High Wind in Alaska, September 26, 2002

NORTH ALASKA FORECAST DISCUSSION
400 AM ADT THU SEP 26 2002

958 MB LOW JUST NORTHWEST OF THE PRIBILOF ISLANDS PUTTING ON CLINIC IN
BAROTROPIC METEOROLOGY WITH BANDED RAIN/CLOUD SPIRAL NOW REACHING SAINT
LAWRENCE ISLAND-YUKON DELTA-KODIAK ISLAND. SYSTEM IS NOW VERTICALLY
STACKED THROUGH 300 MB LEVEL AND WORKING AGAINST A VERY WEAK TEMPERATURE
GRADIENT AT THE SURFACE. 120 KT 300 MB JET STREAK NOSING NORTHWARD ON
EAST SIDE OF THE SYSTEM WILL PUT LEFT-EXIT DYNAMIC LIFT AND GENERAL
DIFFLUENT FLOW OVER LOWER YUKON VALLEY TO ENHANCE PRECIPITATION AND KICK
UP WIND SPEEDS OVER THE NEXT 24 HOURS. PRECIPITATION HAS BEEN GENERALLY
VERY LIGHT WITH THIS SYSTEM...NOME PICKED UP A LITTLE OVER A TENTH SINCE
4 PM WED...AND OTHER NORTON SOUND/WEST COAST POINTS RECEIVED LESS...AND
EXPECTING NO HYDROLOGY NUISANCES THURSDAY AS SYSTEM CREEPS NORTH.

ELSEWHERE...LEE-SIDE TROUGH ON NORTH SLOPE OF THE BROOKS RANGE WORKING
AGAINST PERSISTENT 1028 MB HIGH NORTH OF BANKS ISLAND TO KEEP WIND
SPEEDS IN THE TEENS AT BARTER ISLAND AND BARROW AND BACKING WIND
DIRECTIONS TO EASTERLY...PROVIDING LITTLE HELP FOR ROUNDS OF FOG AND
DRIZZLE ALONG THE IMMEDIATE COAST. DOWN SOUTH...WEAK SURFACE TROUGH
PERSISTS NORTH OF THE ALASKA RANGE THROUGH THE TANANA VALLEY...BUT HAS
CONTRIBUTED LITTLE TO SENSIBLE WEATHER PICTURE. CHINOOK FLOW THROUGH
ALASKA RANGE PASSES STARTING TO PICK UP WITH GUSTS NEAR 30 KT AT
HEALY...AND GUSTS INTO THE TEENS AT DENALI PARK HEADQUARTERS.

MODELS...AGREEING WELL THROUGH SAT MORNING...GRADUALLY LIFTING BERING
SEA TROUGH AND MOVING CLOSED LOW FROM THE PRIBILOFS TO THE SEWARD
PENINSULA BY FRI AFTERNOON...AND VEERING UPPER LEVEL FLOW FROM SOUTH TO
SOUTHWEST TO WEST THROUGH THE NEXT SEVERAL DAYS. ASSOCIATED SURFACE LOW
WILL FILL A FEW MBS PER PERIOD AND END UP IN THE LOW 980S PARKED NEAR
NOME FRI AFTERNOON AND INTO THE WEEKEND. BREAK-OFF LOW WILL FORM NEAR
THE MACKENZIE DELTA TONIGHT...AND RESULTING SEWARD PENINSULA-MACKENZIE
DELTA TROUGH WILL ENHANCE RAIN CHANCES FOR SOUTH SLOPES OF BROOKS RANGE
ON FRIDAY AND SATURDAY.

NORTH SLOPE...PERSISTENT TROUGH NORTH OF BROOKS RANGE WILL BE KEY PLAYER
OVER NEXT COUPLE OF DAYS...KEEPING BREEZY WINDS BACKED TO
EASTERLY/ONSHORE AND ENHANCING RAIN CHANCES THU NIGHT AND FRI. WILL KEEP
SMALL CRAFT PENNANT AT THE MASTHEAD FOR MARINERS...AND EXPECT THIS TO
FLY AT LEAST THROUGH FRI. FOG CALL A CHALLENGE...BUT SLIGHT OFFSHORE
COMPONENT EAST OF BARROW MAY PERMIT SOME CLEARING DURING THE DAY TODAY.
LITTLE TEMPERATURE CHANGE THROUGH THE EARLY WEEKEND.

