING. WINDS WILL NOT
DROP OFF REAL QUICKLY IN THE EARLY EVENING AS A WELL MIXED
ATMOSPHERE WILL CONTINUE TO MIX DOWN WINDS OF 10 TO 20 MPH THROUGH
AT LEAST 00Z. ONCE TEMPERATURES COOL 3 TO 5 DEGREES THEN WINDS WILL
QUICKLY DROP OFF TO LIGHT AND VARIABLE. WINDS WILL SLOWLY INCREASE
OUT OF THE SOUTHEAST AFTER MIDNIGHT WEST OF THE JAMES RIVER AS HIGH
PRESSURE MOVES EAST. OTHERWISE...CU DEVELOPING ACROSS THE AREA WILL
QUICKLY DISSIPATE BY EARLY TO MID EVENING LEAVING CLEAR SKIES. THERE
COULD BE A FEW HIGH CLOUDS RETURNING LATE EVENING BUT THIS WILL NOT
AFFECT COOLING OVERNIGHT. WITH DRY AND COOL AIR IN PLACE...EXPECT
LOWS TO FALL INTO THE LOWER TO MID 40S WITH WARMEST READING TOWARD
CHAMBERLAIN AND GREGORY COUNTY DUE TO INCREASING WINDS. DID ALSO
CONSIDER ADDING PATCHY FOG INTO SW MN AND NW IA...BUT AT THIS
POINT...IT APPEARS ENOUGH MIXING WILL OCCUR THIS AFTERNOON TO REMOVE
THE NEAR SURFACE MOISTURE FROM LAST NIGHTS RAIN. WHILE SOME SHALLOW
RIVER VALLEY FOG IS STILL POSSIBLE...IT DOES NOT APPEAR LIKE IT WILL
BE WIDESPREAD ENOUGH TO WARRANT MENTIONING AT THIS TIME.
SUNSHINE SHOULD BE PREVALENT MONDAY WITH JUST A FEW CLOUDS
ASSOCIATED WITH WEAK SHORT WAVE COMING OVER RIDGE TO THE WEST. WITH
THIS WAVE WILL COME A BAND OF WARM ADVECTION AND INSTABILITY. WIND
FIELDS DO NOT LOOK TOO FAVORABLE BUT WILL LEAVE IN A SLIGHT CHANCE
OF THUNDERSTORMS SOUTH AND EAST MONDAY NIGHT. GUIDANCE LOOKS GOOD
FOR TEMPERATURES MONDAY AND MONDAY NIGHT.
WARMER TEMPERATURES...STRONG SOUTHERLY WINDS...AND CAPPING KEEPING A
LID ON STORM CHANCE STILL LOOKS LIKE THE STORY FOR TUESDAY. WINDS
SHOULD BE UP IN THE WIND ADVISORY CATEGORY BUT WILL HOLD OFF ON THIS
HIGHLIGHT ONE MORE FORECAST FOR DETAIL REFINEMENT. TEMPERATURE
GETTING TO THE 80S LOOKS GOOD WITH 90 POSSIBLE SOUTHWEST.
APPROACH AND PASSAGE OF NEXT COLD FRONT TUESDAY NIGHT AND WEDNESDAY
WILL BRING A THREAT OF STORMS. LIKE YESTERDAYS SYSTEM...
PRECIPITATION SEEMS LIKELY TO LEAN TO BEING POSTFRONTAL. THIS IS
MORE TRUE GIVEN THAT THIS FRONT IS LIKELY TO SLOW AS IT GETS INTO
AREA AND UPPER SUPPORT LAGS. AS FRONT CONTINUES TO POKE
THROUGH...THUNDERSTORM CHANCES WILL LINGER...SO WILL KEEP STORM
CHANCE IN FORECAST THROUGH AT LEAST FRIDAY GIVEN TROUGH TO THE WEST
AND MOISTURE AND INSTABILITY INCREASING FROM THE SOUTH.
MODELS CONTINUE TO AGREE ON STRONG UPPER RIDGING TOWARD THE WEEKEND
WITH THE ECMWF BEING VERY STRONG ON THIS. WARMING FROM THIS RIDGING
SHOULD PUSH TEMPERATURES BACK TO SUMMER LEVELS BY THE WEEKEND AFTER
THE MIDWEEK COOLING. THIS TIME THE SUMMER HEAT SHOULD BE ACCOMPANIED
BY GREATER HUMIDITY. GUIDANCE SEEMS TO BE TOO POKEY ON THIS WARMING
EVEN IF THE MORE MODE MODEST GFS RIDGING IS ACCEPTED.
THE OTHER EFFECT OF THIS RIDGING COULD BE CAPPING AND A TREND TO ANY
STORMS MOVING NORTH OF AREA FOR NEXT WEEKEND. IN CASE THE RIDGING
FORECAST IS OVERDONE...WILL KEEP A SLIGHT CHANCE IN THE WEST AND
NORTH WITH NO MENTION IN MOST OF NORTHWEST IA.
&&
.AVIATION.../FOR THE 00Z TAF ISSUANCE/
VFR CONDITIONS THROUGH THE TAF PERIOD. LINGERING GUSTY WINDS EAST OF
US HIGHWAY 59 AT 20/23Z WILL QUICKLY BECOME LIGHT AND VARIABLE BY
SUNSET. INCREASING SOUTH-SOUTHEAST WINDS WILL SPREAD EAST ACROSS THE
AREA AFTER 21/12Z AS HIGH PRESSURE MOVES EAST INTO MINNESOTA/IOWA.
SOUTHERLY WIND GUSTS OVER 25KTS BECOMING LIKELY ALONG/WEST OF THE
JAMES RIVER BY 18Z MONDAY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KUNR 202042
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
242 PM MDT SUN MAY 20 2012
.DISCUSSION...20Z SURFACE ANALYSIS SHOWED HIGH PRESSURE OVER THE
GREAT PLAINS. SOUTHERLY WINDS HAVE DEVELOPED TO THE WEST OF THE
HIGH...OVER NORTHEASTERN WYOMING AND WESTERN SOUTH DAKOTA. CUMULUS
WERE NOTED DEVELOPING OVER NORTHEASTERN WYOMING AND THE BLACK
HILLS THIS AFTERNOON WHERE SBCAPE HAS RISEN TO 250-500J/KG.
TONIGHT...THE UPPER RIDGE BUILDING OVER MONTANA AND WYOMING WILL
PROVIDE LARGE SCALE DESCENT OVER THE REGION SO ANY THUNDERSTORMS
WILL HAVE TO OVERCOME THAT AND SHOULD THEREFORE BE ISOLATED AND SHORT-LIVED.
LOW LEVEL JET DEVELOPS OVER CENTRAL SOUTH DAKOTA LATE
TONIGHT...WHICH MAY PROVIDE ENOUGH MID LEVEL INSTABILITY FOR
ISOLATED THUNDERSTORMS TO DEVELOP OVER SOUTH CENTRAL SOUTH DAKOTA
LATE TONIGHT/EARLY MONDAY.
MONDAY/MONDAY NIGHT...UPPER/THERMAL RIDGE BUILDS OVER THE FORECAST
AREA. SOUTHERLY LOW LEVEL JET UP TO 40KTS WILL SHIFT FROM WESTERN
SD INTO EASTERN SD...AND THEN REDEVELOP OVER NORTHEAST WY/WESTERN
SD MONDAY NIGHT. CAPPING BECOMES MORE PRONOUNCED...BUT NARROW AXIS
OF 1KJ/KG SBCAPE MAY BE ENOUGH FOR A FEW -TSRA OVER SOUTH CENTRAL
SD DURING PEAK HEATING LATE MONDAY AFTERNOON/EARLY EVENING.
TEMPERATURES WILL BE NOTICEABLY WARMER.
TUESDAY/TUESDAY NIGHT...UPPER RIDGE SHIFTS EAST AS UPPER TROUGH
SHIFTS INTO THE NORTHERN PLAINS WITH UPPER LOW OVER SOUTHERN SK.
SEVERAL SHORTWAVES WILL CROSS THE NORTHERN PLAINS. COOL FRONT MOVES
THROUGH LATE. INSTABILITY/SHEAR ALONG FRONT WILL LIKELY BE
SUFFICIENT FOR A FEW SEVERE STORMS...MAINLY OVER EASTERN PORTIONS
OF THE CWA. BEHIND FRONT...MODERATE BAND OF 850-700MB
FRONTOGENESIS WILL BRING BETTER CHANCES FOR POST FRONTAL
PRECIPITATION. TUESDAY SHOULD BE THE WARMEST DAY WITH 700MB
THERMAL RIDGE PEAKING AROUND 12C.
