Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 302326
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
326 PM AKDT THU JUL 30 2015

.DISCUSSION...
ALOFT...AN OSCILLATING PATTERN FOR THE NEXT WEEK PLUS AS THE LONG
WAVE TROUGH OVER THE MAINLAND GIVES WAY TO RIDGING OVER THE SOUTH
PORTION SUN THROUGH WED WITH HIGHER THAN NORMAL H500 HEIGHTS. THIS
RIDGE THEN BREAKS DOWN WITH A RETURN TO THE LONGWAVE TROUGH OVER
THE MAINLAND LATE NEXT WEEK. CURRENTLY A SHORT WAVE TROUGH FROM
INUVIK CANADA TO GALENA WILL MOVE TO EAGLE TO TALKEETNA 10 AM FRI.
A SECOND SHORT WAVE TROUGH EXTENDING NORTH TO SOUTH OVER THE
CHUKCHI SEA WILL MOVE TO EAGLE TO MOUNT MCKINLEY 4AM SAT AND FULLY
INTO CANADA BY 10 PM SAT. 5760 M HIGH FORMING OVER THE LOWER
KUSKOKWIM VALLEY ON SUN.

SURFACE...1006 MB LOW JUST SOUTHWEST OF WRANGELL ISLAND WILL MOVE
TO 85 MILES NORTHWEST OF BARROW 10 PM FRI DEEPENING TO 1003
MB...THEN MOVING TO 560 MILES NORTH OF PRUDHOE BAY 4PM SAT
DEEPENING TO 996 MB. COLD FRONT FROM LOW SOUTHWESTWARD...MOVING
TO THE CREST OF THE BROOKS RANGE AT 10 AM SAT...WITH A SECONDARY
LOW EAST OF ARCTIC VILLAGE AT THAT TIME. THIS SECONDARY LOW WILL
DISSIPATE SUN AM IN NEARLY THE SAME PLACE. ANOTHER ARCTIC LOW...1003
MB 4AM SUN JUST SOUTH OF WRANGELL ISLAND...WILL MOVE TO THE
CENTRAL CHUKCHI SEA 4PM SUN AND WEAKEN A FEW MBS. THERMAL TROUGH
FROM NORTH OF EAGLE TO NOATAK MOVING TO NORTHWAY TO FORT YUKON 4PM
FRI..AND FROM NORTHWAY TO DAWSON SAT.

MODELS...AGREE FAIRLY WELL IN SHORT TERM AND IN MEDIUM TERM
THROUGH TUE. THEREAFTER THE GFS HAS A MORE INTENSE LOW MOVING
ACROSS THE ARCTIC THAN THE ECMWF...WILL FAVOR THE ECMWF FOR NOW
ON THIS FEATURE.

NORTH SLOPE...A PERIOD OF SW WINDS 25 TO 30 MPH MOVING ACROSS THE
AREA WITH THE FIRST LOW. MOVEMENT IS RATHER FAST SO THE TIME
LENGTH OF THESE WINDS WILL MAINLY BE LESS THAN 12 HOURS. SEAS WILL
BUILD TO 3 TO 5 FEET OVER COASTAL WATERS. WINDS RAPIDLY
DIMINISHING BEHIND THE COLD FRONT. RAIN SPREADING FROM WEST TO
EAST...ACROSS THE WESTERN ZONES FRI...EASTERN ZONES FRI NIGHT AND
SAT AM.

WESTERN ALASKA...A PERIOD OF RAIN MOVING SOUTHEAST OVER AREA WITH
SECOND SHORT WAVE TROUGH FRI PM THROUGH SAT PM. THE LOWER
YUKON...UPPER KUSKOKWIM...AND MIDDLE YUKON VALLEYS WILL LARGELY
STAY DRY DUE TO BUILDING RIDGE OVER AREA.

CENTRAL AND EASTERN INTERIOR...SHOWERS AND ISOLATED THUNDERSTORMS
OVER SOUTHEASTERN THIRD OF AREA TODAY...BUT ON FRIDAY THIS ACTIVE
AREA OF CONVECTION WILL SHIFT TO EAST OF FAIRBANKS. ON SATURDAY
EXPECT CHANCE OF RAIN NORTH OF FAIRBANKS AND EAGLE WITH THE SHORT
WAVE TROUGH MOVING SOUTHEAST OVER THE AREA. EXPECT ONLY A FEW
SHOWERS SUN ACROSS THE AREA AS THE RIDGE ALOFT GAINS STRENGTH
BEHIND THE SHORT WAVES. MAX TEMPS WARMER ON FRIDAY...BUT OVER
MIDDLE AND NORTHERN INTERIOR EXPECT A BIT COOLER SAT WITH INCOMING
SHORT WAVE...THEN WARMER ACROSS ALL AREAS SUN WITH BUILDING
RIDGE.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.FIRE WEATHER...
ISOLATED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND EVENING SOUTH
AND EAST OF A LINE FROM TANANA TO COLDFOOT. SUFFICIENT RH RECOVER
IS EXPECTED TONIGHT. OVERALL...A GENERAL DRYING AND WARMING TREND
IS ANTICIPATED FOR MUCH OF THE INTERIOR THIS WEEKEND AND INTO THE
BEGINNING OF THE NEW WORK WEEK AS THE PATTERN ALOFT TRANSITIONS
TO A RIDGE.

HOWEVER...WEAK DISTURBANCES ALOFT MOVING SOUTHEAST FROM THE WILL
BRING INCREASED CHANCES OF PRECIP TO PORTIONS OF NORTHERN ALASKA.
BEST CHANCES FOR SHOWERS AND ISOLATED THUNDERSTORMS OVER THE
INTERIOR IS LATE SAT AND SUN. RIDGING OVER THE SOUTHERN TWO-
THIRDS OF MAINLAND ALASKA IS EXPECTED TO CONTINUE THROUGH MON.

MINIMUM RELATIVE HUMIDITY VALUES OVER THE AK INTERIOR WILL GENERALLY
REMAIN ABOVE 30 PERCENT TOMORROW AND SAT WITH WINDS REMAINING LIGHT
TO MODERATE...BELOW 15 MPH...THROUGH THE WEEKEND. HOWEVER...MAY SEE
HUMIDITY VALUES DROP BETWEEN 25 AND 30 PERCENT TOMORROW IN AREAS OF
THE YUKON FLATS AND SURROUNDING UPLANDS...AND LIMITED PORTIONS OF
THE SOUTH SLOPES OF THE BROOKS.

&&

.HYDROLOGY...RIVER GAGES OVER THE CHENA BASIN...WHICH HAD SHOWERS
AND LOCAL DOWNPOURS YESTERDAY...ARE TRENDING DOWN JUST NOW AFTER
PEAKING EARLY THIS MORNING. EXPECT ANOTHER BUMP UP IN LEVELS THIS
EVENING WITH MORE SHOWERS AND ISOLATED THUNDERSTORMS...THEN
FALLING STAGES AS OVERALL DRYING OF THE AIRMASS BEGINS.

&&

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

$$
FIRE WEATHER...ET
JL JUL 15



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