Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
000
FXAK67 PAJK 021431
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
531 AM AKST MON MAR 2 2015

.SHORT TERM...EARLY MORNING INFRA-RED SATELLITE IMAGE SHOWS A
WEAK INVERTED TROUGH OF LOW PRESSURE ALONG THE PANHANDLE COAST TO
DIXON ENTRANCE AND PERSISTING HIGH PRESSURE OVER NORTHWESTERN
CANADA. WATER VAPOR IMAGE REVEALS AN UPPER LEVEL OMEGA BLOCK WITH
RIDGE AXIS OVER THE CENTRAL AND EASTERN GULF BORDER. HIGH LEVEL
CLOUD SHIELDS CONTINUE TO RIDE THE RIDGE TOP AND MOVING OVER THE
NORTHEASTERN GULF COAST AND CENTRAL PANHANDLE COAST. FIVE FINGERS
REPORT SMALL CRAFT LEVEL WINDS...BUT ELSEWHERE NO SIGNIFICANT
WINDS/SEAS ARE OBSERVED. BETWEEN THE HIGH OVER CANADA AND LOWER
PRESSURE AREA ALONG THE PANHANDLE COAST...SOME GUSTY OFFSHORE
WINDS ARE REPORTED. MOSTLY CLOUD FREE SKIES OVERNIGHT COOLED
TEMPERATURES DOWN TO THE LOWER TO MID 20S OVER THE NORTHERN AND
CENTRAL PANHANDLE...WHILE SOUTHERN AREAS REMAIN IN THE MID 30S TO
THE LOWER 40S.

MODELS REMAIN IN GENERAL AGREEMENT FOR THE WEAK INVERTED TROUGH
OF LOW PRESSURE REMAINS ALONG THE OUTER COAST TO DIXON ENTRANCE
THIS MORNING AND HIGH PRESSURE CONTINUES OVER NORTHWESTERN CANADA.
AS THE TROUGH DISSIPATES LATE THIS MORNING...OFFSHORE FLOW WILL
WEAKEN AND AS THE RIDGE MOVES CLOSER TO THE PANHANDLE...WINDS WILL
BECOME MORE SOUTHERLY THIS AFTERNOON INTO TONIGHT. WEAK PRESSURE
GRADIENT WILL RESULT NO SIGNIFICANT WINDS OVER SOUTHEAST ALASKA
THROUGH THIS EVENING. A DEVELOPING LOW IN THE FAR WESTERN GULF
WILL PUSH AN OCCLUDED FRONT INTO THE EASTERN GULF TONIGHT AND
SMALL CRAFT LEVEL WINDS WILL PICK UP OVER THE NORTHERNMOST OUTSIDE
WATERS TONIGHT. REFRESHED THE INHERITED FORECAST WITH THE ECMWF
AND GEM GLOBAL FOR THEIR GOOD CONSENSUS.

MOSTLY SUNNY SKIES THIS MORNING ACROSS THE PANHANDLE WITH MID TO
HIGH LEVEL CLOUDS CONTINUALLY MOVING IN FROM THE
NORTHWEST...EXPECT PARTLY CLOUDY SKIES THIS AFTERNOON. INSOLATION
WILL INCREASE THIS AFTERNOON AS SUNSHINE FILTERED THROUGH THE
CLOUD SHIELDS AND DAYTIME TEMPERATURES WILL BE ONCE AGAIN SOARING
INTO THE 40S. CLOUDS WILL CONTINUE TO INCREASE TONIGHT AHEAD OF
THE INCOMING FRONT...BUT THE OVERNIGHT TEMPERATURES WILL COOL DOWN
TO THE MID 20S TO THE LOWER 30S...EXCEPT IMMEDIATE CENTRAL
PANHANDLE COAST WHERE NIGHTTIME TEMPERATURES ARE EXPECTED TO
REMAIN ABOVE FREEZING.

