Brisk Wind Advisory 36, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM ADT SAT MAR 29 2008

.MODEL DISCUSSION...
MODELS IN GOOD AGREEMENT THROUGH TUESDAY. MODELS DIFFER ON RIDGING
OVER THE EASTERN GULF AND PANHANDLE. ECMWF MORE PROGRESSIVE WHEREAS
THE GFS SPLITS A TROUGH OVER THE GULF WED/THU. THE NEXT TROUGH TO DIG
OUT OF THE BERING STRAIT ALSO FASTER AND STRONGER WITH THE ECMWF. THE
GFS ON THE OTHER HAND ALLOWS A SHORT WAVE OUT OF THE NORTH PACIFIC TO
PHASE WITH THE NORTHERN SHORT WAVE. EVENTUALLY A TROUGH SITUATES OVER
WESTERN ALASKA AND EASTERN BERING SATURDAY. THE EXTENT OF THE TROUGH
IN THE GULF IS ALSO IN CONTENTION. THIS IS MAINLY DUE TO THE ANCHOR
LOW WITH THE GFS REMAINING NEAR THE BERING STRAIT WHEREAS THE ECMWF
DEVELOPS ITS ANCHOR LOW NEAR BETHEL. ENSEMBLE MEAN MUCH MORE SMOOTH
AS THE MEMBER SOLUTIONS DIFFER ON THE STRENGTH AND INTENSITY OF EACH
WAVE ACROSS THE GULF AND FROM THE ARCTIC. ESSENTIALLY...THESE
SCENARIOS ALL HINGE ON STRENGTH OF MEAN RIDGE OVER THE GULF AND HOW
IT DEALS WITH IMPENDING SHORT WAVES WEDNESDAY THROUGH THE WEEKEND.

.ANALYSIS...
RIDGE OVER THE GULF WITH A STACKED LOW SOUTH OF DUTCH HARBOR. AN
UPPER LEVEL FRONT PUSHING THROUGH THE MAINLAND FROM AN OLD TRIPLE
POINT LOW AT THE RIDGE AXIS. THE SURFACE FRONT ALONG THE WEST COAST
OF ALASKA. A SHORT WAVE TROUGH MOVING ACROSS THE EASTERN BERING
ENHANCING THE FRONT AND ITS ONSHORE PUSH. THIS IS BRINGING BLIZZARD
CONDITIONS FROM CAPE NEWENHAM THROUGH CAPE ROMANZOF. THE FRONT WILL
WEAKEN THIS EVENING AS THE JET SUPPORT LIFTS NORTH. MEANWHILE THE
STACKED BEGINS TO SPLIT THIS EVENING WITH THE MAIN LOW CENTER MOVING
INTO BRISTOL BAY.

IN THE GULF...THE FLOW GRADUALLY TURNS MORE SOUTHERLY THIS EVENING
WITH THE SURFACE WARM FRONT MOVING NORTH THROUGH THE GULF TO THE
KENAI PENINSULA. KODIAK STARTING OFF AS SNOW THIS AFTERNOON TO WARM
TO A RAIN SNOW MIX AFTER MIDNIGHT. MOISTURE TO SPREAD INTO THE KENAI
PENINSULA. HOWEVER...WITH JET SUPPORT AND A SUPPORTIVE EAST WEST
SURFACE GRADIENT...DOWNSLOPE PRECIP PATTERN WILL BE EVIDENT LATER
TONIGHT AND TOMORROW.

.SHORT TERM FORECAST...
BERING AND ALEUTIANS...
LOW SOUTH OF DUTCH THIS AFTERNOON TO CROSS INTO BRISTOL BAY TONIGHT
THEN SWING INLAND TOMORROW NIGHT NEAR BETHEL. RAIN TO SPREAD ACROSS
THE AREA FROM DUTCH HARBOR EAST TONIGHT AND WANE FROM THE WEST
TOMORROW. ANOTHER LOW TO MOVE SOUTH OF SHEMYA LATE TONIGHT AND BRING
A WARM FRONT ACROSS THE WESTERN ALEUTIANS WITH NEAR GALE FORCE WINDS.
PRECIP TO SPREAD ACROSS THE BERING FROM THIS LOW SUNDAY NIGHT. MOST
OF IT SHOULD BE RAIN AS 850 TEMPS ARE NEAR ZERO. ANOTHER LOW TO SWING
THROUGH SOUTH OF THE ORIGINAL LOW ACROSS DUTCH MONDAY. THE TWO
COMBINE IN THE EASTERN BERING MONDAY NIGHT AS TWO UPPER LOW CENTERS
MERGE WITH WINDS AND PRECIPITATION INTENSIFYING. THE LOW WILL MOVE TO
THE BERING STRAIT TUESDAY WHILE A PORTION SPLITS INTO THE GULF.
ANOTHER WAVE MOVING OUT OF SIBERIA TO HELP PUSH THE SURFACE LOW INTO
THE CHUKCHI SEA.