WEST COAST...CLOUDS AND RAIN INTO THE WEEKEND AS SURFACE LOW PARKS AND
FILLS OVER NOME ON FRIDAY. ALTHOUGH PRECIPITATION HAS BEEN ON THE LIGHT
SIDE SO FAR...STEADIER AND PERSISTENT RAIN OVER THE SOUTHERN SEWARD
PENINSULA ON FRI WILL BE WATCHED FOR POSSIBLE HYDROLOGIC ATTENTION GOING
INTO THE WEEKEND BEFORE RAINS TAPER OFF ON SUNDAY. HOWEVER, A GENERAL
PAUCITY OF PRECIPITATION FOR THE LAST 10 DAYS MAY HELP MITIGATE ANY
HYDRO ANXIETIES WITH THIS SYSTEM. MARINERS...WILL HAUL DOWN GALE
WARNINGS FOR AREAS 14 AND 9B DURING THE DAY ON THU IN EXCHANGE FOR SMALL
CRAFT PENNANT AS PARENT LOW WEAKENS. 08Z NOME TIDE DATA SHOWING A RISE
OF ABOUT 2 FT ABOVE ASTRONOMICAL (NORMAL) TIDES. THIS SHOULD HOLD FOR
THE REST OF TODAY BEFORE DECLINING TONIGHT.

INTERIOR...DYNAMIC ASSIST MOST PRONOUNCED ON EAST SIDE OF CLOSED BERING
SEA LOW WILL WORK WITH WEAK OCCLUSION BANDS TO SMEAR PRECIPITATION
NORTHWARD FROM THE LOWER YUKON VALLEY TO THE SOUTH SLOPES OF THE BROOKS
RANGE THU...AND GRADUALLY WORK THIS EASTWARD. EXPECT BEST RAIN CHANCES
WILL BE GENERALLY WEST OF AN ANAKTUVUK PASS-INDIAN MOUNTAIN-LAKE
MINCHUMINA LINE...WITH A SOUTHERLY CHINOOK FLOW...AND LACK OF
DYNAMICS...LIMITING RAIN FURTHER EAST. LITTLE CHANGE TO THE MILD
TEMPERATURE REGIME.

MEDIUM RANGE...MODELS AGREEING ON THE STORY THROUGH THE WEEKEND...MOVING
CLOSED LOW ALOFT OVER THE SIBERIAN ARCTIC WITH HIGH ALOFT PARKED OVER
THE CENTRAL GULF OF ALASKA. PATTERN PRODUCING A GENTLE SOUTHWEST FLOW
INTO THE FIRST PART OF NEXT WEEK FOR CLOUDY/SHOWERY/COOL CONDITIONS
STATEWIDE. DIFFERENCES EMERGING ON MONDAY AND TUESDAY...AS UKMET DIGS
TROUGH SOUTHWARD ALONG THE DATELINE AND BUILDS RIDGE NORTHWARD INTO THE
HEART OF THE STATE WHILE ECMWF/AVN MUCH LESS AGGRESSIVE WITH TROUGH AND
MORE ZONAL FLOW STATEWIDE. WILL KEEP AN EYE ON BRITISH COLLEAGUES IN THE
NEXT RUN OR TWO...BUT SIDE THIS ROUND WITH EUROPEAN AND DOMESTIC
SOLUTIONS THROUGH MIDWEEK.

.AFG...WATCH/WARNING SUMMARY
PUBLIC...WIND ADVISORY: 213/214
MARINE...GALE: AREAS 14/9B. SCA: 9A/10A/11A/11B

TS SEP 02