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FXAK67 PAJK 220101 AAA
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
322 PM AKDT THU MAY 21 2015

.SHORT TERM...AFTERNOON SATELLITE IMAGE SHOWS A DOMINANT 1026 MB
HIGH PRESSURE RIDGE OVER THE CENTRAL GULF WITH MARINE STRATUS
SLIGHTLY THINNING OUT ACROSS THE OUTER WATERS AND MOVING OFFSHORE
FROM THE PANHANDLE COAST. A WEAK UPPER LEVEL LOW NEAR HYDER PULLS
SOME MID TO HIGH CLOUDS OVER THE NORTHERN AND CENTRAL PANHANDLE.
DAYTIME HEATING OVER BRITISH COLUMBIA ONCE AGAIN TRIGGERS
THUNDERSTORMS. NUMEROUS LIGHTNING STRIKES EAST OF COAST MOUNTAINS
ARE BEING DETECTED. ALONG THE EAST SIDE OF THE HIGH
PRESSURE...GENERAL NORTHWESTERLY WINDS BLOW NEAR SMALL CRAFT LEVEL
OVER CROSS SOUND AND THE OUTSIDE WATERS SOUTH OF CAPE SPENCER WITH
COMBINED SEAS BUILDING TO 8 FEET. NO SIGNIFICANT WINDS ARE OBSERVED
ACROSS THE INNER CHANNELS AND AFTERNOON SEA BREEZES 10 TO 15 MPH
PREVAIL.

MODELS REMAIN IN FAIR AGREEMENT WITH HIGH PRESSURE CONTINUING TO
DOMINATE THE GULF AND A DEVELOPING INVERTED TROUGH OF LOW PRESSURE
OVER SOUTHERN BRITISH COLUMBIA EXTENDING NORTHWESTWARD TO THE
SOUTHERN PANHANDLE BY FRIDAY. REFRESHED THE INHERITED FORECAST WITH
THE NAM12 FOR ITS GOOD INITIALIZATION. THE WEAK UPPER LOW NEAR HYDER
WILL SLOWLY DRIFT SOUTHWARD TO THE EAST OF HAIDA GWAII BY FRIDAY
AFTERNOON AS THE UPPER RIDGE CONTINUES EXPANDING OVER YUKON
TERRITORY.

ISOLATED THUNDERSTORMS WILL CONTINUE THROUGH THE EVENING HOURS
ACROSS BRITISH COLUMBIA AND A FEW OF THEM WILL LIKELY TO MOVE OVER
THE NORTHERN PANHANDLE NEAR THE COAST MOUNTAIN RANGE. THE GENERAL
NORTHWESTERLY LOW LEVEL FLOW WILL WEAKEN THIS EVENING AND EXPECT THE
MARINE STRATUS RETURN TO THE PANHANDLE COAST TONIGHT...EXCEPT
SOUTHERN COASTAL AREAS WHERE SMALL CRAFT LEVEL WINDS DEVELOP BETWEEN
THE PERSISTING HIGH PRESSURE TO THE WEST AND DEVELOPING INVERTED
TROUGH TO THE EAST. NO SIGNIFICANT WINDS ARE EXPECTED ACROSS THE
INNER CHANNELS...BUT THE GENERAL WIND DIRECTION WILL BECOME MORE
NORTHERLY DUE TO THE INVERTED TROUGH. A SPECIAL WEATHER STATEMENT
HAS BEEN POSTED FOR ELEVATED CONCERN OF FIRE DANGER DUE TO CONTINUED
WARM DRY WEATHER ACROSS THE PANHANDLE...EXCEPT THE COASTAL AREAS.

.LONG TERM...MEMORIAL DAY WEEKEND IS STILL LOOKING MOSTLY DRY FOR
THE PANHANDLE AS A LARGE BLOCKING UPPER HIGH CONTINUES TO SIT OVER
WESTERN CANADA. A SURFACE RIDGE OVER THE EASTERN GULF IS ALSO
HELPING KEEP MOST SYSTEMS WELL WEST OF THE AREA. HOWEVER, A WEAK
UPPER LEVEL LOW THAT IS STUCK IN THE WEAK FLOW WILL CONTINUE TO
SIT JUST EAST OF HYDER AND PROVIDE A STARTING POINT FOR AFTERNOON
SHOWERS AND POSSIBLE THUNDERSTORMS ESPECIALLY OVER THE SOUTHERN
PANHANDLE THROUGH THE WEEKEND.