EXTENDED...AN UPPER LEVEL SYSTEM WILL PASS NORTH OF THE AREA DURING
THE MIDDLE AND LATTER PART OF THE WEEK. SOUTHWESTERLY FLOW ALOFT
WILL DEVELOP TO THE SOUTH OF THE SYSTEM OVER THE ROCKIES AND INTO
THE PLAINS. THIS PATTERN WILL LIKELY BRING A SERIES OF UPPER LEVEL
DISTURBANCES ACROSS THE AREA...WITH DAILY CHANCES FOR SHOWERS AND A
FEW STORMS FROM WEDNESDAY THROUGH THE END OF THE WEEK. TEMPERATURES
WILL GENERALLY BE NEAR OR SLIGHTLY BELOW AVERAGE LATE THIS WEEK...
WITH A WARMUP LIKELY OVER THE WEEKEND.
&&
.AVIATION...00Z TAFS
VFR CONDITIONS ARE EXPECTED THROUGH MONDAY...WITH SOUTHERLY WINDS
CONTINUING OVER THE AREA. AN ISOLATED THUNDERSTORM OR TWO WILL BE
POSSIBLE ACROSS NORTHEASTERN WY AND THE BLACK HILLS LATE THIS
AFTERNOON AND EARLY EVENING.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
000
FXUS63 KFSD 202018
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
320 PM CDT SUN MAY 20 2012
.DISCUSSION...
HIGH PRESSURE WILL BUILD INTO THE AREA THIS EVENING. WINDS WILL NOT
DROP OFF REAL QUICKLY IN THE EARLY EVENING AS A WELL MIXED
ATMOSPHERE WILL CONTINUE TO MIX DOWN WINDS OF 10 TO 20 MPH THROUGH
AT LEAST 00Z. ONCE TEMPERATURES COOL 3 TO 5 DEGREES THEN WINDS WILL
QUICKLY DROP OFF TO LIGHT AND VARIABLE. WINDS WILL SLOWLY INCREASE
OUT OF THE SOUTHEAST AFTER MIDNIGHT WEST OF THE JAMES RIVER AS HIGH
PRESSURE MOVES EAST. OTHERWISE...CU DEVELOPING ACROSS THE AREA WILL
QUICKLY DISSIPATE BY EARLY TO MID EVENING LEAVING CLEAR SKIES. THERE
COULD BE A FEW HIGH CLOUDS RETURNING LATE EVENING BUT THIS WILL NOT
AFFECT COOLING OVERNIGHT. WITH DRY AND COOL AIR IN PLACE...EXPECT
LOWS TO FALL INTO THE LOWER TO MID 40S WITH WARMEST READING TOWARD
CHAMBERLAIN AND GREGORY COUNTY DUE TO INCREASING WINDS. DID ALSO
CONSIDER ADDING PATCHY FOG INTO SW MN AND NW IA...BUT AT THIS
POINT...IT APPEARS ENOUGH MIXING WILL OCCUR THIS AFTERNOON TO REMOVE
THE NEAR SURFACE MOISTURE FROM LAST NIGHTS RAIN. WHILE SOME SHALLOW
RIVER VALLEY FOG IS STILL POSSIBLE...IT DOES NOT APPEAR LIKE IT WILL
BE WIDESPREAD ENOUGH TO WARRANT MENTIONING AT THIS TIME.
SUNSHINE SHOULD BE PREVALENT MONDAY WITH JUST A FEW CLOUDS
ASSOCIATED WITH WEAK SHORT WAVE COMING OVER RIDGE TO THE WEST. WITH
THIS WAVE WILL COME A BAND OF WARM ADVECTION AND INSTABILITY. WIND
FIELDS DO NOT LOOK TOO FAVORABLE BUT WILL LEAVE IN A SLIGHT CHANCE
OF THUNDERSTORMS SOUTH AND EAST MONDAY NIGHT. GUIDANCE LOOKS GOOD
FOR TEMPERATURES MONDAY AND MONDAY NIGHT.
WARMER TEMPERATURES...STRONG SOUTHERLY WINDS...AND CAPPING KEEPING A
LID ON STORM CHANCE STILL LOOKS LIKE THE STORY FOR TUESDAY. WINDS
SHOULD BE UP IN THE WIND ADVISORY CATEGORY BUT WILL HOLD OFF ON THIS
HIGHLIGHT ONE MORE FORECAST FOR DETAIL REFINEMENT. TEMPERATURE
GETTING TO THE 80S LOOKS GOOD WITH 90 POSSIBLE SOUTHWEST.
APPROACH AND PASSAGE OF NEXT COLD FRONT TUESDAY NIGHT AND WEDNESDAY
WILL BRING A THREAT OF STORMS. LIKE YESTERDAYS SYSTEM...
PRECIPITATION SEEMS LIKELY TO LEAN TO BEING POSTFRONTAL. THIS IS
MORE TRUE GIVEN THAT THIS FRONT IS LIKELY TO SLOW AS IT GETS INTO
AREA AND UPPER SUPPORT LAGS. AS FRONT CONTINUES TO POKE
THROUGH...THUNDERSTORM CHANCES WILL LINGER...SO WILL KEEP STORM
CHANCE IN FORECAST THROUGH AT LEAST FRIDAY GIVEN TROUGH TO THE WEST
AND MOISTURE AND INSTABILITY INCREASING FROM THE SOUTH.
MODELS CONTINUE TO AGREE ON STRONG UPPER RIDGING TOWARD THE WEEKEND
WITH THE ECMWF BEING VERY STRONG ON THIS. WARMING FROM THIS RIDGING
SHOULD PUSH TEMPERATURES BACK TO SUMMER LEVELS BY THE WEEKEND AFTER
THE MIDWEEK COOLING. THIS TIME THE SUMMER HEAT SHOULD BE ACCOMPANIED
BY GREATER HUMIDITY. GUIDANCE SEEMS TO BE TOO POKEY ON THIS WARMING
EVEN IF THE MORE MODE MODEST GFS RIDGING IS ACCEPTED.
THE OTHER EFFECT OF THIS RIDGING COULD BE CAPPING AND A TREND TO ANY
STORMS MOVING NORTH OF AREA FOR NEXT WEEKEND. IN CASE THE RIDGING
FORECAST IS OVERDONE...WILL KEEP A SLIGHT CHANCE IN THE WEST AND
NORTH WITH NO MENTION IN MOST OF NORTHWEST IA.
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
A FEW MVFR CIGS WILL REMAIN OVER PORTIONS OF SW MN AND NW IA THROUGH
19Z. AS DRIER AIR MOVES IN...THESE CLOUDS WILL MOVE EAST AND
GRADUALLY BE REPLACED BY HIGHER BASED CUMULUS AROUND 4000 OR 5000 AS
HAS ALREADY OCCURRED OVER MUCH OF SE SD AND NORTHEAST NEBRASKA.
THESE CLOUDS WILL DISSIPATE TOWARD SUNSET AS HEATING WANES LEAVING
VFR CIGS AND VSBYS THROUGH 18Z MONDAY. WINDS ARE EXPECTED TO REMAIN
GUSTY...APPROACHING 30 KTS I-29 AND EAST THROUGH MID TO LATE
AFTERNOON DESPITE WEAKENING GRADIENT. HOWEVER...AS TEMPERATURES COOL
AFTER 00Z...WINDS WILL RAPIDLY DIMINISH TO NEAR CALM BY SUNSET.
WINDS WILL GRADUALLY PICK FROM THE SOUTHEAST OVER SOUTHEAST SOUTH
DAKOTA AND NORTHEAST NEBRASKA AFTER 12Z MONDAY./SCHUMACHER
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KABR 202012
AFDABR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
312 PM CDT SUN MAY 20 2012
.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
HIGH PRESSURE WILL REMAIN OVER THE AREA TONIGHT AND INTO THE
MORNING MONDAY...THEN GETS PUSHED EAST AHEAD OF AN APPROACHING
LOW PRESSURE SYSTEM. MAY BE A BIT BREEZY MONDAY AFTERNOON AS THE
PRESSURE GRADIENT TIGHTENS UP BETWEEN THE TWO SYSTEMS. THE LOW
CENTER AND ASSOCIATED FRONTAL BOUNDARY DO NOT MOVE ACROSS THE CWA
UNTIL THE TUESDAY EVENING AND OVERNIGHT HOURS. MODELS CURRENTLY
SHOWING FAIRLY DECENT INSTABILITY AND MOISTURE WITH THE
FRONT...BUT ALSO SHOW H7 TEMPERATURES RISING INTO THE +11 TO +13
DEGREE RANGE...SO MAY BE TOO MUCH OF A CAP IN PLACE TO GET MUCH
GOING IN THE WAY OF CONVECTION. HOWEVER...IF ANY CONVECTION WERE
TO GET GOING IN SPITE OF THE CAP...THEN CONDITIONS WOULD BE
FAVORABLE FOR SEVERE POTENTIAL. WILL STICK WITH CHANCE POPS ACROSS
THE EASTERN CWA TUESDAY NIGHT WHERE THE BEST CONDITIONS WILL BE IN
PLACE...WITH LOWER POPS TO THE WEST.
