Small Craft Advisory 192, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
350 PM AKST MON FEB 24 2014

.SHORT TERM...AFTERNOON SATELLITE LOOP REVEALS A PERSISTING HIGH
PRESSURE AREA OVER NORTHWESTERN CANADA AND A DISSIPATING SURFACE
TROUGH ACROSS THE GULF. ALONG THE TRAILING EDGE OF THE
DISSIPATING TROUGH...SOME BROKEN LAYER OF MID CLOUDS SLOWLY YIELD
TO A FREQUENT SUNNY BREAKS OVER THE SOUTHERN PANHANDLE. MODERATE
TO STRONG NORTHEASTERLY PRESSURE GRADIENT CONTINUES TO PRODUCE
GUSTY OFFSHORE WINDS OUT OF INTERIOR PASSES AND ACROSS THE
NORTHERN INNER CHANNELS. INCREASING INSOLATION HAS CAUSED WEAK
SEA BREEZES FOR IMMEDIATE COASTAL LOCATIONS AND TEMPERATURES SOAR
UP TO THE UPPER 30S TO AROUND 40...EXCEPT WIND SHELTERED AREAS
WHERE DAYTIME HIGHS REMAIN IN THE LOWER TO MID 30S.

 MODELS REMAIN IN FAIR AGREEMENT WITH THE STRONG HIGH PRESSURE
AREA OVER BRITISH COLUMBIA CONTINUES TO PRODUCE OFFSHORE FLOW
ACROSS SOUTHEAST ALASKA WITH GENERALLY DRY WEATHER TONIGHT
THROUGH TUESDAY. REFRESHED THE INHERITED FORECAST PACKAGE WITH
THE NAM AND MADE A FEW FINE TUNES FOR WIND AND TEMPERATURE
FIELDS. A WEAK FRONTAL PASSAGE WILL MOVE NORTHWESTWARD ACROSS THE
CENTRAL AND EASTERN GULF ON TUESDAY NIGHT. AHEAD OF THE INCOMING
FRONT...CLOUDS WILL SLIGHTLY INCREASE TUESDAY AFTERNOON OVER THE
SOUTHWESTERN PANHANDLE FROM THE SOUTH.

 OFFSHORE LOW LEVEL FLOW WILL LIKELY TO DECREASE A LITTLE THIS
EVENING INTO EARLY TONIGHT DUE TO A SLIGHT WEAKENING OF THE HIGH
PRESSURE OVER BRITISH COLUMBIA. THE HIGH PRESSURE...HOWEVER...WILL
SHIFT A LITTLE TO THE SOUTH AND STRENGTHEN AGAIN ON TUESDAY. THIS
WILL LIKELY TO INCREASE OFFSHORE WINDS AGAIN ACROSS THE SOUTHERN
AREAS. POSTED STRONG WIND HEADLINE FOR SOUTHEASTERN PANHANDLE OUT
OF INTERIOR PASSES FROM LATE TONIGHT THROUGH TUESDAY MORNING.
DIURNAL TEMPERATURES FLUCTUATION WILL REMAIN LARGE DUE TO
RADIATION COOLING AT NIGHT AND INCREASING INSOLATION DURING THE
DAY.

.LONG TERM...LARGESCALE HIGH PRESSURE RIDGE OVER SOUTHEAST WILL
CONTINUE THROUGH THE MID-RANGE...AND LIKELY THROUGH MUCH OF THE
LONG-RANGE AS WELL. THIS PATTERN WILL BE CHARACTERIZED BY WEAK
FRONTS SKIRTING THE EASTERN GULF AND THE SOUTHEAST COAST...THE
FIRST TUESDAY NIGHT. ADDED A SLIGHT CHANCE OF RAIN FOR 28/27/23
ZONES FOR TUESDAY NIGHT. CONCERNED THAT EC AND GFS BOTH PUMPING
SOME MOISTURE AT 700 MB ACROSS THE INTERIOR PANHANDLE, BUT SINCE
MOS GUIDANCE STILL GOING PARTLY CLOUDY WITH THE EXCEPTION OF THE
VERY CLOUDY AND A LOT WETTER NAM, STILL CLINGING TO PARTLY CLOUDY
SKIES, BUT BE FOREWARNED. INTERESTINGLY, TEMPERATURES ARE RISING
GREATLY IN THE MODEL OUTPUT STATISTICS...ENOUGH TO WONDER WHETHER
THERE IS A DISCONNECT IN THE CLOUD COVER. BUT PLENTY OF WARM AIR
ADVECTION IS BEING ADVERTISED BY THE MODELS AS WELL. IN FACT,
SITKA AND POINTS SOUTH COULD PUSH 50 BY WEDNESDAY, AND POSSIBLY
AGAIN ON THURSDAY. THUS FAR NOT GOING THAT OPTIMISTIC, BUT THE
TREND IS THERE. DID WARM TEMPERATURES IN GENERAL THROUGH THIS
WEEK, LESS SO INTO THE WEEKEND. EAGLE CREST COULD HAVE SOME NICE
ALMOST SPRING-LIKE SKIING THE NEXT COUPLE OF DAYS. PROBABLY NOT
GREAT FOR STABILITY OF SLOPES THOUGH...WITH SNOW LEVELS RISING UP
THERE. TEMPERATURES WILL BE BELOW FREEZING THOUGH WED MORNING AND
THU MORNING...MAINLY DUE TO SURFACE INVERSIONS.

WITH SUCH AN OUTFLOW PATTERN, WINDS WILL STILL BE A CONCERN. IT
NOW APPEARS THAT WEDNESDAY WILL BE WHEN THE TIGHTER GRADIENTS SET
UP ALONG THE PANHANDLE, AT LEAST FOCUSED WELL ENOUGH TO SEE. SO
INCLUDED GUSTS TO 45 MPH IN SKAGWAY AND GALE IN LYNN CANAL. GIVEN
PARALLEL FLOW IN THE EXTENDED RANGE, WENT MORE CONSERVATIVE ON THE
WINDS THROUGH DAY SEVEN. WENT WITH AN EAST WIND THROUGH CLARENCE
THROUGH MUCH OF THE MID-RANGE. IN REALITY, THESE WINDS WILL BE
BLOWING MAINLY FROM THE NORTHEAST OUT OF THE GAPS...BUT THE
GRADIENT NOT SUPER STRONG HERE, SO FELT THAT EAST MAY BE HAPPY
MEDIUM.

ECMWF USED FOR MAIN GUIDANCE, BUT PATTERN REMAINS VERY SIMILAR.
CONFIDENCE IN LARGESCALE PATTERN GOOD. PATTERN ON DETAILS AVERAGE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM MIDNIGHT AKST TONIGHT THROUGH TUESDAY MORNING
     FOR AKZ029.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-021-022-031-034>036-041-042-
     052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ043-051.

&&

AHN/JWA