Area Forecast Discussion
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FXAK67 PAJK 131325
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
525 AM AKDT SUN JUL 13 2014

.SHORT TERM...A FRONT REMAINS STALLED OVER THE EASTERN GULF AND
EXTENDS NORTH DIAGONALLY ACROSS THE NORTHERN HALF OF THE
PANHANDLE. THE SUB-TROPICAL MOISTURE CONNECTION REMAINS CLEAR AND
COMPLETE AS INDICATED ON AMSU IMAGERY, BUT PRECIPITABLE WATER
VALUES ARE MUCH DIMINISHED FROM YESTERDAY. A WEAK WAVE WILL TRACK
NORTH ALONG THE FRONTAL BOUNDARY AND KEEP RAIN GOING OVER MOST OF
THE SAME AREAS AS YESTERDAY BUT RAINFALL AMOUNTS WILL BE LESS
TODAY AND THEN DIMINISH LATE SUNDAY NIGHT. THE SURFACE RIDGE THAT
HAS PREVENTED THE FRONT FROM MOVING EAST IS ALL BUT GONE AS OF
THIS MORNING, BUT HIGH PRESSURE IS ALREADY BUILDING IN OVER THE
CENTRAL GULF FROM THE SOUTH AND THE SYNOPTIC PATTERN WILL CHANGE
EARLY ON IN THE EXTENDED RANGE FORECAST PERIOD.

&&

.AVIATION...LOW CEILINGS, AREAS OF FOG, AND RESTRICTED
VISIBILITIES WILL IMPACT AVIATION OPERATIONS ONCE AGAIN TODAY
OVER A MAJORITY OF THE PANHANDLE. THE ONLY AREAS THAT ARE NOT
EXPECTED TO BE TROUBLE SPOTS TODAY ARE PETERSBURG, WRANGELL, AND
KETCHIKAN. LOW CLOUDS AND FOG OVER PRINCE OF WALES EARLY THIS
MORNING SHOULD DISSIPATE LATER THIS MORNING. WINDS ALOFT FAIRLY
LIGHT, SO NO TURBULENCE IS EXPECTED IN CLOUD OR ON TOP.

&&

.HYDROLOGY...THE STALLED FRONT HAS RESULTED IN MINOR FLOODING ON
THE TAIYA RIVER NEAR SKAGWAY. A FLOOD ADVISORY REMAINS IN EFFECT
THROUGH MID MORNING WITH THE WATER LEVEL FAIRLY STABLE BETWEEN
16.6 AND 16.7 FEET. BASED ON EXPECTED RAINFALL TODAY, IT IS
LIKELY THAT THE FLOOD ADVISORY WILL HAVE TO BE EXTENDED, BUT A
SIGNIFICANT INCREASE IN THE WATER LEVEL ABOVE WHERE IT IS RIGHT
NOW DOES NOT SEEM AS LIKELY.

&&

 USED A BLEND OF ECMWF AND GEM FOR UPDATES TO PRESSURE AND WIND.
POP AND QPF FROM GEM. TEMPS ADJUSTED PER GFS MOS. FORECAST
CONFIDENCE IS AVERAGE.

&&

.LONG TERM...MODELS REMAIN IN FAIR AGREEMENT THROUGH LATE TUESDAY
FOR THE ALL LEVEL HIGH PRESSURE BUILDS ACROSS THE GULF AS THE
VERTICALLY STACKED LOW WEAKENS AND REMAINS SOUTH OF THE ALEUTIANS.
THE REMNANTS OF THE DISSIPATING FRONTAL PASSAGE CONNECTED TO A
LONG FETCH OF SUBTROPICAL MOISTURE BAND TO THE SOUTH WILL
GRADUALLY TAPER OFF PRECIPITATION TO A CHANCE POP ACROSS THE
NORTHERN HALF OF THE PANHANDLE AND ALONG THE PANHANDLE COASTAL
SECTIONS . EXPECT NO SIGNIFICANT WINDS/SEAS. REFRESHED THE
INHERITED FORECAST PACKAGE WITH THE ECMWF AND GEM FOR THEIR GOOD
CONSENSUS AND CONSISTENCY THROUGH TUESDAY EVENING.

 SYNOPTIC PATTERNS REMAIN THE SAME FOR THE EXTENDED PERIODS WITH
MODEL SPREADS CONTINUALLY MAINTAIN CERTAIN LEVEL OF UNCERTAINTY
FOR THE SECOND HALF OF THE WEEK. MAINTAINED THE WPC ENSEMBLE
SOLUTIONS TO SUPPORT GENERALLY DRY WEATHER ACROSS SOUTHEAST ALASKA
THROUGH THURSDAY WITH POTENTIAL FORMATION OF MARINE STRATUS. A
DEVELOPING LOW IN THE FAR WESTERN GULF WILL TRACK NORTHEASTWARD TO
THE NORTHERN GULF TOWARDS THE WEEKEND. THE RIDGE OF HIGH PRESSURE
WILL CONSEQUENTLY ERODE AND OPEN A DOOR FOR THE INCOMING FRONT.
THE FRONT WILL MOVE INTO THE EASTERN GULF ON THURSDAY NIGHT...THEN
MOVE ONSHORE OVER THE PANHANDLE ON FRIDAY.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...AREAL FLOOD ADVISORY UNTIL 9 AM AKDT THIS MORNING FOR AKZ018.
MARINE...NONE.

&&

$$

FRITSCH/AHN





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