Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 271250
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
450 AM AKDT MON OCT 27 2014

.ANALYSIS AND UPPER LEVELS...
THE DOMINANT FEATURE ON SATELLITE THIS MORNING IS NOT HARD TO PICK
OUT. A BEAUTY OF A LOW PRESSURE SYSTEM IS WRAPPED UP IN THE FAR
NORTHERN BERING SEA. THE SYSTEM LOOKS TO BE FULLY MATURE AT THIS
POINT WITH THE OCCLUSION SPIRALING INTO THE CENTER OF
CIRCULATION. THE CLOUD/PRECIPITATION SHIELD EXTENDS FROM THE
CHUKCHI PENINSULA EASTWARD THOUGH NORTHERN ALASKA DOWN THROUGH THE
ALASKA RANGE. THE COLD FRONT EXTENDS SOUTHWARD INLAND FROM THE
SEWARD PENINSULA THROUGH THE EASTERN BERING SEA...EVENTUALLY
CROSSING THE ALEUTIANS OVER THE ALASKA PENINSULA. THE FRONT IS
BRINGING MAINLY RAIN TO THE KUSKOKWIM DELTA...BUT THE THERMAL
PROFILE SUGGEST SOME SNOW COULD BE MIXING TO THE
SURFACE...ESPECIALLY FURTHER EAST TOWARD THE KILBUCK MOUNTAINS
WHICH ARE AWAY FROM THE SOUTHERLY MARINE INFLUENCED FLOW. COLD
ADVECTION IS EVIDENT ACROSS THE CENTRAL AND WESTERN BERING SEA
WITH MOST OF THE AREA COVERED WITH OPEN CELL CUMULUS...INDICATIVE
OF THE THERMAL IMBALANCE BETWEEN THE COLD CONTINENTAL AIR
STREAMING OVER THE RELATIVELY WARMER WATER. AN AREA OF ENHANCED
COLD CLOUD TOPS BETWEEN THE FRONT AND THE OPEN CELL CUMULUS
BEARS DOWN ON THE PRIBILOF ISLANDS...SIGNS OF AN UPPER LEVEL
SHORTWAVE TROUGH WITHIN THE LONGWAVE. THE REMAINDER OF THE
SOUTHERN MAINLAND IS RELATIVELY QUIET. SUBSIDENCE ASSOCIATED WITH
THE UPPER LEVEL RIDGE IS KEEPING THE LOW LEVELS DRY AND CLEAR
WHILE SOME HIGHER CIRRUS FROM THE BERING SYSTEM STREAM OVERHEAD.
THE CLEAR CONDITIONS ARE FAVORING SOME EFFICIENT RADIATIONAL
COOLING WITH TEMPERATURES...AND DEW POINTS...TO CRASH WITH THE
LOSS OF DAYTIME HEATING. ALONG THE NORTH GULF COAST...OUTFLOW
WINDS ARE BEGINNING TO LOSE THIS PUNCH BUT ARE STILL GUSTY OUT OF
NORTHERN GAPS.

&&

.MODEL DISCUSSION...
GUIDANCE IS IN GREAT AGREEMENT NOW THE THE BERING SYSTEM HAS FULLY
MATURED. THERE IS CONSENSUS ON THE FRONTAL BOUNDARY STALLING OVER
THE SOUTHWEST MAINLAND DIRECTLY OVER THE KILBUCK MOUNTAINS. A
SHORTWAVE TROUGH OVER THE BERING SEA LOOKS TO IMPINGE ON THE
STALLED OUT FRONTAL BOUNDARY AND CREATE A NEW SURFACE LOW ALONG
THE BOUNDARY. MODELS ARE IN GOOD AGREEMENT ON TRACK OF THAT
SHORTWAVE BUT HAVE NOT YET CONVERGED ON A SOLUTION FOR THE SURFACE
LOW EXCEPT THAT IT WILL BE IN THE ALASKA PENINSULA/BRISTOL BAY
VICINITY. THE GENERAL CONSENSUS IS THAT THIS WAVE WILL BECOME THE
NEW CENTER OF CIRCULATION ALOFT AND MOVE INTO THE GULF OF ALASKA.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...MOSTLY QUIET CONDITIONS FOR THE MAINLAND
TODAY. MOSTLY CLEAR OVERNIGHT CONDITIONS WILL MAKE FOR SOME OF THE
COLDEST LOW TEMPERATURES OF THE SEASON. LINGERING MOISTURE OFF THE
SURFACE WILL KEEP THE THREAT FOR SOME PATCHY FOG AND LOW STRATUS
AROUND KNIK ARM THIS MORNING BUT WE SHOULD NOT SEE ANYTHING
WIDESPREAD COMPARED TO YESTERDAY MORNING. BEGINNING THIS AFTERNOON
THE DEVELOPING LOW NEAR THE ALASKA PENINSULA WILL SEND A FRONT
TOWARD KODIAK ISLAND AND BEGIN TO INCREASING THE SOUTHEASTERLY LOW
LEVEL FLOW IN THE GULF. THIS SYSTEM WILL BE THE FOCUS FOR ACTIVE
WEATHER THROUGH THE WEEK. MORE HIGH CLOUDINESS WILL SPREAD
OVERHEAD FROM THE EAST THROUGH MID-WEEK WITH LOW CLOUDS AND
PRECIPITATION SLOWLY MOVING NORTHWARD IN THE GULF...HITTING THE
NORTH GULF COAST BY WEDNESDAY. EXPECT SEASONABLE TEMPERATURES WITH
GRADUALLY INCREASING CLOUDS THROUGH THE WEEK. THE NEXT BEST
CHANCES FOR PRECIPITATION WILL BE ALONG THE NORTH GULF COAST ON
WEDNESDAY WITH RAIN NEAR THE COAST AND A CHANCE FOR SNOW FURTHER
INLAND.

