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000
FXAK67 PAJK 232251
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
251 PM AKDT WED APR 23 2014

.SHORT TERM...SATELLITE IMAGERY THIS AFTERNOON SHOWING A WEAK
BUT RATHER COMPLEX INTERACTION BETWEEN LOW PRESSURE OVER THE
NORTHERN PANHANDLE, HIGH PRESSURE OVER THE AK GULF AND A
DEVELOPING INVERTED TROUGH OVER THE SOUTHERN PANHANDLE EXTENDING
FROM A LOW MOVING TOWARDS THE COAST OF WASHINGTON. THE NORTHER
LOW THAT PRODUCED SHOWERS OVER THE PANHANDLE LAST NIGHT IS
TRACKING NORTHWESTWARD WITH DIMINISHING SHOWERS AND CLEARING
SKIES BEHIND. SOME MORE STRATIFORM CLOUDS OVER THE AK GULF UNDER
THE HIGH PRESSURE RIDGE BUT WITH COLDER AIR MOVING IN FROM THE
SOUTH ALREADY SEEING MORE CONVECTIVE TYPE CLOUDS IN THE SOUTHERN
GULF. THE DEVELOPING INVERTED TROUGH WILL ENHANCE CLEARING OVER
THE SOUTHERN REGIONS WITH SUNNY SKIES EXPECTED FOR THURSDAY.
NORTHERN PANHANDLE WILL STILL HAVE SOME LINGERING REMNANTS OF THE
CURRENT SHORT WAVE FOR THURSDAY, ENOUGH TO KEEP SOME CLOUDS IN
THE FORECAST WITH ISOLATED SHOWERS FOR THE FAR NORTHERN
PANHANDLE. TEMPERATURES DICTATED BY CLOUD COVER TONIGHT AND
TOMORROW WITH THE NORTHERN REGIONS THAT REMAIN CLOUDY SHOWING
SMALLER DIURNAL RANGE WHILE THE SOUTHERN AREAS WHERE SKIES WILL
BE CLEAR WILL HAVE LOWER OVERNIGHT TEMPS AND HIGHS RISING INTO
THE MID TO UPPER 50S ON THURSDAY.

 SOUTHERLY WIND FLOW WILL SHIFT TO THE NORTH AS THE INVERTED
TROUGH DEVELOPS AND SHIFTS THE PRESSURE GRADIENT. WINDS OVER THE
SOUTHERN PANHANDLE AND INNER CHANNELS WILL INCREASE TO THE 15 TO
20 MPH RANGE WITH WITH THIS ADVANCING FEATURE BUT THE WEAK
GRADIENT FOR THE CENTRAL AND NORTHERN REGIONS WILL KEEP WINDS
LESS THAN 15 MPH. WAVES IN THE AK GULF WILL INCREASE THROUGH
THURSDAY FROM SOUTHWEST SWELL PRODUCED BY A LOW IN THE FAR
WESTERN GULF.

 MINOR DIFFERENCES BETWEEN MODELS TODAY. KEPT WITH THE ECMWF DUE
TO ITS CONSISTENCY AND BLENDED SOME 12Z ECMWF WITH INHERITED
GRIDS FOR PRESS WITH A BLEND OF NAM/ECMWF FOR POP. OVERALL
CHANGES WERE MINOR. FORECAST CONFIDENCE IS ABOVE AVERAGE.

&&

.LONG TERM...MODELS REMAIN IN GENERAL AGREEMENT THROUGH THE
WEEKEND WITH DECREASING CLOUDS AND CLEARING PROCESS EXPANDING
NORTHWARD ACROSS SOUTHEAST ALASKA THROUGH LATE FRIDAY. A WEAK
INVERTED TROUGH OF LOW PRESSURE MOVING OVER THE SOUTHERN
PANHANDLE FRIDAY EVENING WILL INCREASE CLOUDS AGAIN WITH
SCATTERED SHOWERS...THEN SPREAD NORTH THROUGH THE WEEKEND.
REFRESHED THE INHERITED FORECAST PACKAGE WITH THE 12Z RUN ECMWF
FOR ITS GOOD CONSISTENCY. THE RESULTANT CHANGES WERE SMALL AND
MADE A FEW TOUCHES TO FINE TUNE OVER PRESSURE AND WIND FIELDS.

 ISOLATED SHOWERS OVER THE NORTHERN AREAS THURSDAY EVENING WILL
BE ENDING...FOLLOWED BY DRY WEATHER WITH DECREASING CLOUDS AND A
BIT WARMING TREND. NO SIGNIFICANT WINDS ARE EXPECTED...EXCEPT ROUGH
SMALL CRAFT LEVEL SEAS CONTINUING OVER THE OUTER WATERS DUE TO
LONG PERIODS SOUTHWEST TO WEST SWELLS FROM THE OPEN SEAS.
INCREASING CLOUDS AGAIN ACROSS THE SOUTHERN AREAS WITH INCREASING
POPS OVER THE WEEKEND WILL COOL DOWN TEMPERATURES A BIT.