WESTERN ALASKA...
FRONT ALONG THE COAST THIS AFTERNOON PRODUCING BLIZZARD CONDITIONS.
THE WINDS TO DIMINISH THIS EVENING THE FRONT LOSES JET SUPPORT.
PRECIP WILL SPREAD ACROSS THE KUSKOKWIM VALLEY TONIGHT WITH THE FRONT
WEAKENING INLAND. THE LOW NEAR DUTCH HARBOR THIS AFTERNOON TO MOVE
INTO BRISTOL BAY. THIS WILL INCREASE PRECIP ONCE AGAIN LATE TONIGHT
AND TOMORROW. HOWEVER...WINDS WILL NOT BE THAT STRONG. THEREFORE...DO
NOT EXPECT BLIZZARD CONDITIONS AGAIN. THE LOW LIFTS ACROSS THE
KUSKOKWIM/YUKON DELTA SUNDAY WITH PRECIP LIFTING ACROSS THE MAINLAND
SUNDAY NIGHT. ANOTHER WARM FRONT TO PUSH ACROSS THE WEST COAST MONDAY
WITH MORE PRECIP ACROSS THE COASTAL LOCATIONS. A LOW WRAPS UP IN THE
EASTERN BERING MONDAY EVENING WITH RAIN ACROSS THE COAST WITH NOT
MUCH INLAND. THIS LOW WILL LIFT TO THE BERING STRAIT TUESDAY WITH
PRECIP SPREADING FARTHER INLAND. WINDS WILL BE A BIT STRONGER ON THE
BACKSIDE OF THE LOW WITH SOME COLD AIR ADVECTION.

SOUTH CENTRAL...
A WARM FRONT IS PUSHING ACROSS KODIAK ISLAND THIS AFTERNOON. SNOW TO
CHANGE TO RAIN FROM SOUTH TO NORTH THIS EVENING. THE PRECIP TO REACH
THE KENAI PENINSULA TONIGHT WITH MOST LOCATIONS REMAINING SNOW.
AS THE FLOW TURNS MORE SOUTHERLY TOMORROW AND WARMS THE AIR
MASS...SNOW WILL CHANGE TO A RAIN SNOW MIX AT LOWER ELEVATIONS. IN
ADDITION...A GOOD EAST WEST GRADIENT WILL PROVIDE FOR MODERATE GAP
WINDS AND A TYPICAL DOWNSLOPE PRECIP PATTERN TOMORROW. THE FRONT
MOVES THROUGH TOMORROW EVENING AND WITH IT COMES A SWITCH IN WIND
DIRECTION. THEREFORE...WE WILL SEE SOME PRECIP SPREAD ACROSS THE
PREVIOUSLY DOWNSLOPED AREAS. THE TURN IN FLOW WILL ALSO WARM THE AIR
MASS INLAND AND PROVIDE A RAIN SNOW MIX AS WELL. MEANWHILE...SNOW
WILL DEVELOP IN THE SUSITNA LATE TONIGHT TOMORROW. DO NOT EXPECT
HEAVY PRECIP FOR SNOW ADVISORY RIGHT NOW. AND AS THE DYNAMICS BECOME
MORE FAVORABLE FOR HEAVIER PRECIP TOMORROW EVENING...THE PRECIP WILL
LIKELY START CHANGING TO RAIN SNOW MIX UP THE VALLEY. THE ENTIRE
SYSTEM SWINGS ACROSS THE AREA MONDAY WITH PRECIP WANING THROUGH THE
DAY FROM THE WEST. ANOTHER FRONT PUSHES TO THE AREA MONDAY NIGHT WITH
CONTINUED WARMING OF THE AIR MASS. TYPICAL DOWNSLOPE PRECIP PATTERN
ONCE AGAIN BY TUESDAY MORNING WITH THE MAIN LOW NEAR NUNIVAK ISLAND.
AS THE FLOW TURNS AGAIN...MAY SEE SOME PRECIP PUSH INTO DOWNSLOPED
AREAS AGAIN TUESDAY NIGHT/WEDNESDAY.

.LONG TERM FORECAST...
MUCH UNCERTAINTY PAST WEDNESDAY MORNING. BROAD BRUSH THE WAY TO GO
TODAY WITH NUMEROUS SYSTEMS TO MOVE THROUGH THE AREA AND THE TIMING
IS IN QUESTION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING ZONES 155 AND 161
MARINE...GALE 130 132 150
FIRE WEATHER...NONE

JN MAR 08