WILL SEE WAA KICK IN ON MONDAY WITH HIGH TEMPERATURES EXPECTED TO
REACH THE MID 70S TO LOWER 80S. WITH STRONGER SOUTHERLY FLOW ON
TUESDAY AND CONTINUED WAA...HIGHS IN THE MID 80S TO LOWER 90S
SHOULD BE ACHIEVED. COOLEST LOW TEMPERATURES WILL BE TONIGHT WITH
40S EXPECTED MOST AREAS...THEN WARMER LOWS IN THE 50S MONDAY NIGHT
AND IN THE MID 50S TO LOWER 60S TUESDAY NIGHT.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
DECENT AGREEMENT BETWEEN DETERMINISTIC GUIDANCE IN THIS
TIMEFRAME...THOUGH MINOR VARIATIONS IN MID AND UPPER FLOW WILL
HAVE DRASTIC CONSEQUENCES ON WHAT IS RAPIDLY BECOMING A FORECAST
DOMINATED BY THE DAILY CHANCE FOR THUNDERSTORMS. START THE PERIOD
OF WITH A DEPARTING SHORTWAVE IN SOUTHWEST FLOW...WITH DECREASING
HEIGHTS AND MUCH COOLER MID LEVEL TEMPERATURES...PROFILES SUPPORT
DAYTIME DRIVEN CONVECTION. A SECOND WAVE DEVELOPS IN THE LEE OF
THE ROCKIES FOR EARLY THURSDAY AND LIFTS NORTHEAST...SOUTH OF THE
CWA...WITH SOME WRAP AROUND STRATIFORM PRECIPITATION FRIDAY AS
WELL. A NOTE OF INTEREST FOR THE END OF THE PERIOD...SOUTHERLY MID
LEVEL FLOW HAS H7/H85 TEMPERATURES WARM UPWARDS OF +14C/+26C
RESPECTIVELY BASED ON A MORE CONSISTENT ECMWF SOLUTION...WHICH
WOULD BE A SIGNIFICANT CLIMATOLOGICAL DEVIATION FOR SPRING.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
HIGH PRESSURE OVER WESTERN SOUTH DAKOTA WILL TRANSITION EAST
OVERNIGHT...WITH WINDS DROPPING TO LIGHT/VARIABLE UNTIL HIGH
PRESSURE MOVES EAST. WINDS WILL BE PRIMARILY OUT OF THE SOUTH FOR
MOST OF THE DAY MONDAY. VFR CONDITIONS EXPECTED OTHERWISE.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
SHORT TERM...PARKIN
LONG TERM...CONNELLY
AVIATION...CONNELLY
WEATHER.GOV/ABERDEEN
000
FXUS63 KUNR 201730
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1130 AM MDT SUN MAY 20 2012
.AVIATION...18Z TAFS
VFR CONDITIONS ARE EXPECTED THROUGH MONDAY...WITH SOUTHEASTERLY
WINDS CONTINUING OVER THE AREA. AN ISOLATED THUNDERSTORM OR TWO
WILL BE POSSIBLE ACROSS NORTHEASTERN WY AND THE BLACK HILLS THIS
AFTERNOON AND EARLY EVENING.
&&
.PREV DISCUSSION... /ISSUED 1012 AM MDT SUN MAY 20 2012/
UPDATE...16Z SFC ANALYSIS SHOWS HIGH PRESSURE OVER THE WESTERN
DAKOTAS/NEBRASKA. SOUTHEASTERN WINDS WILL DEVELOP ACROSS MUCH OF
THE FORECAST AREA TODAY AS THE HIGH PRESSURE SYSTEM CONTINUES TO
GRADUALLY SLIDE SOUTHEASTWARD. PREVIOUS FORECAST REMAINS ON TRACK
SO NO UPDATES PLANNED ATTM.
PREV DISCUSSION... /ISSUED 219 AM MDT SUN MAY 20 2012/
DISCUSSION...08Z SURFACE ANALYSIS SHOWED WEAK HIGH PRESSURE OVER
THE CWA. SHORTWAVE ENERGY NOTED OVER EASTERN MT PER WATER VAPOR...WITH
A FEW MID CLOUDS ASSOCIATED WITH IT. UPPER RIDGE STARTING TO BUILD
OVER THE NORTHERN ROCKIES.
TODAY/TONIGHT...UPPER RIDGE BUILDS INTO MT/WY AS WEAK LEE TROUGH
DEVELOPS FROM CENTRAL MT INTO CENTRAL WY. SURFACE HIGH SHIFTS EAST
WITH WEAK RETURN FLOW ACROSS THE WEST. AROUND 250J/KG SBCAPE
DEVELOPS THIS AFTERNOON/EARLY EVENING AND MAY BE ENOUGH FOR
ISOLATED -TSRA NEAR TERRAIN/LEE TROUGH. SUBSIDENCE UNDER BUILDING
UPPER RIDGE WILL KEEP COVERAGE LIMITED. TEMPERATURES NEAR GUIDANCE.
MONDAY/MONDAY NIGHT...UPPER/THERMAL RIDGE CONTINUES TO BUILD OVER
CWA. SOUTHERLY LOW LEVEL JET UP TO 40KTS WILL SHIFT FROM WESTERN
SD INTO EASTERN SD...AND THEN REDEVELOP OVER NORTHEAST WY/WESTERN
SD MONDAY NIGHT. CAPPING BECOMES MORE PRONOUNCED...BUT NARROW AXIS
OF 0.5-1KJ/KG SBCAPE MAY BE ENOUGH FOR A FEW -TSRA OVER SOUTH
CENTRAL SD DURING PEAK HEATING LATE MONDAY AFTERNOON/EARLY
EVENING. TEMPERATURES WILL BE NOTICEABLY WARMER.
TUESDAY/TUESDAY NIGHT...UPPER RIDGE SHIFTS EAST AS UPPER TROUGH
SHIFTS INTO THE NORTHERN PLAINS WITH UPPER LOW OVER SOUTHERN SK.
SEVERAL SHORTWAVES WILL MOVE THROUGH THE CWA. COOL FRONT MOVES
THROUGH LATE. INSTABILITY/SHEAR ALONG FRONT WILL LIKELY BE
SUFFICIENT FOR A FEW SEVERE STORMS...MAINLY OVER EASTERN PORTIONS
OF THE CWA. BEHIND FRONT...MODERATE BAND OF 850-700MB
FRONTOGENESIS WILL BRING BETTER CHANCES FOR POST FRONTAL
PRECIPITATION. KEPT POPS IN THE CHANCE CATEGORY FOR NOW...BUT
LIKELIES MAY BE NEEDED. TUESDAY SHOULD BE THE WARMEST DAY WITH
700MB THERMAL RIDGE PEAKING AROUND 12C.
EXTENDED...AN UPPER LEVEL SYSTEM WILL PASS NORTH OF THE AREA DURING
THE MIDDLE AND LATTER PART OF THE WEEK. SOUTHWESTERLY FLOW ALOFT
WILL DEVELOP TO THE SOUTH OF THE SYSTEM OVER THE ROCKIES AND INTO
THE PLAINS. THIS PATTERN WILL LIKELY BRING A SERIES OF UPPER LEVEL
DISTURBANCES ACROSS THE AREA...WITH DAILY CHANCES FOR SHOWERS AND A
FEW STORMS FROM WEDNESDAY THROUGH THE END OF THE WEEK. TEMPERATURES
WILL GENERALLY BE NEAR OR SLIGHTLY BELOW AVERAGE LATE THIS WEEK...
WITH A WARMUP LIKELY OVER THE WEEKEND.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...10
LONG TERM....15
AVIATION...15
000
FXUS63 KFSD 201719
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1219 PM CDT SUN MAY 20 2012
.DISCUSSION...
VERY FEW CHANGES TO CURRENT FORECAST. CLOUDS WILL BE A LITTLE SLOWER
CLEARING OUT OF SW MN AS RAIN EXITS COTTONWOOD AND JACKSON COUNTIES
BETWEEN 11 AM AND NOON. HOWEVER...SKIES SHOULD BECOME PARTLY SUNNY
BY MID AFTERNOON. WINDS ARE IN THE 10 TO 20 MPH WITH GUSTS INTO THE
UPPER 20S...LIGHTER WEST OF THE JAMES RIVER. WITH FLOW AT OR ABOVE
20 KTS AT 925 MB...EXPECT WINDS TO REMAIN IN THIS RANGE THROUGH 5 OR
6 PM BEFORE BEGINNING TO DECREASE AS ATMOSPHERE STABILIZES.
OTHERWISE...TEMPS LOOK GOOD. UPDATED GRIDS ALREADY AVAILABLE. ZFP
TO BE UPDATED ONCE RAIN ENDS IN SW MN./SCHUMACHER
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
A FEW MVFR CIGS WILL REMAIN OVER PORTIONS OF SW MN AND NW IA THROUGH
19Z. AS DRIER AIR MOVES IN...THESE CLOUDS WILL MOVE EAST AND
GRADUALLY BE REPLACED BY HIGHER BASED CUMULUS AROUND 4000 OR 5000 AS
HAS ALREADY OCCURRED OVER MUCH OF SE SD AND NORTHEAST NEBRASKA.
