Flash Flood Warning 4, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
204 PM ADT SAT JUL 7 2007

.DISCUSSION...

CURRENT 500 MB HEIGHT AND 850 MB TEMPERATURE PROGS SHOW SIMILAR
OUTCOMES THROUGH 00Z TUESDAY. THIS AFTERNOON...STRONG RIDGING
WILL EXTEND FROM WEST OF SAINT LAWRENCE ISLAND ACROSS THE
NORTHWEST INTERIOR TO THE EASTERN BEAUFORT SEA. THROUGH 00Z
TUESDAY...THE RIDGE WILL WEAKEN WITH THE RIDGE AXIS BEING PUSHED
GRADUALLY SOUTHWARD...TO LIE FROM WEST OF SAINT LAWRENCE ISLAND
EASTWARD ACROSS THE INTERIOR INTO THE YUKON TERRITORY.

ALL MODELS ARE INDICATING DEVELOPMENT OF AN UPPER TROUGH OVER
THE ARCTIC OCEAN WEST OF LATITUDE 160W BY 12Z MONDAY...WITH
THE TROUGH DIGGING SOUTHWARD OVER NORTHWEST ALASKA THROUGH
12Z TUESDAY. THIS DEVELOPING TROUGH WILL WEAKEN THE UPPER RIDGE
AND PUSH THE RIDGE AXIS SOUTHWARD. MODEL RUNS ARE INDICATING
THE TROUGH BECOMING A CUTOFF UPPER LOW OVER NORTHWEST ALASKA
BY 00Z WEDNESDAY...ALTHOUGH THERE ARE SOME DIFFERENCES IN
THE FORECAST POSITION.

A WEAKENING FRONT WILL MOVE EASTWARD ALONG THE ARCTIC COAST
TONIGHT THROUGH SUNDAY. WINDS ALONG THE CENTRAL AND EASTERN
ARCTIC COAST WILL SHIFT FROM THE EAST TO NORTHWEST AND IT
MAY INCREASE THE POSSIBILITY OF SOME STRATUS FORMING
OVER THE OPEN WATER. GFS40 PROGS AT 900 MB AND 950 MB
SUGGESTING ANY STRATUS BEING ADVECTED ONSHORE THROUGH 12Z
TUESDAY...WITH RELATIVELY LOW RH PERSISTING. NAM95 950 MB RH
PROG IS ALSO KEEPING THE HIGHEST RH WELL OFFSHORE. CURRENT
GOES VIS LOOP IS SHOWING A NARROW STRIP OF CLOUDS ASSOCIATED
WITH THE PORTION OF THE FRONT OF 71-72N...AND THIS STRIP
APPEARS TO BE THINNING OUT. EAST OF LONGITUDE 170W...GOES VIS
LOOP SHOWS LITTLE IF ANY STRATUS NORTH OF THE ARCTIC COAST.
HIGH TEMPERATURES AT BARROW TOMORROW AND MONDAY WILL
BE COOLER THAN TODAY AS WINDS SHIFT AND BRING IN SOME
MARITIME AIR.

OVER SAINT LAWRENCE ISLAND AND NORTON SOUND...GOES VIS LOOP
IS SHOWING EXTENSIVE STRATUS...WHICH IS CREEPING SLOWLY EASTWARD
INTO THE EASTERN PORTIONS OF THE SOUND.

OVER THE INTERIOR AND THE SOUTHERN SLOPES OF THE BROOKS RANGE...
A MOIST AND UNSTABLE AIR MASS WILL REMAIN IN PLACE THROUGH
TUESDAY. A WEAK THERMAL TROUGH WILL LIE ACROSS THE BROOKS RANGE
AND NORTHEASTERN INTERIOR TODAY. THE TROUGH WILL EXTEND ACROSS
THE CENTRAL INTERIOR SUNDAY THROUGH TUESDAY. A WEAK SHORT
WAVE TROUGH ALOFT WILL MOVE OUT OF THE SOUTHERN YUKON
TERRITORY INTO INTO THE SOUTHEAST INTERIOR TUESDAY AND THIS MAY
ENHANCE CONVECTION IN THE SOUTHEAST INTERIOR.

SURFACE REPORTS ARE SHOWING DEW POINTS IN THE 50S OVER
ALMOST ALL OF THE INTERIOR THIS MORNING. ISOLATED THUNDERSTORMS
ARE EXPECTED TO DEVELOP OVER THE INTERIOR THIS AFTERNOON WITH
SOLAR HEATING. VIS LOOP IS ALREADY SHOWING CUMULUS DEVELOPMENT IN
ZONES 220 AND 224. AREAS OF RAIN AND SHOWERS IN THE REMNANTS OF
OVERNIGHT THUNDERSTORMS ARE OCCURRING OVER THE SOUTHERN INTERIOR
ZONES...BUT ISOLATED THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS
AFTERNOON AND EVENING AS CLOUD COVER BREAKS UP SOME.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.FIRE WEATHER...
NO RED FLAG PROBLEMS EXPECTED TODAY OR MONDAY WITH
MINIMUM RH ABOVE 30 PERCENT IN MOST INTERIOR AREAS.

&&

.HYDROLOGY...
THIS MORNINGS RAOB AT FAIRBANKS WAS VERY MOIST...WITH 1.25 INCHES
OF PRECIPITABLE WATER. THE AFTERNOON SOUNDING WILL LIKELY HAVE SOMEWHAT
LESS MOISTURE AS CLOUDS BREAK UP...BUT WILL STILL LIKELY AROUND AN
AN INCH. LOCALLY HEAVY RAINFALL AMOUNTS MAY OCCUR IN THUNDERSTORMS
IN THE SOUTHERN INTERIOR THIS AFTERNOON AND EVENING. QUITE A FEW
STATIONS IN THE SOUTHERN INTERIOR HAVE REPORTED 12 HR RAINFALLS OF
0.5 TO 1 INCH.

&&

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

&&

RF JUL 07