Gale Warning 514, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 AM AKDT MON JUL 27 2009

.ANALYSIS AND UPPER LEVELS...
IN THE UPPER LEVELS A PERSISTENT CLOSED LOW CONTINUES TO SPIN NEAR
THE CENTRAL ALEUTIANS...AFFECTING ALL OF WESTERN AND PART OF
SOUTHCENTRAL ALASKA. TO THE EAST A PRONOUNCED RIDGE EXTENDS FROM THE
EASTERN ALASKA INTERIOR INTO THE NORTHWESTERN CONUS.

AT THE SURFACE...THE LARGE UPPER LEVEL LOW HAS MANIFESTED ITSELF AS A
SERIES OF CLOSED LOWS. SEVERAL OF THESE LOWS ARE LOCATED ACROSS THE
BERING...WITH ONE RETROGRADING INTO EASTERN RUSSIA...TWO MORE LOCATED
IN THE NORTHERN PACIFIC...AND ONE APPROACHING THE ALASKA
PENINSULA.THE CLOSEST LOW WILL IMPACT WESTERN ALASKA TODAY...WITH THE
LOWS IN THE PACIFIC MOVING IN MID-WEEK. CONTRASTING THESE SYSTEMS IS
A RIDGE ACROSS THE PANHANDLE...WHICH SHOULD ACT TO LIMIT THE EASTERN
PROGRESSION OF THESE LOWS AS THEY APPROACH THE MAINLAND.

.MODEL DISCUSSION...
MODELS HAVE HAD A DIFFICULT TIME ASSESSING HOW THESE INDIVIDUAL LOWS
WILL REACT WITH THE LARGE RIDGE TO EAST. THE NEWEST RUNS OF BOTH THE
GFS AND THE EUROPEAN TAKE THE INCOMING LOW FURTHER INLAND THAN
YESTERDAYS RUN...AS WELL AS MAKE THE LOW STRONGER. PREVIOUS FORECAST
USED PRIMARILY ECMWF GUIDANCE...AND WILL STICK WITH THAT THINKING FOR
THIS FORECAST AS WELL.

MODELS ARE HAVING A VERY DIFFICULT TIME RESOLVING THE STRENGTH AND
EXACT POSITION OF EACH LOW AS THEY APPROACH THE MAINLAND...SO EVEN
WITH A BLEND OF GUIDANCE...CONFIDENCE IS NOT VERY HIGH.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...
SHORT TERM ATTENTION IS ON THE SERIES OF LOWS FORECASTED TO IMPACT
THE REGION. TODAY THE FIRST LOW WILL MOVE ONTO THE ALASKA PENINSULA
AND WEAKEN...BRINGING WITH IT RAIN TO SOUTHWESTERN AND PARTS OF
SOUTHCENTRAL ALASKA. CURRENT THINKING IS THAT PRECIP WILL EXTEND
ACROSS PRINCE WILLIAM SOUND AND MAY IMPACT ANCHORAGE
ITSELF...ALTHOUGH TOTALS IN THE BOWL ARE NOT EXPECTED TO BE
AS HEAVY AS THE SYSTEM LAST WEEK. A TIGHTENING PRESSURE GRADIENT
BETWEEN THE RIDGE TO THE EAST AND THE LOW TO THE WEST WILL RESULT IN
SOME GUSTY WINDS...ESPECIALLY AROUND HIGHER TERRAIN AND TURNAGAIN
ARM.

.HYDROLOGY...
ACROSS THE KENAI PENINSULA RIVERS CONTINUE TO RUN HIGH. ALTHOUGH
EXCESSIVE RAINFALL IS NOT EXPECTED...WITH RIVERS NEAR ACTION STAGE
ANY ENHANCED PRECIP WILL NEED TO BE MONITORED CLOSELY. A FLOOD WATCH
CONTINUES FOR THE KENAI PENINSULA FOR THIS REASON. IN ADDITION TO THE
FLOOD WATCH...A FLOOD ADVISORY HAS BEEN POSTED FOR THE SKILAK GLACIAL
DAM OUTBURST. CONDITIONS WILL CONTINUE TO BE MONITORED...PLEASE SEE
LATEST FLOOD PRODUCTS FOR MORE INFORMATION.

.SOUTHWESTERN...
RAIN WILL BE PREDOMINANT THROUGH THE FIRST PART OF THE WEEK AS
SEVERAL DISTURBANCES MOVE ON SHORE. THE FIRST LOW WILL MOVE ACROSS
THE ALASKA PENINSULA TODAY...WITH ANOTHER APPROACHING BY 00Z
WEDNESDAY. WIDESPREAD GUSTY WINDS WILL ALSO OCCUR WITH THESE
SYSTEMS...CREATING HAZARDOUS CONDITIONS FOR SMALL CRAFT.

.BERING AND ALEUTIANS...
UNSETTLED WEATHER WILL ALSO OCCUR ACROSS THE ALEUTIANS FOR AT LEAST
THE FIRST HALF OF THE WORK WEEK. AS THE ABOVE MENTIONED LOWS MOVE
TOWARDS MAINLAND ALASKA THEY WILL INTERACT WITH THE
ALEUTIANS...BRINGING RAIN...COOL TEMPERATURES...AND GUSTY WINDS.
WINDS MAY GUST TO GALE FORCE AS EACH OF THESE LOWS
APPROACH...PRIMARILY ACROSS THE CENTRAL AND EASTERN ALEUTIANS.

.LONG TERM FORECAST...
MODELS ARE HAVING A DIFFICULT TIME IN SHORT TERM...SO CONFIDENCE IS
LOW IN LONG TERM. AT CURRENT TIME MODELS ARE FORECASTING THE RIDGE TO
HOLD THROUGH THE WORK WEEK AS SEVERAL LOWS ROTATE THROUGH THE BERING.
DIFFERENCES ARISE ON THE EXACT PLACEMENT AND STRENGTH OF THESE
INDIVIDUAL LOWS...BUT UNSETTLED WEATHER LOOKS LIKELY FOR WESTERN
ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FLOOD WATCH 121 125...FLOOD ADVISORY 121
MARINE...GALE WARNING 130 132 138 150
FIRE WEATHER...NONE

TARALDSEN JUL 09