THESE CLOUDS WILL DISSIPATE TOWARD SUNSET AS HEATING WANES LEAVING
VFR CIGS AND VSBYS THROUGH 18Z MONDAY. WINDS ARE EXPECTED TO REMAIN
GUSTY...APPROACHING 30 KTS I-29 AND EAST THROUGH MID TO LATE
AFTERNOON DESPITE WEAKENING GRADIENT. HOWEVER...AS TEMPERATURES COOL
AFTER 00Z...WINDS WILL RAPIDLY DIMINISH TO NEAR CALM BY SUNSET.
WINDS WILL GRADUALLY PICK FROM THE SOUTHEAST OVER SOUTHEAST SOUTH
DAKOTA AND NORTHEAST NEBRASKA AFTER 12Z MONDAY./SCHUMACHER
&&
.PREV DISCUSSION.../ISSUED AT 340 AM CDT/
BAND OF WRAP AROUND PRECIP WILL SLOWLY LIFT NORTH AND EAST
THROUGH THE FORECAST AREA THIS MORNING. SKIES WILL GRADUALLY CLEAR
BEHIND THIS FEATURE AS SURFACE HIGH PRESSURE BUILDS INTO THE AREA.
AS THE SURFACE RIDGE BUILDS INTO THE AREA...SURFACE WINDS WILL
DECREASE ACROSS THE AREA. WITH CLOUDS HANGING ACROSS THE EASTERN
HALF OF THE FORECAST AREA MUCH OF THE DAY...MIXING WILL NOT BE AS
GREAT AND WITH COOLER TEMPERATURES ALOFT...HIGHS WILL REMAIN IN THE
60S.
WITH DRY AIR MASS IN PLACE TONIGHT SHOULD HAVE GREAT RADIATIVE
CONDITIONS. WITH A FAIR AMOUNT OF RAIN LAST NIGHT AND LIMITED
MIXING TODAY...THERE IS A POTENTIAL FOR FOG ESPECIALLY IN THE
EAST...BUT DRY AIR MASS REALLY LIMITS THE POTENTIAL. LEFT MENTION
OUT OF THE FORECAST FOR NOW...BUT THIS IS SOMETHING FUTURE SHIFTS
WILL HAVE TO WATCH FOR. SIDED WITH LOWS JUST SLIGHTLY COOLER THAN
CONSMOS.
MONDAY APPEARS TO BE A FAIRLY PLEASANT DAY ACROSS THE AREA AS
SURFACE HIGH PRESSURE SHIFTS EAST AND RETURN FLOW INCREASES FROM
WEST TO EAST THROUGHOUT THE DAY. THE SOUTHERLY WINDS WILL HELP DRAW
MOISTURE BACK INTO THE REGION...AND THERE IS A CHANCE FOR ELEVATED
NOCTURNAL CONVECTION MONDAY NIGHT EAST OF THE JAMES.
FAIRLY STRONG SOUTHERLY FLOW IS EXPECTED ON TUESDAY AND INCREASED
WINDS OVER GUIDANCE. WILL BE SIMILAR TO THURSDAY AND FRIDAY OF LAST
WEEK WHERE CONDITIONS WERE CLOSE TO WIND ADVISORY. SHOULD ALSO BE A
WARM DAY...WITH TEMPERATURES CLIMBING WELL INTO THE 80S IN MOST
LOCATIONS.
A COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON
WEDNESDAY...THOUGH TIMING OF THE FRONT IS STILL SOMEWHAT ILL
DEFINED. GRADIENT IS MUCH STRONGER AHEAD OF THE FRONT THAN
BEHIND...AND WILL LIKELY BE ANOTHER WINDY DAY ACROSS THE EASTERN
HALF OF THE FORECAST AREA. WITH TIMING OF THE FRONT
UNCERTAIN...LEFT GUIDANCE POPS AS IS.
TIMING IN THE EXTENDED IS ALSO VERY UNCERTAIN....THOUGH ALL OF THE
SOLUTIONS ADVERTISE A WARM FRONT LIFTING NORTH THROUGH THE REGION
WITH HOT CONDITIONS TO FOLLOW. HAVE WARMED TEMPERATURES ACROSS
SOUTHERN FORECAST AREA ON SATURDAY WITH ALL MODEL SOLUTIONS
SUGGESTING THE FRONT WILL BE FOCUSED FURTHER TO THE NORTH. AS THE
WARM FRONT MOVES THROUGH THE REGION...UPPER LEVEL TROUGH IS ALSO
EXPECTED TO MAKE ITS WAY THROUGH THE REGION CREATING THE POTENTIAL
FOR SEVERE WEATHER...INCLUDING TORNADOES.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KABR 201718
AFDABR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
1218 PM CDT SUN MAY 20 2012
.UPDATE...
NO MAJOR CHANGES MADE TO THE FORECAST THIS MORNING. THE WESTERN
HALF OF THE CWA IS NOW UNDER MOSTLY CLEAR SKIES...AND THE CLOUD
COVER OVER THE EAST IS CONTINUING TO PUSH EAST...EXPECT THE ENTIRE
CWA TO BE MOSTLY SUNNY BY EARLY AFTERNOON. NO CHANGES MADE TO
WINDS OR TEMPERATURES AT THIS TIME.
AVIATION DISCUSSION BELOW HAS BEEN UPDATED...
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH TUESDAY
AN AREA OF LOW PRESSURE OVER THE TWIN CITIES IS WRAPPING LIGHT
SHOWERS INTO EASTERN SOUTH DAKOTA THIS MORNING. THESE LIGHT
SHOWERS MAY HOLD ON UNTIL 12Z...BEFORE PUSHING EAST. THAT
SAID...HAVE ADDED A SMALL POP FOR THE I-29 CORRIDOR UNTIL 15Z. THE
REST OF TODAY AND WILL BE DRY AS A HIGH PRESSURE DRIFTS ACROSS THE
REGION. WITH THE CENTER OF THE HIGH PRESSURE OVER THE CWA
TONIGHT...THIS SHOULD ALLOW FOR LOW TEMPERATURES TO FALL TO THE
LOWER 40S FOR SOME LOCATIONS. AN APPROACHING LOW PRESSURE SYSTEM
FROM THE WEST WILL BRING WAA TO THE WESTERN DAKOTAS BEGINNING
AROUND 12Z MONDAY. AN INCREASING PRESSURE GRADIENT WILL DEVELOP
ACROSS THE NORTHERN PLAINS DURING THE AFTERNOON WITH GUSTY
SOUTHERLY WINDS EXPECTED. WINDS SHOULD REMAIN BELOW ADVISORY
CRITERIA.
WINDS WILL BE STRONG ON TUESDAY AS A STRETCHING SURFACE LOW
PRESSURE WILL BE OFF TO THE WEST OF THE CWA. BASED ON MOMENTUM
TRANSFER IN BUFKIT...WIND GUSTS MAY REACH ADVISORY LEVEL. DEPENDING
ON THE TIMING A COLD FRONT...TUESDAY WILL HAVE THE POTENTIAL TO BE
ABNORMALLY WARM. SOME NAM BASED GUIDANCE IS SHOWING HIGHS IN THE
KPIR AREA COULD REACH THE UPPER 90S. DID INCREASE HIGHS OVER THE
PREVIOUS FORECAST...BUT NOT AS HIGH AS NAM WOULD INDICATE.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
THE 00Z MODELS ARE TRENDING TOWARD EACH OTHER FOR THE LONG
TERM...WITH ALL MODELS INDICATING A TRANSITION TO A NEGATIVE PNA
PATTERN ACROSS THE CONUS. HOWEVER THERE ARE STILL SOME DIFFERENCES
IN THE STRENGTH OF AN INITIAL WAVE MOVING ACROSS THE ROCKIES AND
INTO THE NORTHERN PLAINS TUESDAY NIGHT THROUGH THURSDAY. THE GFS
AND ITS GEFS MEMBERS ARE CONSIDERABLY STRONGER THAN THE ECMWF/GEM
IN PUSHING THROUGH A FRONT AND THEN DRIVING THAT FRONTAL BOUNDARY
FURTHER SOUTH. THE GFS/GEFS ALSO KEEPS THAT FRONT SUPPRESSED TO
THE SOUTH FOR A LONGER PERIOD OF TIME THIS WEEKEND. THE ECMWF
BUILDS MID LEVEL HEIGHTS MUCH FASTER ACROSS THE MID CONUS AND THUS
BRINGS THE SFC/H85 WARM FRONT TO THE NORTH FASTER. SUSPECT ITS
PROBABLY MORE CORRECT GIVEN ITS BETTER CONSISTENCY THE LAST FEW
DAYS. NONETHELESS ITS STILL PRUDENT TO KEEP A MODEL BLEND IN PLACE
BUT WITH A BIT OF A HEDGE TOWARD WARMER TEMPS BY LATE IN THE
WEEKEND. AS FOR PCPN...FORECASTER CONFIDENCE IS QUITE LOW. THE
FRONT MOVING THROUGH TUESDAY NIGHT/WEDNESDAY MAY WELL COME THROUGH
MOSTLY DRY WITH SOMEWHAT CAPPED ATMOSPHERE IN PLACE. BEHIND THE
FRONT WE KEEP A WEST TO SOUTHWEST MID LEVEL FLOW BUT LOSE OUR
INSTABILITY. SO SHOWERS WILL BE POSSIBLE BUT EXACTLY WHEN IS TOUGH
TO PIN DOWN GIVEN MODEL DIFFERENCES. BROAD BRUSH APPROACH
IMPLEMENTED FOR THE TIME BEING.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
HIGH PRESSURE OVER WESTERN SOUTH DAKOTA WILL TRANSITION EAST
OVERNIGHT...WITH WINDS DROPPING TO LIGHT/VARIABLE UNTIL HIGH
PRESSURE MOVES EAST. WINDS WILL BE PRIMARILY OUT OF THE SOUTH FOR
MOST OF THE DAY MONDAY. VFR CONDITIONS EXPECTED OTHERWISE.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...PARKIN
SHORT TERM...SD
LONG TERM...TDK
AVIATION...CONNELLY
WEATHER.GOV/ABERDEEN
000
FXUS63 KUNR 201612
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1012 AM MDT SUN MAY 20 2012
.UPDATE...16Z SFC ANALYSIS SHOWS HIGH PRESSURE OVER THE WESTERN
DAKOTAS/NEBRASKA. SOUTHEASTERN WINDS WILL DEVELOP ACROSS MUCH OF
THE FORECAST AREA TODAY AS THE HIGH PRESSURE SYSTEM CONTINUES TO
GRADUALLY SLIDE SOUTHEASTWARD. PREVIOUS FORECAST REMAINS ON TRACK
SO NO UPDATES PLANNED ATTM.
