Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 231249
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
449 AM AKDT SAT AUG 23 2014

.ANALYSIS AND UPPER LEVELS...
THE DOMINANT FEATURE ON WATER VAPOR IMAGERY THIS MORNING IS A
LARGE UPPER LEVEL LOW PRESSURE CENTERED OVER THE CENTRAL
ALEUTIANS. A LARGE MOISTURE PLUME ASSOCIATED WITH A STRONG
SHORTWAVE TROUGH/JET STREAK IS PUSHING OVER THE EASTERN
ALEUTIANS/ALASKA PENINSULA AND UP OVER THE SOUTHWEST MAINLAND.
THESE FEATURES WILL BE THE FOCUS FOR SENSIBLE WEATHER OVER THE
WEEKEND FOR MOST OF THE SOUTHERN MAINLAND AND ALEUTIANS. RIDGING
IS BUILDING OUT AHEAD OF THE INCOMING FRONT/TROUGH HELPING TO
CLEAR OUT THE LEFTOVER CONVECTIVE CLOUDS FROM YESTERDAY EVENING.
WINDS ARE RELATIVELY LIGHT AND VARIABLE FOR MOST AREAS OF THE
SOUTHCENTRAL AHEAD OF THE INCOMING FRONT. THE BUILDING RIDGE IS
PROMOTING MARINE LAYER STRATUS IN THE COOK INLET REGION AND ALONG
THE NORTH GULF COAST/PRINCE WILLIAM SOUND. OUT WEST THERE ARE TWO
MAIN AREAS OF PRECIPITATION...THE FIRST IS ASSOCIATED WITH THE
TRIPLE POINT SURFACE LOW AND MAIN WARM FRONT. THE OCCLUSION
EXTENDS FURTHER WEST TOWARD THE UPPER LOW CENTER WHERE THE SECOND
AREA OF PRECIPITATION LIES.

&&

.MODEL DISCUSSION...
GUIDANCE IS IN GOOD AGREEMENT SYNOPTICALLY...WHICH HAS COME A
LONG WAY FROM A COUPLE DAYS AND NUMEROUS MODEL RUNS AGO WHERE THEY
WERE STRUGGLING FOR CONTINUITY BOTH TEMPORALLY AND SPATIALLY. THE
GENERAL CONSENSUS IS THE WARM/OCCLUDED FRONT WILL CONTINUE TO PUSH
OVER THE MAINLAND TODAY AND TOMORROW AS THE UPPER LOW SLOWLY
PROPAGATES EASTWARD INTO THE EASTERN BERING SEA. THE MAIN
DISCREPANCY BETWEEN GUIDANCE IS DOWNSLOPE RELATED...CONCERNING
HOW MUCH PRECIPITATION MAKES IT OVER THE CHUGACH...AS USUAL
DEPENDENT ON MODEL RESOLUTION WITH THE HIGHER RESOLUTION MODELS
HITTING DOWNSLOPE DRYING HARDER THAN LOWER RESOLUTION GUIDANCE.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...LOW STRATUS AND FOG WILL CONTINUE TO BUILD
ACROSS THE COOK INLET REGION THIS EARLY MORNING BEFORE RETREATING
BY LATE MORNING. FOG WILL BE LOCALLY DENSE...ESPECIALLY CLOSE TO
THE INLET. A DISTURBANCE ALOFT WILL MOVE FROM SOUTHWEST TO
NORTHEAST TODAY INCREASING THE CHANCE FOR RAIN. THE FRONT WILL
PACK MORE OF A PUNCH AND MOVE IN LATE TONIGHT FOR KODIAK ISLAND
HITTING ANCHORAGE AND THE NORTH GULF COAST IN THE LATE
MORNING/EARLY AFTERNOON. EXPECT LIGHT RAIN TO SPREAD OVER MOST
OF THE SOUTHCENTRAL. THE UPPER TROUGH SWINGS THROUGH POST-FRONT
KEEPING SHOWERS IN THE FORECAST FOR MOST AREAS MONDAY AND TUESDAY.

SOUTHWEST ALASKA...THE MAINLAND SITS BETWEEN TWO MAIN
FEATURES...THE FIRST SHORTWAVE AND TRIPLE POINT WILL SLIDE INTO
THE GULF JUST BRUSHING INTERIOR BRISTOL BAY WHICH SHOULD SEE SOME
LIGHT RAIN AND GUSTY EASTERLY WINDS. THE OCCLUSION AND UPPER
TROUGH WILL BRING A BETTER CHANCE FOR WIDESPREAD STRATIFORM
PRECIPITATION LATE TONIGHT INTO SUNDAY. CONDITIONS WILL BECOME
MORE SHOWERY INTO EARLY NEXT WEEK.

BERING SEA/ALEUTIANS...RAIN AND GUSTY EASTERLY WINDS WILL AFFECT
THE ALASKA PENINSULA EARLY TODAY BEFORE TURNING MORE SHOWERY WITH
LIGHTER WESTERLY WINDS THIS EVENING. THE UPPER LOW OVERHEAD WILL
KEEP AT LEAST SCATTERED SHOWERS IN THE FORECAST FOR THE REMAINDER
OF THE WEEKEND.


&&

.LONG TERM FORECAST...
AN UPPER LEVEL LOW WILL BE POSITIONED OVER THE NORTHERN GULF OF
ALASKA TUESDAY MORNING AS IT TRACKS INTO THE YUKON TERRITORY BY
WEDNESDAY. RESULTING IN SHOWERY CONDITIONS FOR THE SOUTHEAST
MAINLAND. FOLLOWED BY AN UPPER LEVEL WEAK RIDGE BRIEFLY BRINGING
DRIER CONDITIONS FOR THURSDAY. BY FRIDAY AN UPPER LEVEL TROUGH
DROPS DOWN FROM THE NORTH BRINGING MORE CLOUDS AND SHOWERS TO THE
REGION GOING INTO THE WEEKEND. THE BERING SEA WILL HAVE AN UPPER
LEVEL LONG WAVE TROUGH NEAR THE KAMCHATKA PENINSULA DROPPING DOWN
INTO THE WESTERN BERING SEA AND WESTERN ALEUTIANS BY TUESDAY.
THE MODELS ARE STRUGGLING WITH THIS IS FEATURE WITH THE POSITION
OF THE SURFACE LOW AT THE BASE OF THE TROUGH NEAR THE WESTERN
ALEUTIANS. THIS SYSTEM WILL SLOWLY MOVE EASTWARD ACROSS THE
ALEUTIANS FROM WEDNESDAY INTO NEXT WEEKEND. THIS WILL PRODUCE
SHOWERY CONDITIONS WITH MARINE LAYER STRATUS AND FOG.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 130 131 138 150 155.
FIRE WEATHER...NONE. &&

$$
MTL

AUG 14


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