Area Forecast Discussion
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FXAK67 PAJK 031226
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
426 AM AKDT FRI JUL 3 2015

.SHORT TERM...HIGH PRESSURE CONTINUES TO BUILD OVER THE AK GULF
AND EXTEND OVER THE PANHANDLE WITH REMNANTS OF PREVIOUS DAYS LOW
CURRENTLY OVER THE YUKON. SOME LINGERING ISOLATED TO SCATTERED
SHOWERS FOR THE NORTHERN AND CENTRAL PANHANDLE FROM LAST BANDS
MOVING AROUND THE YUKON LOW WITH 500 MB VORT MAX CROSSING OVER THE
AREA. WESTERLY MID LEVEL FLOW MAY KEEP SOME CLOUD COVER FROM AK
GULF MOVING OVER THE PANHANDLE BUT EXPECTING CLEARING SKIES WITH
SUBSIDENCE ON LEE SIDE OF RIDGE. HAVE SOME PATCHY FOG IN OVER THE
CENTRAL PANHANDLE DUE TO LINGERING MOISTURE FROM OVERNIGHT PRECIP
AND POTENTIAL CLEARING SKIES. KEPT FOG OUT OF THE SOUTHERN REGIONS
AS THEY HAVE HAD A LONGER TIME TO DRY OUT. WINDS GENERALLY LESS
THAN 20 KT THIS MORNING AND WILL BECOME LIGHT AS PRESSURE
GRADIENT WEAKENS INTO FRI NIGHT. THE EXCEPTION IS N LYNN CANAL
WITH STRONGER GRADIENT BETWEEN THE GULF/PANHANDLE RIDGE AND THE
YUKON HIGH PRODUCING SMALL CRAFT WINDS INTO THE EARLY EVENING
BEFORE THE GRADIENT COLLAPSES. DAY TIME HIGHS WILL GET INTO THE
MID TO UPPER 60S TODAY DEPENDING ON THE AMOUNT OF CLEARING THE AREA
RECEIVES, WARMEST OVER THE SOUTHERN PANHANDLE. RIVER LEVELS THAT
ROSE IN RESPONSE TO YESTERDAYS RAINFALL HAVE CRESTED AND ARE
QUICKLY DROPPING.

MODELS STILL IN FAIR AGREEMENT. UPDATED WINDS WITH A BLEND OF
NAM/ECMWF. OVERALL NOT MUCH CHANGE TO INHERITED GRIDS. MAIN ISSUE
WITH WINDS WAS DETERMINING IF DIRECTIONS WOULD BE MORE FROM THE
GEOSTROPHIC FLOW AROUND THE GULF RIDGE OR MORE FORCED BY THE
PRESSURE GRADIENT. FORECAST CONFIDENCE IS ABOVE AVERAGE DUE TO
GOOD MODEL CONSISTENCY AND AGREEMENT WITH ANY UNCERTAINTY LIMITED
TO LOW IMPACT FIELDS.

.LONG TERM...MODELS REMAIN IN GENERAL AGREEMENT THROUGH THE
WEEKEND WITH AN UPPER LEVEL RIDGE BUILDS ACROSS THE GULF AND
PANHANDLE. SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE
GULF AND PANHANDLE WITH AN INVERTED TROUGH OF LOW PRESSURE
DEVELOPS OVER VANCOUVER ISLAND. THE INVERTED TROUGH WILL EXTEND TO
THE SOUTHERN PANHANDLE ON SUNDAY. REFRESHED THE INHERITED FORECAST
THROUGH LATE SUNDAY EVENING WITH THE NAM AND ECMWF FOR THEIR GOOD
CONSENSUS. A PLENTY OF SUNSHINE AND DRY WARM WEATHER WILL CONTINUE
ACROSS SOUTHEAST ALASKA THROUGH EARLY NEXT WEEK. THE UPPER LEVEL
RIDGE WILL WEAKEN BY MID WEEK AS AN UPPER LOW NEAR ALASKA
PENINSULA PUSHES A TROUGH EASTWARD INTO THE WESTERN AND CENTRAL
GULF...THEN THE TROUGH FINALLY MOVES OVER THE CENTRAL AND EASTERN
GULF...THEN POSSIBLY TO THE NORTHERN PANHANDLE BY THURSDAY. MODEL
DIFFERENCES BECOME LARGER AND USED THE WPC ENSEMBLE GUIDANCE FOR
NEXT WEEK TO DRAW PREDICTABLE FEATURES FOR THE NORTHERN GULF COAST
AND ACROSS THE NORTHERN HALF OF THE PANHANDLE WITH INCREASING
CLOUDS BY LATE WEDNESDAY AND SLIGHT RAIN CHANCES ON THURSDAY ONWARD.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012.

&&

$$

PRB/AHN

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