&&
.AVIATION...12Z TAF UPDATE
VFR CONDITIONS ARE EXPECTED TODAY INTO TONIGHT...WITH
SOUTHEASTERLY WINDS DEVELOPING OVER THE AREA. AN ISOLATED
THUNDERSTORM OR TWO WILL BE POSSIBLE ACROSS NORTHEASTERN WY AND
THE BLACK HILLS THIS AFTERNOON AND EARLY EVENING...AND OVER PARTS
OF WESTERN AND CENTRAL SOUTH DAKOTA AFTER MIDNIGHT.
&&
.PREV DISCUSSION... /ISSUED 219 AM MDT SUN MAY 20 2012/
DISCUSSION...08Z SURFACE ANALYSIS SHOWED WEAK HIGH PRESSURE OVER
THE CWA. SHORTWAVE ENERGY NOTED OVER EASTERN MT PER WATER VAPOUR...WITH
A FEW MID CLOUDS ASSOCIATED WITH IT. UPPER RIDGE STARTING TO BUILD
OVER THE NORTHERN ROCKIES.
TODAY/TONIGHT...UPPER RIDGE BUILDS INTO MT/WY AS WEAK LEE TROUGH
DEVELOPS FROM CENTRAL MT INTO CENTRAL WY. SURFACE HIGH SHIFTS EAST
WITH WEAK RETURN FLOW ACROSS THE WEST. AROUND 250J/KG SBCAPE
DEVELOPS THIS AFTERNOON/EARLY EVENING AND MAY BE ENOUGH FOR
ISOLATED -TSRA NEAR TERRAIN/LEE TROUGH. SUBSIDENCE UNDER BUILDING
UPPER RIDGE WILL KEEP COVERAGE LIMITED. TEMPERATURES NEAR GUIDANCE.
MONDAY/MONDAY NIGHT...UPPER/THERMAL RIDGE CONTINUES TO BUILD OVER
CWA. SOUTHERLY LOW LEVEL JET UP TO 40KTS WILL SHIFT FROM WESTERN
SD INTO EASTERN SD...AND THEN REDEVELOP OVER NORTHEAST WY/WESTERN
SD MONDAY NIGHT. CAPPING BECOMES MORE PRONOUNCED...BUT NARROW AXIS
OF 0.5-1KJ/KG SBCAPE MAY BE ENOUGH FOR A FEW -TSRA OVER SOUTH
CENTRAL SD DURING PEAK HEATING LATE MONDAY AFTERNOON/EARLY
EVENING. TEMPERATURES WILL BE NOTICEABLY WARMER.
TUESDAY/TUESDAY NIGHT...UPPER RIDGE SHIFTS EAST AS UPPER TROUGH
SHIFTS INTO THE NORTHERN PLAINS WITH UPPER LOW OVER SOUTHERN SK.
SEVERAL SHORTWAVES WILL MOVE THROUGH THE CWA. COOL FRONT MOVES
THROUGH LATE. INSTABILITY/SHEAR ALONG FRONT WILL LIKELY BE
SUFFICIENT FOR A FEW SEVERE STORMS...MAINLY OVER EASTERN PORTIONS
OF THE CWA. BEHIND FRONT...MODERATE BAND OF 850-700MB
FRONTOGENESIS WILL BRING BETTER CHANCES FOR POST FRONTAL
PRECIPITATION. KEPT POPS IN THE CHANCE CATEGORY FOR NOW...BUT
LIKELIES MAY BE NEEDED. TUESDAY SHOULD BE THE WARMEST DAY WITH
700MB THERMAL RIDGE PEAKING AROUND 12C.
EXTENDED...AN UPPER LEVEL SYSTEM WILL PASS NORTH OF THE AREA DURING
THE MIDDLE AND LATTER PART OF THE WEEK. SOUTHWESTERLY FLOW ALOFT
WILL DEVELOP TO THE SOUTH OF THE SYSTEM OVER THE ROCKIES AND INTO
THE PLAINS. THIS PATTERN WILL LIKELY BRING A SERIES OF UPPER LEVEL
DISTURBANCES ACROSS THE AREA...WITH DAILY CHANCES FOR SHOWERS AND A
FEW STORMS FROM WEDNESDAY THROUGH THE END OF THE WEEK. TEMPERATURES
WILL GENERALLY BE NEAR OR SLIGHTLY BELOW AVERAGE LATE THIS WEEK...
WITH A WARMUP LIKELY OVER THE WEEKEND.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
000
FXUS63 KFSD 201539
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1039 AM CDT SUN MAY 20 2012
.DISCUSSION...
VERY FEW CHANGES TO CURRENT FORECAST. CLOUDS WILL BE A LITTLE SLOWER
CLEARING OUT OF SW MN AS RAIN EXITS COTTONWOOD AND JACKSON COUNTIES
BETWEEN 11 AM AND NOON. HOWEVER...SKIES SHOULD BECOME PARTLY SUNNY
BY MID AFTERNOON. WINDS ARE IN THE 10 TO 20 MPH WITH GUSTS INTO THE
UPPER 20S...LIGHTER WEST OF THE JAMES RIVER. WITH FLOW AT OR ABOVE
20 KTS AT 925 MB...EXPECT WINDS TO REMAIN IN THIS RANGE THROUGH 5 OR
6 PM BEFORE BEGINNING TO DECREASE AS ATMOSPHERE STABILIZES.
OTHERWISE...TEMPS LOOK GOOD. UPDATED GRIDS ALREADY AVAILABLE. ZFP
TO BE UPDATED ONCE RAIN ENDS IN SW MN./SCHUMACHER
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
A BAND OF RAIN WILL MOVE THROUGH SOUTHWEST MINNESOTA AND NORTHWEST
IOWA BY LATE MORNING. MAINLY MVFR CEILINGS ASSOCIATED WITH THIS RAIN
AND JUST BEHIND IT WILL ALSO EXIT THE AREA BY ABOUT NOON. AFTER THIS
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. /08
&&
.PREV DISCUSSION.../ISSUED AT 340 AM CDT/
BAND OF WRAP AROUND PRECIP WILL SLOWLY LIFT NORTH AND EAST
THROUGH THE FORECAST AREA THIS MORNING. SKIES WILL GRADUALLY CLEAR
BEHIND THIS FEATURE AS SURFACE HIGH PRESSURE BUILDS INTO THE AREA.
AS THE SURFACE RIDGE BUILDS INTO THE AREA...SURFACE WINDS WILL
DECREASE ACROSS THE AREA. WITH CLOUDS HANGING ACROSS THE EASTERN
HALF OF THE FORECAST AREA MUCH OF THE DAY...MIXING WILL NOT BE AS
GREAT AND WITH COOLER TEMPERATURES ALOFT...HIGHS WILL REMAIN IN THE
60S.
