FXAK68 PAFC 111309
AFDAFC

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM ADT SAT AUG 11 2007

.MODEL DISCUSSION...
MODELS FINALLY GETTING A GRASP ON THE SITUATION. FAIRLY GOOD
AGREEMENT AMONGST THE MODELS. THE 00Z RUN OF THE GFS CORRELATES
NICELY WITH ENSEMBLES FROM PREVIOUS RUNS...AND TRANSITIONS NICELY
INTO THE CLIMATE PREDICTION CENTER (CPC) 6 TO 10 DAY OUTLOOK. 

.ANALYSIS AND UPPER LEVELS...
OUTRAGEOUSLY WARM AIR ALOFT EVIDENT ON THE COLD BAY SOUNDING THIS
MORNING...WITH 67 DEGREES AT 2500 FEET. STRONG "TROPICAL" LOOKING
INVERSION NEAR THE SURFACE KEEPING LAND TEMPERATURES DOWN...EXCEPT
DUTCH HARBOR HAS BEEN IN THE UPPER 60S MOST OF THE NIGHT. 

THERE IS A DEEP UPPER LOW ALONG 170 EAST LONGITUDE AND ANOTHER LOW
DEVELOPING OFF THE BRITISH COLUMBIA COAST. AXIS OF A STRONG RIDGE
WITH IMPRESSIVELY HIGH 500 MB HEIGHTS (590 DM TO 55 NORTH LATITUDE!)
IS ALONG ABOUT 160 WEST...AND IS ESSENTIALLY FULL LATITUDE (FROM THE
TROPICS TO THE NORTH POLE). THE JET STREAM IS PUSHING NORTH AROUND
THE DATE LINE AND THEN SPLITS ALONG THE WEST COAST OF ALASKA...WITH
THE NORTHERN BRANCH HEADING TOWARD THE NORTH POLE...AND THE SOUTHERN
BRANCH SQUEEZING THROUGH THE RIDGE AND DROPPING SOUTHEAST TOWARD
WASHINGTON STATE. 

ALSO OF NOTE...NOCTILUCENT CLOUDS WERE VISIBLE FOR SEVERAL HOURS 
FROM ANCHORAGE AND MCGRATH...AND PROBABLY MANY POINTS IN BETWEEN.
THESE ARE CLOUDS THAT ARE 85 KM ABOVE THE EARTHS SURFACE. THEY ARE
OCCASIONALLY VISIBLE THIS TIME OF YEAR AS THE SKY IS SOMEWHAT DARK
AND THE SUN ANGLE IS SUCH THAT IT SHINES ON THE CLOUDS. THEY APPEAR
BRIGHT BLUE (TYPICALLY). 

.SHORT TERM FORECAST...
AS MENTIONED ABOVE...VERY WARM AIR BEING BROUGHT IN WITH ALMOST
STRAIT SOUTHERLY FLOW. TEMPERATURES IN THE 60S TO POSSIBLY LOWER 70S
IN THE EASTERN ALEUTIANS AND AKPEN TODAY AND SUNDAY. RAIN WILL 
SPREAD EASTWARD ACROSS SOUTHWEST ALASKA TODAY AND TONIGHT...WITH DRY
CONDITIONS IN SOUTH CENTRAL UNDER BUILDING 500 MB HEIGHTS. 

ON SUNDAY AND SUNDAY NIGHT A WEAK SYSTEM WILL TRY TO CROSS THE RIDGE
INTO SOUTH CENTRAL ALASKA BRINGING SOME PRECIPITATION...BUT WILL
BREAK APART AS IT CROSSES THE AREA AND 500 MB HEIGHTS CONTINUE TO
INCREASE. 

.LONG TERM FORECAST...
ON TUESDAY AND WEDNESDAY THE LOW THAT CURRENTLY IS WEST OF THE DATE
LINE WILL UPROOT AND CROSS SOUTHERN ALASKA FOR ANOTHER ROUND OF
PRECIPITATION. AS THIS LOW PUSHES OVER THE RIDGE AND THEN DROPS DOWN
INTO THE TROUGH OFF THE WASHINGTON COAST THURSDAY AND FRIDAY...THE
RIDGE WILL RETROGRADE TO ABOUT 170 WEST LONGITUDE. CONDITIONS WILL
THEN DRY OUT OVER ALASKA BY NEXT WEEKEND. 

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE. 
MARINE...GALE WARNING 170 172 179. 
FIRE WEATHER...NONE. 

LUDWIG AUG 07