Gale Warning 474, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
300 PM AKDT FRI AUG 30 2013

.ANALYSIS AND UPPER LEVELS...
A COLD STACKED LOW IS SITUATED OVER THE NORTHWEST ALASKA COAST THIS
MORNING ALONG WITH A CLOSED LOW OVER THE KAMCHATKA PENINSULA. AN
ACTIVE JET EXTENDS FROM THE NORTH PACIFIC SOUTH OF THE WESTERN
ALEUTIANS INTO THE BEAUFORT SEA. THIS IS MAKING FOR A GOOD ZONAL PUSH
OF MOISTURE ACROSS THE BERING AND MAINLAND. THERE ARE MANY UPPER
LEVEL DISTURBANCES MOVING THROUGH IN THIS FLOW THROUGH SUNDAY WITH
SHOWERS. THE SURFACE LOW IN THE BERING IS MULTI-FACETED AT THIS POINT
BUT IS EXPECTED TO CONSOLIDATE TOMORROW. THE ASSOCIATED OCCLUDED
FRONT IS WORKING ACROSS THE EASTERN BERING THIS AFTERNOON AND EVENING
TO THE WEST COAST.

.MODEL DISCUSSION...
MODELS ARE HANDLING THE FEATURES WELL TODAY. THEY ARE ALL HITTING ON
THE STRONGER SHORT WAVE MOVING THROUGH THE BERING RIGHT NOW THAT WILL
HIT THE COAST TOMORROW MORNING. ALL MODELS ARE TIMED WELL WITH THE
PUSH OF THE CLOSED UPPER LOW OVER THE KAMCHATKA PENINSULA INTO THE
BERING OVER THE NEXT COUPLE DAYS INTO MONDAY AS WELL. THE STACKED LOW
ALONG THE NORTHWEST COAST PUSHES INTO THE CANADIAN ARCHIPELAGO
MONDAY. MODELS DO NOT DIVERGE MUCH IN THE BIG PATTERN INTO FRIDAY
WITH THE TROUGH OVER THE BERING AND RIDGE OVER THE YUKON AND BC.

THIS SETUP WILL INCREASE THE TAP OF MOISTURE INTO THE MAINLAND FOR
NEXT WEEK.

.SHORT TERM FORECAST...
SOUTHCENTRAL/GULF...
THE WESTERLY FLOW WITH SOME LEVEL OF INSTABILITY HAS KEPT SOUTH
CENTRAL AND THE GULF OF ALASKA UNDER SHOWER ACTIVITY RECENTLY. THIS
IS NOT TO CHANGE OVER THE NEXT DAY OR SO. THERE IS ENOUGH INSTABILITY
TODAY TO CREATE SHOWERS OVER THE ENTIRE AREA. HOWEVER...THERE IS
ENOUGH STRATUS HANGING AROUND TO KEEP IT AT BAY AS WELL. POCKETS OF
SHOWERS CAN BE EXPECTED THIS AFTERNOON AND EVENING. FOG WILL DEVELOP
AGAIN TONIGHT AS LOW LEVEL MOISTURE NOT GOING ANYWHERE AND FLOW DOES
NOT PICK UP TIL TOMORROW MORNING. A DISTURBANCE MOVING THROUGH WILL
FACTOR INTO THE EQUATION TONIGHT INTO TOMORROW MORNING. THIS WILL
INCREASE THE MID LEVEL INSTABILITY AND CREATE MORE SHOWERS THAN
TODAY. THIS WILL ALSO TAKE AWAY THE WIDESPREAD DENSE FOG WE HAD THIS
MORNING ALONG THE KENAI/INLET. THERE IS SOME RESPITE EXPECTED SUNDAY
AS THE STRONG LOW IN THE BERING CREATES A SHORT WAVE RIDGE. AS THE
LOW MOVES CLOSER ON SUNDAY NIGHT INTO MONDAY...RAIN WILL BECOME
WIDESPREAD AS WELL AS STRONGER WINDS ESPECIALLY THROUGH THE TYPICAL
GAPS.

