Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 040028
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
428 PM AKDT SUN MAY 3 2015

.ANALYSIS AND UPPER LEVELS...

SOUTHCENTRAL ALASKA AND GULF...
A BROADENING UPPER RIDGE AND ASSOCIATED SURFACE HIGH ARE THE
DOMINATING FEATURES IN THE REGION. THE MORNING UPPER AIR SOUNDING
AT ANCHORAGE INDICATED A STRENGTHENING OF THE SUBSIDENCE INVERSION.
IN RESPONSE THE SURFACE PRESSURE GRADIENT WAS RELATIVELY SLACK
THIS MORNING AND SKIES WHERE FAIRLY CLEAR...WITH THE EXCEPTION OF
SHOWERS ACROSS THE WESTERN GULF AND HIGH AND MID CLOUDS OVER COOK
INLET. SEA BREEZES WERE STARTING TO KICK IN ALONG COASTAL LOCALS
THIS AFTERNOON.

OUT WEST...
A VIGOROUS UPPER LOW AND ASSOCIATED SURFACE TROUGH PRODUCED A
VARIETY OF PRECIPITATION TYPES ACROSS THE SW MAINLAND THIS
MORNING. BRISTOL BAY WAS WARM ENOUGH TO GENERALLY EXPERIENCE
RAIN...RAIN WITH A MIXTURE OF SNOW WAS OBSERVED OVER THE LOWER
KUSKOKWIM VALLEY. OVER THE DELTA...PARTICULARLY IN THE GREATER
BETHEL AREA...RAIN FALLING TROUGH A SHALLOW COLD POOL NEAR THE
SURFACE PRODUCED PERIODS OF FREEZING RAIN. PRECIPITATION
DIMINISHED THIS AFTERNOON AND TEMPS WERE WARMING...SO THE
FREEZING RAIN THREAT WAS ENDING AROUND NOON. STORM FORCE EASTERLY
WINDS WERE OBSERVED ALONG THE CENTRAL ALEUTIANS IN ADVANCE OF AN
APPROACHING AND DEVELOPING LOW CENTER. THE LOWS ASSOCIATED FRONTAL
SYSTEM PRODUCED RAIN ACROSS THE ALEUTIANS.

&&

.MODEL DISCUSSION...

MODELS THROUGH TUE AFTERNOON ARE IN VERY GOOD AGREEMENT AND
REASONABLE. THE HIGHER RESOLUTION MODELS WILL BE USED IN THE NEAR
TERM TIME PERIODS WITH A TRANSITION TO THE GLOBAL MODELS
AFTERWARD.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE FOCUS FOR THE NEXT COUPLE DAYS WILL BE AN UPPER LEVEL LOW
PRESSURE SYSTEM SLIDING INTO THE AREA FROM THE SOUTHWEST MAINLAND.
CURRENTLY THE ONLY EFFECT IS HIGH CLOUDS STREAMING INTO THE AREA
THAT HAVE HAD LITTLE EFFECT ON SURFACE TEMPERATURES. AS THE UPPER
LOW PRESSURE AND COLD POOL ALOFT SWING OVERHEAD TOMORROW NEAR PEAK
HEATING...THE CHANCE FOR SHOWERS INCREASES...HOWEVER MOISTURE IS
LACKING AND INSTABILITY IS MEAGER SO ISOLATED MOUNTAIN SHOWERS
REMAINS THE ONLY CHANCE FOR PRECIPITATION WITH THE BEST CHANCES
BEING OVER THE TALKEETNA MOUNTAINS. LIGHT WINDS AND SEA BREEZES
WILL CONTINUE FOR THE NEXT COUPLE DAYS WITH SLIGHTLY ABOVE NORMAL
TEMPERATURES.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE UPPER LOW OVER THE SOUTHWEST MAINLAND WILL CONTINUE TO SUPPORT
A SHOWERY REGIME THROUGH MONDAY. THE LOW WILL THEN WEAKEN INTO AN
OPEN TROUGH AND BEGIN TO LIFT NORTHEASTWARD ON MONDAY EVENING.
THIS WILL LEAD TO THE POTENTIAL FOR A FEW THUNDERSTORMS OVER THE
KUSKOKWIM VALLEY WHERE A FEW BREAKS OF SUNSHINE DURING THE
AFTERNOON WILL ALLOW FOR SURFACE HEATING AND ENHANCED INSTABILITY.
PRECIPITATION WILL THEN BECOME MORE FOCUSED ALONG COASTAL PORTIONS
OF BRISTOL BAY MONDAY NIGHT INTO TUESDAY AS THE WEAKENING FRONT
APPROACHES FROM THE SOUTHEASTERN BERING.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
RAIN AND GUSTY SOUTHEAST WINDS ASSOCIATED WITH THE FRONT CURRENTLY
IMPACTING THE CENTRAL ALEUTIANS WILL SPREAD EASTWARD TOWARDS
DUTCH HARBOR AND THE ALASKA PENINSULA AND ALSO APPROACH THE
PRIBILOF ISLANDS THROUGH MONDAY NIGHT AS THE FRONT GRADUALLY
WEAKENS. RAIN WILL ALSO CONTINUE ACROSS THE WESTERN AND CENTRAL
ALEUTIANS THROUGH TUESDAY BUT WILL BECOME MORE SHOWERY IN NATURE
AS THE FRONT DEPARTS TO THE EAST AND THE PARENT NORTH PACIFIC LOW
REMAINS SOUTH OF ADAK.

&&

.LONG TERM FORECAST (TUE NIGHT THROUGH SAT NIGHT)...
LOW PRESSURE ACROSS THE BERING WILL WEAKEN AS THE LOW CENTER
MOVES EAST TUESDAY NIGHT WITH A RIDGE BUILDING IN ITS WAKE. THE
LOW TRAVERSES EAST ACROSS THE SOUTHERN SIDE OF THE ALEUTIAN CHAIN
MID WEEK AND MOVES A WEAK FRONT ACROSS THE GULF TO THE COAST WEDNESDAY
INTO THURSDAY. RAIN IS EXPECTED ALONG THE BOUNDARY WITH AN INCREASE
IN SOUTHEASTERLY WINDS. A FEW SHOWERS MAY PUSH INLAND...HOWEVER
THEY WILL BE SHORT LIVED AS A DRY AIR MASS SETS UP ACROSS SOUTHCENTRAL
AT THE BEGINNING OF THE WEEK.

LOW PRESSURE BEGINS TO ADVECT BETTER MOISTURE ACROSS SOUTHCENTRAL
TOWARD THE END OF THE WEEK AS THE UPPER LEVEL RIDGE SHIFTS EAST TO
THE ALCAN BORDER. SOUTHEASTERLY FLOW SETS UP ACROSS THE GULF
THURSDAY AHEAD OF THE MAIN UPPER LOW THAT MOVES TO JUST SOUTH OF
THE ALASKA PENINSULA. THIS SYSTEM BRINGS AN INCREASED CHANCE OF
SHOWERS INTO THE WEEKEND ACROSS THE SOUTHERN MAINLAND AS WEAK
SHORTWAVES MOVE AWAY FROM THE LOW CENTER. MODEL CONSENSUS LIFT THE
LOW CENTER NORTH NEXT WEEKEND AS THE ANOTHER LOW CENTER RACES
IN FROM THE PACIFIC.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 172-175 177 178.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...BC
SOUTHCENTRAL ALASKA...MTL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CB
LONG TERM...KH


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