Prognostic Meteorological Discussion
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827
FXAK02 KWNH 221953
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
353 PM EDT WED MAR 22 2017

VALID 12Z SUN MAR 26 2017 - 12Z THU MAR 30 2017

MODELS CONTINUE TO BE IN GOOD AGREEMENT WITH A LARGE DOME OF HIGH
PRESSURE OVER THE BEARING SEA ON DAY 4/SUNDAY...EVENTUALLY LIFTING
NORTHWARD INTO RUSSIA BY THE END OF THE PERIOD/THURSDAY. AT THE
SAME TIME...ENERGY DETACHING FROM THE WESTERLIES OVER THE WEEKEND
MAY CLOSE OFF A MID-UPPER LEVEL LOW ACROSS THE SOUTHERN TIER OF
THE STATE BY SUNDAY. THIS CUTOFF CIRCULATION SEEMS TO RETROGRADE
SLOWLY WESTWARD ACROSS THE STATE TOWARDS THE NORTHERN ALEUTIANS
AND EASTERN BEARING SEA. THE ENSEMBLE MEANS CONTINUE TO AGREE ON
THIS LOW EVENTUALLY INTERACTING WITH A SERIES OF ACTIVE STORM
SYSTEMS SOUTH OF THE ALEUTIANS MOVING INTO THE GULF OF ALASKA
TOWARDS THE END OF THE PERIOD. THE OPERATIONAL GFS/ECMWF AND THEIR
RESPECTIVE MEANS AND THE 00Z NAEFS CONTINUE TO SHOW GOOD AGREEMENT
BOTH AT THE SURFACE AND IN THE UPPER LEVELS WITH THIS SETUP
THROUGH DAY 5 AND INTO DAY 6. ON DAY 7...THE 00Z ECMWF OPERATIONAL
WANTS TO LIFT A DEEP CYCLONE INTO THE GULF OF ALASKA WHILE THE 12Z
GFS SHOWS JUST A WEAK SHORTWAVE ALONG THE BASE OF A CLOSED LOW
OVER THE ALEUTIANS. THE IDEA OF A DEEP CYCLONE IS NOT SUPPORTED IN
THE MEANS EITHER. REGARDING MODEL PREFERENCE FOR THE WPC
PROGS/500MB CHARTS...WENT WITH AN ALMOST EQUAL BLEND OF THE 12Z
GFS/00Z ECMWF/06 GEFS/00Z ECMEAN/00Z NAEFS DAYS 4 AND
5...TRANSITIONING TO A MOSTLY ENSEMBLE MEAN BLEND BY THE END OF
THE PERIOD TO TRY TO MITIGATE THE DIFFERENCES IN THE DETAILS.

AS FAR AS SENSIBLE WEATHER...BELOW NORMAL TEMPERATURES ACROSS THE
STATE THIS WEEKEND WILL MODERATE TO SLIGHTLY ABOVE BY MID-WEEK.
THE INTERIOR PORTION OF THE STATE SHOULD REMAIN DRY THROUGH THE
MEDIUM RANGE PERIOD BUT DEEP MOISTURE MOVES INTO THE
PANHANDLE/SOUTHERN COAST REGION BY MONDAY AS A CYCLONE/SURFACE
FRONT APPROACHES THE COAST. PRECIPITATION CHANCES WILL BE ON THE
INCREASE ACROSS THE EASTERN ALEUTIAN CHAIN AS WELL AS A SERIES OF
STORMS PASS THROUGH.

SANTORELLI

$$





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