Severe Thunderstorm Warning 8, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
230 PM ADT TUE JUL 10 2007

.DISCUSSION...
WEAK FLOW PATTERN ALOFT WILL PERSIST OVER NORTHERN ALASKA
THROUGH FRIDAY...WITH AN UPPER LEVEL HIGH GRADUALLY BUILDING
OVER THE ARCTIC OCEAN. BY THE END OF THE WEEK...HIGH PRESSURE
RIDGING ALOFT WILL BE ESTABLISHED OVER NORTHWEST CANADA AND
THE EASTERN BEAUFORT SEA...WITH TEMPERATURES WARMING SOME
OVER MUCH OF NORTHERN ALASKA.

TODAY...A BROAD SURFACE LOW PRESSURE TROUGH EXTENDS FROM THE
FORT YUKON AREA SOUTHWESTWARD TO ANVIK. MOIST AND UNSTABLE
AIR REMAINS OVER THE INTERIOR TODAY. THE MOST ACTIVE AREA
FOR THUNDERSTORM DEVELOPMENT THIS AFTERNOON AND EVENING WILL
BE IN AREAS ALONG AND NEAR THE THERMAL TROUGH. MOSTLY
OVERCAST SKIES OVER THE SOUTHERN INTERIOR WILL LIMIT THE HEATING
NEEDED FOR CONVECTION...BUT A FEW THUNDERSTORMS MAY DEVELOP...
MOST LIKELY IN AREAS WHERE THERE ARE BREAKS IN THE CLOUD COVER.
ISOLATED THUNDERSTORMS ARE ALSO EXPECTED ALONG THE BROOKS RANGE.

FOR WEDNESDAY...THE SURFACE TROUGH AXIS IS EXPECTED TO EXTEND
FROM OLD CROW TO BETTLES AND SOUTHWESTWARD TO THE LOWER
YUKON VALLEY. THE MOST UNSTABLE AIR WILL BE OVER THE NORTHERN...
CENTRAL...AND WESTERN INTERIOR...AND THESE AREAS WILL BE MOST
FAVORABLE FOR DEVELOPMENT OF THUNDERSTORMS...ALTHOUGH VERY
ISOLATED ACTIVITY MAY OCCUR IN THE SOUTHEAST INTERIOR. ISOLATED
THUNDERSTORMS ARE ALSO EXPECTED ALONG THE BROOKS RANGE. UPPER
AIR FLOW OVER MOST OF THE INTERIOR WEDNESDAY IS EXPECTED TO
BE A LITTLE MORE CYCLONIC THAN TODAY. A WEAK SHORT WAVE
WILL MOVE ACROSS THE SOUTHEAST INTERIOR...ROTATING AROUND
AN UPPER LOW NEAR THE KENAI PENINSULA.

FOR THURSDAY...A BROAD TROUGH WILL EXTEND ACROSS THE NORTHERN
INTERIOR AND WEST COAST COAST. THE MOST UNSTABLE AIR WILL BE
IN THE NORTHERN AND WESTERN INTERIOR AND ALONG THE BROOKS
RANGE. WEAKLY CYCLONIC FLOW ALOFT WILL PERSIST OVER THE
SOUTHERN AND SOUTHEASTERN INTERIOR.

SOUTHERLY GAP WINDS ARE EXPECTED TO DEVELOP IN THE ALASKA
RANGE THIS AFTERNOON...CONTINUING TONIGHT. WIND GUSTS
ARE NOT EXPECTED TO BE MUCH ABOVE 25 MPH.

GOES VIS LOOP SHOWS NORTON SOUND FREE OF STRATUS...AND
WITH MAINLY NORTH TO NORTHWEST WINDS EXPECTED IN THE NOME
AREA THROUGH WEDNESDAY NIGHT...NO STRATUS IS LIKELY.

STRATUS COVERS OUTER KOTZEBUE SOUND AND THE NORTHERN SEWARD
PENINSULA COAST...BUT THERE IS A CLEAR SLOT EXTENDING FROM
THE KOTZEBUE AREA NORTHWESTWARD ALONG THE COAST DUE TO
OFFSHORE WINDS. KOTZEBUE SHOULD REMAIN FREE OF STRATUS
THIS AFTERNOON AND EVENING.

EXTENT OF STRATUS ALONG AND NORTH OF THE ARCTIC
COAST IS DIFFICULT TO DETERMINE IN SOME AREAS DUE TO
THE PRESENCE OF HIGHER CLOUD COVER. WITH EAST TO NORTHEAST
WINDS EXPECTED TO PERSIST HOWEVER...STRATUS AND AREAS OF
FOG ARE LIKELY TO BE PREDOMINANT AT NIGHT. WITH STRONG HIGH
PRESSURE ALOFT...BREAKS IN THE CLOUDS AND DISSIPATING FOG ARE
A GOOD BET AT LEAST IN SOME AREAS DURING THE DAYTIME HOURS.

AS OF 2 PM...LDS PICKING UP STRIKES IN ZONES 205-215-216-217-218
-219-220-221-222-224. THE MOST ACTIVE AREAS ARE IN THE WESTERN
INTERIOR AND IN ZONES 220-222 NEAR THE NORTHERN EDGE OF CLOUD
COVER IN THE SOUTHEAST INTERIOR.

PAPD RADAR INDICATING MAXIMUM VIL VALUES OF AROUND 30
AND 1 HOUR RAINFALL ESTIMATES OF OVER 1 INCH IN THE
HEAVIER THUNDERSTORMS.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.FIRE WEATHER...
NONE.

&&

.HYDROLOGY...LOCALLY HEAVY DOWNPOURS MAY OCCUR IN THUNDERSTORMS
THIS AFTERNOON AND EVENING. RADAR INDICATING 1 HOUR RAINFALLS
OF MORE THAN 1 INCH IN HEAVIER THUNDERSTORMS. PRECIPITABLE
WATER ON THE FAIRBANKS 12Z RAOB IS 0.9 INCH.

&&

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

&&

RF
 JUL 07