Wind Chill Advisory 17, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTH CENTRAL AND SOUTHWEST ALASKA
500 PM AKST TUE JAN 5 2009

.ANALYSIS AND UPPER LEVELS...STILL HAVE THE OMEGA BLOCK OVER RUSSIA
AND COMPLEX UPPER LEVEL LOW LOW SOUTHWEST  OF SHEMYA MOVING NORTHEAST
WHILE A SECOND LOW OVER THE NORTHEAST GULF CONTINUES TO SLOWLY DRIFT
INTO CANADA. THE ELONGATED TROUGH ALONG THE BERING IS SLOWLY DRIFTING
SOUTH.

AT THE SURFACE...WEAK LOW PRESSURE IN THE NORTHERN GULF IS DRIFTING
SOUTH WHILE THE HIGH PRESSURE OVER THE MAINLAND CONTINUES TO PUSH
COLD AIR SOUTH. THE PRESSURE GRADIENT ALONG THE NORTH GULF COAST IS
RELAXING A BIT.

.MODEL DISCUSSION...CONSISTENCY AND AGREEMENT FOR THE FORECAST AREA
REMAINS DECENT THROUGH THURSDAY. THE BIG ISSUE IS THE PLACEMENT AND
INTENSITY OF THE LOW APPROACHING THE GULF OF ALASKA THURSDAY. AT THIS
POINT WE ARE GOING TO MOVE THE FORECASTS TO THE ECMWF SOLUTION AS IT
HAS BEEN THE MOST CONSISTENT LATELY. THIS WILL INTRODUCE CHANGES IN
THE MARINE FORECAST IN THE GULF COASTAL WATERS THOUGH CONFIDENCE IN
THE FORECAST WILL REMAIN LOW.

THE UPPER LEVEL WEST FLOW WILL BECOME MORE SOUTHERLY AS THE UPPER LOW
MOVES TO SOUTH OF THE EASTERN ALEUTIANS THU. THE MORE SOUTHERLY FLOW
SHOULD HELP TO ALLOW THE MORE MOIST AND WARMER AIR PENETRATE INTO THE
SOUTHERN MAINLAND THIS WEEKEND.

.SHORT TERM FORECAST...

SOUTH CENTRAL...THE MAIN ISSUE REMAINS THE STRONG OUTFLOW GAP WINDS
ALONG THE ALASKA RANGE AND CHUGACH MOUNTAINS. WE ARE ANTICIPATING
SOME RELAXING OF THE GRADIENT WHICH WILL REDUCE THE MAGNITUDE OF THE
CHANNELED WIND WEDNESDAY. LOW WIND CHILL REMAINS A PROBLEM ALONG THE
ALASKA RANGE AND CHUGACH MOUNTAINS TODAY AND TONIGHT BUT EXPECT THE
WIND CHILL TO IMPROVE WEDNESDAY AS WIND DECREASES.

IN THE SOUTHWEST...THE SOUTHWEST MAINLAND WILL CONTINUE WITH OFFSHORE
FLOW INTO THIS COMING WEEKEND. CLOUDS HAVE SPREAD OVER THE WESTERN
ALASKA PENINSULA. THE TROUGH IS ELONGATING TO THE EAST AND THE CLOUDS
SHOULD PUSH OVER THE REMAINDER OF THE PENINSULA TONIGHT AND INCREASE
THE POTENTIAL FOR PRECIPITATION ALONG THE PENINSULA WED NIGHT AND
THU. THE REMNANTS OF THE FRONT STRETCHES ALONG THE LENGTH OF THE
ALEUTIANS AND HAS MODERATE EAST WIND AND SOME SNOW SHOWERS ASSOCIATED
WITH IT THAT SHOULD PERSIST THROUGH WED. AS THE NEXT STORM APPROACHES
FROM THE SOUTH EXPECT NORTHEAST TO NORTH WIND TO INCREASE ALONG THE
CHAIN WED WITH THE CHANCE FOR BLIZZARD CONDITIONS FOR THE CENTRAL
ALEUTIANS AS THIS LOW MOVES NORTH.

.LONG TERM FORECAST...THE MODELS ARE NOT PERFORMING WELL IN THE LONG
TERM SO CONFIDENCE IS LOW BEYOND THURSDAY. AT THIS POINT WE ARE
MOVING THE EXTENDED FORECAST TO THE ECMWF SOLUTION SINCE IT HAS HAD
SOME RUN TO RUN CONTINUITY. THE OVERALL TREND WILL BE FOR THE STORM
TRACK TO BRING THE LOWS FURTHER NORTH FRI AND SAT RESULTING IN WARMER
MORE MOIST CONDITIONS ALONG THE SOUTHERN MAINLAND AND GULF OF ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE WARNING...172 176.
         HEAVY FREEZING SPRAY WARNING...121 129 140 160 179 185.
FIRE WEATHER...NONE

SAM JAN 09