SOUTHWEST ALASKA...A FRONTAL BOUNDARY PARKED OVERHEAD WILL KEEP
RAIN ACROSS THE MUCH OF THE MAINLAND TODAY THOUGH EASTERN PORTIONS
OF INTERIOR BRISTOL BAY AND THE LOWER KUSKOKWIM VALLEY MAY NOT SEE
MUCH PRECIPITATION. RAIN MAY MIX WITH OR TURN TO SNOW NORTH OF
DILLINGHAM. AS A NEW SURFACE LOW DEVELOPS IN BRISTOL BAY THE LOW
LEVEL FLOW WILL TURN TO THE EAST AND NORTH ACROSS THE
DELTA...PROMOTING A CHANGE FROM RAIN TO SNOW. THE SYSTEM WILL MOVE
INTO THE GULF OF ALASKA TUESDAY AFTERNOON AND SLOWLY DIMINISH
PRECIPITATION ACROSS THE REGION.

BERING SEA/ALEUTIANS...A FRONTAL BOUNDARY WILL BRING RAIN FROM
DUTCH HARBOR EASTWARD TODAY THEN TRANSITION TO A MORE SHOWERY
REGIME IN A GUSTY NORTHWESTERLY FLOW. A SOLID AREA OF GALE FORCE
WINDS BEHIND THE FRONT WILL CONTINUE THROUGH TUESDAY NIGHT. A NEW
FRONTAL BOUNDARY WILL HIT THE WESTERN ALEUTIANS ON TUESDAY
BRINGING SOUTHERLY WINDS AND RAIN.


&&

.LONG TERM FORECAST...
ONCE A NORTH PACIFIC LOW DEVELOPS SOUTH OF KODIAK EARLY ON
WEDNESDAY...THE SOUTHERN MAINLAND WILL EXPERIENCE A PERIOD OF
QUIET WEATHER THAT IS EXPECTED TO CONTINUE THROUGH THE WEEK. THERE
IS NOW MUCH BETTER AGREEMENT WITH THE TRACK OF THIS LOW THAN
YESTERDAY...BUT THE CHALLENGE REMAINS IN DETERMINING ITS
INTENSITY. THE LAST 3 RUNS OF THE EC HAVE BEEN THE MOST
AGGRESSIVE...BRINGING A MID 970 MB LOW TOWARDS THE PANHANDLE
THURSDAY EVENING. SIGNIFICANT SPREAD HOWEVER WAS NOTED BY WPC IN
THE EC ENSEMBLE MEMBERS THIS MORNING (AND A MUCH WEAKER EC
ENSEMBLE MEAN) SO THE FORECAST DOES NOT CAPTURE A LOW THIS DEEP
FOR NOW. THIS SHOULD HAVE A MINIMAL IMPACT ON THE SENSIBLE WEATHER
IN OUR AREA...AS THERE IS STILL CONFIDENCE THAT THIS SYSTEM WILL
STAY SOUTH AND EAST OF THE AOR. THE SOUTHERN MAINLAND IS STILL
EXPECTED TO BE GENERALLY CLEAR AND DRY WITH OFFSHORE FLOW FROM
TUESDAY THROUGH LATE IN THE WEEK.

OVER THE BERING SEA REGION THERE IS MUCH BETTER AGREEMENT THAT THE
ALEUTIAN LOW ENTERING THE AREA ON TUESDAY WILL STRUGGLE TO REACH
THE SOUTHWEST COAST BY THE END OF THE WEEK. THIS SYSTEM WILL BRING
RAIN AND SNOW WITH GUSTY WINDS TO THE BERING SEA AND ALEUTIANS
STARTING TUESDAY AND CONTINUING THROUGH LATE IN THE WORK WEEK.
THIS LOW THEN APPEARS TO BRING THE NEXT CHANCE OF PRECIPITATION TO
THE SOUTHERN MAINLAND BY NEXT WEEKEND.


&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 155 165 170 171 172 173 174 175 176 177 178 179 185.
FIRE WEATHER...NONE.

&&

$$

MTL OCT 14



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