Gale Warning 375, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
1240 PM AKDT SAT APR 24 2010

.ANALYSIS AND UPPER LEVELS...A LONG-WAVE TROUGH ENCOMPASSES ALL
OF ALASKA...ALTHOUGH AN EMBEDDED SHORT-WAVE RIDGE EXTENDING FROM
THE YUKON WESTWARD ACROSS SOUTHCENTRAL TO BRISTOL BAY AND THE
EASTERN BERING IS PRODUCING A CRYSTAL CLEAR DAY. A NEAR ZONAL
UPPER JET EXTENDS ACROSS THE NORTH CENTRAL PACIFIC AND CURVES
AROUND A VERTICALLY STACKED LOW WITH STRONG UPPER DIVERGENCE
JUST DOWNSTREAM OF THIS LOW CENTER. EXPECT SURFACE LOW DEVELOPMENT
UNDER THE AREA OF DIVERGENCE THIS AFTERNOON. THE REMNANTS OF
THE ARCTIC FRONT ARE DRAPED ACROSS SOUTHWEST ALASKA RESULTING
IN A SOLID DECK OF CLOUDS BUT LITTLE OR NO PRECIP. LASTLY...A
SURFACE TROUGH LIES JUST SOUTH OF THE ALEUTIANS...HELPING TO
PRODUCE AREAS OF LIGHT PRECIP. ALL IN ALL IT IS A VERY QUIET
WEATHER DAY ACROSS THE ALASKA REGION.

.MODEL DISCUSSION...THERE ARE SOME MINOR DIFFERENCES IN TRACK
AND STRENGTH OF DEVELOPING SYSTEM WHICH MOVES INTO THE GULF SUNDAY.
PREFER THE GFS/EC WHICH HAVE BOTH INDICATED STORM FORCE WINDS
ALONG THE FRONT FOR THE PAST COUPLE MODEL RUNS. NAM SEEMS TO
BE AN OUTLIER WITH A WEAKER FRONT AND A LITTLE BIT DIFFERENT
ORIENTATION TO THE FRONT AS IT REACHES LAND. SOLUTIONS DIVERGE
A LITTLE MORE WITH HANDLING OF NEXT LOW FORMING OVER SOUTHERN
GULF MONDAY MORNING AS MODELS STRUGGLE WITH THE DETAILS OF THE
COMPLEX LOW. WILL TREND TOWARD THE STRONGER GFS SINCE THAT FOLLOWS
THE TREND OF ALL MODELS. OUT WEST...MINOR DIFFERENCES IN POSITIONS
OF WEAK LOWS FORMING ALONG THE TROUGH AXIS WILL HAVE LITTLE IMPACT
ON THE OPERATIONAL FORECAST SINCE WINDS WILL GENERALLY REMAIN AT
SMALL CRAFT LEVEL OR LESS.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...CONDITIONS WILL DETERIORATE RAPIDLY LATE
TONIGHT INTO SUNDAY MORNING ALONG THE COAST AS STRONG LOW MOVES
INTO THE GULF AND FRONT TRACKS TO THE COAST. HOWEVER...THE MAIN
UPPER CENTER WILL STALL SOUTH OF THE GULF AND THEN WOBBLE AROUND
THROUGH MONDAY...SO SURFACE FRONT WILL STALL AS IT REACHES THE
GULF COAST AND THE SURFACE LOW OVER THE GULF WILL ROTATE BACK
SOUTHWARD AROUND THE UPPER CENTER. THE BULK OF PRECIPITATION WILL
FALL ALONG THE COAST WITH JUST A FEW SHOWERS ON THE LEE SIDE OF
THE COASTAL RANGE. PRECIP WILL FALL MAINLY IN THE FORM OF RAIN
WITH WARM ADVECTION ACCOMPANYING THE FRONT. AFTER WHAT SHOULD
BE A WARM DAY ACROSS THE REGION TODAY TEMPERATURES WILL GET EVEN
WARMER SUNDAY FOR INLAND LOCATIONS UNDER OFFSHORE FLOW AHEAD OF
THE FRONT COMBINED WITH THE LOW LEVEL WARM ADVECTION. A SECOND
LOW WILL MOVE INTO THE GULF MONDAY BRINGING ANOTHER ROUND OF
RAIN TO THE COAST WHILE INLAND AREAS REMAIN MOSTLY DRY WITH
WARM TEMPERATURES. ON TUESDAY THE UPPER CENTER WILL BEGIN TO
HEAD OFF TO THE EAST WITH SHOWERS LINGERING ACROSS THE GULF.

SOUTHWEST ALASKA...THE REMNANTS OF THE ARCTIC FRONT WILL SLOWLY
LIFT NORTHWARD TONIGHT AND MONDAY AND CLOUDS ALONG IT WILL
DISSIPATE VERY GRADUALLY. THE STORM MOVING INTO THE GULF SUNDAY
WILL BRING CLOUDS TO EASTERN PORTIONS OF SOUTHWEST ALASKA BY
LATE SUNDAY AND SCATTERED SHOWERS MONDAY AND TUESDAY AS UPPER
FLOW BECOMES MORE EASTERLY AND PUSHES MOISTURE BACK OVER SOUTHWEST
ALASKA.

BERING SEA/ALEUTIANS...SURFACE TROUGH AND WEAK LOWS ALONG THE
ALEUTIANS WILL CONTINUE TO RESULT IN PERIODS OF RAIN AND SNOW
FOR THE NEXT FEW DAYS. WEAK RIDING OVER THE BERING WILL MAINTAIN
AN EXTENSIVE CLOUD DECK WITH A FEW FLURRIES OR SHOWERS AT TIMES.

.LONG TERM FORECAST...A BROAD TROUGH WILL REMAIN OVER MOST OF
THE ALASKA REGION THROUGH NEXT WEEK WITH WARMER (BUT SEASONABLE)
TEMPERATURES ON THE DOWNSTREAM SIDE OF THE TROUGH OVER THE
EASTERN MAINLAND AND COOLER THAN NORMAL TEMPERATURES ON THE
UPSTREAM SIDE OF THE TROUGH OVER THE BERING AND ALEUTIANS. THE
UPPER JET LOOKS TO REMAIN WELL SOUTH OF ALASKA THROUGH THE PERIOD
DON'T EXPECT ANY MAJOR SYSTEMS TO AFFECT THE REGION. INSTEAD...WEAK
FEATURES WILL RESULT IN A SHOWERY REGIME.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING...120 130 132.
         GALE WARNING 150.
FIRE WEATHER...NONE.

SEB APR 10