Gale Warning 454, NWS Anchorage, AK

AREA FORECAST DISCUSSION...CORRECTED
SOUTHCENTRAL AND SOUTHWEST ALASKA
120 PM AKDT SUN MAY 31 2009

.MODEL DISCUSSION...

MODELS ARE IN GOOD AGREEMENT THROUGH THE SHORT TERM...ESPECIALLY FOR
THE EASTERN DOMAIN WHERE THERE IS HIGH CONFIDENCE IN THE RIDGING
NUDGING ITSELF TO THE NORTHWEST FROM THE EASTERN GULF OF ALASKA.
DIFFERENCES ARISE IN THE HANDLING OF THE LARGE LOW COMPLEX JUST SOUTH
OF THE ALEUTIANS AND THE TWO SHORTWAVES AFFECTING THE AKPEN AND
BRISTOL BAY REGIONS BETWEEN THE NAM AND GFS OVER THE COMING
DAYS...WITH THE GFS THE SLIGHTLY QUICKER SOLUTION ESPECIALLY FOR THE
ONE TO AFFECT THAT REGION ON WEDNESDAY.  OVERALL...THE SYNOPTIC
PATTERN WILL BE HIGHLY STABLE THROUGH AT LEAST WEDNESDAY.

.ANALYSIS AND UPPER LEVELS...

ALOFT...A MID-LEVEL RIDGE IS SITUATED OVER THE EASTERN GULF OF ALASKA
WITH SHORTWAVE RIDGING EXTENDING ACROSS SOUTHCENTRAL TO OVER THE Y-K
DELTA REGION BETWEEN A DEPARTING MID-LEVEL LOW TO THE NORTH...AND A
LARGE COMPLEX SET OF LOWS ENCOMPASSING THE REGION FROM THE SOUTHERN
BERING SEA TO THE NORTH PACIFIC OCEAN CENTERED NEAR 170W LONGITUDE.
THE NORTHERN LOW IS RAPIDLY PROGRESSING BACK INTO THE ARCTIC OCEAN.
BETWEEN THE UPPER LOW TO THE SOUTHWEST AND THE UPPER RIDGE TO THE
SOUTHEAST...A STRONG SOUTHERLY JET IS TRANSPORTING COOL AIR AND LOTS
OF MOISTURE ACROSS THE AKPEN...SOUTHWEST ALASKA...AND SOUTHCENTRAL
THIS MORNING.

AT THE SURFACE...HIGH PRESSURE IS IN CONTROL EAST OF KODIAK
ISLAND...WITH A SET OF LOWS STACKED UNDERNEATH THE AFOREMENTIONED
MID-LEVEL LOWS JUST SOUTH OF THE ALEUTIANS NEAR 170W.  SOUTHERLY AND
SOUTH-SOUTHEASTERLY FLOW IS BRINGING ONSHORE FLOW TO THE PACIFIC SIDE
OF THE AKPEN AND THE BRISTOL BAY REGION...WITH PLENTY OF LIGHT RAIN
AND SHOWERS CURRENTLY OVER SOUTHWEST ALASKA THIS MORNING AND EARLY
AFTERNOON.

.SHORT TERM FORECAST...

SOUTH AND EAST OF THE ALASKA RANGE...LIGHT RAIN WHICH HAS AFFECTED
MOST OF SOUTHCENTRAL THIS MORNING HAS MOVED MOSTLY INTO THE NORTHERN
HALF OF THE SUSITNA VALLEY ZONE AND THE HIGHEST ELEVATIONS NORTH OF
SOUTHCENTRAL.  PARTIAL CLEARING IS UNDERWAY THIS AFTERNOON AND EARLY
EVENING AS HIGH PRESSURE BEGINS TO ASSERT ITSELF FROM THE SOUTH AND
EAST.  OVER THE COPPER RIVER BASIN WHERE RIDGING HAS ALREADY ASSERTED
ITSELF...THE BIG ISSUE IS THE FIRE WEATHER DANGER FOR LOW RELATIVE
HUMIDITIES AND STRONG WINDS AS TEMPERATURES WARM DURING THE AFTERNOON
AND EVENING HOURS AND SOUTH TO NORTH PRESSURE GRADIENT DEVELOPS.
THUS...THERE IS A RED FLAG WARNING UNTIL 10 PM FOR ZONE 141.  AS
RIDGING BUILDS NORTH AND WESTWARD INTO THE INTERIOR OF THE
STATE...MOSTLY TRANQUIL WEATHER CONDITIONS WITH PARTLY CLOUDY SKIES
AND SEASONABLE TEMPERATURES ARE ON TAP THROUGH WEDNESDAY.
HOWEVER...WITH KODIAK ISLANDS PROXIMITY TO THE SOUTHERLY ONSHORE
FLOW...RAIN APPEARS LIKELY THROUGH AT LEAST WENDESDAY OFF AND ON
UNTIL THIS STABLE PATTERN REGIME BREAKS DOWN.

SOUTH AND WEST OF THE ALASKA RANGE...ONSHORE FLOW ON THE PACIFIC SIDE
OF THE AKPEN AND FOR THE BRISTOL BAY REGION OF SOUTHWEST ALASKA WILL
RESULT IN MAINLY COOL TEMPERATURES...CLOUDS...AND MOSTLY PERSISTENT
LIGHT RAIN.  A SHORTWAVE AFFECTS THE AKPEN LATER TODAY...WITH A MORE
POTENT ONE TO POSSIBLY AFFECT THE REGION ON WEDNESDAY WITH AN
INCREASE IN WINDS AND MORE WIDESPREAD PRECIPITATION.

.LONG TERM FORECAST...

THERE IS FAIRLY HIGH CONFIDENCE IN THE OVERALL SYNOPTIC PATTERN
THROUGH THE EXTENDED PERIOD.  THE CURRENT STABLE REGIME SHOULD
GENERALLY PERSIST...THOUGH TOWARDS LATE WEEK INTO THE WEEKEND THERE
IS SOME QUESTION AS TO HOW FAR WEST THE RIDGE IS ABLE TO EXTEND...AS
WELL AS IF THE RIDGE WILL MOVE SLIGHTLY TO THE EAST WITH TIME.  THE
MORE THE RIDGE IS ABLE TO BUILD OR EXTEND ACROSS SOUTHCENTRAL...THE
WARMER AND DRIER THE CONDITIONS WILL BE.  SOUTHWEST ALASKA AND THE
AKPEN...AS WELL AS THE CENTRAL AND EASTERN ALEUTIANS...SHOULD REMAIN
FAIRLY COOL AND WET.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...150 155 160 180.
FIRE WEATHER...RED FLAG WARNING...141.

CC MAY 09