Heavy Freezing Spray Warning 39, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
145 PM AKST WED FEB 5 2014

.ANALYSIS AND UPPER LEVELS...
STRONG HIGH PRESSURE ALOFT CONTINUES TO STRENGTHEN AND EXPAND
EASTWARD ACROSS THE BERING SEA. NORTHERLY FLOW AHEAD OF THIS HIGH IS
PUSHING A REMNANT UPPER TROUGH SOUTHWARD ACROSS INTERIOR
ALASKA...THOUGH SATELLITE IMAGERY INDICATES THIS FEATURE IS WEAKENING
RAPIDLY AS IT IS SQUEEZED BETWEEN HIGH PRESSURE CENTERS ON BOTH
SIDES. SOUTHCENTRAL ALASKA IS DRY AND MOSTLY SUNNY TODAY...WHILE THE
SOUTHWEST MAINLAND HAS MORE CLOUDS BUT STILL ONLY LINGERING ISOLATED
SHOWERS APPARENT ON RADAR IMAGERY. A COLD AND DENSE AIRMASS OVER
INTERIOR ALASKA IS PRODUCING MODERATE STRENGTH OUTFLOW WINDS ALONG
THE GULF COAST...WITH PRESSURE GRADIENTS BEING ENHANCED BY A WEAK
TROUGH OVER THE NORTHERN GULF. A LARGE BUT DISORGANIZED LOW PRESSURE
SYSTEM SOUTH OF THE ALEUTIAN CHAIN CONTINUES TO DRIFT SLOWLY WESTWARD
WITH GARDEN-VARIETY GUSTY WINDS ACROSS THE ALEUTIANS BEING THE
BIGGEST IMPACT TO THE STATE AT THIS TIME.

.MODEL DISCUSSION...
MODELS REMAIN IN EXCELLENT SYNOPTIC AGREEMENT...AND CONTINUE TO
SLOWLY IRON OUT THEIR SMALL-SCALE DISCREPANCIES. THESE PRIMARILY
REVOLVE AROUND THE PLACEMENT OF A LOW CENTER THAT WILL DEVELOP OVER
THE NORTHWEST GULF THURSDAY EVENING AND INTENSIFY RAPIDLY THROUGH
FRIDAY MORNING. THE GFS HAS CONSISTENTLY BEEN THE FARTHEST WEST OF
AVAILABLE MODELS...AND WILL CONTINUE TO BE SHUNNED IN FAVOR OF THE
FURTHER EAST NAM/ECMWF/GEM SOLUTION. THE LOCATION THAT WILL BE MOST
SENSITIVE TO THIS EXACT TRACK WILL BE KODIAK ISLAND. WITH THE CURRENT
MODEL PREFERENCE...STRONG WINDS AND A FAIRLY BRIEF PERIOD OF SNOWFALL
COULD CREATE SOME TRAVEL ISSUES DURING THE DAY FRIDAY. HOWEVER...A
FURTHER WEST TRACK WOULD INCREASE CHANCES FOR PROLONGED SIGNIFICANT
SNOW AND BLOWING SNOW CONDITIONS DURING THIS PERIOD.

.SHORT TERM FORECAST...
CLEAR SKIES OVER MOST OF SOUTHCENTRAL WILL GIVE WAY TO SOME HIGH
CLOUDINESS MOVING IN FROM THE NORTHWEST THIS EVENING...ASSOCIATED
WITH THE AFOREMENTIONED UPPER TROUGH OVER THE INTERIOR. THURSDAY WILL
SEE SLOWLY INCREASING CLOUDINESS WITH A CHANCE OF FLURRIES OR LIGHT
SNOW BY LATE AFTERNOON AS THE MUCH-ANTICIPATED UPPER TROUGH
AMPLIFICATION GETS UNDERWAY AND STRONG DYNAMIC FORCING MOVES
OVERHEAD. THE BEST CHANCE FOR ANY MINOR SNOW ACCUMULATIONS WILL BE
GENERALLY FROM PALMER EAST...INCLUDING THE COPPER RIVER BASIN AND
VALDEZ. BY THURSDAY EVENING RAPID INTENSIFICATION OF THE GULF LOW
WILL BEGIN AS COLD AIR ARRIVES FROM THE NORTH. THE MOST UNUSUAL
ASPECT OF THIS DEVELOPING STORM WILL BE HOW QUICKLY STRENGTHENING
OCCURS (GREATER THAN 30 MB IN 18 HOURS). THIS WILL SIGNIFICANTLY
INCREASE GAP WINDS IN MOST OF THE FAVORED AREAS...ESPECIALLY THE
MATANUSKA VALLEY AND THOMPSON PASS. THE SURGE OF COLD AIR WILL ALLOW
WINDS TO ALSO MAKE THEIR WAY DOWN INTO TOWN IN VALDEZ THURSDAY NIGHT
INTO FRIDAY...THOUGH THE STRONGEST WINDS ARE EXPECTED TO REMAIN OVER
THE MATANUSKA VALLEY WHERE UPPER LEVEL SUPPORT IS MORE FAVORABLE.
COUPLED WITH LITTLE OR NO SNOW COVERAGE THESE STRONG WINDS WILL
CREATE DANGEROUS FIRE WEATHER CONDITIONS THAT WILL PERSIST THROUGH
FRIDAY NIGHT....WITH A RARE WINTER-SEASON RED FLAG WARNING NOW IN
EFFECT FOR THE MATANUSKA VALLEY AND WESTERN KENAI PENINSULA. A FINAL
CONCERN WILL BE THE DEVELOPMENT OF VERY COLD WIND CHILLS...ESPECIALLY
THROUGH THE SUSITNA VALLEY AND THOMPSON PASS. WHILE NOT EXPECTED TO
BE COLD ENOUGH FOR AN ADVISORY...WIND CHILLS TO 30 BELOW ARE NOT OUT
OF THE QUESTION IN THESE AREAS AND WILL DEFINITELY BE A CHANGE OF
PACE FROM RECENT BENIGN WEATHER.

