Gale Warning 572, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AKDT MON SEP 22 2008

.ANALYSIS AND UPPER LEVELS...
A SHORT WAVE RIDGE IS IN PLACE OVER SOUTHCENTRAL ALASKA WITH A LARGE
STACKED LOW OVER THE KUSKOKWIM DELTA. ANOTHER STACKED LOW IS NEAR THE
CENTRAL ALEUTIANS WITH A WEAKENING FRONTAL BOUNDARY EXTENDING
SOUTHWARD INTO THE NORTH PACIFIC. RAIN BEGAN EARLIER THAN EXPECTED
FROM THE WESTERN KENAI TO THE SUSITNA VALLEY THIS MORNING WITH
WIDESPREAD SHOWER ACTIVITY CONTINUING OUT WEST.

.MODEL DISCUSSION...
MODELS CONTINUE TO BE IN EXCELLENT AGREEMENT IN THE SHORT TERM. RUN
TO RUN CONSISTENCY IS ALSO FAIRLY GOOD THROUGH THE FIRST 72 HOURS.
BEGINNING THURSDAY NIGHT...THE GFS HAS BEEN TRENDING FURTHER SOUTH
WITH A GULF OF ALASKA LOW AND WEAKER WITH THE APPROACHING ALEUTIAN
FRONT. ALL THESE TRENDS WILL BE REFLECTED IN THE AFTERNOON FORECAST
PACKAGE...THEN TRANSITION TO A GFS/EC BLEND WAS USED FOR THE EXTENDED
FORECAST.

.SHORT TERM FORECAST...

SOUTHCENTRAL...
SOUTHWEST FLOW UP COOK INLET BROUGHT LIGHT RAIN TO THE ANCHORAGE BOWL
A BIT SOONER THAN ANTICIPATED. THE 12Z GFS AND NAM STILL DO NOT PICK
UP ON THE RAIN UNTIL AROUND 6PM THIS EVENING ASSOCIATED WITH A SHORT
WAVE. THE SHORT WAVE IS EVIDENT ON THE WATER VAPOR IMAGERY LOCATED
NEAR THE ALASKA PENINSULA WHICH IS CORRECTLY DEPICTED BY THE MODELS
SO WILL CONTINUE CALLING FOR RAIN OVERNIGHT AND THROUGH WEDNESDAY
MORNING. THIS IS WHERE THE MODELS TRENDING TOWARD A LOW FURTHER SOUTH
IS COMING INTO PLAY FOR THE SOUTH CENTRAL FORECAST. INSTEAD OF
SOUTHWESTERLY FLOW REMAINING ALOFT AND RAIN LIKELY THROUGH
THURSDAY...NOW FLOW WILL BECOME MORE NORTHEASTERLY WHICH WILL DRAW
SOME DRIER AIR SOUTHWARD OVER THE AREA LATE WEDNESDAY THROUGH
THURSDAY. HOW MUCH CLEARING IS STILL UNCERTAIN AS A SADDLE POINT
MOVES OVER SOUTH CENTRAL FRIDAY. SADDLE POINTS ARE GENERALLY
ASSOCIATED WITH OVERCAST CONDITIONS SO WHILE WE MAY SEE A BREAK FROM
THE RAIN IT APPEARS CLOUDS WILL STILL REMAIN OVER THE AREA.

SOUTHWEST ALASKA...
A VERY IMPRESSIVE VERTICALLY STACKED LOW IS LOCATED JUST NORTHWEST OF
BETHEL EARLY THIS AFTERNOON. RAIN IS FALLING FROM THE UPPER
KUSKOKWIM VALLEY TO BRISTOL BAY ASSOCIATED WITH THIS SYSTEM. ONSHORE
FLOW IS KEEPING CEILINGS LOW ALONG THE COAST WITH FOG AND RAIN
REPORTED AT MOST OBSERVATION STATIONS. AS THE SYSTEM SLOWLY WEAKENS
AND DRIFTS SOUTH TOWARD THE ALASKA PENINSULA...SHOWERS WILL DIMINISH
FIRST IN THE UPPER KUSKOKWIM VALLEY TONIGHT AND TAPER OFF TOWARD THE
COASTAL SECTIONS BY LATE WEDNESDAY NIGHT. THE EXCEPTION WILL BE ALONG
THE ALEUTIAN RANGE WHERE SOME SHOWERS MAY STILL SLOSH OVER THE
MOUNTAINS AND AFFECT AREAS LIKE ILIAMNA AND KING SALMON.

BERING SEA/ALEUTIANS...A LONG WAVE RIDGE IS SETTLING OVER EASTERN
SIBERIA. SEVERAL SYSTEMS WILL UNDERCUT THIS AREA OF HIGH
PRESSURE...EACH ONE BEING PUSHED SOUTH TOWARD THE ALEUTIAN RANGE.
ONLY MINIMUM GALES ARE EXPECTED WITH THE FRONTAL SYSTEM APPROACHING
THE WESTERN ALEUTIANS TODAY.

.EXTENDED...
WHILE THE MODELS HAVE BEEN VERY INCONSISTENT WITH THE EXTENDED
FORECAST...IT IS WORTH NOTING ONE FEATURE THAT HAS BEEN ADVERTISED A
COUPLE OF RUNS NOW. A VERY COLD CORE UPPER LOW MAY DROP OUT DUE SOUTH
OUT OF THE ARCTIC BRINGING THE FIRST COOL WEATHER OUTBREAK ACROSS
MOST OF THE INTERIOR LATE THIS WEEKEND INTO EARLY NEXT WEEK. MODELS
HAVE BEEN WILDLY INCONSISTENT WITH THE TIMING AND STRENGTH BUT THERE
IS ENOUGH INDICATIONS THAT THIS COULD BRING THE FIRST SNOWFALL TO
MANY OF THE VALLEYS ACROSS THE INTERIOR.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 175 176.
FIRE WEATHER...NONE.

AB SEP 08