Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 021021
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
221 AM AKDT MON MAY 2 2016

.DISCUSSION...
MODELS IN DECENT AGREEMENT THROUGH 48 HOURS WITH UPPER LEVEL
FEATURES. LONG WAVE TROUGH OVER ALASKA WILL PERSIST THROUGH
AROUND THE MIDDLE PORTION OF THE WEEK AT LEAST. THE RIDGE OVER THE
WESTERN UNITED STATES WILL BEGIN TO PUSH WESTWARD FROM CANADA BY
LATE WED OR THU BUT APPEARS TO GET BEAT BACK AGAIN BY THE TROUGH
TOWARDS THE END OF THE WEEK.

SEVERAL SHORT WAVES WILL MOVE NORTHWARD FROM THE GULF OF ALASKA
THROUGH THE WEEK WHICH WILL ALSO UNDERCUT THE RIDGE OVER WESTERN
CANADA. STRONG VERTICALLY STACKED LOW IN THE WESTERN ALEUTIANS
WILL MOVE EASTWARD TOWARDS THE CENTRAL ALEUTIANS BY TUE
AFTERNOON. AFTER TUE THE MODELS DO NOT RESOLVE THE MOVEMENT TOO
WELL. THE NAM CONTINUES TO CARRY THE LOW EASTWARD TO ABOUT COLD
BAY LATE TUE NIGHT AND THEN WEAKENS IT. MEANWHILE THE GFS AND THE
ECMWF HANG THE LOW BACK AND ALSO CONTINUE TO WEAKEN IT.

COLDER TEMPERATURES WILL CONTINUE TO PERSIST ALONG THE ARCTIC
COAST AS THE LOWER LEVEL COLD AIR REMAINS STUCK THERE WITHOUT ANY
MECHANISM TO FORCE IT OUT.

THE NAM IS COMPLETELY DIFFERENT THAN THE OTHER MODELS IN TERMS OF
SURFACE REFLECTION. THE NEW MODEL RUN AT 06Z INDICATES WITH THE
NEW VERTICALLY STACKED UPPER AND SURFACE LOW MOVING NORTH NEAR THE
ALCAN BORDER THROUGH MON AFTERNOON...THAT THE PRECIP BAND WILL
STAY SOUTH OF THE MIDDLE TANANA VALLEY. WHEREAS THE OTHER MODELS
PAINT THE HIGHEST PRECIP OVER THE MIDDLE TANANA VALLEY. AT THIS
POINT WE ARE WEIGHTING OUR FORECAST MORE IN LINE WITH THE GFS AND
THE ECMWF. THE SHORTWAVE TROUGH WILL INTERACT WITH THE SURFACE
THERMAL TROUGH AND PRODUCE MODERATE RAINFALL OVER A PORTION OF
THE CENTRAL INTERIOR THROUGH TUE.

CONVECTIVE INDICES ARE THE BEST OVER THE WESTERN INTERIOR AND
NEAR THE WEST COAST TO EXTEND DOWN INTO THE Y-K DELTA. THIS WILL
LIKELY PERSIST THROUGH AT LEAST THE MIDDLE PORTION OF THE WEEK.
ALTHOUGH THUNDERSTORMS WILL BE OVER A WIDE AREA BUT LIKELY TO BE
SPARSELY POPULATED IN TERMS ANY LARGE CONCENTRATION.

&&

.FIRE WEATHER...
FOR THE NEXT COUPLE OF DAYS MOISTURE WILL MOVE INTO THE CENTRAL
INTERIOR AND KEEP RH VALUES HIGHER THAN ON PREVIOUS DAYS. THIS
ALONG WITH WEAKER SURFACE WINDS WILL KEEP THE POSSIBILITY OF ANY
RED FLAG CONDITIONS TO A MINIMUM AND ARE NOT LIKELY THROUGH AT
LEAST THE MIDDLE PART OF THE WEEK.

&&

.HYDROLOGY...
ALTHOUGH THE GFS MODEL IS INDICATING RAINFALL IN EXCESS OF 1 INCH
IN SEVERAL AREAS IN THE INTERIOR...THIS REMAINS TO BE SEEN IF IN
FACT THIS IS REALITY. WE ARE NOT BUYING INTO THAT AMOUNT OF
RAINFALL QUITE YET. THE POSSIBILITY FOR HEAVY DOWNPOURS IN
THUNDERSTORMS WILL EXIST THOUGH BUT THERE IS UPPER LEVEL WINDS
SUFFICIENT ENOUGH TO NOT ALLOW ANY CELLS TO REMAIN OVER ANY ONE
AREA TOO LONG.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

CF MAY 16


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