FXAK69 PAFG 171232
AFDAFG

NORTH ALASKA FORECAST DISCUSSION
400 AM AST MON FEB 17 2003

SURFACE CHART DOMINATED BY 1035 MB HIGH 200 NM NORTH OF PRUDHOE BAY WITH
CHAIN OF LOWS PARADING FROM WEST TO EAST SOUTH OF THE ALEUTIANS...WITH A
COUPLE MORE IN PRINCE WILLIAM SOUND AND NEAR SITKA. A 1026 MB LOW
CONTINUES TO HANG IN THERE IN THE MACKENZIE DELTA...BUT HAS GOOD ONLY
FOR SOME WIND SHIFTS IN BEAUFORT SEA COASTAL ZONES AND HAS LITTLE
MOISTURE TO WORK WITH.

SKIES NOW ESSENTIALLY CLEAR EVERYWHERE EXCEPT EXTREME SOUTHEAST
INTERIOR...WHERE NORTHWAY HAS BEEN CARRYING A CEILING AND FLURRIES FOR
MOST OF THE DAY...A BENEFIT OF THE CIRCULATION AND MODEST OVERRUNING
WITH THE PRINCE WILLIAM SOUND LOW.

ALOFT...BROAD MERIDIONAL RIDGE OVER NORTHERN ALASKA WITH SADDLE AXIS
ROUGHLY FROM NORTON SOUND TO EAGLE. SOMEWHAT FASTER EASTERLY FLOW ALOFT
NORTH OF THE SADDLE PROVIDES ONLY OPEN PATH FOR VORTICITY DYNAMICS...BUT
FLOW IS HIGHLY UNIFORM...AND ANY SHORTWAVE DISTURBANCES WOULD HAVE NO
MOISTURE TO WORK AND THUS WILL GENERATE NO WEATHER ENTERTAINMENT. AT 850
MB...COLDER AIR HAS MANAGED TO WORK WESTWARD ALONG THE CREST OF THE
BROOKS RANGE...AND EASTERLY FLOW IN THE SOUTHERN INTERIOR HAS STARTED TO
TAP VERY GENTLY INTO SOME OF THE COLDER 850 MB AIR CURRENTLY OVER THE
CENTRAL YUKON TERRITORY. EFFORT IS TO LITTLE AVAIL...AS CHIEF
TEMPERATURE CONTROLS FOR THE NEXT SEVERAL DAYS WILL BE RADIATIVE AND
DENSITY-DRIVEN PROCESSES UNDER STRONG NIGHTTIME INVERSIONS.

MODELS...AGREEING ON A STEADY STATE SOLUTION WITH LITTLE CHANGE TO THE
PATTERN ALOFT OVER THE NEXT SEVERAL DAYS. LOWS SOUTH OF THE ALEUTIANS
ARE SCOOTED EASTWARD WELL SOUTH OF THE FORECAST AREA. NEXT EXCITEMENT
WILL APPEAR TUESDAY AS A 960 MB LOW NEAR ADAK...AND THIS WILL RAMP UP
WIND SPEEDS OVER THE SOUTHERN AND CENTRAL BERING MARINE AREAS THROUGH
MIDWEEK BEFORE SETTLING BACK DOWN AGAIN AS THE LOW FILLS. NO TEMPERATURE
ADVECTION...AND LITTLE CHANGE FORECAST TO CURRENT TEMPERATURE PATTERN
FOR THIS ROUND OF FORECASTS.

NORTH SLOPE...AC SECTOR POES IMAGERY SHOWING MVFR CLOUDS HEADED SOUTH
TOWARD THE COAST...ARRIVAL LATE AFTERNOON OR EVENING. AVN MOS SHOWING
CLEARING RETURNS LATE MONDAY NIGHT. SURFACE HIGH NORTH OF PRUDHOE BAY
WILL SLIDE ONLY A FEW DEGREES EASTWARD OVER THE NEXT COUPLE OF DAYS WITH
LITTLE UPPER AIR INCENTIVE TO DO MUCH MORE THAN THIS. EFFECT WILL BE
SOME WIND SHIFTS AND REDUCTIONS OVER THE BEAUFORT SEA COAST...AND SOME
SPEEDING UP OF SOUTHEASTERLIES OVER THE WESTERN ARCTIC COAST...AS
SURFACE PRESSURE GRADIENT BETWEEN THE ARCTIC HIGH AND INCOMING ADAK LOW
STRENGTHENS. ARCTIC MARINERS...WILL SEE SUB-ADVISORY WINDS WITH THIS
PATTERN. NO TEMPERATURE CHANGE...NO PRECIPITATION...FOR THE NEXT COUPLE
OF DAYS.

