Gale Warning 135, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1135 AM ADT THU APR 10 2008

.SHORT RANGE...THE LATEST SATELLITE IMAGERY SHOWS THE PANHANDLE
UNDER MOSTLY CLOUDY SKIES WITH DEEP ONSHORE FLOW. THERE IS AREAS
OF RAIN SHOWERS OVER THE SOUTHERN HALF OF SE AK AND A MIXED OF
RAIN AND SNOW BUT NEAR STRONG SHOWERS ALL SNOW OVER THE NORTHERN
HALF. THERE WILL NOT BE THAT MUCH ACCUMULATIONS AS TEMPS WILL BE
ABOVE FREEZING. THESE SHOWERS WILL PERSIST FOR MOST OF THE DAY
BUT THEY WILL BECOME SCATTERED THROUGH THE LATE MORNING INTO THE
AFTERNOON. THERE IS A FEW STRONG VORT MAXS OVER THE GULF THAT
WILL MOVE ONSHORE THIS EVENING TO INCREASE THE CHANCE OF SHOWERS
TO LIKELY OVER THE MOST OF THE AREA THE ONLY EXCEPTION WILL BE
THE FAR NORTHERN AREAS AS THEY MAY SEE SCATTERED SNOW SHOWERS.

A SURFACE RIDGE IS BUILDING OVER THE PANHANDLE THIS MORNING AND
HAS INCREASE THE PRESSURE GRADIENT OVER LYNN CANAL WITH A WEAK
SURFACE LOW OVER THE YUKON. THIS TIGHT GRADIENT HAS INCREASE THE
WINDS TO SMALL CRAFTS OVER THE MARINE AREAS AND WINDY NEAR PAGY
WITH GUSTS CLOSE TO WIND AVY AND BREEZY CONDITIONS NEAR PAHN. THE
RIDGE WILL SLOWLY PUSH TO THE EAST TONIGHT AS A TROF EXTENDING NE
FROM A LOW IN THE NORTH PACIFIC PUSHES AN ASSOCIATED WARM FRONT
OVER THE FAR SOUTHERN ZONE TONIGHT. AS THE GRADIENT WEAKENS THE
WINDS OVER THE FAR NORTHERN AREAS WILL SLOWLY WEAKEN AND SWITCH
TO THE NORTH WITH THE ADVANCE OF THE LOW FROM THE SOUTH.

THE LOW WILL LIFT INTO THE FAR SE GULF BY FRIDAY AFTERNOON AND
DRIFT THE FRONT SLOWLY NORTH OVER THE SOUTHERN HALF WITH
PERSISTENT RAIN. THE NORTH CENTRAL AREAS WILL SEE RAIN LIKELY BY
THE AFTERNOON AND THE FAR NORTHERN AREAS WILL SEE JUST A CHANCE.
THE WINDS WITH THIS SYSTEM WILL INCREASE TO 20 KT LATE TONIGHT
OUT OF THE NORTH BUT WILL BACK AROUND TO THE SE AND INCREASE TO
BE BREEZY OVER THE SOUTHERN LAND AREAS AND SMALL CRAFT WINDS OVER
CLARENCE STRAIT. OTHER SOUTHERN HALF MARINE AREAS WILL REMAIN
NORTH AND BE 20 TO 25 KT LATE TONIGHT BUT MAY WEAKEN SOME THROUGH
FRI AFTERNOON.

.LONG RANGE...MODELS IN AGREEMENT THROUGH 00Z TUESDAY WITH 500 MB
AND SURFACE FEATURES. GFS AND ECMWF INITIALIZED WELL THIS MORNING
IN WATER VAPOR WITH THE LEAD SHORTWAVE IN THE LONG TERM TIME
FRAME NOW NEAR 45N 164W. 12Z UKMET...00Z ECMWF AND 12Z GFS ALL
INDICATE A CONTINUED PROGRESSIVE PATTERN IN THE LONG TERM ACROSS
THE NORTH GULF WITH WESTERLY ONSHORE FLOW AFTER SUCCESSIVE SHORT
WAVES SATURDAY AND EARLY SUNDAY. BLENDED GRIDS TOWARD THE 12Z GFS
AND UKMET SOLUTIONS AS THEY HAD BETTER AGREEMENT AND WEAKER
RIDGING ALONG THE ALASKAN PENINSULA 00Z MONDAY...WHICH SHOULD
RESULT IN A MORE PROGRESSIVE WAVE PATTERN.

BY 12Z SATURDAY A NICE DOUBLE SURFACE WAVE STRUCTURE DEVELOPS IN
THE SOUTHERN GULF WITH THE 1ST SURFACE LOW WEST OF SITKA
WEAKENING AND MOVING ONSHORE NEAR CROSS SOUND. EXPECT RAIN AND
WINDY CONDITIONS ACROSS THE SOUTHERN PANHANDLE WITH THIS LOW
FRIDAY EVENING THROUGH MIDDAY SATURDAY. THE 2ND SURFACE LOW WILL
CONTINUE TO STRENGTHEN IN THE SOUTHERN GULF MIDDAY SATURDAY AND
WILL AGAIN BRING LOCALLY WINDY CONDITIONS TO THE SOUTHERN
PANHANDLE SATURDAY AFTERNOON THROUGH SUNDAY MORNING...WITH A
STRONG 850 MB LOW LEVEL JET MOVING TOWARD AND THEN ALONG THE
COAST MOUNTAINS. EXPECT THE MAJORITY OF THE PANHANDLE TO BE RAIN
WITH THIS SYSTEM AS THE 850 MB TEMPS WILL HAVE WARMED...THE
EXCEPTION BEING AKZ018 AND AKZ019 AT ONSET WITH SNOW NEAR THE
PASSES.

THROUGH SUNDAY INTO MONDAY THE MID WAVE TROUGH IN THE GULF
ADVECTS EASTWARD INTO BC BRINGING TEMPORARY DRIER CONDITIONS IN
THE NORTHWEST FLOW ALOFT ACROSS THE PANHANDLE WITH ONLY ISOLATED
TO SCATTERED SHOWERS. EXPECT THE WET CONDITIONS TO RETURN IN
ONSHORE MID AND SURFACE FLOW BY TUESDAY AHEAD OF THE NEXT UPPER
LEVEL SHORTWAVE INTO THE NORTHERN GULF. MODELS DIVERGE
SIGNIFICANTLY BY WEDNESDAY WITH THE STRENGTH OF A MID LEVEL RIDGE
BUILDING ACROSS THE PANHANDLE FOR WEDNESDAY AFTERNOON. SO WILL
KEEP CHANCE TO LIKELY POPS AS ONSHORE FLOW IS LIKELY TO REMAIN AT
THIS TIME. FORECAST CONFIDENCE IS HIGH THROUGH TUESDAY.

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

MARINE...SCA...PKZ41>43 31 33>36

ABJ/PSS