 MODEL SPREADS BECOME LARGER EARLY NEXT WEEK AS AN UPPER LEVEL
SHORTWAVE TROUGH MOVES ACROSS THE GULF...BUT THE MAIN JET STREAM
WILL REMAIN SOUTH OF THE AREA. BLENDED THE 12Z RUN WPC SOLUTIONS
OF SUPER BLENDING ENSEMBLE APPROACH FOR THE REMAINING LONG TERM
FORECAST PERIODS. MAIN JET STREAM ASSOCIATED WITH THE NEXT DEEP
SHARP UPPER LEVEL SHORTWAVE TROUGH WILL CURVE SOUTHWARD OVER THE
WESTERN GULF INTO NORTH PACIFIC...AND TURN TO NORTH ACROSS THE
EASTERN GULF AND THE PANHANDLE BY MID WEEK. AS THE UPPER LEVEL
PATTERN SHIFTS TO AMPLIFIED MERIDIONAL...UPPER LEVEL DYNAMICS WILL
BRING SOUTHEAST ALASKA A SERIES OF DISTURBANCES ORIGINATING IN
SUB-TROPICS. THIS CAN BE TRANSLATED FOR A SIGNIFICANT WARMING
NEXT WEEK. DAYTIME TEMPERATURES MAY REACH TO THE LOWER 60S OVER
THE SOUTHERN PANHANDLE.

 DUE TO INCREASED UNCERTAINTIES...PREDICTABLE SURFACE FEATURES
ARE DIFFICULT TO PIN POINT BUT A SURFACE LOW PRESSURE SYSTEM
MOVING ACROSS THE GULF IS EXPECTED TO BECOME ACTIVE AS IT MOVES
CLOSER TO SOUTHEAST ALASKA AND INCREASE EASTERLY PRESSURE GRADIENT
TO PRODUCE NEAR SMALL CRAFT LEVEL WINDS AND CONTINUED ROUGH
COMBINED SEAS ACROSS THE OUTER WATERS. IN GENERAL...MAINTAINED
INCREASING CLOUDS AND POPS MAINLY FOCUSING OVER THE SOUTHERN HALF
OF THE PANHANDLE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041>043.

&&

$$

PRB/AHN









000
FXAK67 PAJK 231320
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
520 AM AKDT WED APR 23 2014

.SHORT TERM...UPPER TROF OVER SRN SE AK WILL DRIFT N INTO THE
CENTRAL AREA TONIGHT. VORT MAX OVER THE NRN PANHANDLE WILL DRIFT
WNW INTO THE NE GULF BY LATE THIS AFTERNOON. SFC LOW OVER NRN SE
AK WILL REACH THE FAR NE GULF BY LATE THIS AFTERNOON. INVERTED
TROF WILL DEVELOP NW INTO THE SRN PANHANDLE TONIGHT. USED MAINLY
THE 00Z ECMWF AS IT HAD BEST HANDLE ON THESE FEATURES.

MAIN FORECAST ISSUES WILL BE PRECIP POTENTIAL/CHARACTER AND HOW
QUICKLY ANY CLEARING WILL OCCUR. RIGHT NOW WITH SHORTWAVE OVER THE
NRN PANHANDLE...BROKEN AREA OF PRECIP IS OCCURRING FROM PAGN NWD
TO PAHN. THINK THIS AREA OF PRECIP WILL SHIFT WNW WITH THE
SHORTWAVE WITH A DIMINISHING TREND FROM THE E-SE LATER THIS
AFTERNOON AND TONIGHT. THINK SOME PRECIP WILL REACH THE PAYA AREA
BY LATE THIS AFTERNOON OR EARLY THIS EVENING AS VORT MAX MOVES
INTO THAT AREA. MODEL SOUNDINGS SHOW A WEAK FRONTAL LAYER IN THE
MID-LEVELS OVER THE NRN HALF OF THE AREA...SO WENT WITH PERIODS OF
RAIN THERE. WILL PROBABLY TRANSITION TO SCT SHOWERS TONIGHT BUT
FOR NOW JUST INDICATED DIMINISHING TREND IN STEADIER PRECIP FOR
SIMPLICITY. OVER THE S...WITH COLDER AIR ALOFT...THINK SOME
SHOWERS WILL POP UP WITH THE DAYTIME HEATING OVER AND NEAR THE
MTNS...SO GENERALLY GOING WITH ISO/SCT SHOWERS OVER THE S...WITH
THE BEST THREAT IN ZONE 26. THESE SHOWERS SHOULD DIMINISH THIS
EVENING WITH LOSS OF DAYTIME HEATING.

AS UPPER TROF SHIFTS NWD AND LOW LEVEL N-NW FLOW INCREASES WITH
THE DEVELOPING INVERTED TROF...THINK SRN AREA WILL SEE DECENT
AMOUNT OF CLEARING ESPECIALLY TONIGHT. THERE MAY BE LARGER BREAKS
IN THE CLOUDS THIS AFTERNOON OVER THE FAR SRN AREA HOWEVER. THIS
PART OF THE FORECAST IS TRICKY THOUGH DUE TO SOME MODEL
UNCERTAINTY HANDLING SMALL SCALE FEATURES IN LOW LEVELS THERE.

