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FXAK67 PAJK 232347
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
347 PM AKDT WED JUL 23 2014

.SHORT TERM...AFTERNOON SATELLITE IMAGE SHOWS A WEAK DEVELOPING
LOW EAST OF KODIAK ISLAND MOVES OVER THE NORTHERN GULF WITH ITS
ASSOCIATED WEAK OCCLUDED FRONT STRETCHING SOUTHEASTWARD ACROSS
THE EASTERN GULF. RAIN STARTED EARLY THIS MORNING OVER THE
NORTHEASTERN GULF COAST...INCLUDING YAKUTAT. A TRIPLE POINT
DEVELOPS ALONG THE SOUTHERN PART OF THE FRONTAL BOUNDARY AND
MOVES TOWARD HAIDA GWAII. AROUND THE LOW IN THE NORTHERN
GULF...PREVAILING SOUTHEAST WIND 15 TO 20 KNOTS REPORTED BY BUOY
46082.

 A WEAK RIDGE OF HIGH PRESSURE REMAINS OVER THE PANHANDLE AND
PRODUCES SMALL CRAFT LEVEL SOUTHERLY WINDS ACROSS NORTHERN LYNN
CANAL AND 15 TO 25 MPH SOUTHWEST WIND OVER SKAGWAY AREA. MOSTLY
SUNNY SKIES OVER THE SOUTHERN AREAS MAINTAINS DAYTIME
TEMPERATURES SOARING UP TO THE MID 60S. AHEAD OF THE INCOMING
FRONTAL PASSAGE...WEBCAM IMAGES SHOW GRADUAL INCREASE OF CLOUDS
THIS AFTERNOON ACROSS THE NORTHERN/CENTRAL PANHANDLE AND ALONG
THE PANHANDLE COASTAL AREAS. A PLENTY OF SUNSHINE CONTINUES OVER
THE SOUTHERN ZONES...BUT EXPECT INCREASING CLOUDS OVERNIGHT INTO
THURSDAY MORNING. CATEGORICAL POPS ACROSS THE NORTHEASTERN GULF
COAST TONIGHT WILL GRADUALLY DECREASE TO LIKELY POPS BY EARLY
THURSDAY. THE RAIN BAND WILL CONTINUE TO WEAKEN AS IT MOVES OVER
THE PANHANDLE THURSDAY AND PRODUCE CHANCE TO LIKELY POPS. NO
SIGNIFICANT QPF VALUES ARE DERIVED FROM MODEL OUTPUTS.

 MODELS REMAIN IN FAIR AGREEMENT FOR THE WEAKENING OCCLUDED FRONT
IN THE EASTERN GULF THIS EVENING DISSIPATES LATE TONIGHT AS IT
MOVES ONSHORE OVER THE PANHANDLE. USED A BLEND OF THE ECMWF AND
NAM FOR THEIR GOOD CONSENSUS THROUGH THURSDAY. A STRONGER FRONTAL
PASSAGE IS EXPECTED TO MOVE INTO THE EASTERN GULF LATE THURSDAY.
THE LOW IN THE NORTHERN GULF WILL SLOWLY DRIFT SOUTH TONIGHT THEN
MOVE EAST A LITTLE ON THURSDAY. THE RIDGE OF HIGH PRESSURE OVER
THE PANHANDLE WILL MOVE BACK AND FORTH IN RESPONSE TO THE LOW IN
THE GULF. SOUTHERLY SMALL CRAFT LEVEL WINDS ARE EXPECTED AGAIN
OVER NORTHERN LYNN CANAL BY LATE THURSDAY AFTERNOON.

.LONG TERM...LARGESCALE LOW OVER THE GULF WILL NEAR THE PANHANDLE
FROM THE WEST THURSDAY NIGHT. AFTER STUDYING SOME SOUNDINGS, THIS
COLD POOL ALOFT SHOULD INCREASE THE INSTABILITY ENOUGH FOR
PRECIPITATION TO BE MORE SHOWERY IN NATURE, SO KEPT THIS IDEA FROM
THE PREVIOUS ISSUANCE. PRECIPITATION SHOULD BECOME MORE PRE-
FRONTAL STRATIFORM FOR FRIDAY AS TEMPERATURES ALOFT WARM A TOUCH.
COOLED TEMPERATURES MAINLY BACK INTO THE 50S FOR FRIDAY SINCE RAIN
WILL TEND TO COOL TEMPERATURES AT THE SURFACE. COOLED TEMPS FOR
THE WEEKEND AS WELL, BUT COULD HAVE GONE COOLER AFTER BOOSTING
POPS TO CATEGORICAL FOR THE WEEKEND.

