Small Craft Advisory 428, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
138 PM AKDT THU MAY 29 2014

.ANALYSIS... A WEATHER FRONT EXTENDED ACROSS THE WESTERN
MAINLAND...BRISTOL BAY TO OVER THE WESTERN GULF. A BROAD AREA OF
RAIN WAS EVIDENT ACROSS BRISTOL BAY UNDER STRONG UPPER LEVEL
SUPPORT. BRISK SOUTHEAST FLOW AHEAD OF THE FRONTAL ZONE BROUGHT
RAIN TO PORTIONS OF THE KENAI PEN AND OVER THE SW PORTION OF THE
KUSKOKWIM VALLEY. DOWNSLOPE DRYING KEPT MOST INLAND AREAS DRY OR
ONLY WITH SOME SHOWERS...THOUGH THE KENAI NEXRAD IS SHOWING THE
RAIN SHADOW FILLING IN OVER COOK INLET.

UPPER LEVELS A BROAD UPPER TROUGH EXTENDS FROM A LOW SOUTH OF THE
GULF OF ANADYR TO A DEVELOPING CENTER OVER THE NE PACIFIC. THE
COLD UPPER CENTER OVER THE BERING SEA INTENSIFIES AS IT MOVES OVER
BRISTOL BAY FRI AFTERNOON AND INTO THE SW INTERIOR SAT. THE
SECONDARY CENTER OVER THE NE PACIFIC INTENSIFIES AS IT MOVES TO
NEAR KODIAK ISLAND/SW GULF FRI AFTERNOON...THEN MOVES INTO THE
CENTRAL INTERIOR SAT AFTERNOON. TEMPERATURES WILL DROP
SIGNIFICANTLY WITH THE PASSAGE OF THE THROUGH AND PARENT LOW. SNOW
LEVELS AROUND 2000 TO 2500 FT ARE EXPECTED ACROSS THE KENAI
PEN...COOK INLET AND THE MAT/SUSITNA VALLEY SAT MORNING. FREEZING
LEVEL HEIGHT SHOULD RISE OVER MUCH OF SOUTHCENTRAL AND BRISTOL BAY
WITH THE INTRUSION OF WARMER AIR SUN.

&&

.MODEL DISCUSSION...
MODELS HAD SIMILAR AND REASONABLE INITILIZATONS. SYNOPTIC FORECAST
TRENDS ARE SIMILAR AND APPEAR REALISTIC THROUGH THE SHORT TERM. IN
GENERAL THE NAM/GEM REGIONAL WILL BE USED FOR ADJUSTMENTS TO
AFTERNOON FORECAST PACKAGES.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA... A WEATHER FRONT OVER THE WESTERN GULF
MOVES NORTH ACROSS SOUTHCENTRAL OVERNIGHT AND WEAKENS OVER THE
INTERIOR FRI. THE BRUNT OF THE RAIN WITH THIS FEATURE WILL BE
ALONG THE COASTS AND SE EXPOSURES. HOWEVER...LIGHTER RAIN WILL
SPREAD INLAND WITH THE FRONT TONIGHT...EXCEPT FOR THE COPPER RIVER
BASIN WHICH SHOULD GENERALLY REMAIN OF THE DRIER SIDE WITH
DOWNSLOPE. THE SECOND WEATHER FRONT WILL BE STRONGER AND BRING
ANOTHER BATCH OF RAIN TO TO THE NORTH GULF AND SOUTHCENTRAL FRI
AND FRI NIGHT. COLD AIR WITH AND ON THE BACKSIDE OF THIS FRONT
WILL LOWER FREEZING LEVELS ACROSS THE KENAI PEN/COOK INLET AND
NORTH TO THE SUSITNA VALLEY SAT MORNING AND DROP SNOW LEVELS TO
2000 TO 2000FT. ADDITIONALLY...STRONG UPPER LEVEL DYNAMICS WITH
THE UPPER WAVE AND TRAILING COLD UPPER LOW WILL PRODUCE PERIODS OF
LOCALLY MODERATE IN RAIN WITH THE FRONT AND TRAILING SHOWERS SAT.

PRESSURE GRADIENTS WILL REMAIN FAIRLY TIGHT ACROSS SOUTHCENTRAL
TONIGHT AND INCREASE ON FRI WITH THE APPROACH OF THE NEXT FRONTAL
TROUGH. STRONG GAP WINDS WILL CONTINUE THROUGH SAT IN THE FAVORED
LOCALS (TURNAGAIN ARM...KNIK VALLEY...COPPER RIVER). STRONG
PRESSURE RISING ON THE BACK END OF THE FRONT WILL PRODUCE
GENERALLY BROAD AND BRISK SOUTHERLY FLOW ACROSS COOK INLET SAT.

SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...
AS THE LOW REMAINS NEAR OR OVER THE SOUTHWEST MAINLAND...RAIN CAN
BE EXPECTED TO CONTINUE. COLD AIR WILL MOVE IN FROM THE WEST
TONIGHT THROUGH FRI WILL BRING BRING A MIXTURE OF RAIN AND SNOW TO
MANY AREAS...ESPECIALLY OVER THE SW MAINLAND. LOCALLY HEAVY
RAINFALL CAN BE EXPECTED OVER THE MORE INTERIOR LOCATIONS THROUGH
FRIDAY...ESPECIALLY ALONG THE ALASKA RANGE. THE LOW WILL
EVENTUALLY MOVE OFF TO THE NORTH ON SATURDAY...HOWEVER SHOWER
CHANCES WILL CONTINUE THROUGH THE WEEKEND.

&&

LONG TERM FORECAST...
TEMPERATURES WILL BEGIN TO MODERATE EARLY NEXT WEEK AS UPPER RIDGING
BUILDS INTO SOUTHCENTRAL ALASKA. DRIER CONDITIONS CAN ALSO BE
EXPECTED FOR THE FIRST PART OF NEXT WEEK...ALTHOUGH THERE WILL
REMAIN A CHANCE OF RAIN OVER THE SOUTHWEST MAINLAND.

AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 119
FIRE WEATHER...NONE.

RMC MAY 14