Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 111607
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
807 AM AKDT FRI JUL 11 2014

.ANALYSIS AND UPPER LEVELS...
A LARGE UPPER LEVEL LOW PRESSURE OVER THE EASTERN BERING SEA SITS
IN CONTROL OF THE ACTIVE WEATHER PATTERN. IT STRETCHES FROM THE
SEWARD PENINSULA SOUTHWARD WELL INTO THE NORTH CENTRAL PACIFIC
AND FROM THE CENTRAL BERING SEA THROUGH THE CENTRAL/EASTERN GULF
OF ALASKA. THE PROMINENT FEATURE WITHIN THE UPPER LOW IS A STRONG
SHORTWAVE TROUGH/FRONT COMBO IN THE NORTHERN GULF. A SOLID RAIN
SHIELD ASSOCIATED WITH THE FRONT STRETCHES ACROSS THE NORTH GULF
COAST WESTWARD INTO THE SUSITNA VALLEY. A DOWNSLOPE HOLE IN THE
LEE OF THE KENAI AND CHUGACH RANGES ARE KEEPING AREAS FROM THE
MATANUSKA VALLEY SOUTHWARD THROUGH ANCHORAGE AND KENAI
DRIER...RELATIVELY THAT IS. A DRY SLOT IS EVIDENT ON WATER VAPOR
IMAGERY AS WELL AS RADAR PUSHING INTO THE KENAI PENINSULA EARLY
THIS MORNING. A STRONG BARRIER JET EXTENDS FROM THE NORTH GULF
COAST ACROSS PRINCE WILLIAM SOUND AIDING IN THE TURNAGAIN ARM JET
AS WELL...WHICH IS CURRENTLY BEING DEFLECTED SOUTHWARD INTO COOK
INLET WHILE LIGHT NORTHERLY WINDS REMAIN OVER ANCHORAGE ITSELF.

&&

.MODEL DISCUSSION...
NOW THE THE CURRENT SHORTWAVE/FRONT HAS AMPLIFIED AND IS PUSHING
ONSHORE...GUIDANCE HAS A REALLY GOOD HANDLE ON THE CURRENT
SYNOPTIC PATTERN. SOME SLIGHT POSITIONAL DIFFERENCES IN UPPER LOW
LOCATION BEGIN TO ARISE ON SATURDAY AS RIDGING BUILD IN FROM THE
NORTHERN BERING AND BEGINS TO PUSH THE LOW SOUTHWARD INTO THE
PACIFIC. THE ECMWF AND GFS ARE IN AGREEMENT WITH EACH OTHER WHILE
THE NAM/GEM ARE LAGGING BEHIND. THE SURFACE PATTERN IS FAIRLY
BENIGN WITH WEAK LOW PRESSURE OVER MOST OF THE MAINLAND AND UNDER
THE UPPER LOW WHILE RIDGING BEGINS TO BUILD OVER THE EASTERN GULF
OF ALASKA.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...THE BIGGEST CONCERN RIGHT AWAY THIS MORNING
WILL BE THE NATURE OF THE TURNAGAIN ARM WIND AS THE FRONTAL
OCCLUSION APPROACHES/PASSES. CURRENTLY THE SURFACE PRESSURE
GRADIENT REMAINS STRONGLY DOWN INLET KEEPING THE TURNAGAIN ARM JET
DEFLECTING SOUTH...EVEN AWAY FROM THE HIGHER ELEVATIONS OF THE
ANCHORAGE BOWL. THE SOUTHEASTERLIES SHOULD SHOW UP AT THE HIGHER
ELEVATIONS OF THE ANCHORAGE HILLSIDE THIS MORNING FIRST BEFORE THE
FRONT PASSES TOWARD LATE MORNING. SOUTHEAST WINDS GUSTING 30 TO 40
MPH WILL AFFECT MAINLY SOUTH AND WEST ANCHORAGE BUT MOST OF THE
BOWL WILL GET IN ON THE SOUTHEASTERLIES. WIDESPREAD RAIN WILL
TAPER TO SHOWERY PRECIPITATION ONCE THE FRONT PASSES TODAY.

MOST OF THE SOUTHCENTRAL WILL LIE ON THE PERIPHERY OF THE UPPER
LOW THROUGH THE WEEKEND. WHILE MOST OF THE BAROCLINIC ENERGY HAS
BEEN DISSIPATED BY THE CURRENT FRONT/WAVE...DISTURBANCES ROTATING
AROUND THE UPPER LOW PRESSURE COMBINED WITH SURFACE HEATING SHOULD
MAKE FOR SHOWERY PRECIPITATION ROLLING OFF THE HIGHER TERRAIN.

SOUTHWEST ALASKA...PERIODS OF LIGHT RAIN WILL CONTINUE FOR MOST OF
THE DAY TODAY AS THE UPPER LOW PRESSURE ROTATES DISTURBANCES
OVERHEAD FROM THE EAST. PRECIPITATION WILL BECOME LIGHT AND SHOWER
FOR THE KUSKOKWIM VALLEY AND INTERIOR BRISTOL BAY TOWARD AFTERNOON
WHILE STEADIER LIGHT RAIN WILL DEVELOP OVER THE KUSKOKWIM DELTA
REGION. AFTER TODAY...RAIN SHOWERS WILL REMAIN IN THE
FORECAST...ESPECIALLY ALONG THE ALASKA/ALEUTIAN RANGE WHILE A BAND
OF LIGHT RAIN SHOULD SET UP ALONG THE WEST COAST OF THE DELTA.

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 119 125
FIRE WEATHER...NONE.

&&

$$

MTL JUL 14


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