Funnel Cloud in Alaska, September 7, 2009

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKDT MON SEP 7 2009

.MODEL DISCUSSION...
UPPER LEVEL...ALL MODELS IN RELATIVELY GOOD AGREEMENT THROUGH
THURSDAY. ALL MODELS TAKE THE UPPER LOW OVER THE EASTERN ALEUTIANS
INTO THE WESTERN GULF TUESDAY AS A CLOSED LOW DROPS OUT OF THE ARCTIC
THROUGH THE BERING. THE TWO WRAP UP TOGETHER SOUTH OF THE EASTERN
ALEUTIAN CHAIN WEDNESDAY WITH AN UPPER LEVEL LOW MOVING INTO THE SEA
OF OKHOTSK. THE TWO MAJOR UPPER LOWS TO SWING EAST INTO THURSDAY. BY
FRIDAY...THE DIFFERENCES START TO REALLY SHOW UP. THE GFS NEVER WRAPS
THE EX-TYPHOON DUJUAN INTO THE KAMCHATKA LOW AND PUSHES IT OUT ACROSS
THE BERING AND EVENTUALLY PUSHING INTO THE NORTHEAST PACIFIC.
THEREFORE...THE WESTERN BERING IS MORE PROGRESSIVE. EVEN SO...THE
SPREAD IS LARGE BY SATURDAY AMONG MODELS AND THE ENSEMBLE MEMBERS.

AT THE SURFACE...LARGE DIFFERENCES IN THE HANDLING OF A SHORT WAVE
TROUGH ROTATING AROUND THE STACKED LOW IN THE EASTERN ALEUTIANS. THIS
SHORT WAVE TO DEVELOP A LOW ALONG THE TRIPLE POINT IN THE EASTERN
GULF TONIGHT. THE UKMET NOT THERE AT ALL WHILE THE ECMWF HAS THE LOW
FARTHER WEST AND THE GFS AND NAM ARE IN THE EASTERN GULF. GFS HAS
BEEN RATHER CONSISTENT WITH THIS APPROACH SINCE YESTERDAY AND WE HAVE
GONE THIS WAY WITH OUR FORECAST. BY WEDNESDAY MORNING...THE MODELS
ARE SIMILAR IN THE POSITIONING OF THE LOW AS IT WRAPS BACK TO THE
STACKED LOW NEAR THE AKPEN. ANOTHER LOW MOVING INTO THE PICTURE NEAR
45N 150W WEDNESDAY TO BECOME THE PICTURE BY THURSDAY AS IT DEEPENS
INTO THE 960S THURSDAY. GALE TO STORM FORCE WINDS WRAPPED AROUND THIS
LOW. THE LOW TO BECOME STACKED AND FILL INTO SATURDAY. HOWEVER...BIG
DIFFERENCES IN THE BERING BY THIS TIME. THE GFS IS MORE PROGRESSIVE
AND HANDLES THE EX-TYPHOON DUJUAN DIFFERENTLY THAN THE ECMWF.

.ANALYSIS AND UPPER LEVELS...
THE BIG PLAYER IS THE STACKED LOW OVER THE EASTERN ALEUTIANS EARLY
THIS AFTERNOON WITH HIGH PRESSURE OVER THE PANHANDLE. A MODERATE
FRONT IS STRETCHED FROM THE SOUTHERN GULF INTO BRISTOL BAY WITH NEAR
GALE FORCE WINDS SURROUNDING IT. A 160 KT JET AT THE BASE OF THE
STACKED LOW DRAWING THE LOW SOUTH AND EAST OVER THE NEXT 12 HOURS. A
VORTICITY MAX/SHORT WAVE TROUGH AT THE HEAD OF THIS JET DEVELOPING A
SURFACE LOW ALONG THE TRIPLE POINT IN THE EASTERN GULF THIS EVENING.
IN ADDITION...A CUTOFF LOW IS DROPPING OUT OF THE ARCTIC AND CARVING
OUT A TROUGH OVER THE BERING IN THE NEXT 24 HOURS.

LOTS OF STRATUS ONCE AGAIN OVER SOUTH CENTRAL ALASKA THIS MORNING AND
INTERIOR OF SOUTHWEST ALASKA. MOST OF THIS AREA HAS BURNED OFF EARLY
THIS AFTERNOON. PRECIPITATION HAS NOT STRETCHED TO KODIAK CITY BUT IS
PRESENT FROM THE CENTRAL ALEUTIANS TO THE SOUTHWEST COAST OF ALASKA
AND THE SOUTHERN PORTION OF KODIAK ISLAND.

