Flooding in Alaska, October 3 to 10, 2003

SOUTH/SOUTHWEST ALASKA FORECAST DISCUSSION
900 PM ADT FRI OCT 3 2003

.DISCUSSION...
ANALYSIS - THE HUGE STRONG UPPER RIDGE THAT WAS ALONG THE U.S. WEST
COAST HAS MOVED EAST TO THE U.S. AND CANADIAN ROCKIES AS PART OF A
REALLY UNBALANCED 4-WAVE HEMISPHERIC PATTERN. THE ANCHOR UPPER LOW IS
OVER THE CENTRAL RUSSIAN ARCTIC. THE NEARBY MAJOR UPPER LOW IS
COMPLEX WITH THE MAIN CENTER NEAR SAINT LAWRENCE ISLAND WITH A SECOND
CENTER NEAR 49/174W OVER A 982 MB SURFACE LOW THAT WAS ONCE TYPHOON
KOPPU. A LOW OVER THE CENTRAL INTERIOR AT 990 MB WAS OVER THE EASTERN
GULF LAST NIGHT. THERE ARE EIGHT SURFACE LOWS OVER THE NORTHERN
PACIFIC AND GULF - TOO MANY. 500 MB TEMPS IN THIS SYSTEM ARE AROUND
-30C NEAR THE CENTER. SOUTHERLY FLOW ALOFT IS OVER THE EASTERN HALF
OF THE STATE WITH THE HEAVY RAIN EAST OF PACV AND LOTS IN THE SUSITNA
VALLEY AND SURROUNDING MOUNTAINS. THE FREEZING LEVEL HAS DROPPED TO
4-5000 FEET FOR MOST AREAS. AT 250 MB A VERY STRONG JET IS OVER JAPAN
THEN WEST ALONG 39-43N TO AN EXIT NEAR 43/158W WHERE A COUPLE OF THE
SURFACE LOWS AWAIT THE OPPORTUNITY TO LINE UP IN THE UPPER LEFT HAND
QUAD. A NEGATIVELY TILTED UPPER TROUGH IS JUST SOUTHWEST OF THE GULF
TO SUPPORT ANY ONE OF THESE MINOR SYSTEMS.

FORECASTS - WELL, WHICH SURFACE LOW SO WE SEE AS THE DEVELOPER??
REGARDLESS OF WHICH ON THE WHOLE COMPLEX CONSOLIDATES INTO THE 970S
BY 00Z SUN AROUND 50/155W AS THE SUPPORTING UPPER LOW DEEPENS. THIS
IS AIDED BY THE JET EXTENDING EASTWARD WITH THE SURFACE LOW IN THE
UPPER LEFT QUAD. BY 12Z SUN ALL MODELS REVIEWED SO FAR AGREE THAT THE
LOW WILL TRACK TO 53/153W WITH AN AVERAGE DEPTH OF 972 MB WITH
MODERATE TO STRONG SURFACE PRESSURE GRADIENTS OVER MOST OF OUR HUGE
FORECAST AREA. SEVERAL WARM ADVECTION BANDS WILL BE MOVING OVER THE
GULF FROM THIS SYSTEM BUT WITHOUT OUR PREVIOUS TROPICAL FETCH. LOOK
FOR A VERY MATURE VERTICALLY STACKED SYSTEM IN THE 970S JUST OFF
KODIAK ISLAND. RAIN FORECASTS WILL BE TRICKY ESPECIALLY IN COOK INLET
DUE TO THE SOUTHEASTERLY FLOW ALOFT. THE MESO-ETA INSISTS THAT COOK
INLET WILL LOSE THE RAIN SHADOW SUN NIGHT FOR MORE WET FUN.

.AFC...WATCH/WARNING SUMMARY
PUBLIC...FLOOD WATCH YENTNA 145. FLOOD ADVISORY 101 125.
MARINE...GALE 2B 5AB 12B 13.
FIRE WEATHER...NONE.

JC OCT 03