Gale Warning 444, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
150 PM AKDT THU JUN 27 2013

.ANALYSIS AND UPPER LEVELS...
AT THE UPPER LEVELS THERE IS A CLOSED HIGH OVER THE EASTERN INTERIOR
OF THE STATE AS WELL AS A RIDGE OF HIGH PRESSURE OVER THE EASTERN
BERING SEA. MEANWHILE...A LONGWAVE TROUGH RESIDES OVER THE WESTERN
1/3 OF THE BERING SEA...AND A VERTICALLY STACKED LOW OVER THE FAR
SOUTHERN GULF MOVING AWAY FROM THE REGION. MUCH OF MAINLAND ALASKA IS
CAUGHT BETWEEN THESE WEATHER SYSTEMS...WITH WEAK STEERING FLOW ALOFT.
AT THE SURFACE...WEAK HIGH PRESSURE OVER THE GULF AND EASTERN BERING
IS LEADING TO GENERAL SOUTHERLY FLOW FOR MANY COASTAL AREAS OF THE
MAINLAND...WITH WIDESPREAD MARINE STRATUS AND FOG PLAGUING THE
COASTLINES THIS MORNING FROM COOK INLET TO THE BRISTOL BAY AND
KUSKOKWIM DELTA ZONES. MOSTLY SUNNY SKIES CONTINUE OVER MOST INLAND
AREAS...WHICH WILL LEAD TO ANOTHER DAY OF DIURNAL CONVECTION...ALBEIT
MUCH LESS INTENSE THAN YESTERDAY. OUT WEST...WIDESPREAD MARINE FOG
AND STRATUS ARE EVIDENT ON SATELLITE IMAGERY ACROSS VIRTUALLY ALL OF
THE BERING SEA. A RELATIVELY WEAK LOW AND ASSOCIATED FRONT IS
APPROACHING THE CENTRAL ALEUTIANS TODAY...MIXING THE LOWER ATMOSPHERE
ENOUGH TO LIFT CLOUD HEIGHTS AS WELL AS BRING SOME LIGHT RAIN.

.MODEL DISCUSSION...
THE MAJOR MODELS ARE IN OUTSTANDING OVERALL AGREEMENT THROUGH THE
SHORT TERM FORECAST PERIOD. THE LOW IN THE SOUTHERN GULF WILL
CONTINUE TO RETREAT TO THE SOUTH...ALLOWING HIGH PRESSURE TO REMAIN
IN PLACE ACROSS MUCH OF THE MAINLAND THROUGH SATURDAY. DIURNAL
CIRCULATIONS WILL HELP TO PULL MARINE STRATUS ONSHORE MANY COASTAL
AREAS EACH OF THE NEXT FEW EVENINGS. BY SATURDAY...A PATTERN-CHANGING
LOW CENTER WILL ENTER THE WESTERN BERING AND PULL THE ENTIRE LONGWAVE
TROUGH TO THE EAST AND SETTING UP THE MAINLAND WITH MOIST SOUTHWEST
FLOW FOR THE START OF NEXT WEEK.

.SHORT TERM FORECAST...
SOUTHCENTRAL...WITH THE THERMAL TROUGH REMAINING ALONG THE ALASKA
RANGE EXPECT SOME ISOLATED THUNDERSTORMS TO DEVELOP ONCE AGAIN THIS
AFTERNOON OVER THE COPPER BASIN...NORTHERN SUSITNA VALLEY...AND
TALKEETNA MOUNTAINS NORTH OF PALMER. A WEAK SHORTWAVE MOVING FROM
EAST TO WEST WILL PROVIDE MINIMAL SUPPORT FOR CONVECTION TODAY...BUT
MAY TIP THE SCALES JUST ENOUGH TO BRING SHOWERS AS FAR SOUTH AS THE
NORTHERN KENAI MOUNTAINS LATE THIS AFTERNOON. OVERNIGHT TONIGHT...THE
WEAK SHORTWAVE STALLS OVER UPPER COOK INLET AS WEAK DIFFLUENCE ALOFT
ALSO MOVES INTO THE AREA FROM THE SOUTHWEST. THIS WILL LIKELY RESULT
IN WIDESPREAD LOW CLOUDINESS AND WEAK LIFT ACROSS THE ANCHORAGE AND
MAT-SU REGION TONIGHT THAT CONTINUES THROUGH MUCH OF THE DAY
TOMORROW. A MINIMAL THUNDERSTORM RISK WILL CONTINUE TOMORROW OVER THE
COPPER RIVER BASIN...WHICH LOOKS LIKE IT WILL BE THE MAIN AREA WITH A
CHANCE TO SEE SUFFICIENT SUNSHINE TO DESTABILIZE THE ATMOSPHERE.

