Heavy Freezing Spray Warning 231, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKST SUN DEC 16 2012

.MODEL DISCUSSION...
MODEL SYNOPTIC INITIALIZATIONS WERE REASONABLE AS WELL AS FORECAST
TRENDS. AFTERNOON FORECAST PRODUCTS WILL BE BASED IN PART ON THE GFS
AND ECMWF MODELS...EXCEPT THE NAM WHICH WILL BE USED TO HANDLE
OUTFLOW CONDITIONS IN THE EAST.

.ANALYSIS...
.SOUTHCENTRAL...
STRONG PRESSURE GRADIENTS CONTINUE ALONG THE NORTH GULF COAST WITH
HIGH PRESSURE OVER THE MAINLAND AND LOW PRESSURE OVER THE GULF.
STRONG OUTFLOW WINDS WERE EVIDENT ACROSS THE NORTH GULF COAST WITH
STRONG NW WINDS OVER THE WESTERN GULF. SNOW SHOWERS WERE EVIDENT
ACROSS THE NORTH GULF WITH A FEW SNOW SHOWERS OVER THE COPPER RIVER
BASIN. INCREASED CLOUD COVER ASSOCIATED WITH AN UPPER TROUGH HELP TO
MODERATE OVERNIGHT TEMPS IN THE COPPER RIVER BASIN.

OUT WEST...
WEAK WARM ADVECTION PRODUCED SOME LIGHT SNOW ACROSS THE KUSKOKWIM
DELTA. SNOW OR AND SHOWERS WERE EVIDENT ACROSS THE AK PEN AS A
FRONTAL BAND PUSHED SOUTH. A VIGOROUS LOW PRESSURE SYSTEM OVER THE
CENTRAL BERING SEA AND TRAILING FRONTAL BOUNDARY WAS MOVING EAST
TOWARD THE EASTERN BERING SEA/PRIBILOF ISLANDS. A DEVELOPING NORTH
PACIFIC LOW WAS STARTING TO TAKE SHAPE WELL SW OF THE ALEUTIANS.

.SHORT TERM FORECAST...
OUTFLOW WINDS ARE STILL THE MAIN FEATURE AND WILL CONTINUE THROUGH
MON MORNING AS HIGH PRESSURE CONTINUES OVER THE INTERIOR AND LOW
PRESSURE OVER THE GULF. PRESSURE GRADIENTS SHOULD INCREASE SOME
TONIGHT ALONG THE NORTH GULF AS DECREASING CLOUD COVER ALLOWS TEMPS
TO DROP OVER THE COPPER RIVER AND HELP INTENSIFY THE INTERIOR HIGH.
GALE TO STORM FORCE WINDS/GUSTS WILL CONTINUE TONIGHT THROUGH FAVORED
AREAS ALONG THE NORTH GULF COAST AND WESTERN GULF. MARGINAL HIGH WIND
CONDITIONS FOR TONIGHT IN ZONE 131 ARE STILL A POSSIBILITY WITH
STRONG GRADIENTS(PRESSURE/TEMP) AND SUPPORTING 850/700 MB FLOW. THE
ONLY REAL DETRACTOR IS LACK OF 500 MB SUPPORT. WILL MAKE A DECISION
PRIOR TO FORECAST ISSUANCE. WINDS ACROSS THE REGION WILL DIMINISH ON
MON AS A RIDGE BRIEFLY BUILDS IN ADVANCE OF APPROACHING LOW FROM THE
WEST. THIS LOW CENTER WILL CONTINUE INTO THE SOUTHERN GULF ON MON
NIGHT/TUE. THE MAIN IMPACT TO THE GULF WILL BE RAIN AND SNOW ALONG
THE WINDS TO THE CENTRAL AND WESTERN. THE CURRENT LOW TRACK WOULD
SUGGEST THE PRECIPITATION SHOULD BECOME MIXED AT KODIAK...THOUGH IT
LOOKS LIKE KODIAK CITY AT LEAST WILL GET A FAIR AMOUNT OF SNOW BEFORE
IT BECOMES MIXED.

SOUTHWEST ALASKA...
TEMPERATURES WILL MODERATE BACK ABOVE ZERO...WITH A FEW ISOLATED SNOW
SHOWERS. A MORE SUBSTANTIAL FRONT WILL PUSH OVER MAINLAND SOUTHWEST
ALASKA LATE TONIGHT THROUGH MON...BRINGING ACCUMULATING SNOW ACROSS
THE AREA INTO TUE TUE MORNING. CONDITIONS BECOME SOMEWHAT DRIER ON
TUE NIGHT AND WED AS A RIDGE BUILDS OVER THE EASTERN BERING SEA.

ACROSS THE ALASKA PENINSULA...PERIODIC SNOW SHOWERS WILL CONTINUE
THROUGH THE DAY. A STRONG LOW WILL SLIDE OVER THE AKPEN ON
MON...BRINGING A SHOT OF HEAVY RAIN AND SNOW SHOWERS AND STRONG
WINDS. AN ARCTIC FRONT BEHIND THE LOW WILL BRING VERY STRONG
NORTHWESTERLY WINDS AND SNOW SHOWERS TO THE PENINSULA THROUGH
WED.

ALEUTIANS AND BERING SEA...
A STRONG LOW WILL TRANSLATE FROM WEST TO EAST ACROSS THE ALEUTIANS
LATE THIS AFTERNOON THROUGH MON. PERIODS OF MODERATE TO HEAVY RAIN
AND SNOW WILL ACCOMPANY THE LOW...ALTHOUGH LITTLE TO NO SNOW
ACCUMULATIONS ARE ANTICIPATED. STRONG GALE TO NEAR STORM FORCE WINDS
FROM KISKA EAST AS THE LOW TRACKS OVER THE CHAIN...WITH STRONG
NORTHWESTERLY WINDS CONTINUING OVER THE EASTERN ALEUTIANS
THROUGH TUE.

.LONG TERM FORECAST...
WED AND BEYOND...A DEEP UPPER LOW OVER THE NORTHERN GULF WILL
CONTINUE TO KEEP MUCH OF MAINLAND ALASKA COLD AND DRY...WITH STRONG
OFFSHORE FLOW LASTING INTO FRIDAY. WHILE MUCH DISCREPANCY BEGINS TO
BUILD IN THE GLOBAL MODELS BY THE END OF NEXT WEEK...THE GENERAL
PATTERN WILL FAVOR COLD HIGH PRESSURE OVER INTERIOR ALASKA AND STRONG
FRONTS PUSHING THROUGH THE BERING BEFORE DIVING INTO THE NORTHERN
GULF OF ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WATCH 131.
MARINE...GALES 121 127 128 129 130 132 150 160 165 172 175 179 351
               352 412 413 414.
FIRE WEATHER...NONE.

RMC DEC 12