Flood Watch 3, NWS Anchorage, AK

288 
WGAK68 PAFC 052016
FFAAFC

FLOOD WATCH...RESENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1216 PM AKDT WED SEP 5 2012

AKZ125-052130-
/X.CAN.PAFC.FA.A.0003.000000T0000Z-120906T0000Z/
/00000.0.RS.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WESTERN PRINCE WILLIAM SOUND-
INCLUDING THE CITIES OF...WHITTIER...SEWARD...GIRDWOOD...
MOOSE PASS
1216 PM AKDT WED SEP 5 2012

...FLOOD WATCH IS CANCELLED...

THE FLOOD WATCH FOR THE SEWARD AREA IS HAS BEEN CANCELLED.

$$

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
435 AM AKDT TUE SEP 4 2012

.ANALYSIS AND UPPER LEVELS...

MAIN CENTER OF ACTION IN THE UPPER LEVELS IS CURRENTLY BLOWING
THROUGH THE SOUTHERN BERING SEA ON ITS WAY TO SOUTHWESTERN ALASKA
TONIGHT. THE SYSTEM HAS JUST REACHED MATURITY AND WILL BEGIN TO
SLOWLY WIND DOWN OVER THE NEXT 24 TO 48 HOURS. A POWERFUL
SOUTHWESTERLY JET ALOFT WILL PUSH FROM THE NORTH PACIFIC JUST SOUTH
OF THE ALEUTIANS AND ALASKA PENINSULA TO A POSITION OVER THE KENAI
PENINSULA AND PRINCE WILLIAM SOUND AND THE WESTERN GULF OF ALASKA BY
THIS EVENING. A VERY STRONG PRESSURE GRADIENT ACROSS TURNAGAIN ARM
AND PORTAGE VALLEY WILL BRING HIGH WINDS THROUGH THIS REGION AND INTO
ANCHORAGE FROM LATE THIS AFTERNOON TO SHORTLY AFTER MIDNIGHT.

.MODEL DISCUSSION...

MODELS REMAIN VERY CONSISTENT AND ARE ADAMANT IN BRINGING A
HIGH-IMPACT DAMAGING WIND EVENT TO PORTAGE VALLEY...TURNAGAIN
ARM...AND INTO ANCHORAGE. IN THE EXTENDED TIME FRAME...MODEL
AGREEMENT HAS BEGUN TO INCREASE AND CONFIDENCE IS INCREASING IN A
SLIGHT PATTERN CHANGE BY THIS WEEKEND INTO EARLY NEXT WEEK.

.SHORT TERM FORECAST...

MAIN CONCERN IS THE PROSPECT FOR DAMAGING WINDS IN
ANCHORAGE...ESPECIALLY ALONG THE HILLSIDE AND LOWER ELEVATIONS OF
EAST ANCHORAGE. FOR MORE INFORMATION SEE HIGH WIND AND SPECIAL
WEATHER STATEMENTS ISSUED WITH THE MORNING FORECAST PACKAGE AS THESE
COVER THE EXPECTED IMPACTS VERY WELL. CONFIDENCE IS HIGH GIVEN GREAT
RUN-TO-RUN MODEL CONSISTENCY AND GREAT AGREEMENT AMONG ALL RELIABLE
MODELS.

THE OTHER CONCERN IN THE SHORT TERM IS THE POTENTIAL FOR HEAVY
RAINFALL ALONG THE NORTH GULF COAST AND ALSO ACROSS THE WESTERN
SUSITNA VALLEY. WE WILL BE MONITORING LATEST MODEL QPF (QUANTITATIVE
PRECIPITATION FORECASTS) THROUGH THE MORNING AND ISSUE ANY FLOOD
STATEMENTS AS DEEMED NECESSARY.

GUSTY SOUTH TO SOUTHEAST WINDS WILL CONTINUE THROUGH THURSDAY NIGHT
ACROSS SOUTHERN ALASKA BEHIND THE FRONTAL PASSAGE LATE TUESDAY NIGHT.
SEVERAL WEAK DISTURBANCES WILL MOVE ACROSS THE SOUTHERN MAINLAND
THROUGH THE END OF THE WEEK BRINGING OCCASIONAL RAIN OR SHOWERS.
NORTHEASTERN AND SOUTHEASTERN PRINCE WILLIAM SOUND WILL SEE STEADY
SOUTHWESTERLY ONSHORE FLOW KEEPING MORE STEADY RAIN IN PLACE FROM
TONIGHT THROUGH THURSDAY.

OUT WEST...MUCH WEAKER DISTURBANCES WILL ROTATE AROUND THE SOUTH AND
WEST SIDE OF THE STRONG SYSTEM CURRENTLY OVER THE REGION AS IT MOVES
ONSHORE OVER THE NEXT COUPLE OF DAYS. A STRONGER DISTURBANCE WILL CUT
OFF INTO AN UPPER LOW AND DIVE SOUTHEAST ACROSS THE BERING SEA AND
INTO THE NORTH PACIFIC SOUTH OF KODIAK ISLAND THURSDAY NIGHT INTO
EARLY SATURDAY.

.LONG TERM FORECAST...

WITH A LOW PRESSURE SYSTEM MOVING EAST ACROSS THE SOUTHERN GULF
TOWARDS SOUTHEAST ALASKA BY LATE SATURDAY...LOW-LEVEL FLOW SHOULD
BECOME MORE NORTHERLY AND OFFSHORE AND ALLOW FOR AT LEAST SOME
TEMPORARY DRYING TO TAKE PLACE OVER MOST OF THE SOUTHERN MAINLAND.
THE EXCEPTION WOULD APPEAR TO BE PARTS OF THE COPPER RIVER BASIN AND
EASTERN PRINCE WILLIAM SOUND WHERE DISTURBANCES ARE LIKELY TO ROTATE
AROUND THE UPPER LEVEL CIRCULATION OVER THE SOUTHWESTERN YUKON SUNDAY
THROUGH TUESDAY OF NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING...101 125
MARINE...GALES...125 132 138 140 141 150 155 160 165 171 176 179 180
         185
         STORMS...120 130 170 172 175
FIRE WEATHER...NONE.

29/CC SEP 12