FXAK68 PAFC 041350
AFDAFC
AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
600 AM AKDT SAT JUL 4 2009
.ANALYSIS AND UPPER LEVELS...
IN THE UPPER LEVELS...
HIGHLY AMPLIFIED PATTERN CONTINUES WITH AN OMEGA BLOCK THAT EXTENDS
FROM THE NORTHERN PACIFIC OCEAN THROUGH MUCH OF THE MAINLAND. AN
UPPER LEVEL LOW ON THE NORTHERN PERIPHERY OF THE KAMCHATKA PENINSULA
IS CUT OFF FROM ANY UPPER LEVEL SUPPORT AND WILL SLOWLY DRIFT FURTHER
INTO RUSSIA AND EVENTUALLY DISSIPATE AS A NEW LOW IS SPUN UP SOUTH OF
THE CHAIN LATER THIS AFTERNOON.
AT THE SURFACE...
SURFACE HIGH PRESSURE OVER THE GULF CONTINUES TO WEAKEN AND DRIFT TO
THE SOUTH. WINDS ALONG THE SOUTHCENTRAL COASTS HAVE BECOME OFFSHORE
AND THAT SLIGHT PUSH HAS HELPED TO MOVE THE MARINE LATER WELL OUT TO
SEA...AND IT SHOULD LIKELY REMAIN THAT WAY THROUGH THE WEEKEND. THE
LIGHT WINDS AND RADIATIONAL COOLING DID MANAGE TO FORM FOG ALONG THE
EASTERN SOUND THIS MORNING...AND AREAS LIKE CORDOVA REDUCED
VISIBILITY TO LESS THAN A QUARTER OF A MILE. THE FOG SHOULD NOT LAST
LONG AS DAYTIME HEATING WILL ALLOW THE LOWER ATMOSPHERE TO QUICKLY
MIX OUT ANY OF THE FOG. THE FRONT THAT BLASTED THE AKPEN THURSDAY
NIGHT AND FRIDAY MORNING HAS ALL BUT FADED AS THE BLOCKING HIGH THAT
WAS OVER THE MAINLAND HINDERED ANY EASTERLY PROGRESSION. ONSHORE FLOW
IN BRISTOL BAY AND THE KUSKOKWIM BAY HAS USHERED IN A MARINE LAYER
AND WILL LEAVE THE AREA THICK WITH LOW CLOUDS/STRATUS THROUGH THE
WEEKEND. 
.MODEL DISCUSSION...
MODELS HAVE AN EXCELLENT HANDLE ON THE CURRENT WEATHER PICTURE
THROUGH THE WEEKEND. OVER SOUTHCENTRAL THE SURFACE HIGH WILL
EVENTUALLY WEAKEN AND DIP SOUTH AS A TROUGH OF LOW PRESSURE BUILDS 
OVER THE NORTHEASTERN GULF. OUT WEST ALL OF THE MODELS HANDLE THE
DEEPENING LOW THAT IS SET TO CROSS THE ALEUTIAN CHAIN NEAR ADAK
SUNDAY AFTERNOON. ALL MODELS ARE IN THE SAME GENERAL BALL PARK WITH
INTENSITY AND POSITION EXCEPT FOR THE NAM AND UKMET...WHO ARE LAGGING
BEHIND AND DIFFER BY A FEW HUNDRED MILES FROM THE MAJORITY OF THE
OTHER MODELS. CONFIDENCE IN THE SHORT TERM FORECAST IS ABOVE AVERAGE
THROUGH THE WEEKEND. 
.SHORT TERM FORECAST...
.SOUTHCENTRAL...A BEAUTIFUL 4TH OF JULY IS IN STORE FOR THE MAJORITY
OF SOUTHCENTRAL. TEMPERATURES ALOFT CONTINUE TO WARM AND THUS
STABILIZE THE ATMOSPHERE. OVER THE PREVIOUS DAYS...THUNDERSTORM
ACTIVITY HAS BEEN INITIATED THROUGH DAYTIME SURFACE HEATING AND THEY
WERE AIDED BY UPPER LEVEL VORTICITY MAXIMA THAT SPIN OVER THE AREA.
