Area Forecast Discussion
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FXAK67 PAJK 131450
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
550 AM AKST SAT FEB 13 2016

.SHORT TERM...SHOWERS ARE CLEARING TO THE NORTH AND ANOTHER FRONT
IS FAST APPROACHING FROM THE SOUTHWEST. THE LEADING EDGE OF THE
CLOUD SHIELD HAS BECOME QUITE RAGGED THROUGH THE NIGHT,
COMPLICATING THE ESTIMATION OF THE ARRIVAL OF RAIN ON THE OUTER
COAST. EARLY MORNING RADAR IMAGERY IS STILL INDICATING SHOWERS OFF
THE OUTER COAST, BUT STRATIFORM PRECIPITATION LOOKS LIKE IT WILL
REACH THE PANHANDLE WELL BEFORE THIS EVENING. CATEGORICAL POPS
WILL MOVE IN OVER ALL OF SOUTHEAST EXCEPT POSSIBLY SKAGWAY AND
HYDER BY LATE TONIGHT, IF NOT SOONER.

IN TERMS OF WIND, THIS FRONT IS EXPECTED TO BE A LITTLE LESS
INTENSE THAN YESTERDAY`S FRONT. HAVE ONLY SMALL CRAFT ADVISORIES
FOR THE EASTERN GULF COASTAL MARINE ZONES AND MARGINAL SMALL CRAFT
WINDS LATE FOR FREDERICK SOUND EAST OF CAPE FANSHAW AND CLARENCE
STRAIT. SEA STATE IN THE EASTERN GULF STILL QUITE HIGH, HOWEVER,
WITH CURRENT SEAS 8 TO 10 FEET AND FORECAST TO BUILD 2 TO 3 FEET
OVER THE SHORT TERM. WEAKENING 850 MB WINDS AS THE FRONT MOVES
OVER LAND SUGGESTING WIND SHEAR NOT NECESSARY FOR TAFS THROUGH THE
SHORT TERM.

MODELS ARE STILL NOT DEALING WELL WITH ABNORMALLY HIGH TEMPERATURES
AT THE SURFACE. BASED ON RECENT PERFORMANCE, OPTED TO USE BIAS
CORRECTED MOS FOR TODAY`S HIGHS AND BIAS CORRECTED SREF FOR
TONIGHT`S LOWS. AS IT IS, TEMPERATURE GRIDS STILL NEEDED TO BE
RAISED PRIOR TO THE MORNING FORECAST ISSUANCE TO KEEP UP WITH WARM
OVERNIGHT TEMPS THAT NEVER COOLED DOWN. IN GENERAL TERMS, LOOK FOR
HIGHS TODAY TO BE SIMILAR TO YESTERDAY OR PERHAPS A FEW DEGREES
COOLER. SATURDAY NIGHT`S LOW SIMILAR TO FRIDAY NIGHT`S WITH A FEW
EXCEPTIONS. SPECIFICALLY, THE JUNEAU AREA AND THE FAR NORTHERN
INNER CHANNELS. HAVE SOME ACCUMULATING SNOW IN THE OVERNIGHT
FORECAST FOR THE MENDENHALL VALLEY AS WELL AS HAINES, SKAGWAY, AND
THE ASSOCIATED HIGHWAYS. THOUGH WE MIGHT COOL DOWN LOW ENOUGH FOR
SOME SNOW IN THE MENDENHALL VALLEY FRIDAY NIGHT BUT WITH LOWS
ONLY DOWN TO 40, THAT DIDN`T COME CLOSE TO HAPPENING. HAVE LOW
CONFIDENCE IN OVERNIGHT LOWS FOR THESE 3 LOCATIONS, SO SNOW IS
CERTAINLY NOT A SLAM DUNK. CONFIDENCE IS MUCH HIGHER IN HIGH POPS,
THOUGH. SO DEFINITELY RAIN IF NOT SNOW SATURDAY NIGHT FOR THE
VALLEY AND POINTS NORTH ALONG THE LYNN CANAL CORRIDOR.

USED A BLEND OF ECMWF AND THE CANADIAN NH FOR UPDATES TO
PRESSURE, WIND, POP, AND QPF. CONFIDENCE IN POP AND WIND ABOVE
AVERAGE, CONFIDENCE IN OVERNIGHT LOWS AND PRECIP TYPE OVERNIGHT
FOR THE NORTHERN INNER CHANNELS IS BELOW AVERAGE.

.LONG TERM...THE OVERALL UPPER LEVEL PATTERN FOR THE LONG RANGE
HAS NOT CHANGED ALL THAT MUCH FROM YESTERDAY. STILL LOOKING AT A
RIDGE OVER THE WEST COAST WITH A TROUGH OVER THE ALEUTIANS ISLANDS
THROUGH EARLY NEXT WEEK. MODELS ARE STILL SUGGESTING THAT A RATHER
VIGOROUS SHORT WAVE TROUGH WILL CAUSE A SLIGHT CHANGE IN THIS
OVERALL PATTERN BY MID WEEK AS IT FLATTENS THE WEST COAST RIDGE.
RESULT IS LIGHT UPPER LEVEL FLOW OVER THE PANHANDLE LATE WEEK WITH
SOME COOLER AIR FILTERING INTO THE PANHANDLE.

AT THE SURFACE, MODELS ARE STILL STRUGGLING WITH DETAILS,
PARTICULARLY WITH THE LOW EXPECTED IN THE SE GULF ON TUE. GFS IS
STILL THE FARTHEST WEST WHILE THE ECMWF, AND GEM ARE BRINGING THE
LOW RIGHT UP TO THE SOUTHERN OUTER COAST BY TUE AFTERNOON BEFORE
STALLING AND WEAKENING IT. THE CLOSE AGREEMENT BETWEEN THE GEM
AND ECMWF AS WELL AS SOME ENSEMBLE SUPPORT FOR THAT SOLUTIONS
PROMPTED HEADING MORE TOWARD THE ECMWF AND GEM FOR MID RANGE
UPDATES. THE RESULTS ARE A WET AND BREEZY MID WEEK PERIOD FOR THE
SOUTHERN PANHANDLE WHILE THE NORTHERN PANHANDLE MAY SEE SOME
DRYING AND POSSIBLY SOME COOLER AIR AS EASTERLY DOWNSLOPING FLOW
TAKES OVER.

FARTHER OUT, MODEL AGREEMENT BECOMES WORSE AS THEY STRUGGLE WITH A
A NEW TROUGH COMING OUT OF THE BERING LATE WEEK. DECIDED TO STAY
THE COURSE FOR THE EXTENDED PERIOD WITH ENSEMBLE MEANS AND WPC
DATA.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ034-036-041>043-051-052.
&&

$$

FRITSCH/EAL

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