Heavy Freezing Spray Warning 42, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
515 AM AKST MON JAN 16 2012

.ANALYSIS AND UPPER LEVELS...A HIGHLY AMPLIFIED RIDGE THAT STRETCHES
FROM THE 40 N PARALLEL COVERS MUCH OF THE EASTERN AND CENTRAL BERING
THIS MORNING. AS A RESULT...DRY NORTHERLY UPPER LEVEL FLOW DOMINATES
MAINLAND ALASKA. A 100 KT JET IS LOCATED OVER SOUTHWEST MAINLAND
ALASKA...BUT IT IS ONLY SUPPORTING A WEAK TROUGH OVER THE EASTERN
GULF OF ALASKA. TO THE EAST...THE CLOSEST UPPER LEVEL LOW IS CENTERED
ALONG THE EASTERN BOUNDARY OF THE NORTHWEST TERRITORIES. DESPITE ITS
DISTANCE FROM ALASKA...A SHORTWAVE ASSOCIATED WITH THIS LOW BRIEFLY
BOOSTED GUSTS TO OVER 50 MPH AT VALDEZ THIS MORNING.

.AT THE SURFACE...THE MAIN WEATHER STORY FOR MAINLAND ALASKA
CONTINUES TO BE GUSTY WINDS THROUGH LOCAL GAPS. ALTHOUGH SURFACE HIGH
PRESSURE OVER THE MAINLAND IS DECREASING IN INTENSITY AS THE UPPER
LEVEL RIDGE MOVES WESTWARD...GAP WINDS ARE EXPECTED TO REMAIN STRONG
AND EVEN STRENGTHEN IN SOME PORTIONS OF SOUTHCENTRAL TODAY. BOTH THE
SURFACE PRESSURE GRADIENT AND MID LEVEL WINDS ARE EXPECTED TO HAVE A
MORE FAVORABLE ORIENTATION TODAY AS THE UPPER LEVEL SHORTWAVE
CONTINUES TO PROGRESS WEST. OUT WEST...A STRONG FRONTAL BOUNDARY
EXTENDS ACROSS THE CENTRAL AND EASTERN ALEUTIANS. A LOW LEVEL JET
THAT LIES ALONG THIS BAROCLINIC ZONE IS BRINGING GUSTY WINDS TO THE
REGION. THIS JET IS ALSO HELPING TO TRANSPORT MOISTURE NORTHWARD INTO
THE WESTERN BERING.

.MODEL DISCUSSION...
WITH SUCH STRONG FEATURES IN PLACE...MODELS ARE IN EXCELLENT
AGREEMENT THIS MORNING. THE NAM MODEL WAS FAVORED FOR THE SHORT TERM
DUE TO ITS ABILITY TO CAPTURE ALL OF THE LOCAL GAP WINDS.  IN THE
LONG TERM...MODELS DIVERGE BUT MAINTAIN THE SAME GENERAL FEATURES.  A
BLEND OF THE GFS MODEL AND HPC GUIDANCE WAS USED.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...WELL BELOW-NORMAL TEMPERATURES WILL CONTINUE ACROSS
THE SOUTHCENTRAL REGION THE NEXT FEW DAYS AS CLEAR SKIES PERSIST.
THESE COLD TEMPERATURES...AND THE ANOMALOUSLY STRONG HIGH SURFACE
PRESSURE OVER THE MAINLAND WILL CONTINUE TO SUPPORT GUSTY GAP WINDS.
WITH THE MAIN UPPER LEVEL RIDGE AXIS LOCATED OVER THE BERING...THE
SOUTHCENTRAL REGION WILL BE IMPACTED BY A SERIES OF SHORTWAVES THE
NEXT FEW DAYS. NO GOOD MOISTURE SUPPLY EXISTS NEAR THE SOUTHCENTRAL
REGION...SO THE MAIN IMPACT OF THESE SHORTWAVES WILL BE TO
PERIODICALLY ENHANCE GAP WINDS. THE MOST IMPRESSIVE SHORTWAVE WILL
DIG ACROSS THE REGION TUESDAY AFTERNOON AND HELP TO CUT OFF THE
BERING RIDGE.

.SOUTHWEST MAINLAND...THE PRESSURE GRADIENT BETWEEN THE HIGH PRESSURE
OVER MAINLAND ALASKA AND TROUGHING ACROSS THE WEST AND CENTRAL BERING
WILL SUPPORT NORTHEASTERLY FLOW ACROSS MUCH OF SOUTHWEST MAINLAND
TODAY. THE RIDGE ALOFT SHOULD SUPPORT GENERALLY CLEAR
SKIES...ALTHOUGH SOME MORNING STRATUS IS EXPECTED TO LINGER NEAR
BETHEL.

.ALEUTIANS...THE FRONT THAT LIES ALONG THE CENTRAL ALEUTIANS WILL
MOVE SLOWLY WESTWARD OVER THE NEXT FEW DAYS. THIS BAROCLINIC REGION
WILL SUPPORT STEADY RAIN AND GUSTY WINDS.

.LONG TERM FORECAST...MODELS MAINTAIN RIDGING OVER THE MAINLAND OVER
THE NEXT WEEK...BUT SLOWLY SHIFT THE CENTER OF HIGH PRESSURE WESTWARD
IN TO THE BERING. AS A RESULT...MODELS INDICATE THE POSSIBILITY OF A
STRONG LOW PRESSURE SYSTEM SNEAKING INTO THE EAST GULF BY NEXT
WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...STORM 172 175
         GALE  170 171 176 179 185
         HEAVY FREEZING SPRAY 121 129 138 140 141 165 179
FIRE WEATHER...NONE

ELN JAN 12