OTHERWISE...WITH FAIRLY WEAK PRESSURE GRADIENTS WINDS WILL BE
RATHER LIGHT...GENERALLY UP TO 15 KT. THERE ARE SOME LOCAL
ENHANCEMENTS TO THE WINDS ALONG THE OUTER COAST WITH WEAK TIP JETS
THERE BUT THIS WILL WEAKEN TODAY. A SYSTEM CURRENTLY WELL TO THE
SW OF THE AREA WILL SEND IN INCREASING SWLY SWELLS INTO THE ERN
GULF THRU TONIGHT...BUT CURRENTLY EXPECT THEM TO REMAIN BELOW SCA
LEVELS FOR THE GULF COASTAL WATERS.

&&

.LONG TERM...A COMPACT MIDLEVEL SHORTWAVE TROUGH WILL BE THE
PRIMARY WEATHER MAKER AT THE START OF THE LONG TERM PERIOD. THIS
FEATURE WILL BE LOCATED OVER THE NRN CWA THU AFTERNOON...AND THEN
DEPART NWD INTO THE YUKON TERRITORY BY FRI MORNING. THE UPPER
DISTURBANCE WILL YIELD CLOUDY SKIES AND SHOWERS FOR NRN
AREAS...WHILE SKIES ARE EXPECTED TO BEGIN CLEARING OVER THE SRN
PANHANDLE. AFTERNOON SUNSHINE COMBINED WITH WARMING 850 MB
TEMPERATURES SHOULD AID IN BOOSTING THU HIGHS INTO THE MID TO
UPPER 50S FROM ROUGHLY JUNEAU SWD. DRY MIDLEVEL AIR WILL THEN
SPREAD NWD INTO THE CNTRL/NRN PANHANDLE ON FRI. THIS WILL SUPPORT
PLEASANT AFTERNOON CONDITIONS...WITH TEMPERATURES IN THE LOW TO
MID 50S...AND A WEAK PRESSURE GRADIENT RESULTING IN LIGHT WINDS.
THE LIGHT PRESSURE GRADIENT AND MILD TEMPERATURES MAY ALSO SUPPORT
SEA BREEZE DEVELOPMENT FOR LOCATIONS SUCH AS
JUNEAU...HAINES/SKAGWAY...AND GUSTAVUS.

MEANWHILE...A WEAK UPPER DISTURBANCE LOCATED NEAR COASTAL B.C. WILL
BE ENTRAINED NWD INTO A BROAD AREA OF TROUGHING OCCURRING OVER THE
WRN/CNTRL GULF FRI NIGHT. THIS WILL HERALD THE RETURN OF CLOUDS AND
PRECIPITATION FOR SE AK BEGINNING THIS WEEKEND THROUGH THE
REMAINDER OF THE LONG TERM PERIOD. IN ADDITION...SURFACE LOW
PRESSURE WILL DEEPEN OVER THE GULF...WHICH WILL LEAD TO A
TIGHTENING GRADIENT OVER THE OUTER WATERS BY SAT...INCREASING
ESELY WINDS...AND BUILDING SEAS.

THE 00Z/23 MODEL GUIDANCE WAS IN GENERAL AGREEMENT THROUGH THE
WEEKEND...WITH FORECAST CONFIDENCE ABOVE AVERAGE. MODEL SPREAD
THEN INCREASES WITH THE EVOLUTION OF THE GULF CYCLONE MON THROUGH
WED...AND FORECAST CONFIDENCE SUBSEQUENTLY DECREASES. MINOR
ADJUSTMENTS TO PRESSURE/WINDS /USING 00Z ECMWF BLENDED IN WITH
PREVIOUS FORECAST/...TEMPERATURES...AND POP/QPF WERE MADE THROUGH
SUN...WITH VERY LITTLE CHANGE INTRODUCED TO THE FORECAST FOR MON
AND BEYOND.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.

&&

$$

RWT/GARNER








000
FXAK67 PAJK 222245
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
245 PM AKDT TUE APR 22 2014

.SHORT TERM...UPPER LOW REMAINS OVER THE AK GULF AND PANHANDLE
THROUGH WEDNESDAY. AT THE SURFACE WEAK ARE OF HIGH PRESSURE OVER
THE AK GULF WITH AN INVERTED TROUGH OVER THE PANHANDLE PRODUCING
WEAK GRADIENT. AN SHORT WAVE MOVING IN FROM BRITISH COLUMBIA INTO
THE SOUTHEASTERN GULF THIS AFTERNOON WILL TRACK NORTHWARD WHILE
IT EXTENDS TO THE WEST BY WEDNESDAY MORNING REACHING THE
NORTHEASTERN PANHANDLE BY WEDNESDAY AFTERNOON.