WITH DRY AIR MASS IN PLACE TONIGHT SHOULD HAVE GREAT RADIATIVE
CONDITIONS. WITH A FAIR AMOUNT OF RAIN LAST NIGHT AND LIMITED
MIXING TODAY...THERE IS A POTENTIAL FOR FOG ESPECIALLY IN THE
EAST...BUT DRY AIR MASS REALLY LIMITS THE POTENTIAL. LEFT MENTION
OUT OF THE FORECAST FOR NOW...BUT THIS IS SOMETHING FUTURE SHIFTS
WILL HAVE TO WATCH FOR. SIDED WITH LOWS JUST SLIGHTLY COOLER THAN
CONSMOS.
MONDAY APPEARS TO BE A FAIRLY PLEASANT DAY ACROSS THE AREA AS
SURFACE HIGH PRESSURE SHIFTS EAST AND RETURN FLOW INCREASES FROM
WEST TO EAST THROUGHOUT THE DAY. THE SOUTHERLY WINDS WILL HELP DRAW
MOISTURE BACK INTO THE REGION...AND THERE IS A CHANCE FOR ELEVATED
NOCTURNAL CONVECTION MONDAY NIGHT EAST OF THE JAMES.
FAIRLY STRONG SOUTHERLY FLOW IS EXPECTED ON TUESDAY AND INCREASED
WINDS OVER GUIDANCE. WILL BE SIMILAR TO THURSDAY AND FRIDAY OF LAST
WEEK WHERE CONDITIONS WERE CLOSE TO WIND ADVISORY. SHOULD ALSO BE A
WARM DAY...WITH TEMPERATURES CLIMBING WELL INTO THE 80S IN MOST
LOCATIONS.
A COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON
WEDNESDAY...THOUGH TIMING OF THE FRONT IS STILL SOMEWHAT ILL
DEFINED. GRADIENT IS MUCH STRONGER AHEAD OF THE FRONT THAN
BEHIND...AND WILL LIKELY BE ANOTHER WINDY DAY ACROSS THE EASTERN
HALF OF THE FORECAST AREA. WITH TIMING OF THE FRONT
UNCERTAIN...LEFT GUIDANCE POPS AS IS.
TIMING IN THE EXTENDED IS ALSO VERY UNCERTAIN....THOUGH ALL OF THE
SOLUTIONS ADVERTISE A WARM FRONT LIFTING NORTH THROUGH THE REGION
WITH HOT CONDITIONS TO FOLLOW. HAVE WARMED TEMPERATURES ACROSS
SOUTHERN FORECAST AREA ON SATURDAY WITH ALL MODEL SOLUTIONS
SUGGESTING THE FRONT WILL BE FOCUSED FURTHER TO THE NORTH. AS THE
WARM FRONT MOVES THROUGH THE REGION...UPPER LEVEL TROUGH IS ALSO
EXPECTED TO MAKE ITS WAY THROUGH THE REGION CREATING THE POTENTIAL
FOR SEVERE WEATHER...INCLUDING TORNADOES.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KABR 201519 AAB
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1019 AM CDT SUN MAY 20 2012
.UPDATE...
NO MAJOR CHANGES MADE TO THE FORECAST THIS MORNING. THE WESTERN
HALF OF THE CWA IS NOW UNDER MOSTLY CLEAR SKIES...AND THE CLOUD
COVER OVER THE EAST IS CONTINUING TO PUSH EAST...EXPECT THE ENTIRE
CWA TO BE MOSTLY SUNNY BY EARLY AFTERNOON. NO CHANGES MADE TO
WINDS OR TEMPERATURES AT THIS TIME.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH TUESDAY
AN AREA OF LOW PRESSURE OVER THE TWIN CITIES IS WRAPPING LIGHT
SHOWERS INTO EASTERN SOUTH DAKOTA THIS MORNING. THESE LIGHT
SHOWERS MAY HOLD ON UNTIL 12Z...BEFORE PUSHING EAST. THAT
SAID...HAVE ADDED A SMALL POP FOR THE I-29 CORRIDOR UNTIL 15Z. THE
REST OF TODAY AND WILL BE DRY AS A HIGH PRESSURE DRIFTS ACROSS THE
REGION. WITH THE CENTER OF THE HIGH PRESSURE OVER THE CWA
TONIGHT...THIS SHOULD ALLOW FOR LOW TEMPERATURES TO FALL TO THE
LOWER 40S FOR SOME LOCATIONS. AN APPROACHING LOW PRESSURE SYSTEM
FROM THE WEST WILL BRING WAA TO THE WESTERN DAKOTAS BEGINNING
AROUND 12Z MONDAY. AN INCREASING PRESSURE GRADIENT WILL DEVELOP
ACROSS THE NORTHERN PLAINS DURING THE AFTERNOON WITH GUSTY
SOUTHERLY WINDS EXPECTED. WINDS SHOULD REMAIN BELOW ADVISORY
CRITERIA.
WINDS WILL BE STRONG ON TUESDAY AS A STRETCHING SURFACE LOW
PRESSURE WILL BE OFF TO THE WEST OF THE CWA. BASED ON MOMENTUM
TRANSFER IN BUFKIT...WIND GUSTS MAY REACH ADVISORY LEVEL. DEPENDING
ON THE TIMING A COLD FRONT...TUESDAY WILL HAVE THE POTENTIAL TO BE
ABNORMALLY WARM. SOME NAM BASED GUIDANCE IS SHOWING HIGHS IN THE
KPIR AREA COULD REACH THE UPPER 90S. DID INCREASE HIGHS OVER THE
PREVIOUS FORECAST...BUT NOT AS HIGH AS NAM WOULD INDICATE.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
THE 00Z MODELS ARE TRENDING TOWARD EACH OTHER FOR THE LONG
TERM...WITH ALL MODELS INDICATING A TRANSITION TO A NEGATIVE PNA
PATTERN ACROSS THE CONUS. HOWEVER THERE ARE STILL SOME DIFFERENCES
IN THE STRENGTH OF AN INITIAL WAVE MOVING ACROSS THE ROCKIES AND
INTO THE NORTHERN PLAINS TUESDAY NIGHT THROUGH THURSDAY. THE GFS
AND ITS GEFS MEMBERS ARE CONSIDERABLY STRONGER THAN THE ECMWF/GEM
IN PUSHING THROUGH A FRONT AND THEN DRIVING THAT FRONTAL BOUNDARY
FURTHER SOUTH. THE GFS/GEFS ALSO KEEPS THAT FRONT SUPPRESSED TO
THE SOUTH FOR A LONGER PERIOD OF TIME THIS WEEKEND. THE ECMWF
BUILDS MID LEVEL HEIGHTS MUCH FASTER ACROSS THE MID CONUS AND THUS
BRINGS THE SFC/H85 WARM FRONT TO THE NORTH FASTER. SUSPECT ITS
PROBABLY MORE CORRECT GIVEN ITS BETTER CONSISTENCY THE LAST FEW
DAYS. NONETHELESS ITS STILL PRUDENT TO KEEP A MODEL BLEND IN PLACE
BUT WITH A BIT OF A HEDGE TOWARD WARMER TEMPS BY LATE IN THE
WEEKEND. AS FOR PCPN...FORECASTER CONFIDENCE IS QUITE LOW. THE
FRONT MOVING THROUGH TUESDAY NIGHT/WEDNESDAY MAY WELL COME THROUGH
MOSTLY DRY WITH SOMEWHAT CAPPED ATMOSPHERE IN PLACE. BEHIND THE
FRONT WE KEEP A WEST TO SOUTHWEST MID LEVEL FLOW BUT LOSE OUR
INSTABILITY. SO SHOWERS WILL BE POSSIBLE BUT EXACTLY WHEN IS TOUGH
TO PIN DOWN GIVEN MODEL DIFFERENCES. BROAD BRUSH APPROACH
IMPLEMENTED FOR THE TIME BEING.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS ARE EXPECTED REGION WIDE TODAY. THE ONLY EXCEPTION
WOULD BE SOME PATCHY MVFR FOG UP THE MO VALLEY EARLY THIS
MORNING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...PARKIN
SHORT TERM...SD
LONG TERM...TDK
AVIATION...TDK
WEATHER.GOV/ABERDEEN
000
FXUS63 KABR 201123 AAA
AFDABR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
623 AM CDT SUN MAY 20 2012
.UPDATE...
AVIATION DISCUSSION HAS BEEN UPDATED FOR 12Z TAF ISSUANCE.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH TUESDAY
AN AREA OF LOW PRESSURE OVER THE TWIN CITIES IS WRAPPING LIGHT
SHOWERS INTO EASTERN SOUTH DAKOTA THIS MORNING. THESE LIGHT
SHOWERS MAY HOLD ON UNTIL 12Z...BEFORE PUSHING EAST. THAT
SAID...HAVE ADDED A SMALL POP FOR THE I-29 CORRIDOR UNTIL 15Z. THE
REST OF TODAY AND WILL BE DRY AS A HIGH PRESSURE DRIFTS ACROSS THE
REGION. WITH THE CENTER OF THE HIGH PRESSURE OVER THE CWA
TONIGHT...THIS SHOULD ALLOW FOR LOW TEMPERATURES TO FALL TO THE
LOWER 40S FOR SOME LOCATIONS. AN APPROACHING LOW PRESSURE SYSTEM
FROM THE WEST WILL BRING WAA TO THE WESTERN DAKOTAS BEGINNING
AROUND 12Z MONDAY. AN INCREASING PRESSURE GRADIENT WILL DEVELOP
ACROSS THE NORTHERN PLAINS DURING THE AFTERNOON WITH GUSTY
SOUTHERLY WINDS EXPECTED. WINDS SHOULD REMAIN ADVISORY CRITERIA.