TODAY THERE IS A LACK OF ANY MEANINGFUL TRIGGER FOR STORMS. GUIDANCE
SUGGESTS THAT A LARGE PORTION OF THE AREA MAY BE UNSTABLE...BUT THE
THOUGHT IS THAT TOO MUCH OF THE AREA IS STABLE...SO STORMS THAT DO
FORM TODAY WILL LIKELY REMAIN OVER THE INTERIOR MOUNTAINS. WITH THE
BLOCKING RIDGE ENTRENCHED OVERHEAD...A 'HEATWAVE' OF SORTS IS GOING
TO AFFECT THE AREA THROUGH THE WEEKEND. WHILE NO RECORDS ARE IN
DANGER OF BEING BROKEN...DAYTIME HIGHS THROUGHOUT THE INTERIOR WILL
LIKELY BREAK THE 80 DEGREE RANGE...WHILE THE ANCHORAGE BOWL WILL SEE
LOWER TO MIDDLE 70S IN THE COMING DAYS (RECORD HIGH TEMPERATURES ARE
CURRENTLY IN THE 80S) WHILE OVERNIGHT LOWS WILL REMAIN IN THE MIDDLE
TO UPPER 50S. BEYOND THE WEEKEND...THE ONLY REAL INSPIRATION FOR GOOD
SHOWER ACTIVITY WILL BE LIMITED TO THE EASTERN COPPER RIVER DELTA AS
A SHORTWAVE WILL DIVE OVER THE RIDGE AND MAY BRING SHOWERS SUNDAY AND
INTO MONDAY.
.SOUTHWEST...
THE FRONT THAT MOVED THROUGH THE AREA YESTERDAY CAN ONLY BE SEEN BY
SATELLITE AS CIRRUS THAT STRETCHES FROM NORTON SOUND THROUGH SHELIKOF
STRAIT. BEHIND THE FRONT WINDS HAVE SHIFTED TO THE SOUTHWEST AND THE
FLOW IS BRINGING A JUICY MARINE LAYER ONSHORE. COASTAL AREAS WILL BE
MUCH COOLER THAN AREAS INLAND TODAY WITH NO SHORTAGE OF CLOUDS.
GUIDANCE IS SUGGESTING THE POSSIBILITY FOR THUNDERSTORM ACTIVITY IN
THE LOWER KUSKOKWIM VALLEY TODAY...BUT OPTED AGAINST IT AS CONDITIONS
DONT SEEM TOO VIABLE FOR ANY REAL CONVECTIVE ACTIVITY. THE NEXT
SYSTEM TO AFFECT WILL BE IN THE FORM OF A SLOW AND WEAK WEATHER FRONT
ON MONDAY. THIS FRONT SHOULD NOT BRING ANY PRECIPITATION TO THE
MAINLAND...ONLY AREAS ALONG THE PACIFIC AKPEN.  
.BERING SEA AND ALEUTIANS...
SOUTHERLY FLOW AND AN ABUNDANCE OF CLOUDS WILL BE AROUND FOR TODAY.
THE NEXT SYSTEM WILL MOVE ACROSS THE CENTRAL CHAIN LATE TONIGHT AND
INTO TOMORROW MORNING. PRECIPITATION WILL BE WIDESPREAD ACROSS THE
AREA FROM COLD BAY THROUGH ADAK. WINDS WILL INCREASE TO GALE FORCE
LATE TOMORROW WITH PRECIPITATION LASTING THROUGH MONDAY. 
.LONG TERM FORECAST...
THE ECMWF AND GFS HAVE COME INTO GOOD AGREEMENT FOR THE MEDIUM TO
LONG TERM FORECAST AND THE GFS WAS RELIED ON FOR THE LONG RANGE
FORECAST TONIGHT. THIS FORECAST WILL KEEP A RIDGE OVER THE MAINLAND
WITH A WEAK TROUGH THAT WILL BUILD IN OVER THE GULF. THE MEAN
LONGWAVE TROUGH THAT HAS BEEN OVER THE BERING WILL EVENTUALLY FLATTEN
AND WINDS WILL TURN TO MORE OF A ZONAL COMPONENT AND ANY SYSTEMS IN
THE BERING/WESTERN PACIFIC NEXT WEEK WILL NOT BE VERY INTENSE AND
WILL NOT MOVE QUICKLY.
.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...NONE
FIRE WEATHER...NONE
SSS JUL 09