Small Craft Advisory 356, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
147 PM AKDT MON APR 28 2014

.ANALYSIS AND UPPER LEVELS...
THE UPPER LEVEL PATTERN IS IN THE MIDDLE OF A SHIFT WHICH WILL
RESULT IN HIGH PRESSURE OVER MOST OF THE STATE WITH ABOVE NORMAL
TEMPERATURES. THE UPPER LEVEL LOW OVER THE GULF OF ALASKA...AND
THE TROUGH FROM IT THAT EXTENDS INTO SOUTHCENTRAL...IS BEGINNING
TO GET SQUEEZED BY AMPLIFYING UPPER LEVEL RIDGES. ONE IS ALONG THE
WEST COAST OF NORTH AMERICA AND THE OTHER IN THE BERING SEA.
BY TUESDAY...THE LOW IN THE GULF WILL CUTOFF...AND WILL AMPLIFY
THE WESTERN U.S. RIDGE AXIS INTO ALASKA. THIS FEATURE WILL
INTERACT WITH THE BERING SEA RIDGE...FORMING A STRONG 500 MB HIGH
LATITUDE BLOCK (570+ DM) OVER SOUTHERN ALASKA. ACCOMPANYING THIS
WILL BE WARM TEMPERATURES...SOME OF WHICH MAY APPROACH RECORD
LEVELS. AFTER TUESDAY...VERY DRY AND WARM CONDITIONS LOOK TO
PERSIST OVER SOUTHCENTRAL ALASKA THROUGH THE WEEKEND.
&&

.MODEL DISCUSSION...
THE NUMERICAL MODELS REMAIN IN EXCELLENT AGREEMENT WITH THE LARGE
SCALE PATTERN INTO NEXT WEEKEND...BUT CONTINUE TO STRUGGLING WITH
THE SURFACE LOW ROTATING INTO THE GULF OF ALASKA ON TUESDAY.
HOWEVER...THE SENSIBLE WEATHER IMPACTS ARE LARGELY NEGLIGIBLE. THE
GFS WAS FAVORED THROUGH THE FORECAST PERIOD WITH SOME NAM DETAILS
BEING UTILIZED IN INLAND AREAS.
&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
THE TROUGH THAT STRETCHES FROM KODIAK ISLANDS THROUGH THE NORTH
GULF COAST IS SERVING AS A CATALYST FOR SOME RAIN SHOWERS THIS
AFTERNOON. A FEW OF THESE SHOWERS ARE ALSO DEVELOPING IN A
SOMEWHAT UNSTABLE ATMOSPHERE OVER THE SUSITNA VALLEY AND WESTERN
KENAI PENINSULA AS WELL. THERE HAS BEEN ENOUGH DAYTIME HEATING IN
THESE AREAS TO KICK OFF THE CONVECTION...WHICH WILL RAPIDLY
DIMINISH IN THE EVENING.
TUESDAY WILL DRY OUT AND WARM UP AS HIGH PRESSURE ALOFT BUILDS
IN. A FEW RAIN SHOWERS MAY CLIP THE ALASKA RANGE...BUT MOST
LOCATIONS WILL BE DRY. WEDNESDAY THROUGH FRIDAY WILL PROGRESSIVELY
WARM AS A STOUT UPPER LEVEL RIDGE BUILDS IN. EACH DAY WILL BE WELL
ABOVE AVERAGE...WITH TEMPERATURES FRIDAY POSSIBLY REACHING RECORD
HIGHS ACROSS SOME LOCATIONS. EVEN ANCHORAGE...WHICH NORMALLY SEES
A SEA BREEZE IN THE AFTERNOON...MAY HAVE STRONG ENOUGH NORTHERLY
WINDS TO ALLOW TEMPERATURES TO REACH THE MID TO UPPER 60S...AND
POSSIBLY INTO THE LOWER 70S. THE MAT-SU VALLEY WILL LIKELY SEE
SOME LOCATIONS HIT THE 70 DEGREE MARK.

SOUTHWEST ALASKA...
HIGH PRESSURE OVER THE REGION IS KEEPING CLEAR SKIES OVER A GOOD
PART OF THE INLAND AREAS...BUT ALSO CONTRIBUTING TO DENSE FOG
ALONG THE BERING SEA COAST. NEAR THE ALASKA AND ALEUTIAN RANGES
THERE IS ENOUGH INSTABILITY AND OROGRAPHIC LIFT TO CAUSE A FEW
RAIN SHOWERS THIS AFTERNOON AND EVENING. SOME WILL DRIFT TOWARD
THE LOWER ELEVATION OF THE BRISTOL BAY REGION BUT WILL BE LESS
NUMEROUS THE FARTHER WEST ONE GOES.
A FRONT TRACKING ACROSS THE NORTHERN BERING SEA WILL LIKELY BRING
SOME RAIN TO THE NORTHERN COAST OF THE KUSKOKWIM DELTA TONIGHT AND
SOME CLOUDS FARTHER INLAND TOMORROW...BUT THIS WILL PASS THROUGH
QUICKLY AS IT WEAKENS AND HIGH PRESSURE BUILDS IN EVEN STRONGER
TOMORROW AFTERNOON.

BERING SEA/ALEUTIANS...
THE FRONT THAT IS IN THE NORTHERN BERING SEA WILL CONTINUE TO
WEAKEN AS IT HEADS EASTWARD OVERNIGHT AND HIGH PRESSURE BUILDS IN
BEHIND IT. THIS WILL KEEP WIDESPREAD FOG OVER A GOOD PART OF THE
BERING SEA. THERE IS A MODERATE LOW SOUTHWEST OF ATTU THAT
WILL STRENGTHEN A LITTLE AS IT MOVES INT THE WESTERN BERING SEA
TOMORROW. THE HIGH PRESSURE IN THE EASTERN BERING SEA WILL KEEP
IT IN THE WESTERN BERING AS IT HEADS NORTHWARD. THE WEATHER FRONT
ASSOCIATED WITH THIS LOW THIS WILL BRING RAIN TO THE ALEUTIANS AS
IT MOVES THROUGH THE AREA.

&&

.LONG TERM FORECAST...
THE SECOND HALF OF THE WEEK WILL SEE CLEAR AND DRY CONDITIONS WITH
WELL ABOVE NORMAL TEMPERATURES OVER SOUTH CENTRAL AND SOUTHWEST
ALASKA. THIS WILL INCREASE THE RISK OF FIRE DANGER...ESPECIALLY
SINCE MOST OF THE TREES AND OTHER PLANTS HAVE NOT GONE THROUGH
'GREEN UP' YET. THE BIGGEST QUESTION THIS EQUATION WILL BE HOW
STRONG THE WINDS BECOME. STRONGER NORTHERLY WINDS WILL NOT ONLY
CAUSE HIGHER TEMPERATURES BUT ALSO INCREASE THE RATE OF SPREAD FOR
ANY FIRES THAT DO OCCUR. THAT WILL BE THE BIGGEST ITEM TO WATCH AS
THE WEEK PROGRESSES. &&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 173 175 176 177.
FIRE WEATHER...RED FLAG WARNING 171.
&&

APR 14