Gale Warning 320, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT FRI APR 22 2011

.MODEL DISCUSSION...THE MODELS ARE IN AMAZINGLY GOOD AGREEMENT
THROUGH THE FIRST 60 HRS CONSIDERING THE COMPLEXITY OF THE SYNOPTIC
PATTERN. THE NAM OVERALL BEST HANDLES MOST OF THE LOCAL EFFECT OF
WIND PRECIPITATION SHADOWING IN THE EAST AND WILL USED HEAVILY IN
THIS FORECAST PACKAGE. THE GFS LOOKS REASONABLE OUT IN THE WESTERN
DOMAIN.

.UPPER LEVELS...
500MB...A BROAD RIDGE WITH ITS AXIS EXTENDS FROM THE SE GULF  OF THE
ALASKA TO OVER THE NORTH GULF COAST. BY SAT AFTERNOON...THE RIDGE
AXIS EXTENDS FROM BRITISH COLUMBIA NW TO OVER INTERIOR ALASKA. THE
RIDGE THEN UNDERGOES LITTLE CHANGE THROUGH MON AFTERNOON. THE
OCCLUDED LOW CENTER SOUTH OF THE EASTERN ALEUTIANS APPEARS TO MERGE
WITH A SECONDARY DEVELOPMENT TO THE SE SAT. THE GENERAL AREA OF LOW
PRESSURE THEN LIFTS NORTH TO OVER BRISTOL BAY SUN AFTERNOON. THE
COMPLEX CONTINUES NW AND WEAKENS AS YET ANOTHER LOW COMPLEX MOVES SE
ACROSS THE CENTRAL BERING SEA.

AT THE SURFACE...FRONTAL TROUGH EXTENDING FROM SW ALASKA...THROUGH
THE NW GULF...TO THE EASTERN GULF CONTINUES TO PUSH NORTH TODAY AND
WEAKENS. A SECONDARY FRONT WELL SOUTH OF THE GULF MOVES TO OVER
BRISTOL BAY AND THE NORTH GULF COAST LATE SAT AFTERNOON...THEN
CONTINUES NORTH AND WEAKENS INTO SUN. THE MAIN LOW CENTER SOUTH OF
THE EASTERN ALEUTIANS APPEARS TO MERGE WITH A DEVELOPING LOW TO THE
SE TONIGHT. THE COMBINED CENTER THEN MOVES TO NEAR KODIAK ISLAND AND
SLOWLY WEAKENS ON SUN.

.SHORT TERM FORECAST...
STRONG PRESSURE GRADIENTS WILL CONTINUES ACROSS MUCH OF SOUTHCENTRAL
ALASKA INTO SUN AFTERNOON AS FRONTAL TROUGHS MOVE NORTH AND THE LOW
COMPLEX LIFTS NORTH. STRONGEST GRADIENTS LIKELY THROUGH SAT WITH
RESULTANT VERY STRONG GAP FLOWS...AND GALES/STORMS OVER THE
GULF...AND BARRIER JET DEVELOPMENT ALONG THE NORTH GULF COAST. WINDS
SHOULD SLOWLY WEAKEN THROUGH SUN AS GRADIENTS RELAX SOME. A TYPICAL
PRECIPITATION PATTERN WILL HOLD OVER THE NEXT COUPLE OF DAYS WITH
GENERALLY DRY DOWN-SLOPING CONDITIONS IN VALLEYS AND ABUNDANT
PRECIPITATION ALONG COASTS AND EAST/SE EXPOSURES. TEMPS SHOULD BE
WARMING OVER THE THROUGH THE WEEKEND...SO THE LIONS SHARE OF THE
PRECIPITATION SHOULD BE RAIN. HOWEVER...HIGHER ELEVATIONS AND SOME
COLD SPOTS PRONE TO COLD AIR DAMMING WILL SEE SOME SNOW OR MIXED
PRECIPITATION TYPES.

.SOUTHWEST MAINLAND...A SERIES OF FRONTS ROTATING AROUND A LOW SOUTH
OF DUTCH HARBOR WILL RESULT IN RAIN AND SNOW SHOWERS ACROSS MUCH OF
THE SOUTHWEST MAINLAND OVER THE NEXT FEW DAYS.

.ALEUTIANS...THE LOW SOUTH OF DUTCH HARBOR WILL CONTINUE TO BRING
RAIN AND SNOW SHOWERS TO THE ALEUTIANS OVER THE NEXT SEVERAL DAYS.
DRIER CONDITIONS WILL OCCUR TO THE WEST AS THE UPPER LEVEL RIDGE OVER
THE BERING MOVES SOUTHWARD. HOWEVER...CLOUDS ARE EXPECTED TO PERSIST
ACROSS THE REGION.

.LONG TERM FORECAST...AN ACTIVE PATTERN WILL CONTINUE THROUGH NEXT
WEEK. MODELS ARE SHOWING LOW PRESSURE SYSTEMS PROGRESSING THROUGH THE
BERING AND GULF WHICH WILL RESULT IN UNSETTLED WEATHER ACROSS MUCH OF
THE FORECAST AREA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE...125 129 130 132 138 140 141 165 170
         HEAVY FREEZING SPRAY...179 185.
.AER/ALU...WATCH/WARNING SUMMARY

RMC APR 11