WINDS WILL BE STRONG ON TUESDAY AS A STRETCHING SURFACE LOW
PRESSURE WILL BE OFF TO THE WEST OF THE CWA. BASED ON MOMENTUM
TRANSFER IN BUFKIT...WIND GUSTS MAY REACH ADVISORY LEVEL. DEPENDING
ON THE TIMING A COLD FRONT...TUESDAY WILL HAVE THE POTENTIAL TO BE
ABNORMALLY WARM. SOME NAM BASED GUIDANCE IS SHOWING HIGHS IN THE
KPIR AREA COULD REACH THE UPPER 90S POSSIBLE. DID INCREASE HIGHS
OVER THE PREVIOUS FORECAST...BUT NOT AS HIGH AS NAM WOULD INDICATE.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
THE 00Z MODELS ARE TRENDING TOWARD EACH OTHER FOR THE LONG
TERM...WITH ALL MODELS INDICATING A TRANSITION TO A NEGATIVE PNA
PATTERN ACROSS THE CONUS. HOWEVER THERE ARE STILL SOME DIFFERENCES
IN THE STRENGTH OF AN INITIAL WAVE MOVING ACROSS THE ROCKIES AND
INTO THE NORTHERN PLAINS TUESDAY NIGHT THROUGH THURSDAY. THE GFS
AND ITS GEFS MEMBERS ARE CONSIDERABLY STRONGER THAN THE ECMWF/GEM
IN PUSHING THROUGH A FRONT AND THEN DRIVING THAT FRONTAL BOUNDARY
FURTHER SOUTH. THE GFS/GEFS ALSO KEEPS THAT FRONT SUPPRESSED TO
THE SOUTH FOR A LONGER PERIOD OF TIME THIS WEEKEND. THE ECMWF
BUILDS MID LEVEL HEIGHTS MUCH FASTER ACROSS THE MID CONUS AND THUS
BRINGS THE SFC/H85 WARM FRONT TO THE NORTH FASTER. SUSPECT ITS
PROBABLY MORE CORRECT GIVEN ITS BETTER CONSISTENCY THE LAST FEW
DAYS. NONETHELESS ITS STILL PRUDENT TO KEEP A MODEL BLEND IN PLACE
BUT WITH A BIT OF A HEDGE TOWARD WARMER TEMPS BY LATE IN THE
WEEKEND. AS FOR PCPN...FORECASTER CONFIDENCE IS QUITE LOW. THE
FRONT MOVING THROUGH TUESDAY NIGHT/WEDNESDAY MAY WELL COME
THROUGH MOSTLY DRY WITH SOMEWHAT CAPPED ATMOSPHERE IN PLACE. THEN
BEHIND THE FRONT WE KEEP A WEST TO SOUTHWEST MID LEVEL FLOW BUT
LOSE OUR INSTABILITY. SO SHOWERS WILL BE POSSIBLE BUT EXACTLY
WHEN IS TOUGH TO PIN DOWN GIVEN MODEL DIFFERENCES. BROAD BRUSH
APPROACH IMPLEMENTED FOR THE TIME BEING.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
VFR CONDITIONS ARE EXPECTED REGION WIDE TODAY. THE ONLY EXCEPTION
WOULD BE SOME PATCHY MVFR FOG UP THE MO VALLEY EARLY THIS
MORNING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...SD
LONG TERM...TDK
AVIATION...TDK
WEATHER.GOV/ABERDEEN
000
FXUS63 KFSD 201045
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
545 AM CDT SUN MAY 20 2012
.DISCUSSION.../ISSUED AT 340 AM CDT/
BAND OF WRAP AROUND PRECIP WILL SLOWLY LIFT NORTH AND EAST
THROUGH THE FORECAST AREA THIS MORNING. SKIES WILL GRADUALLY CLEAR
BEHIND THIS FEATURE AS SURFACE HIGH PRESSURE BUILDS INTO THE AREA.
AS THE SURFACE RIDGE BUILDS INTO THE AREA...SURFACE WINDS WILL
DECREASE ACROSS THE AREA. WITH CLOUDS HANGING ACROSS THE EASTERN
HALF OF THE FORECAST AREA MUCH OF THE DAY...MIXING WILL NOT BE AS
GREAT AND WITH COOLER TEMPERATURES ALOFT...HIGHS WILL REMAIN IN THE
60S.
WITH DRY AIR MASS IN PLACE TONIGHT SHOULD HAVE GREAT RADIATIVE
CONDITIONS. WITH A FAIR AMOUNT OF RAIN LAST NIGHT AND LIMITED
MIXING TODAY...THERE IS A POTENTIAL FOR FOG ESPECIALLY IN THE
EAST...BUT DRY AIR MASS REALLY LIMITS THE POTENTIAL. LEFT MENTION
OUT OF THE FORECAST FOR NOW...BUT THIS IS SOMETHING FUTURE SHIFTS
WILL HAVE TO WATCH FOR. SIDED WITH LOWS JUST SLIGHTLY COOLER THAN
CONSMOS.
MONDAY APPEARS TO BE A FAIRLY PLEASANT DAY ACROSS THE AREA AS
SURFACE HIGH PRESSURE SHIFTS EAST AND RETURN FLOW INCREASES FROM
WEST TO EAST THROUGHOUT THE DAY. THE SOUTHERLY WINDS WILL HELP DRAW
MOISTURE BACK INTO THE REGION...AND THERE IS A CHANCE FOR ELEVATED
NOCTURNAL CONVECTION MONDAY NIGHT EAST OF THE JAMES.
FAIRLY STRONG SOUTHERLY FLOW IS EXPECTED ON TUESDAY AND INCREASED
WINDS OVER GUIDANCE. WILL BE SIMILAR TO THURSDAY AND FRIDAY OF LAST
WEEK WHERE CONDITIONS WERE CLOSE TO WIND ADVISORY. SHOULD ALSO BE A
WARM DAY...WITH TEMPERATURES CLIMBING WELL INTO THE 80S IN MOST
LOCATIONS.
A COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON
WEDNESDAY...THOUGH TIMING OF THE FRONT IS STILL SOMEWHAT ILL
DEFINED. GRADIENT IS MUCH STRONGER AHEAD OF THE FRONT THAN
BEHIND...AND WILL LIKELY BE ANOTHER WINDY DAY ACROSS THE EASTERN
HALF OF THE FORECAST AREA. WITH TIMING OF THE FRONT
UNCERTAIN...LEFT GUIDANCE POPS AS IS.
TIMING IN THE EXTENDED IS ALSO VERY UNCERTAIN....THOUGH ALL OF THE
SOLUTIONS ADVERTISE A WARM FRONT LIFTING NORTH THROUGH THE REGION
WITH HOT CONDITIONS TO FOLLOW. HAVE WARMED TEMPERATURES ACROSS
SOUTHERN FORECAST AREA ON SATURDAY WITH ALL MODEL SOLUTIONS
SUGGESTING THE FRONT WILL BE FOCUSED FURTHER TO THE NORTH. AS THE
WARM FRONT MOVES THROUGH THE REGION...UPPER LEVEL TROUGH IS ALSO
EXPECTED TO MAKE ITS WAY THROUGH THE REGION CREATING THE POTENTIAL
FOR SEVERE WEATHER...INCLUDING TORNADOES.
&&
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
A BAND OF RAIN WILL MOVE THROUGH SOUTHWEST MINNESOTA AND NORTHWEST
IOWA BY LATE MORNING. MAINLY MVFR CEILINGS ASSOCIATED WITH THIS RAIN
AND JUST BEHIND IT WILL ALSO EXIT THE AREA BY ABOUT NOON. AFTER THIS
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. /08
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KFSD 200839
AFDFSD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
340 AM CDT SUN MAY 20 2012
.DISCUSSION.../ISSUED AT 340 AM CDT/
BAND OF WRAP AROUND PRECIP WILL SLOWLY LIFT NORTH AND EAST
THROUGH THE FORECAST AREA THIS MORNING. SKIES WILL GRADUALLY CLEAR
BEHIND THIS FEATURE AS SURFACE HIGH PRESSURE BUILDS INTO THE AREA.