.LONG TERM...THE FIRST IN A SERIES OF UPPER WAVES/FRONTS IS INTO
THE YAKUTAT AREA BY TUE MORNING...BUT IT IS WEAK WITH THE ONLY
SIGNIFICANT PRECIP INTO YAKUTAT LATE TUE WITH LIGHT PRECIP OVER
MOSTLY THE NORTHERN PANHANDLE ON TUE AFTERNOON/EVENING. NORTHERN
FRINGE AT SEA LEVEL MAY SEE SOME LIGHT SNOW MIXED IN. THE NEXT
WAVE IS STRONGER AND CLOSED ALOFT BY 03Z WED OVER THE SOUTHWESTERN
GULF WITH A TRACK INTO THE CENTRAL GULF LATER ON WED. THIS ONE
SETS UP MOIST ONSHORE FLOW FOR THE ENTIRE PANHANDLE...WITH A
CONNECTION TO PACIFIC MOISTURE FROM THE SOUTH LATE WED. IT IS AT
THIS POINT WHERE WE SEE MODEL DISAGREEMENT WITH THE NAM SHOWING AN
ORGANIZED CLOSED LOW ALOFT WEST OF MARINE ZONE 310 AT 18Z THU AND
THE EC SHOWING OPEN WEAKER TROUGHING...PROGRESSIVE...MOVING
THROUGH THE PANHANDLE AT THIS TIME. GEM SOLUTION WAS MOSTLY
SIMILAR TO THE EC FOR THIS WAVE. MEANWHILE THE GFS SHOWS A LARGE
HIGH AMPLITUDE TROUGH CENTERED OVER THE WESTERN GULF AT THIS TIME
WITH CONVOLUTED DETAILS...ONE OF WHICH IS A WEAK WAVE IMPINGING ON
THE PANHANDLE. THUS THE NAM PREDICTION AT 72-84 HRS IS THE
OUTLIER. THIS MODEL DISAGREEMENT ON DETAILS REDUCES CONFIDENCE
SOMEWHAT IN THE FORECAST FOR DAY 3 ONWARDS...THOUGH GENERAL
AGREEMENT ALOFT IN THE LARGE SCALE FEATURES OF THE EC/GEM/GFS WAS
REASONABLE THROUGH THE END OF THE WEEK. WENT WITH EXISTING 12Z WPC
GUIDANCE FOR THE REMAINDER OF THE FORECAST FOR PRESSURE AND WINDS.
THE EC WAS THE MODEL OF CHOICE FOR THE WPC GUIDANCE AND THIS WAS ALSO
THE PREFERRED APPROACH FOR THERMODYNAMIC UPDATES TO THE MODEL
FIELDS. THOUGH THERE IS NOT A LOT OF CONFIDENCE IN THERMODYAMIC
DETAILS...APPEARS THAT THE YAKUTAT AND SKAGWAY AREAS ON WEDNESDAY
MORNING AND THE SKAGWAY AND JUNEAU AREAS ON THURSDAY MAY SEE A
PERIOD OF MIXED PRECIP. THE NORTHERN FRINGE ALONG WITH YAKUTAT BY
WEEKEND CONTINUE TO HAVE SHOTS FOR SNOW...BUT NO INTERIOR SOURCE
OF COLD AIR IS EVIDENT SO A TEMPORARY MIXED SCENARIO AT BEST IS
ANTICIPATED. REMAINDER OF THE WEEK REMAINED MOIST AS PATTERN
ADVERTISED BY WPC/EC REMAINS PROGRESSIVE WITH GENERAL ONSHORE FLOW
AND PERIODS OF RAIN INTO THE WEEKEND. ALL MODELS PERSIST IN
BRINGING A STRONGER TROUGH INTO THE WESTERN GULF BY LATE WEEKEND
WITH DEEP SWLY MOIST FLOW CONTINUING. RAINY WEATHER CONTINUES
RIGHT ON INTO EARLY NEXT WEEK ON THE EC/WPC GRIDS.

UTILIZED 00Z EC/NAM UPDATES AND MOS GUIDANCE FOR MOST THERMAL
UPDATES IN THIS PACKAGE. MODEL CONFIDENCE WAS AVERAGE AT BEST FROM
WEDNESDAY ONWARDS BUT THE GENERAL PICTURE OF AN EXTENDED RAINY
PERIOD FROM LATE WED INTO THE WEEKEND IS THE MOST LIKELY SCENARIO
AT THIS POINT... WITH A HIGH POP/LOW QPF SITUATION FROM MIDWEEK INTO EARLY
WEEKEND. GENERAL INCREASE IN SWLY LOW LEVEL WINDS BEGINNING OVER
THE WEEKEND...BUT THERE STILL APPEARS TO BE LITTLE THREAT OF
HAZARD-LEVEL WINDS THROUGH THE WEEK AT THIS POINT.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ052.

&&

$$

AHN/WESLEY

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU











USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.