Area Forecast Discussion
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269
FXAK67 PAJK 292354
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
354 PM AKDT FRI APR 29 2016

.SHORT TERM...THE CURRENT SATELLITE IMAGERY SHOWS SCATTERED TO
NUMEROUS RAIN SHOWERS MOVING OVER THE AREA ASSOCIATED WITH A
UPPER TROF. THIS TROF WILL MOVE TO THE EAST THROUGH TONIGHT BUT
THERE IS ENOUGH INSTABILITY THAT SOME OF THESE SHOWERS ARE STRONG
WITH SOME ICE PELLETS EMBEDDED. THE WINDS ACROSS THE AREA ARE ON
THE LIGHT THIS AFTERNOON BUT THERE WILL AN INCREASE LATE TONIGHT
FROM SOUTH TO NORTH. THERE IS A VERY STRONG LOW PRESSURE SYSTEM
DRIFTING INTO THE SOUTHERN GULF THIS SYSTEM WHICH WILL LIFT A
STORM FORCE FRONT INTO THE GULF OVERNIGHT. THIS SYSTEM WILL WEAKEN
SOME THROUGH THE NEXT 24HRS BUT STILL PRODUCE STORM FORCE WINDS
OVER THE NORTHERN GULF FROM A BARRIER JET ENHANCEMENT. THE FRONT
WILL TAP INTO SOME TROPICAL MOISTURE AND WITH STRONG UPLIFT FROM
DIVERGENCE ALOFT FROM THE 130KT JET AND A TROPOSPHERIC FOLD. RAIN
WILL SPREAD INTO THE AREA FROM THE WEST THROUGH THE MORNING AND
WILL BECOME HEAVY AT TIMES. THERE IS OVER 200% PW VALUES AND RAIN
AMOUNTS WILL RANGING FROM 1 TO 2 INCHES WITH THE HIGHEST AMOUNTS
OVER THE SOUTHERN HALF. THE FRONT WILL BE RIGHT OVER SEAK BY
SATURDAY AFTERNOON AND BEGIN TO STALL.

WINDS OVER LAND WILL INCREASE ALONG THE COAST THROUGH THE MORNING
AS THE FRONT APPROACHES ALONG WITH INCREASED 925MB WINDS FROM THE
SOUTHEAST. THE STRONG WINDS WILL SPREAD INLAND THROUGH THE DAY
WITH STRONG WINDS ALONG THE COAST IN THE MORNING AND THEN OVER
ZONES 25,26,28 BY THE AFTERNOON WITH GUSTS RANGING FROM 40 TO 50
MPH.

THERE IS ABOUT AVERAGE FORECASTER CONFIDENCE THROUGH THE FIRST
24HRS WITH NOT MANY BIG CHANGES FROM PREVIOUS FORECAST. USED A MIX
OF THE NAM AND HIRES MODELS FOR ANY CHANGES.

.LONG TERM...FRONT WILL HANG UP OVER THE SRN AREA SAT NIGHT AS A
LOW PRESSURE WAVE ORGANIZES WELL TO THE S AND BEGINS TO HEAD N
TOWARD THE ERN GULF. THE WAVE WILL INTENSIFY AND HEAD THROUGH THE
ERN GULF AROUND SUN NIGHT...WITH MODELS STILL HAVE TIMING
DIFFERENCES ON THIS WAVE. THE FRONT WILL BE FORCED BACK TO THE NW
OVER THE ERN GULF AND SE AK SUN AND SUN NIGHT...THEN PUSH BACK
ONSHORE MON. THE FRONT MAY END UP GETTING HUNG UP AGAIN MON NIGHT
AND TUE BUT MODELS DIFFER ON THIS AS WELL. LOOKS QUIETER FOR
MIDWEEK WITH SFC RIDGE BUILDING INTO THE AREA...THEN THERE MAY BE
ANOTHER FRONTAL SYSTEM MOVING IN FOR LATE WEEK. MADE MOSTLY MINOR
ADJUSTMENTS AT MOST FOR SAT NIGHT-MON...THEN USED LATEST WPC FOR
MON NIGHT ONWARD.