.SHORT TERM FORECAST...
.SOUTH CENTRAL...
WEAK UPPER LEVEL LOW OVER THE AREA TO LIFT NORTH TONIGHT.
HOWEVER...ENOUGH INSTABILITY LEFT FOR SHOWERS AND THUNDERSTORMS OVER
THE COPPER BASIN AND ALONG THE TALKEETNA MOUNTAINS AND ALASKA RANGE
AGAIN. MEANWHILE...A FRONT IS WORKING NORTH IN THE GULF WITH A TRIPLE
POINT LOW DEVELOPING IN THE EASTERN GULF. PRECIPITATION TO BE MAINLY
ALONG THE COAST WITH THE FRONT AND THROUGH KODIAK ISLAND. VALDEZ MAY
BE SPARED HEAVIER PRECIP A BIT DUE TO SOME LEE SIDE DRYING IN THE
AREA. THE TRIPLE POINT LOW TO WRAP AROUND THE GULF THROUGH TOMORROW
AND WEDNESDAY. THIS WILL INCREASE SOME WINDS ALONG THE NORTHERN GULF
COAST TOMORROW AFTERNOON AND NIGHT. A BRIEF SHOT OF PRECIP MAY WORK
INLAND AS THIS LOW GETS CLOSE TO THE COAST TUESDAY EVENING. NEXT
SYSTEM TO MOVE INTO THE SOUTHERN GULF IS LARGE WITH GALE TO STORM
FORCE WINDS AND LARGE WAVES WEDNESDAY NIGHT THROUGH THURSDAY. LOW TO
BECOME STACKED THURSDAY NIGHT AND START TO FILL WITH LIGHTER WINDS
AND DECREASED WAVES. ONCE AGAIN...MOST PRECIP TO REMAIN ALONG THE
COAST EXCEPT A SHORT WAVE PUSHING INLAND WITH THE LOW THURSDAY. GOOD
WINDS THROUGH TURNAGAIN ARM THROUGHOUT THE NEXT FEW DAYS AS A RESULT.

.SOUTHWEST ALASKA...
STACKED LOW JUST SOUTH OF THE EASTERN ALEUTIANS WITH PRECIP MOVING
INTO BRISTOL BAY AND ALONG THE YK DELTA THIS AFTERNOON. MODERATE
WINDS WITH THE FRONT AND EXPECT SOME GAP FLOWS IN EXCESS OF 45 MPH
ALONG THE ALEUTIAN MOUNTAIN CHAIN THROUGH TUESDAY. PRECIP WILL SPREAD
INLAND TONIGHT AS THE LOW WORKS INTO BRISTOL BAY. IN ADDITION...THE
UPPER LOW FROM THE ARCTIC TO PUSH INTO THE EASTERN BERING ENHANCING
PRECIP CHANCES ALONG THE YK DELTA. A BROAD AREA OF LOW PRESSURE TO
REMAIN IN SOUTHWEST ALASKA THROUGH THURSDAY WITH SOME PRECIP.
HOWEVER...THE LARGE LOW IN THE GULF TO BRING SOME DRYING NORTHEAST
FLOW TO THE AREA AS WELL.

.BERING SEA AND ALEUTIANS...
A LOW NEAR THE EASTERN ALEUTIAN CHAIN BRINGING PRECIP FROM THE
CENTRAL ALEUTIANS EASTWARD. THE LOW TO ROTATE INTO BRISTOL BAY
TUESDAY WITH AN UPPER LEVEL LOW PUSHING SOUTH THROUGH THE BERING.
THIS UPPER LEVEL FEATURE TO BRING COLDER AIR AND STRENGTHEN THE
GRADIENT FROM THE LOW IN THE GULF ESPECIALLY WEDNESDAY. EXPECT GALE
FORCE WINDS WITH STORM GUSTS FOR THE CENTRAL BERING AND ALEUTIANS.
EX-TYPHOON DUJUAN TO WORK TOWARD THE WESTERN ALEUTIANS WEDNESDAY
NIGHT INTO THURSDAY WITH LARGE AMOUNTS OF PRECIP SPREADING INTO THE
CENTRAL ALEUTIANS BY THURSDAY AFTERNOON. STRONG WINDS SHOULD
ACCOMPANY THIS SYSTEM AS WELL. THE WINDS IN THE CENTRAL AND EASTERN
BERING SHOULD BEGIN TO DROP OFF AT THIS TIME AS THE HIGH PRESSURE IN
BETWEEN THE WESTERN ALEUTIAN LOW AND THE GULF LOW WEAKENS AND THE
COLD ADVECTION IS OVER.

.LONG TERM FORECAST...
LONG TERM GETS DICEY AFTER THURSDAY WITH THE INTERACTION OF
EX-TYPHOON DUJUAN AND THE CHANGE IN THE LONG WAVE PATTERN TO MORE
PROGRESSIVE OR NOT. OVERALL...A SLIGHTLY BELOW NORMAL TEMPERATURES
WITH SOME PRECIPITATION AT TIMES FOR THE EXTENDED.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 165 170 171 179 185
FIRE WEATHER...NONE

JN SEP 09