 SCATTERED RAIN SHOWERS AND INCREASING CLOUD COVER WILL EXTEND
NORTHWARD WITH THE ADVANCING SHORT WAVES FOLLOWED BY SOME
CLEARING SKIES OVER THE SOUTHERN PANHANDLE LATE TONIGHT. FOG
DEVELOPMENT IS POSSIBLE OVER THE SOUTHERN REGIONS LATE TONIGHT
DUE TO THESE CLEARING SKIES. NOT MUCH IN THE WAVE OF PRECIP
ACCUMULATION FROM THIS WEAK WAVE. THERE WILL BE LESS DIURNAL
TEMPERATURE RANGE WITH THE INCREASED CLOUD COVER KEEPING
OVERNIGHT LOWS A BIT WARMER TONIGHT AND HIGHS SLIGHTLY LOWER FOR
TOMORROW.

 ISSUE FOR WINDS TODAY IS THE NORTHERLY AND WESTERLY WIND FLOW V
SEA BREEZE DEVELOPMENT FOR SOME LOCATIONS. THE JUNEAU WESTERLY
SEA BREEZE IS IN PHASE WITH THE FLOW PATTERN WHILE SKAGWAY
SOUTHERLY SEA BREEZE IS IN OPPOSITION. AT THIS TIME THE HIGH THIN
STRATUS OVER THE NORTHERN PANHANDLE WAS NOT ENOUGH TO LIMIT THE
AFTERNOON SOUTHERLY SEA BREEZE DEVELOPMENT THERE. WINDS WILL
SHIFT AS THE SHORT WAVES TRACK NORTHWARD TONIGHT INTO WEDNESDAY,
BUT OVERALL SPEEDS WILL BE LESS THAN 15 KTS. WITH INCREASED CLOUD
COVER FOR WEDNESDAY NOT EXPECTING ANY SEA BREEZE.

 MAIN MODEL DIFFERENCES WERE WITH THE TIMING OF THE BRITISH
COLUMBIA WAVE. NAM WAS THE SLOWEST AND MORE OF AN OUTLIER
COMPARED TO THE ECMWF/GFS/GEM. ECMWF WAS MAINTAINED GOOD RUN TO
RUN CONSISTENCY SO REMAINED MODEL OF CHOICE. THERE WERE ONLY
MINOR DIFFERENCES WITH THE 12Z MODEL RUNS SO CHANGES TO THE
INHERITED FORECAST PACKAGE WERE LIMITED. FORECAST CONFIDENCE IS
ABOVE AVERAGE.

&&

.LONG TERM...MODELS ARE IN GENERAL AGREEMENT THROUGH FRIDAY
EVENING WITH A WEAKENING UPPER LEVEL SHORTWAVE TROUGH MOVING
NORTHWARD ACROSS SOUTHEAST ALASKA THROUGH LATE THURSDAY...FOLLOWED
BY GENERALLY DRY AIR MASS EXPANDS FROM THE SOUTH. A WEAK INVERTED
TROUGH OF LOW PRESSURE WILL MOVE OVER THE SOUTHERN PANHANDLE LATE
LATE THURSDAY NIGHT INTO FRIDAY...BRINGING CLOUDS AND SCATTERED
SHOWERS. REFRESHED THE INHERITED FORECAST PACKAGE WITH THE 12Z RUN
ECMWF AND NAM. THE RESULTANT CHANGES ARE SMALL AND MOSTLY COSMETIC
TOUCHES OVER PRESSURE AND WIND FIELDS.

 SCATTERED SHOWERS ACROSS THE NORTHERN AREA WEDNESDAY NIGHT WILL
BECOME ISOLATED ON THURSDAY AS THE DRY WEATHER CONTINUES TO
EXPANDS NORTHWARD. DECREASING CLOUDS AND WARMING TREND WILL GRANT
THE PANHANDLE PLEASANT WEATHER ON THURSDAY. RELAXED PRESSURE
GRADIENTS WILL PROMPT NO SIGNIFICANT WINDS ACROSS SOUTHEAST
ALASKA. INCREASING CLOUDS AGAIN OVER THE SOUTHERN AREAS WITH
SCATTERED SHOWERS WILL COOL DOWN TEMPERATURES A BIT ON FRIDAY.

 MODEL SPREADS BECOME LARGER OVER THE WEEKEND INTO NEXT WEEK AS
ANOTHER UPPER LEVEL SHORTWAVE TROUGH TRIES TO MOVE NORTHEASTWARD
ACROSS THE GULF...BUT THE MAIN JET STREAM WILL REMAIN SOUTH OF THE
AREA. BLENDED THE 12Z RUN WPC SOLUTIONS OF ECMWF ENSEMBLE APPROACH
FOR THE REMAINING LONG TERM FORECAST PERIODS.

 FOR EARLY NEXT WEEK...THE 250 MB JET STREAM ASSOCIATED WITH THE
NEXT DEEP SHARP UPPER LEVEL SHORTWAVE TROUGH WILL CURVE SOUTHWARD
OVER THE WESTERN GULF AND TURN TO NORTH ACROSS THE EASTERN GULF
AND THE PANHANDLE TUESDAY AND WEDNESDAY. AS THE UPPER LEVEL
PATTERN SHIFTS FROM NEAR ZONAL FLOW TO MERIDIONAL...UPPER LEVEL
DYNAMICS WILL BRING SOUTHEAST ALASKA A SERIES OF DISTURBANCES
ORIGINATING IN SUB-TROPICS. THIS CAN BE TRANSLATED FOR A
SIGNIFICANT WARMING NEXT WEEK. DUE TO INCREASED
UNCERTAINTIES...PREDICTABLE SURFACE FEATURES ARE DIFFICULT TO PIN
POINT BUT INCREASED CLOUDS AND POPS MAINLY OVER THE SOUTHERN HALF
OF THE PANHANDLE.


