Blizzard and High Wind in Alaska, March 27 to 28, 2003

NORTH ALASKA FORECAST DISCUSSION
230 PM AST WED MAR 26 2003

THE AVIATION AND ETA MODELS HAVE SIMILAR SOLUTIONS OUT TO 60 HOURS THIS
MORNING. THE TROUGH ALOFT FROM KAKTOVIK TO CAPE NEWENHAM IS SLIDING
VERY SLOWLY TO THE SOUTHEAST...AND IS DUE TO RUN FROM INUVIK TO PRINCE
WILLIAM SOUND FRIDAY AFTERNOON. THE SLOW MOVEMENT OF THIS SYSTEM AND
THE THERMAL GRADIENT IN ADVANCE OF IT SUGGEST MORE LIGHT SNOW OVER THE
SOUTHEAST INTERIOR. THE FAIRBANKS NEXRAD SHOWS VERY SLOW CLEARING FROM
THE NORTHWEST. THE TOPS OF THE CLOUDS ARE NEAR 12000 FEET.

THE ETA MODEL MOVES THIS TROUGH ALOFT A LITTLE FASTER TO THE EAST
THAN THE AVIATION. BUT THE IMPLICATIONS FOR THE WEATHER IN THE
SOUTHEAST INTERIOR ARE NOT MUCH DIFFERENT BETWEEN THE TWO.

AT THE SURFACE...HIGH PRESSURE OVER THE ARCTIC AND BERING SEA COASTS
WILL RETREAT TO THE EAST. LOW PRESSURE OVER THE WEST BERING SEA IS
ADVANCING EAST...IT WILL BE JUST SOUTH OF PROVIDENIYA FRIDAY AFTERNOON.
THE FRONT IN ADVANCE OF THIS LOW WILL REACH THE BERING SEA COAST OF
NORTHERN ALASKA AT THE SAME TIME. SNOW WILL BEGIN OVER THE WEST COAST
FRIDAY MORNING AS THE FRONT APPROACHES.

THE LOW ALOFT WITH THE BERING SEA LOW IS FORECAST TO MOVE ASHORE OVER
THE YUKON DELTA FRIDAY NIGHT...TO BE SOUTH OF DENALI PARK SATURDAY
NIGHT...AND IN THE NORTH GULF OF ALASKA SUNDAY. THIS FEATURE SHOULD
BRING LIGHT SNOWFALL TO MUCH OF THE INTERIOR OVER THE WEEKEND. IT LOOKS
LIKE MOST OF THE SNOW WILL BE ON THE NORTH SLOPES OF THE ALASKA RANGE.
IT IS NOT YET CLEAR IF THERE WILL BE HEAVY SNOWFALL. NORTH FLOW ON THE
BACK SIDE OF THE LOW ALOFT WILL BRING CLEARING FROM THE WEST TO THE
INTERIOR SATURDAY NIGHT THROUGH SUNDAY NIGHT.

IN THE ARCTIC...IT IS STILL CLEAR AND COLD WITH VERY LITTLE WIND.
PATCHY FOG WILL REMAIN ON THE COAST. NORTHEAST WINDS SHOULD SET IN
FRIDAY NIGHT AND BECOME LIGHT WEST ON SUNDAY. SOME LOW CLOUDS AND
AREAS OF FOG CAN BE EXPECTED ON THE COAST WHERE THE WIND IS ON SHORE.
INFRARED SATELLITE IMAGERY INDICATES 40 BELOW TEMPERATURES AT MORNING
OVER THE INLAND FLATS.

IN THE WEST...SOME VERY THIN STRATUS REMAINS OVER THE NORTH SIDE OF
THE SEWARD PENINSULA. THIS LAST SHRED OF CLOUD WILL CLEAR LATE TONIGHT
AS WINDS OVER THAT AREA SHIFT FROM LIGHT NORTH TO SOUTHEAST. SNOW WILL
BEGIN OVER THE BERING SEA COAST OF NORTHERN ALASKA FRIDAY MORNING...
AND END EARLY SUNDAY AND WINDS SHIFT TO THE NORTH. THE CLEARING THAT
BEGINS SUNDAY MAY LAST WELL INTO NEXT WEEK.

IN THE INTERIOR...THE DECK OF STRATO CUMULUS OVER THE UPPER KOYUKUK
VALLEY EXPANDED OVER THE YUKON FLATS AND PART OF THE SOUTH SIDE OF THE
BROOKS RANGE OVER NIGHT TUESDAY NIGHT. FOR THE PAST 2 DAYS...THIS
DECK OF CLOUDS APPEARS TO BE FORMING UNDER AN AREA OF LIGHT WINDS
ALOFT...IN THE LOWEST 10000 FEET OR SO. ITS LOCATION ALSO MATCHES A
MODERATE THERMAL GRADIENT AT 850 MB...SITUATED NORTHEAST TO SOUTHWEST.
THE THERMAL GRADIENT IS FORECAST TO WEAKEN TONIGHT AND THURSDAY...WHILE
FLOW ALOFT REMAINS VERY LIGHT. SO IF THESE CLOUDS CLEAR TONIGHT AND
EARLY THURSDAY...THE THERMAL GRADIENT WOULD BE THE SUSPECT MECHANISM.
IF THE CLOUDS DO NOT CLEAR...THE LIGHT WINDS ALOFT WILL BE THE SUSPECT.
I DO NOT THINK THE CLOUDS THERE WILL CLEAR TONIGHT. STAY TUNED FOR THE
OUTCOME OF THIS EXPERIMENT.

THE AREA OF SNOW OVER THE SOUTHEAST INTERIOR LOOKS LIKE IT WILL SHRINK
IN EXTENT...BUT NOT END ON THE YUKON BORDER UNTIL FRIDAY. JUST AS
THIS HAPPENS...A FRESH BATCH OF SNOWFALL SHOULD SPREAD INTO THE FAR
SOUTHWEST...AND THEN INTO THE SOUTH INTERIOR ON SATURDAY. TEMPERATURES
WILL REMAIN NEAR OR BELOW NORMAL...AND COOL NEXT WEEK WITH THE NORTH
FLOW.

IN THE MEDIUM RANGE...THE ECMF AND MRF MODELS ARE FORECASTING HIGH
PRESSURE ALOFT AND AT THE SURFACE TO BUILD OVER NORTHERN ALASKA FROM
THE WEST EARLY NEXT WEEK...AND TO STAY OVER THE REGION MOST OR ALL OF
THE WEEK. THIS SUGGESTS A LONG PERIOD OF MOSTLY SUNNY AND QUIET
WEATHER FOR NORTHERN ALASKA NEXT WEEK.

.AFG...WATCH/WARNING SUMMARY
PUBLIC. NONE.
MARINE. GALE WEST PART OF AREA 14. BRISK WIND ADVISORY EAST PART OF
AREA 14 AND WEST PART OF AREA 9B.

TF MAR 03