Area Forecast Discussion
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000
FXAK67 PAJK 301225
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
425 AM AKDT SAT APR 30 2016

.SHORT TERM...OUR STORM FORCE FRONT ADVANCES QUICKLY FROM THE
CENTRAL GULF AND WILL BRING WIND AND HEAVY RAIN TO SOUTHEAST
ALASKA TODAY. THE STRONGEST PORTION OF THE FRONT WILL REACH THE
NORTHERN GULF BY THE AFTERNOON AFFECTING YAKUTAT WITH GUSTS UP TO
40 MPH LATE THIS AFTERNOON. THE EASTERN PORTION OF THE FRONT WILL
BE WEAKENED BY THE TERRAIN SOMEWHAT, BUT GRADIENTS ACROSS THE
CENTRAL INNER CHANNELS WILL BE SUFFICIENT FOR SOLID SMALL CRAFT
SOUTHEASTERLIES AND FOR THE SOUTHERN PANHANDLE AND CROSS SOUND FOR
GALES. 925 MB SOUTHEASTERLY JET OF 40 TO 55 KT IMPRESSIVELY
SPREADS ACROSS AROUND 80 PERCENT OF THE PANHANDLE WITH ALL BUT THE
FAR NORTHERN INNER CHANNELS COVERED. FOR THIS REASON, WE HAVE
ADDED STRONG WIND HEADLINES FOR MANY LOCATIONS IN THE NORTHERN AND
CENTRAL PANHANDLE THAT WERE NOT COVERED PREVIOUSLY. AIRPORT
LOCATIONS MAY NOT VERIFY 40 MPH WIND GUSTS, BUT IN MORE EXPOSED
SPOTS, IT WILL BE WINDY. IN OUR RECOLLECTION IT HAS BEEN MANY
WEEKS SINCE THE PANHANDLE HAS EXPERIENCED SUCH A WIDESPREAD WIND
EVENT, ALTHOUGH IT MUST BE NOTED THAT WE ARE NOT EXPECTING
DAMAGING HIGH WINDS OF 60 KT OR GREATER. NONETHELESS, THERE WILL
LIKELY BE IMPACTS. THE FRONT WILL STALL OVER THE CENTRAL
PANHANDLE TONIGHT, AND GRADIENTS AND WINDS WILL RELAX...ALTHOUGH
RIDGING OVER THE NORTHERN INTERIOR SHOULD PUSH WINDS IN SKAGWAY
AND LYNN CANAL HIGHER SATURDAY NIGHT THAN SATURDAY ITSELF.

THE OTHER STORY CONTINUES TO BE THE RAIN. RAIN BANDS WILL BE HEAVY
AT TIMES TODAY PANHANDLE-WIDE AS THE FRONT INITIALLY PUSHES
ONSHORE. BUT AS IT STALLS OVER THE SOUTH TONIGHT, THE HIGHEST
PRECIPITABLE WATER WILL REMAIN OVER PRINCE OF WALES ISLAND AND THE
SOUTHERN INNER CHANNELS...THEREFORE HIGH RAIN RATES WILL PERSIST
HERE WHILE AREAS NORTH AND WEST OF PETERSBURG AND KAKE SHOULD SEE
LIGHTER TOTALS WITH WIDESPREAD SHOWERS TONIGHT. NAEFS MEAN
PRECIPITABLE WATER FIELDS BOOST CONFIDENCE IN HIGHER RAIN AMOUNTS
WITH VALUES OF 4 PLUS STANDARD DEVIATIONS ABOVE NORMAL FOR THIS
TIME OF YEAR OVER THE SOUTHERN PANHANDLE. ALL TOLD THE NORTHERN
PANHANDLE SHOULD RECEIVE ANYWHERE BETWEEN A HALF TO 1.5 INCHES
TODAY, WHILE THE SOUTH WILL MORE THAN OUTDO THE NORTH WITH 1 TO 3
INCHES. RIVERS AND STREAMS...ESPECIALLY OVER THE SOUTH WILL RISE
SIGNIFICANTLY OVER THE NEXT 24 HOURS, ESPECIALLY TONIGHT, BUT
FLOODING IS NOT EXPECTED.