THE ONLY BREAK IN THIS PATTERN APPEARS TO BE ON SUN AND MON AS A
WEAK TROUGH TRIES TO BREAK THROUGH THE SURFACE RIDGE FROM THE
WEST. IT DOES NOT HAVE MUCH SUCCESS IN THAT ENDEAVOR BUT ENOUGH
WILL GET THROUGH TO BRING AT LEAST A CHANCE OF RAIN TO YAKUTAT ON
SUN AND INCREASED CLOUD COVER TO THE REST OF THE PANHANDLE ON SUN
AND MON. AS SUCH DAYTIME HIGH TEMPS WILL BE ABOUT 5 TO 10 DEGREES
COOLER ON SUN AND MON DUE TO THE HIGHER CONCENTRATION OF CLOUDS.
MODEL SOLUTIONS HAVE GOTTEN JUST A BIT WETTER AND CLOUDIER
COMPARED TO THE DRY FORECAST FROM YESTERDAY WITH SUPPORT THIS TIME
FROM SEVERAL MODELS RATHER THEN JUST ONE.

INTO NEXT WEEK, THE SURFACE RIDGE REBUILDS OVER THE GULF AND STAYS
IN PLACE FOR THE REST OF THE LONG RANGE. THE MAIN DIFFERENCE
BETWEEN THIS AND THE PRE-TROUGH PATTERN IS THAT THE UPPER LOW NEAR
HYDER HAS BEEN PUSHED OFF TO THE EAST TAKING ITS VORTICITY WITH IT.
SO CHANCES FOR AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS THE
PANHANDLE ARE LESS NEXT WEEK.

DURING ALL OF THIS, THE MARINE LAYER CLOUDS WILL CONTINUE THEIR
DIURNAL SHIFT INTO AND OUT OF THE OUTER COAST AND INNER CHANNELS. IT
WILL ADVANCE VARYING DISTANCES EACH NIGHT DEPENDING ON THE GENERAL
LOCAL FLOW. FOR INSTANCE, IT WILL NOT ADVANCE VERY FAR INLAND FRI
NIGHT DUE TO WEAK OFFSHORE FLOW BUT SHOULD JUMP INLAND A FAIR
DISTANCE SAT NIGHT AS LOCAL FLOW TURNS MORE ONSHORE RATHER THEN
OFFSHORE.

LONG RANGE MODELS ARE STILL IN RATHER GOOD AGREEMENT THROUGH AT
LEAST MID NEXT WEEK. MAIN CHANGES WERE FOR A LITTLE WETTER TROUGH
COMING THROUGH FOR THE SECOND HALF OF THE MEMORIAL DAY WEEKEND.
MAINLY STAYED WITH NAM FOR FORECAST UPDATES WITH WPC FOR LATER
PERIODS.

&&

.FIRE WEATHER...FIRE FUELS REMAIN EXCEPTIONALLY DRY ACROSS THE
CENTRAL AND NORTHERN INNER CHANNELS. GREATEST FIRE DANGER IS
EXPECTED ON FRI AND SAT AS A WEAK OFFSHORE FLOW WEAKENS SEA
BREEZES SLIGHTLY. HIGH TEMPS ARE EXPECTED TO REACH INTO THE 70S
ACROSS THE CENTRAL AND NORTHERN INNER CHANNELS WITH MIN RH VALUES
GETTING DOWN INTO THE 30 PERCENT RANGE. WINDS ARE NOT EXPECTED TO
BE STRONG WITH 10 TO 20 MPH FROM SEA BREEZE EFFECTS BEING THE MAIN
ISSUE. AS SUCH RED FLAG CONDITIONS ARE NOT EXPECTED AT THIS TIME
BUT ISOLATED BRIEF AREAS OF EXTREME FIRE DANGER CAN NOT BE RULED
OUT, ESPECIALLY ON FRI. CONDITIONS ARE LESS SEVERE ALONG THE OUTER
COAST AND SOUTHERN PANHANDLE AS THE MARINE LAYER HAS BEEN KEEPING
THINGS RATHER COOL AND MOIST. FIRE DANGER IMPROVES INTO THE SECOND
HALF OF THE HOLIDAY WEEKEND AS A WEAK TROUGH BRINGS IN SOME
INCREASED CLOUD COVER FOR MOST OF THE PANHANDLE AND LOW LEVEL FLOW
TURNS MORE ONSHORE. HIGH TEMPERATURES WILL COOL OFF A BIT AS A
RESULT AND INCREASED LOW LEVEL MOISTURE WILL LOWER MIN RH VALUES
INTO SUN AND MON.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ022-033-041>043.

&&

$$

AHN/EAL

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