&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ042.

&&

$$

PRB/AHN










000
FXAK67 PAJK 221314
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
514 AM AKDT TUE APR 22 2014

.SHORT TERM...RATHER QUIET ACROSS THE AREA THIS MORNING WITH
SOME AREAS OF HIGH CLOUDS AND PATCHY FOG. THE HIGH CLOUDS OVER
THE NORTHERN PANHANDLE ARE FROM A WEAKENING UPPER TROUGH THAT IS
DROPPING SW OUT OF THE YUKON WHILE THE HIGH CLOUDS OVER THE SOUTH
ARE FROM THE LEADING EDGE OF ANOTHER WEAK UPPER TROUGH THAT WILL
BE LIFTING NW OVER THE PANHANDLE THROUGH TONIGHT. IN ADDITION
NIGHTTIME MICROPHYSICS IMAGES FROM MODIS AND VIIRS REVEAL SOME
PATCHY FOG AND LOW CLOUDS AROUND PRINCE OF WALES ISLAND AND
YAKUTAT. THE FOG AROUND PRINCE OF WALES HAS PROVED TO BE DENSE IN
SOME PLACES AS HYDABURG AND KLAWOCK BOTH HAVE HAD VISIBILITIES OF
A QUARTER MILE AT TIMES THIS MORNING. AS SUCH A DENSE FOG
ADVISORY WAS ISSUED FOR HYDABURG AND KLAWOCK AREAS UNTIL 8 AM
WHEN THE FOG IS EXPECTED TO BURN OFF AS THE SUN RISES.

THE WEATHER TODAY IS EXPECTED TO BE RATHER NICE FOR MOST OF THE
PANHANDLE. MOSTLY CLEAR TO PARTLY CLOUDY SKIES ARE EXPECTED WITH
HIGH INTO THE UPPER 40 TO MID 50S FOR MOST PLACES. WINDS ARE ALSO
EXPECTED TO BE LIGHT THOUGH SOME HIGHER WINDS FROM SEA BREEZES
COULD CROP UP THIS AFTERNOON. THE EXCEPTION IS THE SOUTHERN
PANHANDLE WHERE CLOUDS WILL BE INCREASING TODAY AS THE UPPER
TROUGH OVER BRITISH COLUMBIA STARTS TO MOVE IN.

INTO TONIGHT, CLOUDS WILL INCREASE FOR MOST AREAS AS THE UPPER
TROUGH MOVES NW. SHOWERS WILL ALSO START TO BECOME A THREAT FROM
SOUTH TO NORTH TONIGHT. THE SOUTHERN PANHANDLE WILL HAVE THE BEST
CHANCE OF RAIN LATE THIS AFTERNOON AND EVENING WHILE THE NORTH
WILL SEE THE BEST CHANCE THIS EVENING INTO THE LATE NIGHT. IT WILL
NOT QUITE GET TO YAKUTAT BY LATE TONIGHT. RAINFALL WILL BE RATHER
LIGHT WITH HIGHER AMOUNTS OBSERVED THE CLOSER TO THE COAST
MOUNTAINS YOU ARE DUE TO DOWNSLOPING FLOW. THE SOUTHERN PANHANDLE
MAY START CLEARING AND DRYING OUT LATER TONIGHT WHICH COULD LEAD
TO FOG FORMATION AGAIN THERE. AS SUCH I HAVE INSERTED SOME PATCHY
FOG INTO THE FORECAST FOR LATE TONIGHT FOR THE SOUTH.

SHORT RANGE MODELS WERE IN GOOD AGREEMENT THOUGH THERE WERE SOME
DETAIL DIFFERENCES FOR THE INCOMING TROUGH. PRIMARILY WENT WITH
THE NAM AND SOME ECMWF FOR OVERALL UPDATES AS BOTH LOOKED TO HAVE
MORE OF THE CURRENT DETAILS. OVERALL CHANGES WERE MINOR.

&&

.LONG TERM...MODEL GUIDANCE CONTINUES TO COME INTO BETTER
AGREEMENT WITH THE TRACK AND AMPLITUDE OF A COMPACT MIDLEVEL
SHORTWAVE TROUGH MOVING N ACROSS THE PANHANDLE WED MORNING
THROUGH THU AFTERNOON. MODEST ASCENT/MOISTENING ASSOCIATED WITH
THIS FEATURE COMBINED WITH A COLD MIDLEVEL AIRMASS /-30 TO -35C
AT H5/ WILL SUPPORT SCATTERED RAIN SHOWERS WED AFTERNOON OVER THE
NRN HALF OF THE CWA...THEN BECOMING ISOLATED ON THU. MEANWHILE...A
DRY MIDLEVEL AIRMASS IS FORECAST TO SPREAD ACROSS THE SRN HALF OF
THE CWA THU MORNING AND AFTERNOON AS THE PREVIOUSLY MENTIONED
DISTURBANCE EXITS N. THE COMBINATION OF DECREASING CLOUDS AND
INCREASING 850 MB TEMPERATURES PROMPTED A BUMP UP IN THU DAYTIME
HIGHS FOR SRN AREAS...WITH VALUES EXPECTED TO REACH THE MID TO
UPPER 50S.

