Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 272142
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
142 PM AKDT SUN JUL 27 2014

.UPPER LEVELS...THE HIGH AMPLITUDE PATTERN CONTINUED ITS HOLD
ACROSS THE REGION. A BROAD BLOCKING RIDGE WAS EVIDENT OVER THE
BERING SEA AND EASTERN RUSSIA. TO THE EAST THE LONG WAVE TROUGH
EXTENDED FROM A LOW NEAR THE POLE TO A WEAK CUT-OFF LOW COMPLEX
OVER THE GULF.

THE HIGH AMPLITUDE RIDGE OVER THE BERING SEA /ALEUTIANS HOLDS
THROUGH EARLY TUE WITH A SLIGHT DRIFT TO THE EAST. A SHORT WAVE
OVER THE ARCTIC OCEAN DROPS SOUTH ALONG THE FORWARD SIDE OF THE
RIDGE MON AND MERGES WITH THE CUT-OFF LOW COMPLEX OVER THE GULF
TUE. THE BRUNT OF THE ENERGY AND ASSOCIATED PRECIPITATION SHOULD
HOLD WEST OF THE ALASKA RANGE AND ONLY PROVIDE FOR A GLANCING BLOW
TO SOUTHCENTRAL. THE GULF CUT-OFF BECOMES A LITTLE MORE
ORGANIZED WITH TIME AND SETS UP GENERALLY EASTERLY FLOW ACROSS
SOUTHCENTRAL AND WITH THAT THE THREAT OF EASTERLY WAVES BY MID-
WEEK. THE SLIGHT WEAKENING AN ORIENTATION OF THE BERING SEA RIDGE
ALLOWS FOR SHORT WAVES TO PENETRATE A LITTLE FURTHER EAST AND
NORTH AS THE FLOW BECOMES MORE SOUTHERLY ACROSS THE WESTERN AND
CENTRAL ALEUTIANS MON NIGHT/TUE.

AT THE SURFACE...

SOUTHCENTRAL...A RELATIVELY COMPACT SURFACE CENTER IS EVIDENT
OVER THE NORTH GULF. A WEAK EASTERLY WAVE MOVING SLOWLY WEST
ACROSS THE COPPER RIVER BASIN/NORTH GULF COAST IS PRODUCING
WIDESPREAD RAIN OVER THESE LOCALS. GENERALLY FAIR SKIES WERE
EVIDENT WEST OF THIS FEATURE THIS MORNING.

ELSEWHERE...A BOARD RIDGE OVER THE BERING SEA CONTINUED STRATUS
AND FOG OVER MUCH OF THE ALEUTIANS...AK PEN...AND BERING SEA. THE
SW MAINLAND EXCEPT FOR COASTAL LOCALS AND THE DELTA WHERE UNDER
RELATIVELY FAIR SKIES. A WEAK WAVE MOVING SOUTH TOWARD THE DELTA
THREATENED SHOWERS.

&&

.MODEL DISCUSSION...
MODELS ARE IN RELATIVELY GOOD SHORT TERM AGREEMENT IN THE
SYNOPTIC UPPER LEVEL PATTERN. THE ECMWF OVERALL IS CONSISTENT ON
THE HANDLING OF THE MAIN UPPER FEATURES ESPECIALLY THE SHORT WAVE
TRACKING SOUTH ALONG THE RIDGE MON/TUE. MODELS ARE ALSO HINTING
AT AN EASTERLY WAVE MOVING ACROSS SOUTHCENTRAL BY MID-WEEK.
SURFACE PATTERNS ARE ALL GENERALLY IN THE BALL PARK. THE NAM WILL
BE USED FOR LOCAL EFFECTS AND THE HEMISPHERIC MODELS FOR THE
REMAINDER.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
RAIN ASSOCIATED WITH A WEAK EASTERLY WAVE ACROSS THE COPPER RIVER
BASIN AND NORTH GULF COAST SHOULD DIMINISH OVER NIGHT. SKIES
SHOULD BE GENERALLY PARTLY CLOUDY TO THE WEST WITH THE THREAT OF
SHOWERS TONIGHT AND AN ISOLATED THUNDERSTORM ALONG THE TALKEETNA
MOUNTAINS THIS EVENING. EXPECT THE THREAT OF SHOWERS OVER MOST
AREAS MON AFTERNOON THROUGH TUE WITH BROAD CYCLONIC FLOW ACROSS
THE REGION. AS MENTIONED ABOVE...MODELS ARE HINTING AT AN EASTERLY
WAVE DEVELOPING AND MOVING WEST ACROSS THE AREA MID-WEEK. THERE IS
STILL SOME UNCERTAINTY WITH TIMING AND STRENGTH...BUT IF THESE
FEATURE MATERIALIZES...THEN IT WILL BRING INCREASING CLOUDS WITH
THE POTENTIAL FOR WIDESPREAD WETTING RAINS.

SOUTHWEST ALASKA...
STRATUS AND FOG ARE LIKELY OVER THE DELTA TONIGHT AND TUE WITH
WEAK WESTERLY FLOW. PATCHY FOG IS ALSO A POSSIBILITY OF COASTAL
BRISTOL BAY. A SHORT WAVE DROPPING SOUTH OUT OF NW ALASKA MON
WILL BRING RAIN TO THE KUSKOKWIM VALLEY AND EASTERN BRISTOL BAY
MON NIGHT. RAIN SHOULD CHANGE OVER TO SHOWERS BY TUE.

BERING SEA/ALEUTIANS...
WIDESPREAD LOW CLOUDS...FOG...AND SOME DRIZZLE WILL AFFECT THE
EASTERN HALF OF THE AREA THROUGH WED. RAIN AND SOME WIND
ASSOCIATED WITH THE FRONT WILL AFFECT THE WESTERN AND CENTRAL
ALEUTIANS DURING THE PERIOD.

&&

.LONG TERM FORECAST...
AN OMEGA BLOCK SETTING UP SHOP OVER THE BERING SEA AND MAINLAND
WILL DOMINATE THE PATTERN...AT LEAST FOR THE BEGINNING OF THE
EXTENDED FORECAST. THE SAME HIGH AMPLITUDE RIDGE CURRENTLY OVER
THE BERING WILL CLOSE OFF AT THE UPPER LEVELS...BOOKENDED BY TWO
UPPER LOW PRESSURE CENTERS...ONE OVER THE GULF OF ALASKA AND THE
OTHER SOUTHWEST OF THE WESTERN ALEUTIANS. THE GULF SYSTEM WILL
CONTROL SENSIBLE WEATHER ACROSS THE SOUTHCENTRAL WITH THE MAIN
FEATURE BEING AN EASTERLY WAVE TOWARD THE BEGINNING OF THE
FORECAST. GUIDANCE HAS COME INTO BETTER AGREEMENT WITH PLACEMENT
AND TIMING OF THE FEATURE BUT THESE DISTURBANCES GENERALLY GIVE
GUIDANCE FITS WITH BOTH TIMING AND INTENSITY. THAT SHORTWAVE WILL
AFFECT THE SOUTHCENTRAL MAINLAND MID TO LATE WEEK. BEYOND THAT
TIMEFRAME PRECIPITATION CHANCES REVOLVE AROUND DIURNAL CONVECTION
OVER THE MOUNTAINS...MOSTLY DRY AT THE LOWEST ELEVATIONS BUT
CHANCES FOR SHOWERS ALONG HIGHER TERRAIN. THE UPCOMING PATTERN
LOOKS TO BE VERY CLIMATOLOGICAL AS FAR AS TEMPERATURES AND
PRECIPITATION GO.


&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

$$

RMC/MTL JUL 14



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