Gale Warning 749, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
530 AM AKDT SUN OCT 17 2010

.ANALYSIS AND UPPER LEVELS...AN IMPRESSIVE UPPER LEVEL LOW CENTERED
OVER BRISTOL BAY COVERS MUCH OF THE BERING AND SOUTHWEST MAINLAND
ALASKA. THIS LOW IS DRAWING IN DRY COLD AIR FROM SIBERIA WHICH IS
BEING WRAPPED INTO THE CENTER OF THE LOW. THE UPPER LEVEL JET COVERS
MUCH OF THE NORTH PACIFIC WITH A JET STREAK THAT IS SUPPORTING A
SURFACE LOW OVER THE BERING. MEANWHILE...AN IMPRESSIVE DOWNWARD
STRATOSPHERIC INTRUSION IN THE VICINITY OF THE UPPER LEVEL JET
CONTINUES TO FEED DRY STABLE AIR DOWNWARDS TOWARDS THE SURFACE. A
BROAD RIDGE OVER THE WEST BERING IS BEGINNING TO BUILD AND IS
EXPECTED TO MOVE EASTWARD ACROSS THE BERING OVER THE NEXT SEVERAL
DAYS.

.AT THE SURFACE...A WELL-WRAPPED MATURE CYCLONE CONTINUES TO MEANDER
AROUND THE BRISTOL BAY REGION. IT HAS NOW PASSED ITS PEAK INTENSITY
AND IS NOW AT 966 MB. MODELS ARE INDICATING THAT THIS LOW WILL
DIMINISH GRADUALLY OVER THE NEXT SEVERAL DAYS AND MOVE SOUTHEAST
ACROSS THE ALASKA PENINSULA INTO THE NORTH PACIFIC OCEAN. ITS
ASSOCIATED OCCLUDED FRONT IS APPROACHING THE GULF COAST AND IS
SUPPORTING PRECIPITATION AND GUSTY WINDS ALONG THE COAST.
MEANWHILE...A SHORTWAVE THAT IS CURRENTLY PROPAGATING AROUND THE
BRISTOL BAY LOW IN THE NORTH PACIFIC WILL INTENSIFY OVER THE NEXT FEW
DAYS AND GROW TO BE THE DOMINANT LOW AS IT MOVES INTO THE GULF.

.MODEL DISCUSSION...
MODELS HAVE HAD A DIFFICULT TIME PREDICTING THE POSITION OF THE
COMPLEX PROMINENT LOW AS IT WOBBLES AROUND IN THE BERING. THIS HAS
MADE IT DIFFICULT TO FORECAST THE POSITION OF THE HIGH WINDS ACROSS
THE EAST ALEUTIANS. MODELS ARE ALSO HAVING ISSUES OVER THE GULF OF
ALASKA REGARDING THE TRACK OF SEVERAL AREAS OF LOW PRESSURE NORTH
THROUGH THE GULF OF ALASKA TODAY THROUGH MONDAY. USED A BLEND OF THE
0Z GFS AND ECMWF FOR THIS.

.SHORT TERM FORECAST...
SOUTHCENTRAL...
AN OCCLUDED FRONT ASSOCIATED WITH THE EAST BERING LOW HAS BEEN
BRINGING RAIN AND SHOWERS ACROSS MUCH OF THE SOUTHCENTRAL COAST AND
WESTERN COOK INLET OVERNIGHT WITH A DOWNSLOPE HOLE OVER EAST COOK
INLET. THIS FRONT HAS GENERATED GUSTS NEAR 40 KTS ALONG THE COAST AS
IT APPROACHES. RAIN AND SNOW AT HIGHER ELEVATIONS IS EXPECTED TO
PERSIST ACROSS THESE AREAS SUNDAY AS THE FRONT CONTINUES TO MOVE
INLAND.  MODELS ARE CURRENTLY INDICATING THAT THE ANCHORAGE BOWL AND
WESTERN KENAI PENINSULA WILL CONTINUE TO BE DOWNSLOPED THROUGHOUT
MUCH OF THE DAY...ALTHOUGH A FEW SHOWERS ARE POSSIBLE.

SOUTHWEST MAINLAND...EXPECT RAIN AND SNOW SHOWERS TO CONTINUE TO
IMPACT THE SOUTHWEST MAINLAND OVER THE NEXT FEW DAYS AS THE BERING
LOW MOVES SOUTHEAST. STEADY RAIN WILL ESPECIALLY FALL ACROSS THE
ALASKA PENINSULA AS THE LOW TRACKS RIGHT OVER THE AKPEN SUNDAY
EVENING. THIS LOW WILL ALSO SUPPORT GUSTY WINDS ACROSS THE
AKPEN...PARTICULARLY THROUGH CHANNELED TERRAIN. STRONG NORTHERLY
WINDS BEHIND THE LOW WILL USHER IN COOLER AIR ACROSS THE BERING INTO
SOUTHWEST ALASKA.

BERING/ALEUTIANS/ALASKA PENINSULA...MODELS ARE INDICATING THE
PRESENCE OF A LOW LEVEL JET WRAPPING AROUND THE SOUTHWEST QUADRANT OF
THE BERING LOW.  ALTHOUGH THE BRUNT OF THE JET IS ACROSS THE
OBSERVATION SPARSE REGION OF THE EASTERN ALEUTIANS...BUOY 46073 HAS
REPORTED PEAK WINDS UP TO 58 KT THIS MORNING WHICH CORRELATES WELL
WITH MODEL PREDICTION. AS A RESULT...THE HIGH WIND WARNING FOR THE
EAST AND CENTRAL ALEUTIANS IS EXPECTED TO REMAIN IN EFFECT INTO THE
AFTERNOON. THE HIGHEST WIND GUSTS ARE EXPECTED TO OCCUR WEST OF DUTCH
HARBOR. STEADY RAIN IS EXPECTED TO FALL ACROSS MUCH OF THE CENTRAL
AND EAST ALEUTIANS AS THIS LOW PRESSURE SYSTEM MOVES SOUTHWARD OVER
THE NEXT FEW DAYS.

.LONG TERM FORECAST...
AN ACTIVE PATTERN WILL CONTINUE OVER THE NEXT WEEK. THE JET STREAM
WILL CONTINUE TO UNDULATE ACROSS THE NORTH PACIFIC AND WILL SUPPORT
THE DEVELOPMENT AND PROPAGATION OF MULTIPLE LOW PRESSURE SYSTEMS
ACROSS THE REGION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING ZONE 185 AND 187.
MARINE...STORM WARNING ZONES 170 172 413.
         GALE WARNING ZONES 120 125 130 155 171 175 176 179 180 185
          352 411 412 414.
FIRE WEATHER...NONE.

ELN OCT 10