Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 281217
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
417 AM AKDT TUE OCT 28 2014

.ANALYSIS AND UPPER LEVELS...
THE FLOW ALOFT BECOMES A LITTLE MORE COMPLEX THIS MORNING. A
LONGWAVE TROUGH STRETCHES FROM THE POLE SOUTHWARD THROUGH THE
ALASKA PENINSULA. THE REMNANTS OF A STRONG STORM SPINS OVER THE
NORTHERN BERING SEA. A NEW SYSTEM HAS DEVELOPED OVER THE ALASKA
PENINSULA AND IS QUICKLY BECOMING THE DOMINANT CIRCULATION ALOFT.
A NICE COMPACT CIRCULATION...THIS SYSTEM IS CALLED AN INSTANT
OCCLUSION. THE FRONTAL BOUNDARY FROM THE LAST BERING SEA STORM
STALLED OUT OVER THE EASTERN BERING SEA. A STRONG SHORTWAVE TROUGH
WITHIN THE COLD AIR ALOFT APPROACHED THE FRONTAL BOUNDARY AND
TAPPED IT`S ENERGY...QUICKLY DEVELOPING A CIRCULATION AND HAVING
THE SATELLITE PRESENTATION OF A MATURE SYSTEM WITH A COMMA
HEAD AND BACK BENT OCCLUSION DESPITE AN INNOCULOUS 990 MB
PRESSURE. THE MAIN EFFECT OF THIS SYSTEM IS A QUICKER UPTICK IN
STRONG WINDS FROM THE EASTERN ALEUTIANS TO THE ALASKA
PENINSULA. THE FRONT ASSOCIATED WITH THE SYSTEM IS APPROACHING
KODIAK ISLAND. THE NORTHERN SECTION OF THE FRONT...OVER THE
KUSKOKWIM DELTA...IS TAKING ON DEFORMATION BAND CHARACTERISTICS
BETWEEN THE TWO WEATHER SYSTEMS. AS THE LOW LEVEL WIND FIELDS
RESPOND TO THE NEW SURFACE LOW...COOLER NORTHERLY WINDS ARE
PROMOTING SNOW TO BEGIN TO MIX IN AROUND THE BETHEL AREA.

FURTHER EAST...THE PATTERN IS MUCH MORE BENIGN. A CLOSED HIGH
PRESSURE ALOFT SITS OVER THE CANADIAN YUKON WHILE A NORTH PACIFIC
SYSTEM MOVES ASHORE THE PANHANDLE. THE ONLY SIGNS OF FOG AND
STRATUS AROUND THE SOUTHCENTRAL EARLY THIS MORNING ARE A
PERSISTENT STRATUS DECK OVER THE COPPER RIVER BASIN. OTHERWISE NO
SIGNS...YET...OF LOW CLOUDS/FOG IN THE KNIK ARM REGION.

&&

.MODEL DISCUSSION...
GUIDANCE REMAINS IN PRETTY GOOD AGREEMENT THROUGH THE NEXT 48
HOURS OR SO. SOME SLIGHT DIFFERENCES ARISE AS THE CURRENT SYSTEM
MOVES IN TO THE GULF AND ROTATES A SHORTWAVE NEAR THE NORTH GULF
COAST. CONSENSUS SAYS THERE WILL AT LEAST BE AN INVERTED TROUGH
ASSOCIATED WITH THIS FEATURE BUT SOME MODELS ARE HINTING AT AN
ACTUAL CLOSED CIRCULATION. THE STRENGTH OF THAT SYSTEM WILL AFFECT
OUTFLOW WINDS ACROSS THE NORTH GULF COAST AS WELL AS THE NATURE OF
PRECIPITATION. BOTH DOMAINS PREFERRED THE EUROPEAN MODEL WITH THIS
FORECAST PACKAGE.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...HIGH CIRRUS WILL CONTINUE TO STREAM OVERHEAD
TODAY. THE THREAT FOR EARLY MORNING FOG/STRATUS SHOULD BE VERY
REDUCED THIS MORNING FOR A FEW REASONS. THE AFOREMENTIONED HIGH
CIRRUS OVERHEAD SHOULD LIMIT RADIATIONAL COOLING. DEW POINTS ARE
STARTING OFF A BIT LOWER THIS MORNING AND DEPTH OF MOISTURE OFF
THE SURFACE ARE NOT AS GREAT AS YESTERDAY EVIDENCED BY THE DEW
POINT TRACE ON THE 28TH/00Z PANC SOUNDING. LASTLY...THE SURFACE
WINDS ARE RESPONDING TO THE DEVELOPING SURFACE LOW OVER THE ALASKA
PENINSULA TURNING MORE NORTHERLY AROUND THE AREA...AS WELL AS A
GUSTY MATANUSKA VALLEY WIND WHICH SHOULD CONTINUE TO ADVECT DRIER
AIR SOUTHWARD OVER THE KNIK ARM REGION.