SOUTHWEST/AKPEN...
THE LOW IN THE WESTERN BERING IS PUSHING AN OCCLUDED FRONT TO THE
COAST TONIGHT. WINDS WILL BE MAX SMALL CRAFT FOR THE EVENING AND
QUICKLY DIE OFF TOMORROW MORNING. HOWEVER...IT LOSES SOME OF ITS
PUNCH AS IT MOVES INLAND DUE TO JET ENERGIES SPLITTING ALONG THE
COAST. DIRECTLY BEHIND THIS FRONT IS ANOTHER WAVE WITH UPPER LEVEL
JET SUPPORT TO BRING MODERATE RAIN AND WINDS TO THE KUSKO COAST AND
VALLEY SATURDAY. THE LOW IN THE WESTERN BERING WRAPS UP SATURDAY
NIGHT INTO SUNDAY WITH ANOTHER FRONT MOVING TO THE COAST BY SUNDAY
MORNING. THE UPPER LEVEL TROUGH DIGS IN THE BERING INTO THE NORTH
PACIFIC SUNDAY BRINGING DEEPER MOISTURE TO THE COAST. THIS TAP WILL
CONTINUE INTO MONDAY BEFORE SWINGING INTO THE GULF MONDAY
AFTERNOON/EVENING.

BERING SEA/ALEUTIANS...
GOOD FRONT MOVING THROUGH THE CENTRAL AND EASTERN BERING THIS
AFTERNOON AND EVENING. HIGH END SMALL CRAFT WINDS WITH MODERATER
PRECIP AND IFR CONDITIONS. THE FRONT TO WEAKEN OVERNIGHT AT THE WEST
COAST OF ALASKA. WINDS WILL DIMINISH AS WELL. THE UPPER LOW OVER
KAMCHATK BECOMES STACKED SATURDAY AND WRAPS UP WELL IN THE WESTERN
BERING. WINDS WILL INCREASE AROUND THE LOW AS WELL AS PRECIP. ANOTHER
MODERATE FRONT WILL PUSH ACROSS THE BERING SATURDAY AND SATURDAY
NIGHT. THE LOW CONTINUES TO DEEPEN SATURDAY NIGHT INTO SUNDAY WITH
WINDS INCREASING AROUND THE LOW TO NEAR STORM FORCE ON THE BACKSIDE
OF THE LOW IN THE WESTERN BERING BY SUNDAY EVENING. THE STRONG JET
MAX DIVING INTO THE TROUGH MAKES THE FLOW MORE MERIDIONAL FOR A
STRONGER TAP OF MOISTURE INTO THE SYSTEM AS WELL AS A STRONGER COLD
AIR TAP ON THE BACKSIDE OF THE LOW. THE LOW STARTS TO FILL ON MONDAY
AND MOVES INTO THE EASTERN BERING TUESDAY.

.LONG TERM FORECAST...
THE MODELS HAVE A GOOD OVERALL HANDLE ON A LONG WAVE TROUGH IN THE
EASTERN BERING REMAINING THROUGH LATE NEXT WEEK WITH A RIDGE OVER THE
YUKON AND ALBERTA/BC. THE ENERGY FLOWING AROUND THE TROUGH IS
SOMEWHAT AT DEBATE FOR SURFACE FEATURES. OVERALL...MILD AND WET FOR
THE MAINLAND WITH SOME WIND. COOLER AND SHOWERY OVER THE BERING SEA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 172 175 176.
FIRE WEATHER...NONE.

NELSON AUG 13

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1250 AM AKDT SAT AUG 31 2013

AKZ181-311500

...MINOR ASH FALL POSSIBLE BETWEEN PERRYVILLE AND CHIGNIK...

THE ONSET OF DARKNESS AND INCREASED CLOUD COVER HAVE MADE INDEPENDENT
DETECTION OF ASH ON SATELLITE IMAGERY VERY DIFFICULT AT VENIAMINOF
VOLCANO. HOWEVER...INSTRUMENTATION AT THE VENIAMINOF SUMMIT STILL
SUGGESTED ELEVATED LEVELS OF ACTIVITY. WINDS WILL CONTINUE TO
TRANSPORT THE ASH TO THE EAST WHICH COULD BRING SOME VERY LIGHT
ASHFALL TO AREAS ALONG THE ALASKA PENINSULA BETWEEN PERRYVILLE AND
CHIGNIK INTO THE DAY SATURDAY.

JAM/CB