FOR SAT NIGHT...PRECIP WILL TRANSITION TO SHOWERS BEHIND THE FRONT
WITH THE MOST ACTIVITY OVER THE NE GULF COAST IN THE DEEPER COLD
AIR. STEADIER RAIN WILL PERSIST OVER THE SE HALF OF THE AREA WITH
FRONT STALLED OUT. STILL COULD SEE LOCALLY HEAVY RAINFALL OVER THE
SE HALF OF THE AREA SAT NIGHT. WINDS AHEAD OF THE FRONT WILL DROP
OFF SOME AS UPPER SUPPORT GOES INLAND.

FOR SUN-MON...WITH LOW PRESSURE WAVE MOVING IN AND FRONT HEADING
BACK TO THE NW...THE STEADIER RAIN WILL SPREAD BACK TO THE N AND
IT WILL BECOME LOCALLY HEAVY ESPECIALLY SUN NIGHT. SEE THE SPECIAL
WEATHER STATEMENT FOR EXPECTED RAINFALL AMOUNTS. MAY NEED TO BOOST
WINDS A BIT ON E SIDE OF THE WAVE BUT GIVEN THE MODEL DIFFERENCES
ON IT DID NOT WANT TO ADJUST ATTM.

AFTER MON...LOOKS LIKE TRANSITION BACK TO SHOWERY WEATHER UNLESS
FRONT GETS HUNG UP AGAIN FOR MON NIGHT AND TUE. PRECIP THREAT
SHOULD DIMINISH FOR MIDWEEK...THEN MAY INCREASE FOR LATE WEEK AS
ANOTHER FRONTAL SYSTEM MOVES TOWARD THE AREA. MODELS DIFFER ON HOW
FAR E THIS WILL GET THOUGH BEFORE GETTING HELD UP.

&&

.MARINE...GALE FORCE WINDS WILL MOVE INTO THE CENTRAL GULF TONIGHT
AND SPREAD INTO THE EASTERN GULF TONIGHT. THEY WILL INCREASING TO
STORMS ALONG THE NORTHERN GULF FROM THE BARRIER JET MENTIONED
ABOVE. CROSS SOUND WILL SEE THE SOUTH WINDS BACK AROUND TO THE
EAST TONIGHT AND INCREASE TO GALE FORCE AS THE FRONT MOVES INTO
THE EASTERN GULF. THE INSIDE WATERS WILL SEE THE WINDS INCREASE
LATE TONIGHT THROUGH SATURDAY FROM SOUTH TO NORTH. MAX GALES WILL
DEVELOP OVER CLARENCE STRAIT WITH 35 KT FROM THE SOUTHEAST OVER
THE SOUTHERN HALF OF THE MARINE WATERS. THE REST OF THE N/S
CHANNELS WILL SEE WINDS INCREASE TO SMALL CRAFT WINDS. THERE WILL
BE A BIT MORE WIND IN E/W CHANNELS DUE TO THE GRADIENT
ORIENTATION.

&&

.HYDROLOGY...RIVERS AND STREAMS WILL BEGIN TO RISE THROUGH
SATURDAY AND SUNDAY BUT AT THIS TIME NO FLOODING IS EXPECTED. SEE
THE SPECIAL WEATHER STATEMENT FOR MORE INFORMATION ON THIS
SITUATION.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING FOR
     AKZ025-026-028.
     STRONG WIND FROM SATURDAY MORNING THROUGH SATURDAY AFTERNOON FOR
     AKZ023-027.
MARINE...STORM WARNING FOR PKZ052.
     GALE WARNING FOR PKZ022-034>036-041>043-051.
     SMALL CRAFT ADVISORY FOR PKZ012-013-021-031>033-053.
&&

$$

ABJ/RWT

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