Gale Warning 109, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 PM AKST WED JAN 30 2013

.ANALYSIS AND UPPER LEVELS...

UPPER LEVEL TROUGHS EXTEND SE AND SW FROM A BROAD NORTHERN BERING LOW
THIS AFTERNOON WITH NUMEROUS ILL-DEFINED ASSOCIATED WAVES IN THE GULF
AND OVER THE AKPEN. AT THE SURFACE...A BROAD AREA OF LOW PRESSURE IS
OVER THE NORTHERN HALF OF THE BERING WITH WEAK LOW PRESSURE OVER
BRISTOL BAY. A TROUGH OF LOW PRESSURE EXTENDS FROM THE BRISTOL BAY
LOW ACROSS THE AKPEN TO THE SOUTHEASTERN GULF. THIS TROUGH IS MOVING
INTO THE KENAI PENINSULA.

.MODEL DISCUSSION...

HOWEVER...OVERNIGHT MODELS HAD DIFFICULTY TIMING THE WIDESPREAD
DRYING OVER THE KENAI PENINSULA THIS MORNING. 12Z MODELS ARE IN
GOOD AGREEMENT DEALING WITH THE POSITION AND MOVEMENT OF THE WAVE
APPROACHING THE KENAI...BUT THE NAM IS THE MOST SUCCESSFUL IN
CATCHING UP TO ACTUAL CONDITIONS. IT IS BEST AT PORTRAYING DOWNSLOPE
DRYING NORTHWEST OF THE KENAI AND CHUGACH MOUNTAINS...FOLLOWED BY
PRECIPITATION RETURNING TO THE KENAI AND SOUTHCENTRAL THIS AFTERNOON
INTO THE EVENING...AS THE UPPER LEVEL TROUGH MOVES NORTHEAST. THIS
UPPER LEVEL TROUGH WILL THEN LINGER ACROSS SOUTHCENTRAL UNTIL MOVING
TO THE ALCAN THU AFTERNOON INTO THU EVENING. ON FRI A FRONT FROM A
NORTH PACIFIC LOW ENTERS THE GULF AND REACHES THE NORTHEAST GULF
COAST FRI NIGHT BEFORE DISSIPATING. A THIRD FEATURE IN THE FORM OF
YET ANOTHER WEAK WAVE APPROACHES THE GULF COAST FRI NIGHT INTO SAT.

IN THE WEST...HIGH PRESSURE BUILDS OVER THE EASTERN BERING BEHIND THE
AKPEN/KENAI PENINSULA WAVE. THIS KEEPS AN ELONGATED TROUGH OF LOW
PRESSURE OVER THE WESTERN BERING. LOWS DEVELOP ALONG THIS
TROUGH AND FINALLY CONSOLIDATE WITH A CENTER SOUTH OF THE CENTRAL
ALEUTIANS FRI NIGHT AND A FRONT AFFECTING THE CHAIN FRI NIGHT THROUGH
SAT. THE FORECAST FOR BOTH DOMAINS UTILIZES THE NAM THROUGH THE SHORT
TERM.

.SHORT TERM FORECAST...

IN THE WEST...SCATTERED SNOW SHOWERS TONIGHT DIMINISH ON THU. SNOW
WILL DEVELOP LATER ON THU AS SOUTHERLY SMALL CRAFT AND GALE FORCE
WIND AFFECT THE WESTERN ALEUTIANS THROUGH FRI. AS THE CONSOLIDATED
LOW NEAR THE CENTRAL ALEUTIANS MOVES EAST...SNOW SHOWERS WILL BEGIN
TO DIMINISH OVER THE CHAIN THROUGH SUN.

FOR SW AK...HIGH PRESSURE WILL END PRECIPITATION TONIGHT AND KEEP THE
AREA DRY UNTIL WRAPAROUND MOISTURE FROM THE EASTWARD MOVING ALEUTIAN
LOW ARRIVES SAT AFTERNOON.

SOUTH AND EAST OF THE AK RANGE...SNOW OVER SOUTHCENTRAL TONIGHT MAY
MIX WITH A BIT OF FREEZING RAIN OVER THE NORTHERN KENAI AND ANCHORAGE
BOWL. OTHERWISE SNOW WILL MOVE NORTH WITH SIGNIFICANT AMOUNTS IN
UPSLOPE AREAS OF THE SUSITNA VALLEY. WARM AIR ALOFT WILL END
OVERNIGHT AND SNOW SHOWERS WILL LINGER ACROSS THE REGION UNTIL THE
UPPER TROUGH MOVES TO THE ALCAN THU NIGHT. A FRONT ASSOCIATED WITH A
NORTHERN PACIFIC LOW WILL BRING ANOTHER ROUND OF RAIN AND SNOW TO
COASTAL AREAS FRI INTO SAT.

.LONG TERM FORECAST...

IN THE WEST SNOW WILL DEVELOP MON INTO TUE. SW AK WILL DRY LATER ON
MON INTO TUE...AND SOUTHCENTRAL WILL HAVE COASTAL RAIN AND INLAND
SNOW SHOWERS AS A SERIES OF FRONTS MOVES INLAND THROUGH TUE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALES 120 125 150 155
         HEAVY FREEZING SPRAY 179
FIRE WEATHER...NONE

DS JAN 13