Area Forecast Discussion
Issued by NWS

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FXAK67 PAJK 021334 CCA
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE JUNEAU AK
534 AM AKDT MON MAY 2 2016

.SHORT TERM...THE LOW IN THE NORTHEAST GULF THAT HAS TRAVELED UP
THE COAST WILL SHORTLY JUMP ASHORE NEAR CAPE FAIRWEATHER. AS A
RESULT WINDS ACROSS THE CENTRAL PANHANDLE ARE SHIFTING TO A BREEZY
SOUTH FROM A LIGHTER NORTH. A RIDGE BUILDS BEHIND THE SYSTEM AS IT
MOVES INTO CANADA AND THUS PRESSURE RISES ACROSS THE PANHANDLE AND
PRESSURE FALLS IN THE CANADIAN YUKON WILL YIELD STRONG WINDS
THROUGH SKAGWAY AND 30 KT SOUTHERLIES THROUGH LYNN CANAL. IN
ADDITION, WE EXPECT WESTERLIES TO BLOW INTO CROSS SOUND AND ICY
STRAIT LATER THIS MORNING. THESE WILL BEGIN DIMINISHING LATE
AFTERNOON AND RAPIDLY INTO THE EVENING AS GRADIENTS SLACKEN AND THE
RIDGE BROADENS.

MODERATE RAIN BANDS HAVE BEEN SOLID FROM THE CENTRAL PANHANDLE
NORTHWARD ALL NIGHT LONG WITH SOME OF THE MOST IMPRESSIVE TOTALS
COMING IN THE DRIEST PORTIONS OF SOUTHEAST ALASKA: HAINES AND
SKAGWAY WHERE 12 HOUR TOTALS HAVE BEEN AROUND 1 INCH. SOUTH OF
JUNEAU AND GUSTAVUS ALL THE WAY TO PRINCE OF WALES ISLAND...12
HOUR AMOUNTS HAVE BEEN SIMILAR WITH AROUND 1 INCH. KETCHIKAN AND
METLAKATLA CEASED RAINING YESTERDAY EVENING, PERHAPS DRY-SLOTTING
TO THE EAST OF THE STALLED FRONT. THIS FRONT OF WHICH WE SPEAK
HAS BEEN POSITIONED ACROSS SOUTHEAST ALASKA FOR THE LAST TWO DAYS
NOW. AND UNFORTUNATELY IT WILL MAKE LITTLE PROGRESS OUT OF OUR
REGION TONIGHT AS THE NORTH-SOUTH 300 MB JET REFUSES TO GIVE IT
ANY MOMENTUM EASTWARD. THUS THE SOUTHERN PANHANDLE WILL STILL
EXPERIENCE RAIN, ALTHOUGH MUCH LIGHTER THAN THE LAST COUPLE OF
DAYS DUE TO THE WEAKENING FRONT. TO THE NORTH, RAIN WILL CONTINUE
TO FALL HEAVY AT TIMES THROUGH MUCH OF THE MORNING FOLLOWING THE
LOW AS IT LIFTS ONSHORE. SCATTERED SHOWER ACTIVITY WILL PERSIST
ACROSS THE NORTHEAST GULF COAST INTO TONIGHT.

WITH CLEARER SKIES, SATURATED CONDITIONS, AND LIGHT WINDS THIS
MORNING THROUGH MISTY FJORDS, WE MADE A LATE UPDATE TO ADD SOME
AREAS OF FOG. THERE MAY BE SOME BREAKS TONIGHT IN THE CLOUD
COVER, AND WITH EXTREME SATURATION OF THE GROUND, THERE IS SOME
RISK OF PATCHY FOG TONIGHT, BUT IMPACTS SHOULD BE MINIMAL. IT
SHOULD BE A TYPICAL MISTY EARLY MORNING UNDER CLOUDY SKIES AFTER
RECENT RAINS: THE KIND OF MORNING THAT ROUTINELY PROVIDES
DELIGHTFUL VIGNETTES FOR PHOTOGRAPHERS, ARTISTS, AND ANYONE ELSE
WHO APPRECIATES OUR BEAUTIFUL AND WET CORNER OF THE WORLD.

FEW CHANGES WERE MADE TO THE FORECAST. THE GREATEST CHALLENGE WAS
HANDLING THE TIMING OF THE WIND SHIFTS ACROSS THE NORTH.

.LONG TERM...A RIDGE OF HIGH PRESSURE WILL RESIDE OVER THE
PANHANDLE AT THE BEGINNING OF THE EXTENDED RANGE ON TUESDAY. THIS
RIDGE WILL PERSIST INTO THURSDAY BEFORE WEAKENING AND SHIFTING EAST
IN RESPONSE TO A LOW PRESSURE SYSTEM AND ASSOCIATED FRONT MOVING
INTO THE GULF. THE RIDGE WILL ACT TO DECREASE PRECIPITATION CHANCES
ACROSS THE PANHANDLE THROUGH THURSDAY. HOWEVER CONTINUED ONSHORE
FLOW AND WEAK IMPULSES WILL KEEP ISOLATED TO SCATTERED SHOWERS IN
THE FORECAST. WINDS WILL BE ON THE LIGHTER SIDE WITH MUCH OF THE
AREA UNDER A WEAK SURFACE PRESSURE GRADIENT. THE EXCEPTION WILL BE
ACROSS THE NORTHERN INNER CHANNELS AND SKAGWAY WHERE SOUTHERLY
WINDS WILL BE ENHANCED DUE TO THE PRESSURE GRADIENT BETWEEN THE
RIDGE AND A WEAK THERMAL LOW IN THE YUKON.

MODELS INDICATE A POTENT SYSTEM WILL EJECT INTO THE CENTRAL GULF
THURSDAY INTO FRIDAY UNDER A 150 KT SOUTHWESTERLY UPPER LEVEL JET.
WHILE THERE ARE SOME TIMING AND STRUCTURE DIFFERENCES AT THE
SURFACE BETWEEN MODELS, GENERAL CONSENSUS IS THE ASSOCIATED FRONT
WILL BEGIN TO IMPACT THE PANHANDLE THURSDAY NIGHT AND INTO FRIDAY.
ENSEMBLE STANDARDIZED ANOMALIES INDICATE THIS SYSTEM WILL LIKELY
PRODUCE ANOTHER ROUND OF MODERATE TO HEAVY RAIN AS PRECIPITABLE
WATER VALUES ARE PROGGED TO BE 3-4 STANDARD DEVIATIONS ABOVE NORMAL
FOR THIS TIME OF YEAR. AT THIS POINT IT ALSO LOOKS LIKE THE
PANHANDLE CAN EXPECT ANOTHER PERIOD OF GUSTY WINDS WITH THIS
SYSTEM.

USED THE 06Z NAM/00Z GFS FOR UPDATES TO THE INHERITED FORECAST.

&&

.HYDROLOGY...SIGNIFICANT RISES WERE RECORDED BY GAUGES ACROSS THE
SOUTH, BUT THESE SHOULD BEGIN TO CREST SOON. NORTHERN STREAMS
BEGAN TO RISE MORE SHARPLY AFTER MIDNIGHT AND WILL CONTINUE INTO
TODAY. HOWEVER, NO FLOOD ISSUES ARE EXPECTED.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM 10 AM THIS MORNING TO 4 PM AKDT THIS AFTERNOON
     FOR AKZ018.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-021-022-031>036-041>043.
     SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ051>053.
&&

$$

JWA/TPS

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