WEST COAST...REMAINING CLEAR AND CONSTANT THROUGH TUESDAY...WHEN A FEW
HIGH CLOUDS SHOULD REAPPEAR OVER THE YUKON DELTA/LOWER YUKON VALLEY
ASSOCIATED WITH ADAK LOW OCCLUSION...AND THESE CLOUDS WILL REACH NORTON
SOUND BY WEDNESDAY. EXPECTING LITTLE TO NO PRECIPITATION WITH THESE AS
DYNAMICS ARE EXTREMELY WEAK AND THE SCARCE MOISTURE IS TOO HIGH IN THE
ATMOSPHERIC COLUMN TO REACH THE GROUND. MARINERS...WILL FEEL THE LASH OF
THE ADAK SYSTEM IN AREA 14 WITH A DEVELOPING MIDWEEK GALE SOUTHWEST OF
SAINT MATTHEW ISLAND. SOME SPEEDIER WINDS WILL WORK NORTHWARD UP THE
BERING SEA THROUGH THE LAST HALF OF THE WORK WEEK.

INTERIOR...MORE OF THE SAME FOR THE NEXT COUPLE OF DAYS. OVERCAST/BROKEN
SKIES HANGING IN THERE AT NORTHWAY...AND AVN MOS HAS FORECAST CLEARING
HERE TO NO AVAIL. SOME HIGH CLOUDS GENERALLY SOUTH OF A
UNALAKLEET-MCGRATH LINE ON TUESDAY...AND NOME-GALENA LINE ON TUESDAY
NIGHT. NO MOISTURE PLUS NO DYNAMICS EQUALS NO PRECIPITATION WITH THIS.
TEMPERATURE REGIME WILL CONTINUE...RADIATIVE COOLING AT NIGHT VERSUS
DAYTIME SOLAR INSOLATION WITH DOWNHILL GRAVITY TRANSPORT OF COLDER
DENSER AIR TO BUILD STRONG NIGHTTIME INVERSIONS AND COLD TEMPERATURES IN
VALLEY BOTTOMS.

MEDIUM RANGE...MODELS ALL MAINTAINING BROAD FLAT-TOPPED RIDGE OVER STATE
THROUGH THE WEEKEND...AND TRYING TO KISS THE ARCTIC COAST WITH A
SHORTWAVE EXTENDING FROM THE POLAR VORTEX BY THE WEEKEND. IF THE
SHORTWAVE VERIFIES...EXPECT ONLY SCATTERED/BROKEN VFR CLOUDS MAINLY FROM
THE BROOKS RANGE NORTHWARD WITH LITTLE ELSE. ALL SOLUTIONS ALSO MAINTAIN
CLOSED LOW OVER THE ALEUTIAN CHAIN TO PROVIDE DYNAMIC SUPPORT FOR
SURFACE COUNTERPART. WITH SURFACE HIGH OVER THE SOUTHERN BEAUFORT SEA
GRADUALLY MOVING EASTWARD...SURFACE PRESSURE GRADIENT WILL REMAIN STRONG
OVER THE BERING SEA TO KEEP WIND SPEEDS UP IN THE MARINE AREAS....AND
OVER HILLTOPS AND THROUGH PASSES IN THE INTERIOR THROUGH THE FIRST HALF
OF THE WEEKEND.  A VERY DRY PATTERN...NO PRECIPITATION EXPECTED...AND
CONTINUED BASICALLY CLEAR SKIES WITH LITTLE CHANGE IN THE TEMPERATURE
REGIME.

.AFG...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...HEAVY FREEZING SPRAY WARNING: AREA 14
         BRISK WIND ADVISORY: AREA 14

$$
TS FEB 03