SOUTHWEST...AREAS OF LOW CLOUDS AND FOG WITH SPRINKLES OR FLURRIES
WILL CONTINUE UNTIL WIDESPREAD DRY OFFSHORE FLOW BEGINS TO BECOME
MORE ESTABLISHED DURING THE DAY THURSDAY. CLOUDS WILL DIMINISH AS
WINDS CONTINUE TO INCREASE FRIDAY MORNING...WITH STRONGEST WINDS
LIKELY ALONG THE BRISTOL BAY AND DELTA COASTLINES FRIDAY AFTERNOON
AND EVENING. THESE WINDS SHOULD REMAIN BELOW WARNING LEVEL...BUT WILL
DEFINITELY BE STRONGER THAN A TYPICAL NORTHERLY FLOW PATTERN.
DROPPING TEMPERATURES WILL ALSO DROP WIND CHILLS BELOW ZERO IN MOST
PLACES...AND PERHAPS WELL BELOW ZERO BY FRIDAY NIGHT.

BERING SEA AND ALEUTIANS...HIGH PRESSURE WILL REMAIN IN CONTROL
THROUGHOUT THE SHORT TERM PERIOD ACROSS THE MAJORITY OF THE AREA.
THIS WILL MEAN A CONTINUATION OF LOW LEVEL TEMPERATURE INVERSIONS AND
RESULTING AREAS OF LOW CLOUDS AND FOG. THE BIG WESTERN GULF LOW WILL
PASS SOUTH OF THE ALASKA PENINSULA ON FRIDAY NIGHT...THIS WILL
ENHANCE INSTABILITY SNOW SHOWER ACTIVITY OVER THE EASTERN
BERING...AND LIKELY KEEP THE EASTERN HALF OF THE ALEUTIANS UNDER
CLOUDY AND SHOWERY CONDITIONS ON FRIDAY AND SATURDAY.

.LONG TERM FORECAST (FROM PREVIOUS DISCUSSION)...
BY SUNDAY...A DEEP LOW WILL BE IN THE NORTH PACIFIC...WITH NORTHEAST
FLOW ALOFT OVER ALASKA. COLD AIR WILL REMAIN OVER THE REGION...WITH
CONTINUED NORTHERLY GAP WINDS PUSHING THROUGH FAVORED MOUNTAIN
LOCATIONS. PRECIPITATION THREATS WILL BE RELEGATED TO THE NORTHERN
GULF COAST AND KODIAK ISLAND. DRY WEATHER AND OFFSHORE FLOW WILL
LIKELY CONTINUE THROUGH TUESDAY...WITH CONTINUED FIRE WEATHER
CONCERNS ACROSS THE MATANUSKA VALLEY AND WESTERN KENAI
PENINSULA...AND BLOWING DUST AND SILT BLOWING THROUGH THE MATANUSKA
VALLEY. A BRIEF REPRIEVE MAY DEVELOP MIDWEEK AS A HIGH PRESSURE RIDGE
ALOFT SLIDES INTO SOUTHERN ALASKA.