THE NEXT IN A SERIES OF SMALL-SCALE UPPER WAVES IS THEN FORECAST
TO MOVE N INTO THE CWA FRI AND SAT. CONFIDENCE IS NOT HIGH IN THE
EXACT EVOLUTION OF THIS NEXT FEATURE...BUT AN INCREASE IN CLOUDS
AND LOW PRECIPITATION CHANCES APPEARS PLAUSIBLE. NUDGED FRI HIGH
TEMPERATURES DOWN FROM THOSE EXPECTED ON THU DUE TO THE INCREASE
IN CLOUD COVER. IN FACT...LITTLE AIRMASS CHANGE IS FORECAST FRI
THROUGH TUE. THUS...HIGHS IN THE LOW TO MID 50S AND LOWS IN THE
30S ARE MAINTAINED DURING THE REMAINDER OF THE LONG-TERM.
ENSEMBLE AND DETERMINISTIC MODEL GUIDANCE SHOWS A SYNOPTIC-SCALE
TROUGH WILL BECOME POSITIONED OVER THE GULF AND NERN PAC BY THE
START OF THE NEXT WORK WEEK. THOUGH PREDICTABILITY IS FAIRLY HIGH
WITH THIS LARGE TROUGH...CONFIDENCE IS LOW WITH REGARD TO EMBEDDED
IMPULSES PINWHEELING NWD FROM THE TROUGH INTO SE AK. FOR THIS
REASON...WPC GUIDANCE BASED ON THE ENSEMBLE ECMWF WAS PRIMARILY
USED FOR THE LATER HALF OF THE EXTENDED.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...DENSE FOG ADVISORY UNTIL 8 AM AKDT THIS MORNING FOR AKZ027.
MARINE...SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041>043-051.

&&

$$

EAL/GARNER







000
FXAK67 PAJK 212350
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
350 PM AKDT MON APR 21 2014

.SHORT TERM...SATELLITE IMAGERY THIS AFTERNOON SHOWING REMNANTS
OF A SURFACE LOW IN THE EASTERN GULF THAT WILL CONTINUE TO WEAKEN
AS IT PULLS OFF THE THE WEST THROUGH MONDAY EVENING. A MID LEVEL
LOW ROTATING OVER THE AK GULF AND PANHANDLE WILL KEEP 500 MB
VORTICITY OVER THE REGION. SOUTHEASTERLY FLOW OVER THE PANHANDLE
AND EASTERN GULF ALONG WITH THE 500 MB VORTICITY PRODUCING
ISOLATED TO SCATTERED SHOWER ACTIVITY, MAINLY OVER THE SOUTHERN
AND COASTAL PANHANDLE. ELSEWHERE THE MID LEVEL LOW MOSTLY
PRODUCING SOME SCATTERED CLOUD COVER, BUT WITH PLENTY OF CLEAR
BREAKS WHICH INCREASED DAY TIME HEATING WITH TEMPS RISING INTO
THE MID 50S. THE HEATING AND UNSTABLE RISING AIR MASS PRODUCING
AFTERNOON FAIR WEATHER CUMULUS CLOUDS OVER THE MOUNTAINS. AS THE
LOW PULLS AWAY WEAK SURFACE HIGH WILL MOVE OVER THE PANHANDLE
TONIGHT THEN INTO THE NORTHEASTERN AK GULF TUE. AN INVERTED
TROUGH WILL THEN DEVELOP OVER THE PANHANDLE ON TUE WITH ANOTHER
WEAK WAVE OVER BRITISH COLUMBIA JUST REACHING THE SOUTHEASTERN
PANHANDLE TUESDAY AFTERNOON. GENERAL SOUTHEASTERLY WIND FLOW WITH
SOME LOCATIONS GETTING WEAK SEA BREEZE. AS THE GULF LOW MOVES OFF
AND THE INVERTED TROUGH MOVES IN WINDS WILL SHIFT TO THE NORTH
THIS EVENING. THE NORTHERN PANHANDLE AND INNER CHANNELS WILL
REMAIN NORTHERLY DUE TO THE WEAK GRADIENT BUT THERE WILL BE
SHIFTS TO THE SOUTH TUESDAY FOR CENTRAL AND SOUTHERN LOCATIONS AS
THE WEAK BRITISH COLUMBIA WAVE MOVES IN. OVERALL WINDS WILL BE
LESS THAN 15 MPH WITH WEAK GRADIENTS AND LIGHT 850 MB WINDS. ANY
SEE SEA BREEZE DEVELOPMENT IN THE AFTERNOON, WITH THE EXCEPTION
OF THE NORTHERN LOCATIONS WHERE THE PRESSURE GRADIENT MAY BE JUST
ENOUGH TO KEEP NORTHERLY FLOW IN PLACE EVEN WITH DAY TIME
HEATING. SOME UNCERTAINTY WITH WIND DIRECTIONS DUE TO SUCH WEAK
FORCING MECHANISMS AND WHICH LOCAL EFFECTS WILL WIN OUT. EVEN
THOUGH THERE ARE CLEARING SKIES TONIGHT THINK THOSE LOCATIONS
THAT RECEIVED PRECIP WITH EITHER DRY OUT THIS EVENING TO LIMIT
MOISTURE AVAILABLE FOR FOG FORMATION, AND THE UNSTABLE AIR MASS
WILL KEEP ENOUGH MIXING TO LIMIT AND FOR DEVELOPMENT.