THIS WILL BE THE DEVELOPING STORY FOR THE WEEKEND. AS UPPER LOW
ENTRENCHES SOUTHWARD OVER THE GULF, THE TRAJECTORY OF SUBTROPICAL
MOISTURE WILL AIM NORTHEASTWARD TOWARD THE PANHANDLE. AT THIS
POINT, NOT GOING HEAVY FOR ANY SPOTS, BUT AS NOTED IN THE
HYDROLOGY PORTION OF THE DISCUSSION, TWO MODELS ARE SUGGESTING THE
POSSIBILITY. POPS WERE PUSHED TO CATEGORICAL FOR MOST ALL THE
PANHANDLE...ALTHOUGH WE DID DECREASE THEM A BIT FOR YAKUTAT. SOME
SOUTHEAST FLOW AT TIMES WHEN THE LOW OFFSHORE WILL TILT MORE
NEGATIVELY MAY KEEP AMOUNTS OF RAIN DOWN FOR NORTHERN INTERIOR
ZONES SUCH AS JUNEAU, BUT FEEL FAIRLY CONFIDENT THAT EVEN THESE
AREAS WILL BE WET. WHAT IS A LITTLE CONCERNING IS THAT SOUTHERLY
FLOW LOOKING MORE LIKE IT WILL PERSIST INTO NEXT WEEK, AND THAT
WILL KEEP RAIN CHANCES ON THE HIGH SIDE...SO FELT THE PREVIOUS
FORECAST WAS GOOD.

WINDS WILL BE GENERALLY ON THE LOWER SIDE...MAY GET A LITTLE
BREEZY ON FRIDAY ON PRINCE OF WALES AS FRONT PUSHES INTO THE
PANHANDLE. CLARENCE STRAIT/CROSS SOUND FROM THE SE AND E
RESPECTIVELY...SHOULD REACH 20 KT WITH THIS FRONT. THERE IS SOME
UNCERTAINTY IN THE MID-RANGE...WITH HOW THE MODELS SHORTWAVES
ROTATING AROUND THE MAIN UPPER LOW, BUT ALL TENDED TOWARDS A
SLOWER PROGRESSION OF THE ONE ROTATING NORTHWESTWARD FOR THE
WEEKEND, SO RESERVED THE BULK OF CHANGES FOR FRI NIGHT THROUGH
SUN.

PATTERN SO STABLE IN THE LONG-TERM THAT WPC LEANED HEAVILY ON 00Z
WED ECMWF THROUGH DAY 7...BUT THIS MADE LITTLE DIFFERENCE TO OUR
CURRENT FORECAST, SO NO REAL CHANGE TO EXTENDED FORECAST. ECMWF
USED FOR CHANGES DURING THE WEEKEND.

&&

.HYDROLOGY...AS UPPER LEVEL TROUGH DIGS SOUTHWARD OVER THE GULF TO
TAP SUBTROPICAL MOISTURE, AND THE WEEKEND`S SOUTHERLY FLOW
POSSIBLY LASTS THROUGH EARLY NEXT WEEK, RAINFALL AMOUNTS OVER THE
CWA WILL INCREASE, AND AT LEAST THE GEM AND THE GFS ARE
POTENTIALLY FLAGGING SOME BOUTS OF HEAVY RAIN OVER PARTS OF THE
PANHANDLE. MORE FOCUS WILL BE DIRECTED AT THE CHILKAT...THE
TAIYA...AND THE ALSEK RIVERS AS WEEKEND NEARS. BEST GUESS FOR NOW
IS THAT THESE RISES DO NOT OCCUR UNTIL SUNDAY AT LEAST.

&&

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


$$

AHN/JWA










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