Gale Warning 999, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AST TUE DEC 18 2007

.ANALYSIS...
THIS AFTERNOON...A SURFACE LOW CONTINUES TO WEAKEN NEAR SHEMYA WITH A
DISSIPATING FRONT OVER THE BERING ACROSS THE EASTERN ALEUTIANS INTO
THE NORTHERN PACIFIC. A 130 KT JET NEAR 43N HELPING TO STRETCH THE
FRONT. A RESIDUAL COLD CORE LOW IN THE GULF WITH A LARGE AREA OF
CONVECTION ENCIRCLING THE LOW. WITH THE COLD AIR POOLED INLAND...A
STRONG SURFACE GRADIENT EXISTS AROUND THE FRINGE OF THE LOW CREATING
SOME MODERATE TO STRONG GAP WINDS ALONG THE COAST. MOST PRECIPITATION
LIMITED TO THE VICINITY OF THE FRONT AND ALONG THE COAST.

.UPPER LEVELS AND MODEL DISCUSSION...
COLD CORE LOW NORTH OF THE URALS WITH A LOW JUST WEST OF THE
KAMCHATKA PENINSULA WITH ANOTHER LOW ANCHORED NEAR BARROW. A PIECE OF
THE KAMCHATKA LOW TO MOVE ACROSS THE BERING WITH THE LOW NEAR BARROW
RETROGRADING TOWARD THE BERING THIS WEEK. THE TWO TO MERGE INTO A
TROUGH LATE THIS WEEK OVER WESTERN ALASKA/EASTERN BERING. THIS LONG
WAVE PATTERN TO REMAIN THROUGH EARLY NEXT WEEK.

MODELS IN GOOD AGREEMENT SYNOPTICALLY FOR THE MOST PART. THE
DIFFERENCES RELATE TO THE ENERGIES ROTATING AROUND THE LARGE LOW
COMPLEXES. THE MAIN MESSAGE IS THAT THE BROAD TROUGH OVER THE BERING
WITH AN ANCHOR OVER THE MAINLAND AND EASTERN SIBERIA WILL CONSOLIDATE
INTO ONE COLD TROUGH OVER WESTERN ALASKA/EASTERN BERING THE END OF
THIS WEEK. THIS TRANSITION IS LEADING TO MANY UNCERTAINTIES IN THE
FORECAST LATER THIS WEEK ESPECIALLY AT THE SURFACE.

.SHORT TERM FORECAST...
SOUTHCENTRAL...
THE LOW IN THE GULF TO REMAIN OVER THE AREA THROUGH WEDNESDAY WITH A
REINFORCING SHORT WAVE MOVING THROUGH SOUTH CENTRAL. THIS WILL KEEP
THE GRADIENT OVER THE GULF COAST WITH MODERATE TO STRONG GAP WINDS
CONTINUING. PRECIPITATION TO REMAIN IN THE GULF OR IMMEDIATE COASTAL
AREAS. HOWEVER...THE LOW CLOUDS AND SNOW SHOWERS WILL CONTINUE IN THE
COPPER RIVER BASIN. THE LOW IS PUSHED OUT OF THE REGION THURSDAY AS A
LOW/FRONT TO MOVE IN FROM THE SOUTH AND BRING SNOW AND RAIN TO
KODIAK. THE FRONT WILL WORK TO THE NORTHERN COAST THURSDAY NIGHT.

ALEUTIANS...
THE LOW NEAR SHEMYA CONTINUING TO WEAKEN AND PULL WEST WITH A
DISSIPATING FRONT OVER THE BERING INTO THE EASTERN ALEUTIANS THROUGH
TONIGHT. MEANWHILE...A STRONG LOW TO DEVELOP SOUTH OF SHEMYA AND
CROSS THE CHAIN BETWEEN ADAK AND SHEMYA WEDNESDAY MORNING. THIS WILL
BRING GALE TO NEAR STORM FORCE WINDS AND PLENTY OF PRECIPITATION TO
THE WESTERN ALEUTIANS. THE LOW TO REMAIN IN THE WESTERN BERING WITH A
FRONT STRETCHING OUT ACROSS THE INTO THURSDAY MORNING. THE LOW TO
WEAKEN THURSDAY NEAR ADAK WITH THE ASSOCIATED FRONT DOING THE SAME.
STRONG WINDS WILL BE ON THE NORTH SIDE OF THIS SYSTEM WITH VERY COLD
AIR TO THE NORTH.

WESTERN ALASKA...
COLD AIR IN PLACE WITH MODERATE NORTHERLY WINDS TO REMAIN OVER THE
AREA THROUGH WEDNESDAY. THE LOW IN THE BERING TO BRING SOME WARMER
TEMPS AND PRECIP TO THE EXTREME COAST AND ALASKA PENINSULA THURSDAY.
COLD AIR TO REMAIN IN PLACE FARTHER INLAND.

.LONG TERM FORECAST...
STARTING THURSDAY...THE UNCERTAINTY IN THE FORECAST IS VERY LARGE.
MODEL GUIDANCE HAS BEEN ALL OVER THE PLACE. SYNOPTICALLY...COLD AIR
MASS WITH SNOW SHOWERS THROUGH THE BERING WITH SYSTEMS ROTATING
THROUGH THE GULF TO THE PANHANDLE OR NORTHERN GULF COAST WITH STRONG
WINDS AND NEAR TO SLIGHT ABOVE NORMAL PRECIPITATION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...STORM 176
         GALE 170 172 175 179
         HEAVY FREEZING SPRAY 121 129 130 138 140 141 150 180 185
FIRE WEATHER...NONE

JN DEC 07