 MODEL WERE IN GOOD AGREEMENT FOR GENERAL SYNOPTIC PATTERN BUT
THERE WERE DIFFERENCES WITH THE WAVE MOVING IN TUESDAY AFTERNOON
AND OTHER WEAK SURFACE FEATURES. LEANED MORE TOWARD AN ECMWF/NAM
BLEND WITH SOME GFS ADDED FOR POP FIELDS. CHANGES WERE MINOR,
MOSTLY DEALING WITH LOCAL WIND EFFECTS WHERE SYNOPTIC FLOW WAS
EITHER ENHANCED BY SEA BREEZE DEVELOPMENT OR OVER CAME IT.
FORECAST CONFIDENCE IS ABOVE AVERAGE.

.LONG TERM...THERE STILL IS SOME DIFFERENCES WITH THE UPPER LEVEL
SHORTWAVE THAT WILL MOVE OVER THE NORTHERN HALF OF THE AREA
TUESDAY NIGHT INTO WED. THE NEWER MODEL RUNS THOUGH ARE STARTING TO
SHOW SOME AGREEMENT THAT SOMETHING WILL MOVE OVER THE AREA AND
PRODUCE SOME SCATTERED SHOWERS. BESIDES THIS UPPER LEVEL FEATURE
THE PANHANDLE WILL SEE A VERY NICE SPRING WEEK WITH GENERALLY
LIGHT WINDS AND RELATIVELY DRY CONDITIONS. TEMPS WILL REMAIN TO
ABOVE NEAR NORMAL FOR THIS TIME OF YEAR FOR HIGHS WITH LOW NEAR OR
BELOW NORMAL WITH BREAKS IN THE CLOUD COVER.

THE SYNOPTIC PATTERN WILL KEEP THE STORM TRACK TO THE SOUTH WITH
THE JET REMAINING AROUND 50N. THE JET WILL BEING TO SLIDE BACK
NORTH THROUGH THE WEEKEND INTO NEXT WEEK AND WITH THAT START TO
TRACK WEATHER SYSTEMS INTO THE GULF. SO WITH THAT SAID POPS START
TO INCREASE FROM SOUTH TO NORTH ON SATURDAY AND SUNDAY BUT THERE
IS LOW CONFIDENCE ON THE TIMING OF THE PRECIP AS THE EC IS DRIER
THAN THE GFS. THE EC ENSEMBLE MEAN WAS THE PREFERRED MODEL FOR THE
EXTEND SO THERE IS JUST A CHANCE OVER THE NORTH AND LIKELY OVER
THE SOUTH AT THIS TIME.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ022-043-051.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041-042-052.

&&

$$

PRB/ABJ







000
FXAK67 PAJK 211344
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
544 AM AKDT MON APR 21 2014

.SHORT TERM...DEJA VU WITH ANOTHER TROUGH AND ITS ASSOCIATED
BOUNDARY OR FRONT MOVING NORTHWARD FROM THE SOUTHERN INTO THE
CENTRAL AND POSSIBLY THE NORTHERN PANHANDLE. BOUNDARY LAYER WINDS
SEEM TO BE WEAKER WITH THIS ONE BUT THIS DOES NOT MEAN IT DID NOT
STRIKE WITH A PUNCH. LINCOLN ROCK GUSTED TO NEAR HURRICANE FORCE
IN CLARENCE STRAIT, AND THE STRONG WINDS FOR THE SOUTHERN INSIDE
CHANNELS DID VERIFY. HYDABURG SHOWED SOME STRONG WINDS, AS WELL.
SITKA MAY SEE SOME HIGHER GUSTS THIS MORNING AS WELL, BUT THE
TROUGH IS WEAKENING AS IT LIFTS NORTHWEST BACK OUT INTO THE GULF.
SO WE HAVE NO STRONG WIND HEADLINES THIS MORNING...EVEN IN THE
FRONT`S PATH SUCH AS BARANOF ISLAND. NEITHER DID WE EXTEND THE
SOUTHERLIES FARTHER NORTH THAN GLACIER BAY/NORTHERN
CHATHAM/STEPHENS PASSAGE. WE DO NOT THINK THEY WILL BE NEARLY AS
STRONG AS YESTERDAY EITHER.

