Small Craft Advisory 102, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
301 PM AKST SUN FEB 5 2012

.SHORT TERM...A LOW PRESSURE SYSTEM CURRENTLY WEST OF DIXON
ENTRANCE IS BRINGING SCATTERED LIGHT SHOWERS TO THE SOUTHERN
PANHANDLE. THIS LOW WILL WEAKEN AS IT SLOWLY MOVES TO THE NNW
TONIGHT. THIS WILL CAUSE THE SHOWERS TO ALSO MOVE NORTH...HOWEVER
THE OFFSHORE FLOW AHEAD OF THE SYSTEM WILL KEEP THE AREA DRY
LONGER AND MAINLY SEEING CLOUDS WITH THE FRONT.

 AN AREA OF STRONG WINDS NEAR THE LOW CENTER WILL CAUSE GALE
FORCE WINDS OVER THE SOUTHERN OUTSIDE WATERS TONIGHT. A SAR PASS
OVER THE LOW THIS MORNING CLEARLY SHOWED WINDS OF 35 TO 40KT.
THESE WINDS WILL ALSO IMPACT THE LAND AREAS ALONG THE SOUTHERN
OUTER COAST THIS EVENING. HAVE CONTINUED THE STRONG WIND HEADLINE
FOR THE HYDABURG/KLAWOCK AREAS WHERE GUSTS OF 40MPH ARE POSSIBLE.
THE METLAKATLA AND SITKA AREAS WILL ALSO SEE SOME GUSTY WINDS
THIS EVENING OF ABOUT 30 TO 35MPH.

 QPF AMOUNTS WITH THIS SYSTEM ARE VERY LIGHT WITH HIGHEST AMOUNTS
ALONG THE OUTER COAST. NORTHERN AREAS WILL BE COLD ENOUGH TONIGHT
FOR THE ISOLATED SHOWERS TO MIX WITH SNOW...HOWEVER WITH LITTLE
TO KNOW ACCUMULATION.

 MODELS CONTINUE TO DIFFER ON LOW PLACEMENT AND SPEED. THE NAM
WAS THE FASTEST AND DETERMINED AN OUTLIER. THE GFS AND ECMWF CAME
MORE IN LINE WITH EACH OTHER TODAY AND WERE USED FOR MOST UPDATES.
FORECASTER CONFIDENCE IS AVERAGE.

 &&

 .LONG TERM...MID LEVEL HIGH PRESSURE BLOCKING RIDGE WILL REMAIN
OVER THE WESTERN US AND CANADA WITH QUASI STATIONARY MID LEVELS
LOWS OVER HUDSON BAY AND KAMCHATKA PENINSULA THROUGH THE WEEK. A
SERIES OF LOW PRESSURE SYSTEMS WILL ROTATE AROUND THE KAMCHATKA
LOW MOVING INTO THE AK GULF THROUGH THE WEEK.

 FOR THE START OF THE LONG RANGE FAIRLY QUITE WEATHER AS THE
MONDAY LOW AND ASSOCIATED FRONT LIFT NORTH EXITING THE REGION.
SURFACE HIGH PRESSURE OVER THE YUKON WITH NEXT LOW PRESSURE
SYSTEM MOVING INTO THE SOUTHWESTERN GULF WILL KEEP A SOUTHWEST TO
NORTHEAST PRESSURE GRADIENT PRODUCING EASTERLY OUTFLOW WINDS,
STRONGEST OUT OF INTERIOR PASSES AND CHANNELED TERRAIN. AS THE
LOW IS TO THE WEST OF THE REGION NOT EXPECTING THE OUTFLOW WINDS
TO BE EXCEPTIONALLY STRONG. THE FRONT ASSOCIATED WITH THE LOW
WILL TRACK NORTHWARD OVER THE AK GULF AND PANHANDLE WEDNESDAY
INTO WEDNESDAY NIGHT. FRONT SHOULD BE FAIRLY WEAK SO NOT
EXPECTING ANY SIGNIFICANT PRECIP. DETAILS OF SURFACE FEATURES
BECOME UNCERTAIN BY WED WITH ISSUES ON TIMING AN LOCATION OF THE
WESTERN LOW AND REGARDING LOW DEVELOPMENT ALONG THE FRONT. FOR
THURSDAY INTO THE WEEKEND THE NEXT LOWS DETAILS ARE STILL
SKETCHY. SEEING LARGE DIFFERENCES WITH THE LOCATION AND STRENGTH
OF THIS LOW SO KEEPING UNCERTAINTY WORDING IN THE FORECAST.
850 MB TEMPS FOR TUE ARE AROUND 3C WITH A SLIGHT COOL DOWN THU
WITH 850 MB TEMPS DROPPING TO AROUND -3C.THIS FLUCTUATION WILL
CONTINUE THROUGH THE WEEK SO NO LONG COLD SPELLS BUT WILL SEE A
MIX OF RAIN AND SNOW OVER THE CENTRAL AND NORTHERN REGIONS,
ESPECIALLY OVERNIGHT.

 MODELS WERE IN GOOD AGREEMENT AT THE START OF THE LONG TERM. RUN
TO RUN CONSISTENCY FOR THE GFS STILL SEEMS THE BEST, HOWEVER THE
EC PERFORMANCE HAS IMPROVED. 12Z EC BEGAN TO SLOW DOWN THE
WESTERN GULF LOW. UKMET FELL MORE IN LINE THE THE 12Z ECMWF. GFS
BECOMES MORE OF AN OUTLIER BY 18Z WED SHOWING TRIPLE POINT LOW
DEVELOPMENT ALONG THE FRONTAL BOUNDARY. FOR THE THURSDAY LOW THE
GFS IS MUCH DEEPER, 970 MB, AND FURTHER WEST THAN THE ECMWF,
995 MB. UPDATED GRIDS WITH 12Z GFS TO DAY 3 THEN TRANSITIONED TO
12Z EC THEN TO HPC GUID FOR THE REMAINDER OF THE LONG RANGE
FORECAST. OVERALL CHANGES ARE MINOR WITH SOME DECREASE IN WINDS
MONDAY NIGHT AS PRESSURE GRADIENT IS A BIT WEAKER. FORECAST
CONFIDENCE IS ABOUT AVERAGE FOR THE START OF THE LONG TERM BUT
DROPS SIGNIFICANTLY BY WEDNESDAY AS MODEL SPREAD INCREASED.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 6 PM AKST THIS EVENING FOR AKZ027.
MARINE...GALE WARNING FOR PKZ041>043.
         SMALL CRAFT ADVISORY FOR PKZ012-013-021-022-031>036-051-052.

&&

HANNON/PRB