Storm Surge in Alaska, September 8 to 11, 2003

NORTH ALASKA FORECAST DISCUSSION
230 PM ADT MON SEP 8 2003

THE SURFACE ANALYSIS FOR 10 AM ADT/1800 GMT HAS 2 LOWS IN THE
ARCTIC, BOTH CENTRAL PRESSURE 982 MB LOW #1 AT 75.5N 157W AND
LOW #2 AT 77N 177W. THESE, AND THE STRONG LOW ALOFT ASSOCIATED
WITH THEM, WILL BE THE CONTROLLING FEATURES ON THE NORTHERN ALASKA
WEATHER MAP FOR THE REST OF THIS WEEK.

THE COLD FRONT FROM LOW #1 EXTENDS SOUTHWEST THROUGH UMIAT TO
GAMBELL, THENCE WEST INTO CHUKOTKA. SATELLITE IMAGERY SHOWS A
VERY DISTINCT BACK EDGE ON THIS FRONT IN THE ARCTIC. SKIES IN THE
ARCTIC TO THE WEST OF THIS FRONT ARE PARTLY CLOUDY. DURING THE
PAST SEVERAL HOURS, PEOPLE AT UMIAT REPORTED A DENSE SNOWFALL,
WITH SOME ACCUMULATION UNDERWAY, WHILST BARROW HAS HAD BRISK
WESTERLIES AND...BRIGHT SUNSHINE

AN AREA OF BEAUTIFUL CLEAR WEATHER, ABOUT 200 MILES WIDE, PRECEDES
THE FRONT, OUT OVER THE INTERIOR. THE UPLANDS BETWEEN THE YUKON
AND TANANA RIVERS (THE SOUTHEAST INTERIOR) ARE STILL CLOUDY AND A
FEW SHOWERS STILL LINGER THERE. THE TROUGH ALOFT ASSOCIATED WITH
THIS MOST PERSISTENT DECK OF CLOUDS IS FLATTENING, AND IS DUE TO
EXIT INTO THE CENTRAL YUKON TERRITORY (WITH THE CLOUDS) LATE THIS
EVENING.

THE AVIATION AND ETA MODELS HAVE SIMILAR FORECASTS: LOOPING THE
ARCTIC LOWS GRADUALLY SOUTHEAST THROUGH WEDNESDAY. THE AVIATION
MODEL COMBINES THE SURFACE LOWS AND BRINGS THE CONSOLIDATED CENTER
DOWN TO A LOCATION JUST EAST OF BARROW THURSDAY AFTERNOON. AT
THIS TIME THE WINDS ON THE WEST ARCTIC COAST SHIFT FROM BRISK
WESTERLY TO NORTHWEST. BY FRIDAY MORNING THE COMBINED LOW CENTER
IS IN THE EAST BEAUFORT SEA, WHERE IT IS FORECAST BY THE AVIATION
MODEL TO LOOP AROUND COUNTERCLOCKWISE THROUGH FRIDAY NIGHT.

ALOFT, THE MODELS BRING INCREASING WESTERLIES DOWN OVER THE AREA
NORTH OF 66 DEGREES NORTH LATITUDE BY TUESDAY AFTERNOON. ON
WEDNESDAY NIGHT, THE AVIATION MODEL FORECASTS THE WESTERLIES TO
DESCEND OVER THE REST OF NORTHERN ALASKA WEDNESDAY NIGHT. THE
TEMPERATURES ALOFT FORECAST BY THE AVIATION MODEL FOR THURSDAY
AFTERNOON ARE COLD ENOUGH FOR SNOW AT EAGLE, FAIRBANKS AND DENALI
PARK. THE AVIATION MODEL HAS A PENCHANT FOR OVERDOING SUCH
PATTERNS, SO THE FORECASTS ARE ESCHEWING HEAVY DUTY WINTER WEATHER
FOR NOW.

NOTE THAT THE COMPUTER MODELS HAVE SHOWN REAL VARIANCE FROM RUN
TO RUN ON THE INTERIOR ALASKA FORECAST FOR THE SECOND HALF OF THIS
WEEK. THE 12Z AVIATION RUN DID NOT TAKE COLD AIR ALOFT SOUTHWARD
QUITE SO VIGOROUSLY AS THE AVIATION RUN 6 HOURS LATER.

IN THE ARCTIC...SNOW IN THE EAST WILL MOVE TO THE LOWER MACKENZIE
VALLEY BY TUESDAY AFTERNOON. MORE SNOW SHOWERS WILL RESUME IN THE
WEST TONIGHT AND CONTINUE FOR A NUMBER OF DAYS.

IN THE WEST...AN OUTBREAK OF RAIN AND SNOW IN THE KOTZEBUE SOUND/
KOBUK VALLEY REGION TUESDAY NIGHT AND WEDNESDAY. SNOW IN THE
NOATAK AND NORTH KOBUK VALLEYS THEN...AND RAIN SPREADING TO THE
SEWARD PENINSULA.

IN THE INTERIOR...SOME LIGHT RAIN, BRIEFLY, OVER THE NORTHEAST
AND SOUTHWEST TONIGHT, ENDING OVER THE SOUTH SLOPES OF THE
EAST BROOKS RANGE TUESDAY. RAIN MOVING IN FROM THE NORTHWEST
WEDNESDAY, EXITING TO THE YUKON THURSDAY. SNOW AND RAIN MOVING
IN FROM THE NORTHWEST FRIDAY, WITH SNOW IN THE NORTH AND SOUTHERN
HIGHLANDS FRIDAY NIGHT.

IN THE MEDIUM RANGE...THE ECMF AND MRF MODELS CONTINUE TO
SCRAMBLE TO KEEP UP WITH ALL OF THE CHANGES, AND BOTH DIVERGE
FROM ONE ANOTHER AND FROM PREVIOUS RUNS BY ABOUT FRIDAY. THE
ECMF SUGGESTS MORE ZONAL (WEST TO EAST) FLOW THAN THE MRF, WHICH
STILL IS FORECASTING COLD AIR TO MOVE OVER MUCH OF THE INTERIOR
LATE THIS WEEK, COLD ENOUGH FOR SOME SNOW AND WINTER WEATHER.

.AFG...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY AREAS 10B, 11A, 11B.

TF SEP 03