POP FIELDS WERE DIFFICULT TO READ. I WOULD EXPECT A DIMINISHING
TREND IN THE AFTERNOON AS THE SYSTEM PULLS AWAY FROM THE COAST,
BUT SOME DIVERGENCE IN MID-LEVEL FLOW THIS AFTERNOON WITH EC GOING
A BIT MORE SOUTHEAST THAN GFS/NAM. ALSO...AM CONCERNED ABOUT A
COLD POOL OF AIR MOVING NORTHWARD INTO THE PANHANDLE BEHIND THE
TROUGH. A THUNDERSTORM STRIKE WAS DETECTED IN SOME OF THE
CONVECTION MOVING UP FROM THE SOUTH. WE PLACED A SLIGHT CHANCE OF
THUNDERSTORMS FOR MARINE ZONES 41 AND 42 FOR THIS AFTERNOON AS
THIS AREA LIFTS NORTHWARD. BUT ALSO, KEPT THINGS MOSTLY CLOUDY FOR
MUCH OF THE PANHANDLE...AS ONCE THIS CONVECTION HITS THE
PANHANDLE...THERE MAY BE SOME STRATIFICATION. WHAT DOES THIS MEAN?
I AM SUGGESTING THE POSSIBILITY THAT WE WILL SEE MORE SUN IN THE
MORNING THAN THE AFTERNOON.

THINGS BECOME MORE DIVERGENT TONIGHT. DECIDED ON A DRYING TREND
BUT INTERESTINGLY ECMWF SHOWING AN EASTERLY WAVE PUSHING THROUGH
THE NORTHERN PANHANDLE LATE TONIGHT. GRAND COALITIONS OF MODEL POP
FIELDS DID NOT YIELD A SATISFACTORY RESULT, SO ERRED ON THE SIDE
OF DRYING SINCE EASTERLY WAVES ARE SOMETHING MODELS TYPICALLY
STRUGGLE WITH. BASED ON TEMPERATURES THIS MORNING AND THE
POSSIBILITY OF CLEARER SKIES TONIGHT, FORECASTED TEMPERATURES MAY
BE A LITTLE TOO WARM.

CONFIDENCE IN FORECAST A LITTLE GREY TODAY. WE SHOULD SEE SUN,
BUT PROBABLY NOT MANY SHOWERS, BUT THERE WILL BE SOME. SKY COVER
SHOULD BE FUN TO WATCH. USED A VARIETY OF DIFFERENT MODELS. ECMWF
FOR OVERALL PRESS/WIND. NAM, GFS, GEM, AND ECMWF FOR POP/QPF.

&&

.LONG TERM...THE 00Z/21 SUITE OF MODEL GUIDANCE SHOWED QUITE A BIT
OF VARIABILITY WITH THE EVOLUTION OF A SMALL-SCALE MIDLEVEL SHORTWAVE
TROUGH ADVANCING NNWWD ALONG THE COAST OF SERN AK DURING MIDWEEK.
FOR EXAMPLE...THE 00Z GFS AND UKMET WERE FASTER WITH THE
PROGRESSION OF THIS FEATURE...WHILE THE 00Z ECMWF...GEM...AND NAM
WERE SLOWER. GIVEN THIS VARIABILITY...DID NOT MAKE SUBSTANTIAL
CHANGES TO WINDS...BUT DID BUMP UP POPS AND CLOUDS SLIGHTLY FOR
THE NRN CWA WED AFTERNOON AND NIGHT.

AFTER THIS FEATURE EXITS N OF THE REGION ON FRI...THE LARGE-
SCALE PATTERN WILL BE DOMINATED BY A PROGRESSIVE SERIES OF UPPER
WAVES WITH EMBEDDED IMPULSES. WEAK SURFACE HIGH PRESSURE DURING
MIDWEEK WILL BE REPLACED WITH A SRN GULF CYCLONE BY THE WEEKEND.
SSELY LOW-LEVEL FLOW WILL STRENGTHEN AHEAD OF THIS NEXT AREA OF
LOW PRESSURE...AND FAVOR SEASONABLE TEMPERATURES OVER SE AK.
OTHERWISE...STRONGEST FORCING FOR ASCENT SAT-MON EITHER REMAINS S
OF THE CWA...OR ROTATES NWD OVER THE GULF. THUS...LOW
PRECIPITATION CHANCES WILL MAINLY BE ASSOCIATED WITH MINOR
DISTURBANCES TRAVERSING THE AREA. PREDICTABILITY IS NOT HIGH WITH
THESE FEATURES ATTM...THUS MAINTAINED WPC POP GUIDANCE.

TEMPERATURES/DEWPOINTS/RH WERE REFRESHED WITH A MULTI-MOS
BLEND...CHANGES WERE MINOR. FORECAST CONFIDENCE IS BELOW AVERAGE
FOR POPS/WIND...AND AROUND OR SLIGHTLY ABOVE AVERAGE FOR
TEMPERATURES.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ036.
         SMALL CRAFT ADVISORY FOR PKZ022-033>035-041>043-051-052.

&&

$$

JWA/GARNER







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