THE ONLY REAL CHANGE TO THE FORECAST WAS EXPANDING THE AREA OF
STRONG WINDS TO YAKUTAT, HOONAH, ANGOON, AND ELFIN COVE. WE ALSO
MOVED UP SOME OF THE ONSETS BEFORE NOON IN WESTERN PORTIONS OF THE
PANHANDLE. FEW CHANGES NEEDED. WE WILL LET THE SPS EXPIRE. ITS
MESSAGE HAS BEEN ABSORBED BY THE PUBLIC AND THE TIME IS NIGH. THE
FORECASTS ARE STAMPED FIRMLY WITH RAIN AND STRONG WINDS.
CONFIDENCE GOOD TO AVERAGE.

.LONG TERM...THE FRONT WILL BE STALLED OVER THE SOUTHERN PANHANDLE
AT THE BEGINNING OF THE EXTENDED RANGE ON SUNDAY MORNING. A WAVE OF
LOW PRESSURE WILL DEVELOP AND MOVE INTO THE EASTERN GULF SUNDAY
AFTERNOON INTO SUNDAY NIGHT. THE WAVE WILL THEN MOVE INLAND NEAR
YAKUTAT EARLY MONDAY. THERE REMAINS TIMING DIFFERENCES WITH THIS
WAVE AS THE NAM/GFS ARE 6-9 HOURS QUICKER THAN THE ECMWF. BASED
UPON THIS OPTED TO STAY THE COURSE WITH THE PREVIOUS FORECAST WHICH
REPRESENTED THE NAM/GFS SOLUTION WELL. THE WAVE WILL ENHANCE
RAINFALL RATES AGAIN OVER THE SOUTHERN PANHANDLE SUNDAY AFTERNOON
AND THIS HEAVY RAIN WILL PROGRESS NORTHWARD REACHING THE NORTHERN
PANHANDLE SUNDAY NIGHT INTO EARLY MONDAY. PRECIPITABLE WATER VALUES
REACH 1-1.1 INCHES WHICH IS 4 STANDARD DEVIATIONS ABOVE NORMAL FOR
EARLY MAY WHICH INDICATES THAT HEAVY RAIN IS INDEED LIKELY. ANOTHER
PERIOD OF GUSTY WINDS WILL ACCOMPANY THE WAVE ESPECIALLY AS IT
MOVES INLAND EARLY MONDAY WITH SIGNIFICANT PRESSURE RISES OCCURRING
OVER THE PANHANDLE. RAINFALL TOTALS ARE EXPECTED TO RANGE FROM 1-3
INCHES FOR THE SUNDAY THROUGH MONDAY MORNING TIME FRAME.

THE WEATHER PATTERN WILL BE MUCH QUIETER AFTER MONDAY WITH A
SURFACE RIDGE OF HIGH PRESSURE BUILDING INTO THE AREA AND
DECREASING PRECIPITATION CHANCES BY MID WEEK. MODELS INDICATE
ANOTHER FRONT WILL MOVE INTO THE GULF BY LATE WEEK. HOWEVER THERE
ARE DIFFERENCES IN THE STRENGTH OF THE RIDGE AND HOW MUCH EASTWARD
PROGRESS THIS FRONT IS ABLE TO MAKE.

USED THE 00Z NAM/GFS FOR UPDATES THROUGH DAY 4 THEN CONTINUED WITH
WPC GUIDANCE FOR THE REMAINDER OF THE FORECAST.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM 10 AM AKDT THIS MORNING THROUGH THIS EVENING
     FOR AKZ024-026>028.
     STRONG WIND FROM 1 PM AKDT THIS AFTERNOON THROUGH THIS EVENING
     FOR AKZ025.
     STRONG WIND FROM 10 AM AKDT THIS MORNING THROUGH THIS AFTERNOON
     FOR AKZ021>023.
     STRONG WIND FROM 1 PM AKDT THIS AFTERNOON THROUGH THIS AFTERNOON
     FOR AKZ017.
MARINE...STORM WARNING FOR PKZ052.
     GALE WARNING FOR PKZ022-033>036-041>043-051-053.
     SMALL CRAFT ADVISORY FOR PKZ011>013-021-031-032.
&&

$$

TPS/JWA

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