Small Craft Advisory 404, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
1251 PM AKDT SAT AUG 23 2008

.SHORT TERM...LIGHT RAIN AND DRIZZLE CONTINUE ACROSS MOST OF THE
SOUTHEAST ALASKA THIS MORNING IN BETWEEN A WEAKENING LOW IN THE
NORTH CENTRAL GULF AND A NEWLY ORGANIZING LOW IN THE SOUTH
EASTERN GULF. JUST AHEAD OF THE NEW FRONT THAT STRETCHES
SOUTHWARD FROM SOUTHERN PANHANDLE COAST...RAIN INTENSITY BECOMES
A BIT STRONGER. THE FRONT HAS ITS TRIPLE POINT RIGHT OVER THE
QUEEN CHARLOTTE ISLANDS AS OF THIS WRITING. PRESSURE GRADIENT HAS
RELAXED ACROSS THE FORECAST AREA AS OF THIS TRANSITION TIME.

 MODELS ARE IN GENERAL AGREEMENT WITH THE INCOMING LOW FROM THE
SOUTH. THE NAM HAS SHOWN A BETTER TREND OVER THE PAST COUPLE OF
DAYS AND WILL BE USED PRIMARILY FOR THE AFTERNOON PACKAGE. THE
GFS HAS A LITTLE MORE EASTWARD TREND WITH THE LOW FOR LATE
TONIGHT AND SUNDAY...WHILE THE NAM KEEPS THE LOW DRIFTING
NORTHWARD ALONG THE PANHANDLE COAST. THE LOW WILL DEEPEN TO
991 MB NEAR SITKA BY LATE TONIGHT OR EARLY SUNDAY MORNING AND
CONTINUE TO MOVE NORTH INTO SOUTHERN YUKON BY SUNDAY
AFTERNOON...IN WHICH TIME A RIDGE OF HIGH PRESSURE BUILDS FROM
THE SOUTHEAST. THE LOW WILL BECOME A RESIDUAL OVER SOUTHWEST
CORNER OF YUKON TERRITORY AND THE BUILDING RIDGE WILL INCREASE
THE PRESSURE GRADIENT ACROSS THE ALASKA PANHANDLE THROUGH SUNDAY
EVENING. AS THE LOW DEEPENS NEAR SITKA LATE TONIGHT INTO EARLY
SUNDAY MORNING...THE MOISTURE CHANNEL WILL CONTINUE TO INTENSIFY.
WILL GO WITH LIKELY TO CATEGORICAL POPS BUT WORDING SHOULD BE
LIGHT RAIN AND/OR DRIZZLE. THE ONLY SIGNIFICANT WIND SHOULD BE
CONFINED OVER THE SOUTHERN MOST INSIDE WATERS TONIGHT THROUGH
SUNDAY MORNING. OTHERWISE...WINDS FOR MOST ZONES SHOULD BE IN
15 TO 20 MPH RANGE.

.LONG TERM...PLANETARY SCALE CIRCULATION INCLUDES A 500H LOW
OVER NRN GREENLAND.  A TROUGH ALF EXTENDS ALONG A CLOSE TO STRAIGHT
LINE TO OVER SEWARD AND SSW OVR THE NPAC.  THIS TROUGH WILL SLOWLY
RETROGRADE THIS WEEK, BUT WHAT MATTERS MOST IS THAT THE LARGE SCALE
SW FLOW TOWARD OUR FCST DOMAIN WILL PERSIST WITH LITTLE CHANGE.

THE FLOW OVER THE ENTIRE GLFALSK HAS BEEN CYCLONIC DUE TO A PARENT
LOW ALOFT ABT 400 NM S OF SEWARD.  THIS LOW WILL BE EJECTED NE OUT
OF OUR AREA MONDAY, AND THE MODEL CONSENSUS FOR THIS IS GOOD.  MODEL
CONSENSUS, AS WELL AS CONFIDENCE IN THE FCST PKG RAPIDLY DECREASES
BGNG ABOUT 00Z WED.  SEE NEXT PARA.

THE SPREAD OUT BETWEEN THE GFS AND THE ECMWF BECOMES LARGE BGNG ABT
00Z ON WED 27TH.  THE NCEP MSLP NORMALIZED ENSEMBLE SPREAD ALSO
RAPIDLY INCREASES AT ABT THE SAME TIME.  COORDINATION WITH THE
ANCHORAGE FO HAS ENCOURAGED THE ECMWF SOLN FOR NOW, BUT A MODEL
RESOLUTION FOR WED ONWARD IS STILL SOUGHT.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ036.

SJA JBT