Small Craft Advisory 50, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
1141 AM AKDT TUE JUL 19 2011

.DISCUSSION...
UPPER LOW CENTERED OVER THE EASTERN GULF COAST WILL
CONTINUE ON ITS SOUTHEASTWARD TRACK. SHOWER ACTIVITY
OVER THE EASTERN BROOKS RANGE AND SOUTHEAST INTERIOR
WILL COME TO AN END TONIGHT AS THE UPPER LOW EXITS.
THE CENTRAL AND EASTERN INTERIOR WILL ENJOY A PERIOD
OF MORE PLEASANT WEATHER THROUGH WED NIGHT UNDER A WEAK
UPPER RIDGE.

SHORT WAVE TROUGH WITH A WEAK UPPER LOW CENTER WILL MOVE
EASTWARD...MOVING ONSHORE EAST OF NUNIVAK ISLAND AROUND MID
DAY WED...THEN WEAKENING OVER THE NORTHERN SUSITNA VALLEY BY THU
AFTERNOON. CURRENT MODELS HAVE SIMILAR SHORT WAVE POSITIONS
THROUGH 00Z THU...THROUGH 00Z FRI THE ECMWF MOVES THE SHORT WAVE
A LITTLE FASTER AND FARTHER TO THE SOUTH THAN THE GFS/NAM. THE
OPERATIONAL GFS HAS GOOD SUPPORT FROM ITS ENSEMBLE MEAN ON THE
HANDLING OF THIS FEATURE WHILE IT IS PRETTY MUCH MEANED OUT BY
THE ECMWF ENSEMBLE. NAM/GFS PREFERRED IN THE SHORT TERM HANDLING
OF THIS SHORT WAVE FEATURE. ASSOCIATED 1003 MB SURFACE LOW
ABOUT 150 MILES NORTH OF ATTU MOVING TO NEAR NUNIVAK ISLAND BY
00Z THU.

A LARGER SCALE UPPER TROUGH FROM THE CHUKCHI SEA SOUTHWESTWARD
WILL MOVE SLOWLY EASTWARD ACROSS THE NORTHERN PARTS OF THE CWA
THROUGH 00Z FRI...THEN SLOWLY WEAKEN. NOT MUCH DIFFERENCE EARLY
IN THE MODEL RUNS ON THIS FEATURE.

RAIN OR SHOWERS OVER NORTHWEST ALASKA TONIGHT AS A FRONT MOVES ON
SHORE...TAPERING OFF TO ISOLATED OR SCATTERED SHOWERS OVER NW
ALASKA/WESTERN BROOKS RANGE/WESTERN ARCTIC COAST WED.

RAIN OR SHOWERS BEGINNING WED OVER THE SOUTHERN WEST COAST/EXTREME
SOUTHWEST INTERIOR WED...SPREADING TO THE SOUTHERN PARTS OF
WESTERN INTERIOR WED NIGHT WHILE TAPERING OFF OVER THE SOUTHERN
WEST COAST AREAS. SOME SHOWERS CONTINUING OVER THE WESTERN
INTERIOR/BROOKS RANGE/PORTIONS OF THE ARCTIC THU AS THE LARGER
SCALE TROUGH AND THE SOUTHERN SHORT WAVE MOVE EAST.

MEDIUM RANGE FORECAST...
CURRENT GFS AND ECMWF BRINGING A WEAKENING STORM AND ASSOCIATED
DEEP UPPER LOW ONSHORE NEAR DALL POINT BY EARLY SUN. 12Z GFS/00Z
ECMWF AND 00Z ECMWF ENSEMBLE MEAN SHOWING SIMILAR POSITIONS FOR
00Z SUN...OPERATIONAL RUNS CARRYING DEEPER SURFACE AND UPPER
LOWS. TODAYS HPC SOLUTION USES SIGNIFICANT CONTRIBUTIONS FROM
THESE MODELS IN PRODUCING THE MANUAL GRAPHICS OUT THROUGH DAY 6.
AHEAD OF THIS STORM...A FEW DAYS OF WARM AND PLEASANT WEATHER WITH
THE PRECEDING TRANSITORY UPPER RIDGE.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.FIRE WEATHER...
TEMPERATURES A LITTLE ABOVE NORMAL IN THE INTERIOR WED AND
THU WITH WEAK UPPER RIDGING. SLIGHTLY WARMER AND DRIER CONDITIONS
OVER THE INTERIOR SAT...AND OVER THE EASTERN INTERIOR SUN...AS
A STRONGER UPPER RIDGE TRANSITS EAST.

&&

.HYDROLOGY...
NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

RF JUL 11