SOUTHWEST MAINLAND...TRAPPED MOISTURE OVER EASTERN SECTIONS OF THE
BRISTOL BAY ZONE AND LOWER KUSKOKWIM VALLEY WILL SLOWLY BURN OFF THIS
AFTERNOON...BUT NOT IN TIME TO ALLOW MUCH IN THE WAY OF ATMOSPHERIC
DESTABILIZATION. AND WITH THE THERMAL TROUGH RETREATING TO THE
NORTHEAST DO NOT EXPECT ANY SIGNIFICANT THUNDERSTORM ACTIVITY TO
REPEAT THIS EVENING. FOG AND STRATUS BURNED OFF EARLY THIS AFTERNOON
OVER THE DELTA AND ALONG THE ALASKA PENINSULA...BUT SHOULD RETURN
OVERNIGHT TONIGHT AS ONSHORE FLOW CONTINUES ACROSS THE AREA. BY LATE
FRIDAY AFTERNOON SCATTERED SHOWERS WILL DEVELOP INLAND AS DIURNAL
HEATING COMBINES WITH MINOR DYNAMIC SUPPORT FROM SOME SHORTWAVES
AHEAD OF THE BERING TROUGH.

BERING SEA AND ALEUTIANS...WIDESPREAD FOG AND STRATUS WILL HANG ON
FOR ANOTHER DAY BEFORE MORE UNSETTLED WEATHER STARTS TO MOVE IN FROM
THE WEST FRIDAY NIGHT. A WEAK LOW SOUTH OF THE CENTRAL ALEUTIANS THIS
AFTERNOON IS BRINGING SOME INCREASED WINDS AND RAIN...BUT IS
WEAKENING AND WILL NOT BE STRONG ENOUGH TO IMPACT THE ORGANIZATION OF
MARINE FOG/STRATUS ACROSS A LARGER AREA. THE MAIN WEATHER IMPACT OVER
THE NEXT SEVERAL DAYS WILL BE THE VERTICALLY STACKED LOW MOVING IN
THIS WEEKEND. THE WEATHER FRONT WILL NOT BE OVERLY STRONG...GENERALLY
NOT EXCEEDING 30 KTS...BUT WILL CHANGE THE OVERALL WEATHER PATTERN
AND BRING A WETTER PATTERN BACK TO THE REGION.

.LONG TERM FORECAST...
BY MONDAY THE LONGWAVE TROUGH SLIDE EAST AND BE CENTERED OVER THE
WEST COAST OF ALASKA. THIS WILL SET MOST OF THE STATE UP UNDER
SOUTHWEST FLOW AT ALL LEVELS. THIS IS A HIGH-CONFIDENCE RAINY PATTERN
FOR VIRTUALLY ALL AREAS OF THE MAINLAND...WHICH WILL BRING AN END TO
THE CYCLE OF DIURNAL CONVECTION AND INSTEAD RESULT IN WETTER
CONDITIONS OVER A MUCH BROADER AREA. TEMPERATURES WILL DROP TO NEAR
NORMAL...OR EVEN SLIGHTLY BELOW NORMAL FOR THE START OF NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...NONE
FIRE WEATHER...NONE

DIXON JUN 13