SEASONABLE TEMPERATURES AND LIGHT WINDS WILL CONTINUE TODAY FOR
MOST OF THE SOUTHCENTRAL. THERE IS A SLIGHT CHANCE FOR RAIN
SHOWERS AROUND KACHEMAK BAY. THE NEXT REAL CHANCE FOR
PRECIPITATIONCOMES ON WEDNESDAY AFTERNOON AS THE GULF SYSTEM
ROTATES A WAVE NORTHWARD. MOST OF THIS ACTIVITY SHOULD REMAIN
ALONG THE NORTH GULF COAST...POSSIBLY INTO THE SOUTHERN COPPER
RIVER BASIN.

SOUTHWEST ALASKA...A FRONTAL BOUNDARY/DEFORMATION ZONE SITS OVER
THE KUSKOKWIM DELTA THIS MORNING BRINGING MOST RAIN TO THE AREA
BUT SOME SNOW HAS MIXED IN AT TIMES AND IS MORE LIKELY TOWARD THE
NORTHERN PORTION OF THE ZONE. PRECIPITATION WILL GRADUALLY
DECREASE IN INTENSITY TODAY AS THE MAIN SYSTEM MOVES INTO THE
GULF. CLOUDS WILL DECREASE OVERNIGHT TONIGHT FOR MOST AREAS AS
LIGHT NORTHERLY WINDS REMAIN. TEMPERATURES WILL REMAIN SLIGHTLY
ABOVE NORMAL WHILE DRY CONDITIONS PERSIST THROUGH THURSDAY.

BERING SEA/ALEUTIANS...MOST OF THE AREA IS ON THE BACKSIDE OF THE
LOW PRESSURE SYSTEM UNDER WEAK COLD ADVECTION ALOFT. GALE FORCE
WINDS EXTEND FROM THE CENTRAL TO EASTERN BERING SEA ALONG WITH
RAIN AND SNOW SHOWERS. WINDS WILL SLOWLY TAPER FROM WEST TO EAST
BETWEEN NOW AND WEDNESDAY AFTERNOON. A FRONTAL BOUNDARY ENTERS THE
WESTERN BERING SEA TODAY AND SLOWLY PROGRESSES EASTWARD WHILE
WEAKENING THROUGH THURSDAY BRINGING AREAS OF SNOW AND RAIN.


&&

.LONG TERM FORECAST...
STARTING LATE THIS WEEK THERE IS NOW GOOD MODEL AGREEMENT THAT A
MORE ACTIVE WEATHER PATTERN IS EXPECTED FOR THE MAINLAND BY THIS
WEEKEND. THE MODELS HAVE TRENDED SLIGHTLY STRONGER WITH A LOW
CROSSING THE ALEUTIANS MID WEEK...WHICH IS NOW EXPECTED TO BE AT
LEAST GALE FORCE. THIS LOW WILL THEN SLOWLY MOVE THROUGH THE
BERING ON FRIDAY...AND INTO THE GULF BY EARLY IN THE WEEKEND.

THE APPROACHING ALEUTIAN LOW WILL BRING GALE FORCE WINDS AND
GUSTY WINDS TO THE CENTRAL AND WESTERN ALEUTIANS STARTING LATE
WEDNESDAY OR THURSDAY. THIS SYSTEM THEN LOOKS TO KEEP THE BERING
SEA AND ALEUTIANS WITH RAINY AND WINDY INTO EARLY NEXT WEEK.

WHILE THERE REMAINS SOME UNCERTAINTY TO THE EXACT LOW PLACEMENT
AND INTENSITY IN THE GULF THIS WEEKEND...THERE IS INCREASING
CONFIDENCE THAT THE CLEAR AND COLD PATTERN CURRENTLY OVER
SOUTHCENTRAL WILL BECOME CLOUDY...WARMER...AND POSSIBLY WET BY
THIS WEEKEND. THE GULF COAST AND KODIAK ISLAND WILL LIKELY SEE
RAINY AND WINDY WEATHER STARTING ON FRIDAY AND CONTINUING THROUGH
THIS WEEKEND. HOW THIS SYSTEM TO SOUTHCENTRAL IS STILL UNKNOWN...AS
LOW PLACEMENT AND STRENGTH WILL HAVE A SIGNIFICANT IMPACT TO THE
PRECIPITATION FORECAST.


&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 150 155 165 170 171 172 173 174 175 176 179 185.
FIRE WEATHER...NONE.

&&

$$

MTL OCT 14



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