Flash Flood Warning 4, NWS Fairbanks, AK

NORTH ALASKA FORECAST DISCUSSION
600 AM ADT SAT JUL 2 2005

.DISCUSSION...
BROAD TROUGH ALOFT OVER THE STATE ANCHORED BY CLOSED LOW OVER
BEAUFORT SEA SOUTHWARD TO CLOSED LOW IN NORTHERN GULF OF ALASKA.
TWO VERY WEAK RIDGES BRACKET THIS TROUGH...ONE FROM THE RUSSIAN
FAR EAST SOUTHEASTWARD TO THE ALASKA PENINSULA...AND THE OTHER
FROM CENTRAL BC NORTHEASTWARD TO CENTRAL YT IN CANADA. AT THE
SURFACE...THERMAL TROUGH PERSISTS FROM BETTLES SOUTHEAST TO EAGLE
WITH WEAK SURFACE LOWS SITTING UNDER THEIR COUNTERPARTS ALOFT OVER
THE BEAUFORT SEA AND NORTHERN GULF OF ALASKA. SURFACE RIDGE
EXTENDS FROM GULF OF ANADYR SOUTHEAST ACROSS THE BERING SEA TO THE
WESTERN TIP OF THE ALASKA PENINSULA.

MODELS...AGREEING REASONABLY ON PROGRESSIVE PATTERN PUSHING TROUGH
EASTWARD INTO CANADA AS RIDGE BUILDS NORTHWARD FROM GULF OF ALASKA
ACROSS THE ALASKA RANGE SUNDAY MORNING AND CLOSES UP OVER THE
TANANA VALLEY ON MONDAY AFTER DECAPITATION BY FAST FLOW ACROSS THE
GULF OF ALASKA TO THE SOUTH.

NORTH SLOPE...SHORTWAVES SWEEPING EASTWARD ABOUT BEAUFORT SEA
CLOSED LOW SMEARING SHOWERS FROM BARROW EASTWARD SATURDAY AND
EXITING INTO THE MACKENZIE DELTA SATURDAY NIGHT. THESE SHOWERS
COULD END IN BRIEF BURSTS OF SNOW AS COLD AIR WORKS SOUTHWARD ON
WEST SIDE OF CLOSED LOW AS IT PROGRESSES EASTWARD INTO CANADA.
MARINERS EXPECT SUB ADVISORY WINDS BACKING FROM NORTHEAST TO
NORTHWEST THROUGH REMAINDER OF THE WEEKEND.

WEST COAST...DOMINATED BY BERING SEA RIDGE ALOFT AND AT THE
SURFACE FOR CLEAR SKIES MAINLY FROM SEWARD PENINSULA SOUTHWARD AND
STRATUS FORMING OVER COASTAL POINTS FROM BERING STRAIT NORTHWARD.
TEMPERATURES WILL BE A LITTLE COOLER UNDER THE STRATUS AND WARMING
IN CLEARER AREAS. AS THERMAL TROUGH OVER INTERIOR BUTTS UP AGAINST
HIGH PRESSURE OVER RUSSIAN FAR EAST...MARINERS WILL PICK UP
ADVISORY WINDS OVER THE CHUKCHI SEA STARTING TONIGHT WITH ROUGH
SEAS NEAR BERING STRAIT...AND HAVE HOISTED SMALL CRAFT PENNANT
STARTING TONIGHT FOR ZONES 210 AND 220.

INTERIOR...ACTIVE CONVECTIVE 5000-STRIKE DAY ON FRIDAY OVER THE
EASTERN HALF OF THE INTERIOR SOUTH OF THE BROOKS RANGE...AND
EXPECTING A SIMILAR PATTERN TODAY. SURFACE THERMAL LOW WILL
PERSIST FROM BETTLES TO EAGLE TO FOCUS PRECIPITATION AND DRAW IN
MOIST WESTERLY FLOW SOUTH OF THE TROUGH FOR ANOTHER DAY OF CLOUDS
AND SHOWERS FROM THE YUKON VALLEY SOUTHWARD AND EAST OF TANANA.
SHORTWAVES ROTATING FROM EAST TO WEST ABOUT GULF OF ALASKA CLOSED
LOW WILL ENHANCE SHOWERS OVER ALASKA RANGE AND SOUTH OF THE
FORTYMILE RIVER. WEST OF TANANA AND BETTLES...GOOD CLEARING TODAY
WITH SOME AFTERNOON CUMULUS AND ISOLATED THUNDERSTORMS POSSIBLE.

MEDIUM RANGE...DIFFERENCES EMERGING IN HANDLING PROGRESSIVE
PATTERN WITH EUROPEAN COLLEAGUES DEEPENING POLAR VORTEX AND
SWINGING CLOSED LOWS OVER THE GULF OF ALASKA LEAVING BULK OF STATE
UNDER WEAK SADDLE RIDGE FOR CLEAR SKIES AND LOW FLOW ALOFT.
DOMESTIC VERSION MUCH SLOWER IN MOVING CLOSED LOWS
THROUGH...DEEPENING TROUGHS OVER THE BERING SEA AS RIDGE PARKS
OVER THE EASTERN INTERIOR. CONSENSUS SUGGESTS CLEARING AND DRYING
THROUGH EARLY WORK WEEK FOR EASTERN INTERIOR...LITTLE CHANGE FOR
THE WEST COAST...AND A MORE ACTIVE SHORTWAVE SWEEP OF THE NORTH
SLOPE FROM WEST TO EAST ABOUT DEEPENING POLAR VORTEX.

.HYDRO...FRIDAY NIGHT FLASH FLOODS TURNING INTO POSSIBLE SATURDAY
RIVER PROBLEMS FOR CHATANIKA AND CHENA RIVERS NEAR FAIRBANKS. WITH
RAIN ENDING AT NENANA AROUND MIDNIGHT...WILL EXPECT FLASH FLOOD
WARNING TO HAVE RUN ITS COURSE AND WILL EXPIRE AT 6 AM THIS
MORNING...AND WATCH MORNING STAGE READINGS ON THE NENANA RIVER FOR
POSSIBLE PROBLEMS THERE.

.FIRE WEATHER...NO DANGEROUS FIRE WEATHER EXPECTED THROUGH THE
WEEKEND. SPOT TO WATCH WILL BE EASTERN ZONE 218 FOR SUNDAY AS
NORTHEAST FLOW PICKS UP AND HUMIDITIES MAY DROP BRIEFLY BELOW 40
PERCENT. ANY EXCURSION INTO RED FLAG CRITERIA SHOULD BE BRIEF AND
CONFINED TO USUAL WINDY SPOTS.

.AFG WATCH/WARNING/ADVISORIES...
PUBLIC...NONE
MARINE...SMALL CRAFT ADVISORY: ZONES 210/220
HYDRO...FLASH FLOOD WARNING: ZONES 221/222/223/225
FIRE...NONE

TS JUL 05