Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 161948
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
1148 AM AKDT TUE SEP 16 2014

.DISCUSSION...

FAIRLY BENIGN WEATHER WILL PREVAIL THROUGH THE FORECAST PERIOD
WITH A GRADUAL COOLING TREND TOWARDS NORMAL TEMPERATURES THROUGH
THE WEEKEND. THE 16/12Z MODEL GUIDANCE IS IN RELATIVELY GOOD
AGREEMENT WITH SUBTLE DIFFERENCES IN PRECIPITATION TIMING AND
COVERAGE. THERE IS SOME DIFFERENCES WITH PLACEMENT OF SYNOPTIC
FEATURES IN THE LONG RANGE GUIDANCE...HOWEVER THERE IS A GENERAL
CONSENSUS THAT A BROAD TROUGH WILL RESIDE OVER MAINLAND ALASKA AND
GULF OF ALASKA WITH A RIDGE OVER THE BERING SEA AND BERING STRAIT
AFTER FRIDAY.

AN UPPER LEVEL LOW OVER THE ALEUTIAN ISLANDS AND ITS SURFACE
REFLECTION ARE FORECAST TO MAKE EASTWARD PROGRESS OVER THE NEXT 48
HOURS. BY THURSDAY AFTERNOON...AN ELONGATED UPPER LEVEL
LOW/SURFACE LOW WILL RESIDE OVER THE SOUTHWEST ALASKA AND
NORTHERN GULF OF ALASKA...WITH A TROUGH EXTENDING NORTHEAST AND
OVER MAINLAND ALASKA. THE UPPER LEVEL LOW AND ITS SURFACE
REFLECTION WILL WEAKEN AND BECOME A BROAD OPEN TROUGH AS IT
REMAINS OVER MAINLAND ALASKA THROUGH THE WEEKEND. THIS GENERAL
SETUP TRANSLATES TO ISOLATED AND SCATTERED SHOWERS ACROSS MOST OF
THE WEST COAST...NORTHERN INTERIOR AND NORTH SLOPE.

NEARLY 200 LIGHTNING STRIKES WERE OBSERVED YESTERDAY FROM KOTZEBUE
TO EAGLE ON MONDAY. LIFTED INDICES ARE FORECAST TO BE SLIGHTLY
NEGATIVE AND WITH ANOTHER SHORTWAVE FORECAST TO MOVE OVER THE
INTERIOR THIS EVENING...SIMILAR TO WHAT WAS OBSERVED YESTERDAY. SO
WILL ADD MENTION OF ISOLATED THUNDERSTORMS OVER THE INTERIOR FROM
KALTAG TO EAGLE THIS EVENING.

SOUTHERLY FLOW WILL CONTINUE OVER THE SOUTHERN
INTERIOR THROUGH LATE WEDNESDAY...KEEPING IT DRY AND PARTLY
CLOUDY. GAP WINDS IN THE ALASKA RANGE ARE FORECAST TO CONTINUE
THROUGH WEDNESDAY EVENING AND THEN DIMINISH WEDNESDAY NIGHT.

AS NOTED ABOVE...A GRADUAL COOL DOWN TOWARDS NEAR NORMAL
TEMPERATURES IS FORECAST FOR THE REMAINDER OF THE WEEK AND INTO
THE WEEKEND. AS THE UPPER LOW/SURFACE LOW SHIFTS EAST...NORTHERLY
SURFACE FLOW WILL SET UP ACROSS THE SOUTHERN CHUKCHI SEA...BERING
STRAIT AND INTO THE BERING SEA. THIS WILL OPEN THE GATES TO MUCH
COLDER H850 TEMPERATURES BEING ADVECTED SOUTH OVER THE WEST COAST
AND WESTERN INTERIOR. EVEN THOUGH THERE ARE SOME DIFFERENCES
BETWEEN MID AND LONG RANGE GUIDANCE ON THE PLACEMENT OF THE
STRONGEST COLD AIR ADVECTION...THERE WILL BE A SHIFT FROM BEING
WARMER THAN NORMAL TO NORMAL...OR EVEN SLIGHTLY COLDER THAN NORMAL
CONDITIONS BY LATE THIS WEEKEND. FOR THE INTERIOR...TEMPERATURES
WILL FALL TO NORMAL THIS WEEKEND AND TO BELOW NORMAL NEXT WEEK.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NORTH WINDS STRENGTHENING
THROUGH THE BERING STRAIT THURSDAY AND FRIDAY COULD BRING SOME
MODERATE SURF TO THE NORTH SHORE OF SAINT LAWRENCE ISLAND AND
BERING STRAIT.

&&

.FIRE WEATHER...GAP WINDS GUSTING TO 30 MPH IN THE ALASKA RANGE
PASSES WILL CONTINUE THROUGH LATE WEDNESDAY. THERE ARE SOME
CONCERNS FOR ZONES 223 AND 226...WHERE RELATIVE HUMIDITY WILL
APPROACH 30 PERCENT WEDNESDAY. HOWEVER...RED FLAG CRITERIA WILL
NOT BE MET.


&&

.HYDROLOGY...NONE.


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FOR WINDS FOR PKZ210-PKZ220-PKZ225.
&&

$$

LTH SEP 14


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