AS THE SURFACE RIDGE BUILDS INTO THE AREA...SURFACE WINDS WILL
DECREASE ACROSS THE AREA. WITH CLOUDS HANGING ACROSS THE EASTERN
HALF OF THE FORECAST AREA MUCH OF THE DAY...MIXING WILL NOT BE AS
GREAT AND WITH COOLER TEMPERATURES ALOFT...HIGHS WILL REMAIN IN THE
60S.
WITH DRY AIR MASS IN PLACE TONIGHT SHOULD HAVE GREAT RADIATIVE
CONDITIONS. WITH A FAIR AMOUNT OF RAIN LAST NIGHT AND LIMITED
MIXING TODAY...THERE IS A POTENTIAL FOR FOG ESPECIALLY IN THE
EAST...BUT DRY AIR MASS REALLY LIMITS THE POTENTIAL. LEFT MENTION
OUT OF THE FORECAST FOR NOW...BUT THIS IS SOMETHING FUTURE SHIFTS
WILL HAVE TO WATCH FOR. SIDED WITH LOWS JUST SLIGHTLY COOLER THAN
CONSMOS.
MONDAY APPEARS TO BE A FAIRLY PLEASANT DAY ACROSS THE AREA AS
SURFACE HIGH PRESSURE SHIFTS EAST AND RETURN FLOW INCREASES FROM
WEST TO EAST THROUGHOUT THE DAY. THE SOUTHERLY WINDS WILL HELP DRAW
MOISTURE BACK INTO THE REGION...AND THERE IS A CHANCE FOR ELEVATED
NOCTURNAL CONVECTION MONDAY NIGHT EAST OF THE JAMES.
FAIRLY STRONG SOUTHERLY FLOW IS EXPECTED ON TUESDAY AND INCREASED
WINDS OVER GUIDANCE. WILL BE SIMILAR TO THURSDAY AND FRIDAY OF LAST
WEEK WHERE CONDITIONS WERE CLOSE TO WIND ADVISORY. SHOULD ALSO BE A
WARM DAY...WITH TEMPERATURES CLIMBING WELL INTO THE 80S IN MOST
LOCATIONS.
A COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON
WEDNESDAY...THOUGH TIMING OF THE FRONT IS STILL SOMEWHAT ILL
DEFINED. GRADIENT IS MUCH STRONGER AHEAD OF THE FRONT THAN
BEHIND...AND WILL LIKELY BE ANOTHER WINDY DAY ACROSS THE EASTERN
HALF OF THE FORECAST AREA. WITH TIMING OF THE FRONT
UNCERTAIN...LEFT GUIDANCE POPS AS IS.
TIMING IN THE EXTENDED IS ALSO VERY UNCERTAIN....THOUGH ALL OF THE
SOLUTIONS ADVERTISE A WARM FRONT LIFTING NORTH THROUGH THE REGION
WITH HOT CONDITIONS TO FOLLOW. HAVE WARMED TEMPERATURES ACROSS
SOUTHERN FORECAST AREA ON SATURDAY WITH ALL MODEL SOLUTIONS
SUGGESTING THE FRONT WILL BE FOCUSED FURTHER TO THE NORTH. AS THE
WARM FRONT MOVES THROUGH THE REGION...UPPER LEVEL TROUGH IS ALSO
EXPECTED TO MAKE ITS WAY THROUGH THE REGION CREATING THE POTENTIAL
FOR SEVERE WEATHER...INCLUDING TORNADOES.
&&
.AVIATION.../FOR THE 00Z TAF ISSUANCE/
SHOWERS/THUNDERSTORMS FILLING IN ACROSS EASTERN NEBRASKA AS UPPER
WAVE LIFTS NORTHEAST THROUGH THE CENTRAL PLAINS. THIS PRECIPITATION
WILL LIFT NORTH-NORTHEAST ACROSS THIS FORECAST AREA THIS EVENING...
WITH MAINLY ELEVATED SHOWERS IN WESTERN AREAS...WHILE THUNDER MORE
LIKELY ALONG/EAST OF LAKE ANDES-DE SMET LINE THROUGH 04Z-06Z. MVFR
TO IFR VISIBILITY/CEILINGS LIKELY WITH THUNDERSTORMS...ESPECIALLY
EAST OF IA/MN STATE HIGHWAY 60 WHERE STRONGEST STORMS ARE MORE
LIKELY THROUGH THE EVENING. INSTABILITY AND ASSOCIATED TSRA COVERAGE
SHOULD DIMINISH AFTER 06Z. HOWEVER AREAS OF RAIN/MVFR CEILINGS COULD
LINGER EAST OF THAT LAKE ANDES-DE SMET LINE MUCH OF THE NIGHT. BY
14Z SUNDAY...IMPROVEMENT TO WIDESPREAD VFR CONDITIONS EXPECTED AS
HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
000
FXUS63 KUNR 200819
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
219 AM MDT SUN MAY 20 2012
.DISCUSSION...08Z SURFACE ANALYSIS SHOWED WEAK HIGH PRESSURE OVER
THE CWA. SHORTWAVE ENERGY NOTED OVER EASTERN MT PER WATER VAPOUR...WITH
A FEW MID CLOUDS ASSOCIATED WITH IT. UPPER RIDGE STARTING TO BUILD
OVER THE NORTHERN ROCKIES.
TODAY/TONIGHT...UPPER RIDGE BUILDS INTO MT/WY AS WEAK LEE TROUGH
DEVELOPS FROM CENTRAL MT INTO CENTRAL WY. SURFACE HIGH SHIFTS EAST
WITH WEAK RETURN FLOW ACROSS THE WEST. AROUND 250J/KG SBCAPE
DEVELOPS THIS AFTERNOON/EARLY EVENING AND MAY BE ENOUGH FOR
ISOLATED -TSRA NEAR TERRAIN/LEE TROUGH. SUBSIDENCE UNDER BUILDING
UPPER RIDGE WILL KEEP COVERAGE LIMITED. TEMPERATURES NEAR GUIDANCE.
MONDAY/MONDAY NIGHT...UPPER/THERMAL RIDGE CONTINUES TO BUILD OVER
CWA. SOUTHERLY LOW LEVEL JET UP TO 40KTS WILL SHIFT FROM WESTERN
SD INTO EASTERN SD...AND THEN REDEVELOP OVER NORTHEAST WY/WESTERN
SD MONDAY NIGHT. CAPPING BECOMES MORE PRONOUNCED...BUT NARROW AXIS
OF 0.5-1KJ/KG SBCAPE MAY BE ENOUGH FOR A FEW -TSRA OVER SOUTH
CENTRAL SD DURING PEAK HEATING LATE MONDAY AFTERNOON/EARLY
EVENING. TEMPERATURES WILL BE NOTICEABLY WARMER.
TUESDAY/TUESDAY NIGHT...UPPER RIDGE SHIFTS EAST AS UPPER TROUGH
SHIFTS INTO THE NORTHERN PLAINS WITH UPPER LOW OVER SOUTHERN SK.
SEVERAL SHORTWAVES WILL MOVE THROUGH THE CWA. COOL FRONT MOVES
THROUGH LATE. INSTABILITY/SHEAR ALONG FRONT WILL LIKELY BE
SUFFICIENT FOR A FEW SEVERE STORMS...MAINLY OVER EASTERN PORTIONS
OF THE CWA. BEHIND FRONT...MODERATE BAND OF 850-700MB
FRONTOGENESIS WILL BRING BETTER CHANCES FOR POST FRONTAL
PRECIPITATION. KEPT POPS IN THE CHANCE CATEGORY FOR NOW...BUT
LIKELIES MAY BE NEEDED. TUESDAY SHOULD BE THE WARMEST DAY WITH
700MB THERMAL RIDGE PEAKING AROUND 12C.
EXTENDED...AN UPPER LEVEL SYSTEM WILL PASS NORTH OF THE AREA DURING
THE MIDDLE AND LATTER PART OF THE WEEK. SOUTHWESTERLY FLOW ALOFT
WILL DEVELOP TO THE SOUTH OF THE SYSTEM OVER THE ROCKIES AND INTO
THE PLAINS. THIS PATTERN WILL LIKELY BRING A SERIES OF UPPER LEVEL
DISTURBANCES ACROSS THE AREA...WITH DAILY CHANCES FOR SHOWERS AND A
FEW STORMS FROM WEDNESDAY THROUGH THE END OF THE WEEK. TEMPERATURES
WILL GENERALLY BE NEAR OR SLIGHTLY BELOW AVERAGE LATE THIS WEEK...
WITH A WARMUP LIKELY OVER THE WEEKEND.
&&
.AVIATION...12Z TAFS
VFR CONDITIONS ARE GENERALLY EXPECTED TODAY INTO TONIGHT...WITH
SOUTHEASTERLY WINDS DEVELOPING OVER THE AREA. AN ISOLATED
THUNDERSTORM OR TWO WILL BE POSSIBLE ACROSS NORTHEASTERN WY AND
THE BLACK HILLS THIS AFTERNOON AND EARLY EVENING.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...HELGESON
LONG TERM....26
AVIATION...26
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