Severe Thunderstorm Warning 1, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM ADT WED JUN 15 2005

.DISCUSSION...
THE OMEGA BLOCK OVER THE MAINLAND WILL PERSIST THROUGH THE END OF
THIS WEEK BEFORE SLOWLY BEING PUSHED OFF TO THE EAST THIS WEEKEND.
THEREFORE, NO MAJOR CHANGES IN THE SHORT TERM FORECAST ARE EXPECTED.
MAIN CONCERNS REMAIN THE CONVECTIVE POTENTIAL OVER THE INLAND REGIONS
ALONG THE THERMAL TROUGH EXTENDING ALONG THE ALASKA RANGE TO THE
LOWER YUKON VALLEY. THUNDERSTORMS HAVE ALREADY STARTED IN THE
NORTHEAST KUSKOKWIM VALLEY AND ALONG THE ALASKA RANGE FROM WINDY PASS
EAST. THE REMNANTS OF THE THUNDERSTORMS OVER THE CENTRAL AND WESTERN
KUSKOKWIM VALLEY APPEAR TO BE SHADING THAT REGION TODAY AND THUS
INHIBITING THE CONVECTIVE DEVELOP. CONDITIONS APPEAR TO REMAIN
SIMILAR THURSDAY WITH REGARD TO CONVECTIVE POTENTIAL. THE VERTICAL
TOTALS AND K-INDEX ALONG WITH CAPE CONTINUE TO SUPPORT A VERY GOOD
POSSIBILITY OF THUNDERSTORMS IN THE COPPER RIVER BASIN THURSDAY WITH
A MORE LIMITED CHANCE OF THUNDERSTORMS AS YOU MOVE WEST TO THE
KUSKOKWIM VALLEY.

FURTHER WEST WE HAVE THE LARGE LOW TRACKING TO THE CENTRAL ALEUTIANS
WITH THE ASSOCIATED FRONT OUT IN ADVANCE OF THIS LOW THROUGH THE
UNALASKA AREA. WIND IS NOT A MAJOR FACTOR WITH THIS LOW, MAINLY SMALL
CRAFT CONDITIONS OR LOWER. POST FRONTAL CONDITIONS HAVE SIGNIFICANT
LOW CLOUDS AND LIGHT RAIN OR DRIZZLE, SO THE MAIN ISSUE WILL BE IN
THE AVIATION REALM. LOW CEILINGS AND VISIBILITIES WILL BE THE PROBLEM
AREAS FOR THE ALEUTIANS FROM CAPE SARICHEF WEST. THE FRONT IS SLOWLY
MOVING EAST BUMPING INTO THE BLOCKING RIDGE AND WEAKENING. WE EXPECT
THE FRONT TO BE ALONG THE BERING SEA COAST LATE THURSDAY NEARLY
DISSIPATED.

IN THE LONGER TERM A WAVE FORMING SOUTH OF THE MAIN LOW WILL BE
MOVING NORTHEAST ALONG THE WEAK FRONTAL BOUNDARY TO THE SAND POINT
AREA FRI EVENING. THIS LOW IS SPAWNING OFF OF A TROPICAL STORM NOW
OFF OF THE JAPANESE COAST AND SHOULD HAVE AMPLE MOISTURE WITH IT. BY
SATURDAY THE MOISTURE TRAIN ASSOCIATED WITH THIS LOW EXTENDS 1800
MILES TO THE SOUTHWEST. THE MAIN PROBLEM WITH THE EXTENDED FORECAST
IS A TIMING DIFFERENCES BETWEEN THE GFS AND MESO-ETA. THE GFS IS MUCH
FASTER IN THE MOVEMENT OF THE LOW AND FRONT HAVING THE FRONT THROUGH
SOUTH CENTRAL ALASKA FRI NIGHT AND SATURDAY WHILE THE MESO ETA IS
JUST GETTING THE FRONT INTO SOUTH CENTRAL ALASKA SAT AFTERNOON. ONE
WOULD NORMALLY EXPECT THE LOW TO PROGRESS SLOWLY SINCE WE HAVE A
BLOCKING RIDGE, BUT THIS SYSTEM IS OF TROPICAL ORIGIN AND THEY
TYPICALLY HAVE ENOUGH ENERGY TO DISPLACE THE RIDGE. EITHER WAY, WE
EXPECT THE PATTERN TO SHIFT FOR THE WEEKEND FROM THE PREVAILING HOT
DRY PATTERN TO A MORE COOL MOIST PATTERN.

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

SAM JUN 05