Small Craft Advisory 90, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 PM AST THU JAN 31 2008

.MODEL DISCUSSION...MODELS ARE SLOWLY IMPROVING AND BECOMING MORE
CONSISTENT. LATEST RUNS KEEP THE LOWS AT OR JUST SOUTH OF THE
ALEUTIANS AS THEY DEVELOP ALONG THE JET. THIS IS GOOD SINCE IT IS THE
SOLUTION THAT HAS BEEN USED THE LAST FEW DAYS IN THE FORECASTS AS THE
MODELS WERE CHANGING SIGNIFICANTLY FROM RUN TO RUN. IN PARTICULAR THE
GFS HAS STABILIZED AND IS THE BASIC GUIDANCE FOR THE FORECAST
PACKAGES TODAY.

.ANALYSIS AND UPPER LEVELS...STRONGEST PART OF THE 250 MB JET
CONTINUES TO BE OFF EASTERN ASIA OUT TO AROUND 170E. IT THEN WEAKENS
SOME AS IT SKIRTS JUST SOUTH OF THE ALEUTIAN ISLANDS AND THE GULF OF
ALASKA. THE BIGGEST LOW IN THE AREA IS NEAR KISKA AND SITUATED IN THE
UPPER LEVEL TROUGH. THIS LOW WILL DRIFT WESTWARD AS THE UPPER TROUGH
AMPLIFIES OVER THE FAR WESTERN BERING SEA. THIS AMPLIFICATION WILL
COINCIDE WITH THE BUILDING OF THE UPPER LEVEL RIDGE OVER THE ALASKA
PENINSULA THAT WILL PUSH THE JET FARTHER NORTH AND INCREASE ITS SPEED
TO OVER 150 KT THIS WEEKEND.
THE OCCLUDED FRONT ASSOCIATED WITH THIS LOW IN THE WEST IS MOVING
ACROSS THE ALEUTIANS AND INTO THE ALASKA PENINSULA.
A WEAK SHORT WAVE IS OVER SOUTH CENTRAL ALASKA THIS AFTERNOON AND
MOVING EASTWARD. THIS WAVE HAS BROUGHT SOME MID LEVEL CLOUDS BUT NO
PRECIPITATION.
HIGH PRESSURE AT THE SURFACE EXTENDS OUT OF THE YUKON THROUGH
SOUTHWEST ALASKA AND THEN OVER THE ALASKA PENINSULA. THIS HIGH
PRESSURE WILL MAINLY REMAIN IN PLACE THROUGH THE WEEKEND.
A WEAK LOW ALONG THE NORTH GULF COAST IS ENHANCING WINDS ALONG THE
COAST. THIS LOW WILL PERSIST FOR ANOTHER DAY BEFORE FINALLY
DISSIPATING.

.SHORT TERM FORECAST...AREAS OF FOG AND STRATUS WILL DEVELOP IN
MAINLAND ALASKA AGAIN...ESPECIALLY NEAR THE COASTS OR IN VALLEYS.
PRECIPITATION WILL BE LIMITED TO THE ALASKA PENINSULA AND ALEUTIAN
ISLANDS ALONG THE FRONT.
THOMPSON PASS HAS HAS A WIND CHILL ADVISORY THE LAST FEW DAYS WITH
STRONG WINDS AND TEMPERATURES BELOW ZERO DROPPING WIND CHILLS TO 40
BELOW. THIS IS EXPECTED TO SLOWLY IMPROVE AS THE GRADIENT WILL RELAX
AND WINDS DECREASE TONIGHT.

.LONG TERM FORECAST...NOT A LOT OF CHANGE IN THE OVERALL PATTERN FOR
MOST OF THE AREA. PRECIPITATION WILL BE PUSHED A LITTLE FARTHER NORTH
THIS WEEKEND IN RESPONSE TO THE JET STREAM AND LOW PRESSURE TRACK
MOVING NORTHWARD. SURFACE HIGH PRESSURE WILL REMAIN OVER THE INTERIOR
OF THE STATE. THE OVERALL PATTERN CHANGE IS SO LITTLE THAT AT 120
HOURS OUT IT LOOKS A LOT LIKE IT DOES FOR THE MODEL INITIALIZATION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 172 175 176.
         HEAVY FREEZING SPRAY 121 185.
FIRE WEATHER...NONE.

JAN 08