Flood in Alaska, December 23, 2004

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST THU DEC 23 2004

.SHORT RANGE...A FRONTAL BOUNDARY WILL BE SLOW TO MOVE THROUGH
THE PANHANDLE TONIGHT KEEPING RAIN GOING IN ALL ZONES THROUGH
TONIGHT. RAIN WILL BE HEAVY AT TIMES OVER THE CENTRAL AND
SOUTHERN PANHANDLE AS A JET MAX MOVES THROUGH LATER THIS
AFTERNOON INTO TONIGHT. THE NORTHWEST PANHANDLE WILL ALSO
CONTINUE TO SEE MODERATE RAINFALL INTO TONIGHT WHICH IS RAISING
CONCERN FOR THE SITUK RIVER NEAR YAKUTAT. THE RIVER HAS REACHED
ACTION STAGE AND WITH RAIN AND A WARM AIRMASS OVER THEM INTO
TONIGHT IT IS AT LEAST LOOKING LIKE A FLOOD ADVISORY WILL BE
NECESSARY INTO TONIGHT. COORDINATING WITH THE RFC AND WSO PAYA AT
THIS TIME AND AWAITING THEIR INPUT FOR FLOODING POTENTIAL. WILL
CONTINUE THE WIND ADVISORY INTO THIS EVENING OVER ZONES 18 19 22
AND 23. WILL ALSO CONSIDER A WIND ADVISORY FOR THE SOUTHERN THIRD
FOR LATE THIS AFTERNOON AND EVENING AS THE GRADIENT INCREASES.

AN UPPER LEVEL LOW WILL MOVE SOUTHEAST INTO THE NORTHERN GULF ON
FRI THEN MOVE SOUTHEAST OVER THE EASTERN GULF INTO FRI NIGHT. A
995 MB SURFACE LOW OVER THE NORTHERN GULF WILL WEAKEN AS IT MOVES
SOUTHEAST OVER THE EASTERN GULF. A COLD FRONT WILL MOVE ACROSS
THE GULF LATE TONIGHT AND OVER THE NORTHWEST PANHANDLE EARLY FRI
MORNING THEN ACROSS THE REMAINDER OF THE PANHANDLE THROUGH FRI
AFTERNOON. COLDER AIR DOES MOVE IN BEHIND THIS FRONT AND WILL
CHANGE THE PRECIP TYPE TO SNOW SHOWERS. SO RAIN WILL CHANGE TO
SNOW SHOWERS OVER THE NORTHWEST PANHANDLE EARLY FRI MORNING THEN
OVER THE REMAINDER THU AFTERNOON AND EVENING.

AN ARCTIC HIGH OVER INTERIOR ALASKA WILL BEGIN BUILDING SOUTH
OVER THE NORTHERN HALF OF THE PANHANDLE FRI NIGHT. THE ARCTIC
FRONT WILL MOVE AS FAR SOUTH AS FREDERICK SOUND AND PASI BY SAT
MORNING. THE MOISTURE MAY BE SLOW TO CLEAR WITH LOW PRESSURE
STILL OVER THE EASTERN GULF. SO WILL CONTINUE WITH MOSTLY CLOUDY
SKIES AND CHANCE TO SLIGHT CHANCE POPS FOR SNOW. TEMPS WILL DROP
INTO THE TEENS AND TWENTIES OVER THE NORTHERN HALF OF THE
PANHANDLE WITH WINDY CONDITIONS DEVELOPING. WIND ADVISORIES WILL
BE NECESSARY FOR ZONES 18 19 20 WITH NORTHERLY GALES OVER THE
NORTHERN AND CENTRAL INNER CHANNELS. WIND ADVISORY GUSTS WILL
ALSO OCCUR OVER ZONE 17 OUT OF PASSES AND WILL THEREFORE MENTION
HIGHER GUSTS OUT OF PASSES IN THE NORTHERN OUTSIDE WATERS.
FREEZING SPRAY WILL ALSO BE POSSIBLE OVER THE NORTHERN INNER
CHANNELS.

.LONG RANGE...WITH THE UPPER LEVEL RIDGE OVER CENTRAL ALASKA AND
THE DEPARTING UPPER LOW SOUTHWEST OF THE QUEEN CHARLOTTE ISLANDS
FRIDAY...COLD AIR WILL CONTINUE TO FUNNEL INTO SOUTHEAST ALASKA
THROUGH THE WEEKEND. THE UPPER HIGH IS FORECASTED TO TIP OVER THE
PANHANDLE THROUGH SUNDAY AFTERNOON AS A STRONG SURFACE HIGH
SWINGS THROUGH THE YUKON AND IN TO BC. THIS WILL KEEP IT VERY
COLD...CLEAR AND VERY WINDY OUT OF INTERIOR PASSES.

THERE IS LOW CONFIDENCE ON THE TRACK OF THE NEXT SIGNIFICANT
WEATHER SYSTEM THAT WILL MAKE IT INTO THE CENTRAL GULF BY MONDAY.
THE GFS DEEPENS THE LOW TO 968MB AND BRINGS IT ACROSS THE
NORTHERN GULF AND THEN DOWN THE COASTAL AREAS...THE DGEX DEVELOPS
THE LOW WAY FURTHER SOUTH...ACROSS THE SOUTHERN GULF...AND NOT AS
DEEP(974MB). THE ECMWF WAS THE MIDDLE OF THE ROAD WITH THE LOW IN
THE NORTH CENTRAL GULF AND WITH A CENTRAL PRESSURE OF 978MB.
EITHER WAY THERE WILL BE A CHANGE IN AIR MASS AND WITH THAT THERE
WILL BE A LIKELY PROB THAT THERE WILL BE SIGNIFICANT SNOW AMOUNTS
AS THERE WILL BE PLENTY OF COLD AIR IN THE LOWER LAYER IN THE
NORTHERN AND MORE EASTERN ZONES. ONCE THIS LOW MOVES SOUTHEAST
AND OUT OF THE FORECAST AREA TUESDAY NIGHT THERE WILL BE ANOTHER
SHOT OF COLD AIR FROM THE NORTH. THE COLD...CLEAR AND WINDY
CONDITIONS WILL DOMINATE LATE NEXT WEEK.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WIND ADVISORIES ZONES 18 19 22 23 25 27 28
         FLOOD WARNING ZONE 18
MARINE...GALES MARINE ZONES 12 13 31 34 36 42 43
         SCA 11 22 32 33 41 51 52
TAR / ABJ