THE ECMWF ENSEMBLE...GFS ENSEMBLE...AND NAEFS CONTINUE TO HINT AT A
DEEP TROUGH FORMING OVER SOUTHWEST ALASKA IN THE EXTENDED RANGE
FRIDAY AND BEYOND. THIS WILL LIKELY KEEP SOUTHERN ALASKA BELOW
AVERAGE TEMPERATURE. DEPENDING ON HOW FAR WEST THE TROUGH
DEVELOPS...SNOW THREATS WILL INCREASE FOR PARTS OF SOUTHERN ALASKA
INTO THE WEEKEND...BUT THOSE DETAILS ARE STILL QUITE UNCERTAIN.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WATCH 111
MARINE...STORM 127
         GALE 119 120 121 126 128 129 125 130 131 132 136 137 138 139
              140 150 180
FIRE WEATHER...RED FLAG WARNING 111 121

AMD/JA FEB 14

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1105 AM AKST WED FEB 5 2014

AKZ101-111-121-060300-

...DANGEROUS FIRE WEATHER CONDITIONS TO IMPACT PARTS OF SOUTHCENTRAL
ALASKA THURSDAY EVENING THROUGH FRIDAY EVENING...

AN ARCTIC AIR MASS IN NORTHEAST ALASKA WILL MOVE RAPIDLY INTO SOUTH
CENTRAL ALASKA THURSDAY NIGHT INTO FRIDAY AND BRING WINDY AND COLDER
CONDITIONS TO THE REGION. THIS SYSTEM WILL BRING DANGEROUS FIRE
WEATHER CONDITIONS TO PARTS OF THE MATANUSKA VALLEY AND WESTERN
KENAI PENINSULA...AND AS A RESULT RED FLAG WARNINGS HAVE BEEN ISSUED
FOR THESE AREAS FROM 6 PM THURSDAY TO MIDNIGHT AKST FRIDAY NIGHT.

NORTHEASTERLY WINDS RANGING FROM 40 TO 65 MPH WITH POSSIBLE GUSTS TO
80 MPH IN THE MATANUSKA VALLEY AND NORTHERLY WINDS 15 TO 30 MPH WITH
GUSTS TO 50 MPH ALONG THE WESTERN KENAI PENINSULA WILL COMBINE WITH
LOW HUMIDITY TO CREATE CONDITIONS SUSCEPTIBLE TO RAPID FIRE GROWTH
AND SPREAD.

ANOTHER IMPACT FROM THIS SYSTEM WILL BE WINDS CHILLS. THE WIND CHILLS
FROM THE MATANUSKA VALLEY THROUGH WESTERN KENAI PENINSULA...INCLUDING
THE ANCHORAGE AREA...ARE EXPECTED TO DROP TO NEAR...OR EVEN
BELOW...ZERO DEGREES AT TIMES.

RESIDENTS ARE ENCOURAGED TO CHECK YOUR LOCAL CONDITIONS AND CONSULT
WITH YOUR LOCAL COMMUNITY RESOURCES BEFORE BURNING AND ALWAYS BE
FIREWISE.

SPECIAL WEATHER STATEMENT...CORRECTED
NATIONAL WEATHER SERVICE ANCHORAGE AK
1105 AM AKST WED FEB 5 2014

CORRECTED TYPO

AKZ101-111-121-060300-

...DANGEROUS FIRE WEATHER CONDITIONS TO IMPACT PARTS OF SOUTHCENTRAL
ALASKA THURSDAY EVENING THROUGH FRIDAY EVENING...

AN ARCTIC AIR MASS IN NORTHEAST ALASKA WILL MOVE RAPIDLY INTO SOUTH
CENTRAL ALASKA THURSDAY NIGHT INTO FRIDAY AND BRING WINDY AND COLDER
CONDITIONS TO THE REGION. THIS SYSTEM WILL BRING DANGEROUS FIRE
WEATHER CONDITIONS TO PARTS OF THE MATANUSKA VALLEY AND WESTERN
KENAI PENINSULA...AND AS A RESULT RED FLAG WARNINGS HAVE BEEN ISSUED
FOR THESE AREAS FROM 6 PM THURSDAY TO MIDNIGHT AKST FRIDAY NIGHT.

NORTHEASTERLY WINDS RANGING FROM 40 TO 65 MPH WITH POSSIBLE GUSTS TO
80 MPH IN THE MATANUSKA VALLEY AND NORTHERLY WINDS 15 TO 30 MPH WITH
GUSTS TO 50 MPH ALONG THE WESTERN KENAI PENINSULA WILL COMBINE WITH
LOW HUMIDITY TO CREATE CONDITIONS SUSCEPTIBLE TO RAPID FIRE GROWTH
AND SPREAD.

ANOTHER IMPACT FROM THIS SYSTEM WILL BE WIND CHILLS. THE WIND CHILLS
FROM THE MATANUSKA VALLEY THROUGH WESTERN KENAI PENINSULA...INCLUDING
THE ANCHORAGE AREA...ARE EXPECTED TO DROP TO NEAR...OR EVEN
BELOW...ZERO DEGREES AT TIMES.

RESIDENTS ARE ENCOURAGED TO CHECK YOUR LOCAL CONDITIONS AND CONSULT
WITH YOUR LOCAL COMMUNITY RESOURCES BEFORE BURNING AND ALWAYS BE
FIREWISE.