Gale Warning 842, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AKST SUN NOV 8 2009

.MODEL DISCUSSION...MODELS REMAIN IN GOOD AGREEMENT IN THE SHORT TERM
IN THE GULF OF ALASKA REGION AND THEN DIVERGE GREATLY TOWARD THE
MIDDLE TO LATER PART OF THE WEEK. THEY ARE STILL A BIT UNSETTLED IN
THE BERING SEA.
FOR THE GULF FROM WEDNESDAY ON THE MODELS ARE IN A STATE OF FLUX. THE
GFS TOOK A WILD CHANGE FROM PREVIOUS RUNS FOR WEDNESDAY NIGHT AND
THURSDAY DEVIATING FROM THE LONG WAVE PATTERN IT HAD ESTABLISHED FROM
NUMEROUS PREVIOUS MODELS RUNS. THE ECMWF HAS ALSO MADE A BIT OF A
CHANGE BUT HAS NOT JUMPED TO A COMPLETELY DIFFERENT LONG WAVE
SITUATION AS THE GFS HAS. THERE IS NOTHING ABOUT THE TWO MODELS THAT
AGREE FROM WEDNESDAY NIGHT ON IN THE GULF AND EASTERN PART OF THE
FORECAST AREA. THE SUSPICION IS THAT THE SOLUTIONS WILL BRING THE LOW
A BIT WEAKER AND FARTHER EAST AS NEWER MODEL RUNS COME IN.

TAKING A LOOK AT THE BERING SEA REGION SHOWS THE GFS AND ECMWF BEING
CLOSE ON THE TIMING AND STRENGTH OF THE FIRST LOW THAT WILL MOVE
THROUGH THE NORTHERN BERING SEA. THE UKMET IS A LITTLE TOO FAR SOUTH
AND THE NAM WANTS TO HAVE A SECONDARY CENTER SOUTH OF THE MAIN LOW
THAT DOES NOT LOOK LIKELY.
FOR THE SECOND LOW THE THREE HEMISPHERIC MODELS ARE PUTTING THE SAME
TRACK BUT VARY ON THE INTENSITY. THE STRONGEST IS THE ECMWF RUN FROM
12Z TODAY WHICH DROPS IT INTO THE LOWER 960S BY TUESDAY NIGHT NORTH
OF THE BERING STRAIT. THE GFS IT ABOUT 10 MB WEAKER AND UKMET IS
WEAKER THAN THAT. THE MAIN ISSUE TO WATCH FOR SOUTHWEST ALASKA WITH
THIS SYSTEM IS THE SLIGHT THREAT OF COASTAL FLOODING IN THE NORTHERN
PART OF THE KUSKOKWIM DELTA. THIS PROBABLY WILL NOT HAPPEN DUE TO THE
TRACK BUT IT IS WORTH WATCHING IF THE LOW BECOMES AS STRONG AS THE
ECMWF IS FORECASTING...THOUGH IT IS NOT EXPECTED TO BE THAT STRONG AT
THIS POINT.

.ANALYSIS AND UPPER LEVELS...THERE IS A LONG WAVE TROUGH THAT
STRETCHES DOWN THE ALCAN BORDER AND THROUGH THE EASTERN GULF OF
ALASKA. THIS TROUGH WILL REMAIN NEARLY STATIONARY FOR THE NEXT DAY
AND THE LIFT TO THE NORTHEAST MONDAY NIGHT. THE UPPER LEVEL RIDGE IN
THE NORTH PACIFIC THAT EXTENDS NORTHWARD INTO THE CENTRAL BERING SEA
WILL EASE EASTWARD AND TWO LOWS WILL RIDE OVER IT IN THE NORTHERN
BERING SEA IN THE FIRST PART OF THE WEEK.
NARROWING DOWN THE FOCUS THERE IS AN UPPER LEVEL SHORT WAVE THAT IS
MOVING EASTWARD FROM BRISTOL BAY WHICH WILL COMBINE WITH A SURFACE
LOW THAT IS STRENGTHENING NEAR MIDDLETON ISLAND. THIS IS WHAT IS
BRINGING SOME SNOW INTO AREAS OF SOUTH CENTRAL ALASKA AND THE GULF
COAST TODAY INTO TONIGHT.

.SHORT TERM FORECAST...THE TRICKIEST AREA OF THE FORECAST TODAY IS IN
THE COOK INLET REGION AS TO WHETHER THERE WILL BE MUCH SNOW WITH THE
SHORTWAVE THAT IS APPROACHING THE AREA. THE SET UP IS NOT ONE THAT
SHOULD GIVE MUCH SNOW IN THE ANCHORAGE OR MAT-SU VALLEY AREAS BUT ONE
INCH OR LESS NEAR SEA LEVEL RANGING UP TO 3 INCHES AT ELEVATION LOOKS
REASONABLE.
THE COPPER RIVER BASIN SHOULD SEE CONTINUED LIGHT SNOWFALL WITH THIS
SYSTEM.
THE ALASKA PENINSULA THROUGH ALEUTIAN ISLANDS WILL CONTINUE IN THE
GUSTY NORTHWEST WINDS AND RAIN OR SNOW SHOWERS.

.LONG TERM FORECAST...THE CONFIDENCE IN THE FORECAST FOR THE MIDDLE
TO LATER PART OF THE WEEK IS MUCH LOWER TODAY THAN YESTERDAY AS THE
MODELS HAVE MADE SOME MAJOR CHANGES. IF MODELS DO INDEED BRING A
WEAKER LOW EAST OF COOK INLET AS SPECULATED IN THE MODEL DISCUSSION
SECTION...THE CHANCE OF SNOWFALL IN SOUTH CENTRAL ALASKA WILL BE
INCREASED AGAIN FOR LATER THIS WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 130 150 172.
FIRE WEATHER...NONE.

NOV 09