Small Craft Advisory 382, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM ADT WED MAY 4 2005

.DISCUSSION...

THE MAJOR REORIENTATION OF LARGE SCALE 500 MB FEATURES CONTINUES. THE
HIGH THAT PREVIOUSLY DOMINATED THE BERING AND EASTERN SIBERIA
CONTINUES TO SHIFT WEST. THE MAJOR LOW THAT CROSSED THE DATELINE
SOUTH OF THE ALEUTIANS YESTERDAY HAS SLOWED AND CONTINUES TO DEEPEN.
AND FLOW OVER INTERIOR ALASKA HAS CHANGED FROM EASTERLY TO
SOUTHWESTERLY AS A DEEP COLD LOW DROPS SOUTH OUT OF THE ARCTIC AND
INTO THE BERING STRAITS. A STRONG NORTH TO SOUTH JET IS CARRYING VERY
COLD AIR SOUTHWARD ACROSS EASTERN SIBERIA...INTO THE WESTERN
BERING...AND AROUND THE WEST SIDE OF THE LOW IN THE NORTH PACIFIC.

GFS UKMET AND NAM MODELS IN GOOD AGREEMENT UNTIL ABOUT 05/06Z.
FOLLOWING THIS ITS DIFFICULT TO DECIDE WHICH OF THE THREE DIVERGENT
SOLUTIONS IS BEST. THE CAUSE OF THE DIVERGENCE IS SOMEWHAT EASIER TO
DETERMINE HOWEVER...AND ORIGINATES WITH AN IMPULSE ROUNDING THE
ARCTIC NEAR 70N 178E AT 05/06Z. THE TWO GLOBAL MODELS HAVE THIS
IMPULSE STRONGER AND SLOWER THAN THE NAM. BY 05/18Z THE TWO GLOBAL
MODELS DIG A NEW LOW OUT OF THE BASE OF THE RIDGE IN CENTRAL SIBERIA
WHILE THE NAM DROPS ITS WEAKER VERSION OF THE IMPULSE DOWN THE
STRAITS...RIGHT BEHIND THE LOW CURRENTLY IN THE BERING STRAITS. THIS
DIFFERENCE IN TURN RESULTS IN A GROWING DIFFERENCE IN HOW THE MODELS
DUMBBELL THE NEW LOW AROUND THE MAJOR LOW SOUTH OF THE
ALEUTIANS...AND IN HOW THEY HANDLE THE LOW CURRENTLY IN THE STRAITS.

NONE OF THIS MAKES MUCH OF A DIFFERENCE IN THE EASTERN DOMAIN THROUGH
DAY THREE...BUT FOR THE BERING SEA AND ALEUTIANS...THE TWO GLOBAL
MODELS MORE CLOSELY RESEMBLE EACH OTHER THAN ANY COMPARISON INVOLVING
THE NAM. THEREFORE FOR NOW THE GFS SEEMS THE SAFEST CHOICE IN THE
BERING BEYOND 30 HRS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FLOOD WARNINGS FOR MCGRATH AND ANIAK...ZONE 151.
         ICE JAM FLOOD WATCH FOR UPPER AND LOWER KALSKAG...ZONE 151.
MARINE...GALES 3B 3C 5A 5B 6A 6B 8 12A 12B 13A 14 GULF OF ALASKA
         BERING SEA
FIRE WEATHER...NONE.

STKM APR 05