Wind Chill Advisory 25, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKDT SUN MAR 15 2009

.MODEL DISCUSSION...MODELS ARE IN PRETTY GOOD AGREEMENT THROUGH ABOUT
120 HOURS WITH THE LARGE SCALE PATTERN. AS EXPECTED THERE ARE SOME
DISCREPANCIES REGARDING EXACT POSITION AND INTENSITY OF WEAK LOWS IN
THE GULF OF ALASKA AS THEY ROTATE AROUND UNDER THE UPPER LEVEL LOW
TOWARD THE MIDDLE AND END OF THE WEEK.

.ANALYSIS AND UPPER LEVELS...THERE IS A STRENGTHENING UPPER LEVEL
RIDGE OVER THE CENTRAL BERING SEA AND A DIGGING LONGWAVE TROUGH OVER
THE GULF OF ALASKA. AN UPPER LEVEL LOW IS NEAR THE YUKON TERRITORY
AND IS ON THE MOVE TOWARD THE SOUTHWEST BRINGING A STRONG DOSE OF
ARCTIC AIR TO MAINLAND ALASKA. A 150 KT JET DROPS DOWN THE FRONT OF
THE RIDGE IN THE BERING SEA AND CROSSES THE ALEUTIANS NEAR DUTCH
HARBOR BEFORE CONTINUING SOUTHEAST INTO THE NORTH PACIFIC AND
BECOMING ZONAL AROUND 45 DEGREES LATITUDE.

AT THE SURFACE...A 981 MB LOW IS IN THE EASTERN GULF AND MOVING TO
THE NORTHWEST. THIS LOW IS COMBINING WITH HIGH PRESSURE IN THE
CENTRAL BERING SEA TO CREATE STRONG NORTHWESTERLY WINDS OVER THE
EASTERN ALEUTIANS AND SOUTHWEST ALASKA COAST...AND COLD NORTHERLY
OUTFLOW WINDS TO FAVORED AREAS OF THE SOUTHCENTRAL COAST SUCH AS
THOMPSON PASS...SEWARD...WHITTIER...AND THE COPPER RIVER DELTA.

.SHORT TERM FORECAST...
.EAST OF THE ALASKA RANGE...THE MAIN CHALLENGE WILL BE THE GAP WINDS
IN BOTH INLAND AND COASTAL AREAS. WITHOUT UPPER LEVEL JET SUPPORT THE
WINDS SHOULD REMAIN PRIMARILY BELOW WARNING LEVEL THROUGH THOMPSON
PASS AND IN THE MATANUSKA VALLEY. IN ADDITION...WIND CHILLS WILL
REACH ADVISORY CRITERIA IN THE SUSITNA VALLEY AND THOMPSON PASS
SUNDAY NIGHT. AS THE LOW IN THE GULF ROTATES INTO THE WESTERN GULF ON
MONDAY KODIAK ISLAND HAS THE POTENTIAL FOR A WINTER STORM...DEPENDING
ON HOW QUICKLY THE LOW WEAKENS AND THE EXACT TRACK. CONFIDENCE IS TOO
LOW TO ISSUE ANY HEADLINES AT THIS TIME.

.SOUTHWEST ALASKA...GUSTY NORTHERLY WINDS WILL CONTINUE ALONG THE
KUSKOKWIM DELTA AND WILL INTENSIFY DURING THE DAY OVER THE UPPER
KUSKOKWIM VALLEY AND DELTA AS WELL AS THE BRISTOL BAY AREA. A WIND
CHILL ADVISORY HAS BEEN ISSUED FOR ALL OF THE SOUTHWEST MAINLAND.

.BERING SEA/ALEUTIANS...STRONG NORTHWEST FLOW WITH SNOW SHOWERS WILL
CONTINUE FOR SEVERAL DAYS ALONG THE ALASKA PENINSULA AND EASTERN
ALEUTIANS. A WEATHER FRONT WILL STALL AND WEAKEN OVER THE WESTERN AND
CENTRAL ALEUTIANS THROUGH MONDAY AFTERNOON BRINGING MINIMAL WEATHER
IMPACTS.

.LONG TERM FORECAST...THE BERING SEA RIDGE LOOKS TO STAY ESTABLISHED
THROUGH THE END OF THE WEEK. THIS MEANS A CONTINUATION OF GENERALLY
CLEAR AND UNSEASONABLY COLD WEATHER ACROSS MUCH OF MAINLAND ALASKA
AND STRONG WINDS ALONG THE NORTHERN GULF COAST AND EASTERN ALEUTIANS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...WIND CHILL ADVISORY 131 145 151 155 161
MARINE...STORM 120 130 150 155
          GALE 121 125 129 132 138 140 160 165 180 170 172 175 176
               179 351 352 411 412 413 414
FIRE WEATHER...NONE

AMD MAR 09