Gale Warning 490, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
1245 PM AKDT THU JUL 8 2010

.ANALYSIS AND UPPER LEVELS...THE SYSTEM WHICH BROUGHT RAIN TO
PORTIONS OF SOUTHCENTRAL LAST NIGHT IS WEAKENING AS IT ROTATES
WESTWARD INTO SOUTHWEST ALASKA. A SURFACE RIDGE IS BUILDING IN
BEHIND IT CAUSING WINDS TO KICK UP IN ALL THE USUAL SPOTS. THE
DOMINANT FEATURE FOR TODAY AND THE NEXT COUPLE DAYS IS A DEEP
VERTICALLY STACKED LOW SOUTH OF ADAK. WITH AN ESTIMATED CENTRAL
SURFACE PRESSURE OF AROUND 970 MB AND STORM FORCE WINDS ALONG
THE CENTRAL ALEUTIANS...THIS IS A POWERFUL STORM FOR THIS TIME
OF YEAR. THE LOW HAS BECOME NEARLY STATIONARY AS THE UPPER JET
SUPPORT MOVES OFF TO THE EAST AND EXPECT THE LOW IS NEAR ITS
LOWEST PRESSURE. SATELLITE IMAGERY SHOWS A SECOND LOW FORMED
LAST NIGHT DOWNSTREAM IN AN AREA OF GOOD UPPER DIVERGENCE AND
IS TRACKING NORTHEASTWARD TOWARD THE EASTERN GULF.

.MODEL DISCUSSION...THE MODELS DID NOT PICK UP ON THE SECONDARY
DOWNSTREAM LOW DEVELOPMENT OVERNIGHT. THE 12Z RUNS NOW SHOW
SOME INDICATION OF A LOW...BUT IT APPEARS UNDERDONE BASED ON
SATELLITE IMAGERY. THERE ARE NO SIGNS OF DEEPENING AND THE TRACK
WILL TAKE IT AWAY FROM THE ANCHORAGE FORECAST AREA..SO IT IS NOT
OF MUCH CONCERN. OTHERWISE...MODELS ARE IN VERY GOOD AGREEMENT
THROUGH THE NEXT THREE DAYS WITH HANDLING OF THE ALEUTIAN SYSTEM.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...HIGH PRESSURE WILL PROVIDE A BRIEF RESPITE
OF DRY WEATHER TONIGHT INTO FRIDAY. IN FACT THERE WILL BE AT LEAST
PARTIAL CLEARING ACROSS THE REGION BEGINNING LATER THIS AFTERNOON
AND EVENING AND FRIDAY SHOULD START OUT MOSTLY SUNNY. HOWEVER...THE
FRONTAL SYSTEM EXTENDING FROM THE ALEUTIAN LOW WILL QUICKLY MOVE
INTO THE GULF FRIDAY MORNING AND THEN INLAND FRIDAY NIGHT...RESULTING
IN WIDESPREAD RAIN. THE ACTUAL LOW WILL THEN TRANSITION INTO THE
GULF LATE SATURDAY AND INLAND TO THE YUKON SUNDAY WHICH MEANS
CLOUDS AND SHOWERS WILL DOMINATE THROUGH THE WEEKEND. IMPROVING
CONDITIONS DO LOOK LIKELY HEADING INTO THE BEGINNING OF NEXT WEEK.

SOUTHWEST ALASKA...THE REMNANTS OF THE GULF LOW WILL TRACK WESTWARD
ACROSS INTERIOR SOUTHWEST ALASKA TONIGHT. A LOT OF THE MOISTURE
WILL GET HUNG UP ALONG THE ALASKA RANGE. HOWEVER...THE COMBINATION
OF THE REMNANT UPPER SHORT-WAVE AND A GOOD AMOUNT OF SUNSHINE TODAY
WILL TRIGGER CONVECTION THIS AFTERNOON AND EVENING. AS THE UPPER
FEATURE EXITS FRIDAY THE ALEUTIAN FRONT WILL BEGIN TO PROGRESS
NORTHWARD...WITH RAIN OVERSPREADING MOST OF THE REGION BY LATE
FRIDAY. CONDITIONS WILL REMAIN FAIRLY CLOUDY AND WET SATURDAY AS
THE LOW PASSES JUST TO THE SOUTH OF THE ALASKA PENINSULA. DRYING
AND WARMING WILL THEN BEGIN ON THE BACK SIDE OF THE SYSTEM ON SUNDAY.

BERING SEA/ALEUTIANS...WINDS AND RAIN WILL SPREAD FURTHER OUT FROM
THE LOW CENTER TONIGHT AS UPPER LEVEL SHORT-WAVES ROTATE AROUND
THE UPPER CENTER. THE SYSTEM WILL THEN WEAKEN AS IT PROGRESSES
EASTWARD FRIDAY AND SATURDAY AND A FAIRLY STRONG RIDGE WILL BUILD
IN FROM THE WEST. THIS RIDGE LOOKS LIKE IT WILL PROVIDE BENIGN
WEATHER FOR THE CENTRAL TO EASTERN BERING AND ALEUTIANS THROUGH
AT LEAST THE MIDDLE OF NEXT WEEK.

.LONG TERM FORECAST...MEDIUM RANGE MODELS ARE IN GENERAL AGREEMENT
ON PLACEMENT OF UPPER RIDGE OVER THE BERING AT THE BEGINNING OF
NEXT WEEK. HOWEVER...THERE IS VERY POOR AGREEMENT ON HOW THE PATTERN
EVOLVES AFTER THIS AND RUN-TO-RUN CONTINUITY IS NOT GOOD. THEREFORE
FORECAST CONFIDENCE HEADS DOWNHILL QUICKLY AS WE HEAD THROUGH NEXT
WEEK.

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

SEB JUL 10