FXAK69 PAFG 062254
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
154 PM AKST SUN DEC 6 2009

HIGH AMPLITUDE SOUTHERLY FLOW COVERS THE BERING AND WESTERN
AK...WHILE VERY STRONG UPPER RIDGE IS BUILDING N OVER SERN QUARTER
OF STATE. MODELS ALL IN GOOD AGREEMENT THROUGH SHORT TERM...BUT
DIFFERENCES BETWEEN 12Z GFS AND 12Z ECMWF AFTER DAY FIVE.

DEEP VERTICALLY STACKED LOW WITH 960 MB SURFACE LOW JUST S OF ADAK
TODAY WILL LIFT NW INTO CENTRAL BERING TONITE/MON AS UPSTREAM RIDGE
AMPLIFIES N TO COVER ALL AK BUT IMMEDIATE W COAST BY MON AFTERNOON. 

ONLY SIGNIFICANT PRECIP. WILL BE SOME -SN OVER N SLOPE TONIGHT
AS SHORT WAVE ROLLS N AND E AROUND TOP OF THE RIDGE...AND ALONG
W COAST TONIGHT FROM FRONTAL BAND STEMMING FROM ALEUTIANS LOW. IT 
WILL BE RAIN FROM SEWARD PEN. SOUTH...AND -SN AND -FZDZ TO THE N.
THIS WILL END MON. AS UPPER RIDGE EXPANDS N AND W. 

MAIN STORY NEXT 3 DAYS WILL BE NEAR-RECORD TEMPERATURES SURFACE
(WHEREVER MIXING OCCURS) AND ALOFT WITH THE 575 DM UPPER RIDGE.
IT WILL BE CENTERED OVER S-CENTRAL AK AND AK RANGE TOMORROW UNTIL
AT LEAST 12Z THU. 850 MB TEMPERATURES FROM W COAST AND BROOKS 
RANGE S WILL BE +2 TO +8C! UPLANDS AND HILLS ABOVE VALLEY
INVERSIONS IN THE INTERIOR SHOULD SEE TEMPS. AROUND 35-40F TOMORROW
INTO WED. CLEARING SKIES TOMORROW OVER INTERIOR THOUGH WILL ALLOW
STRONG VALLEY INVERSIONS TO FORM...SO VALLEYS COULD DROP BACK
BELOW 0F MONDAY NITE. WITH RIDGE BECOMING CENTERED OVER CENTRAL
AK...AK RANGE WIND ISSUES END TONITE. LACK OF MIXING FROM LIGHTER
WINDS WILL HELP LIMIT WARMING POTENTIAL OF THIS VERY MILD AIRMASS.
NEEDLESS TO SAY...NO SNOW EXPECTED OVER INTERIOR THROUGH THE LONG
TERM...AS MODELS DO AGREE IN KEEPING THE RIDGE OVER THE REGION THROUGH
AT LEAST 108 HOURS.

DIFFERENCES IN MODELS ARE AFTER 120 HOURS...WITH WEAKENING OF UPPER
RIDGE...AND COLD AIR TROUGH/INSTRUSION FROM NWRN CANADA W INTO THE ERN
INTERIOR. 12Z GFS MUCH STRONGER/COLDER THAN ECMWF WITH THIS. ECMWF WAS 
SOMEWHAT STRONGER WITH THE COOLING IN EARLIER RUNS...BUT IT BACKED OFF
ON THE TODAY'S RUN. DECIDED TO TREND MORE WITH THE NEW 12Z ECMWF RUN
SOLUTION FOR EXTENDED TEMPS. MODELS OFTEN ERODE LARGE UPPER RIDGES TOO
QUICKLY IN EXTENDED PERIODS.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FOR AKZ227.

BRISK WIND ADVISORY FOR PKZ200-PKZ210-PKZ245.
&&

$$

MAR DEC 09