Severe Thunderstorm Warning 2, NWS Boise, ID

SOUTHWEST IDAHO/SOUTHEAST OREGON AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE IDAHO
300 PM MDT TUE MAY 16 2000

SPLIT UPPER FLOW PATTERN OVER WESTERN NORTH AMERICA NEXT COUPLE DAYS
WITH H5 RIDGE AXIS WESTERN CANADA AND CLOSED H5 LOW CENTER NORTHEAST
NV SLOWLY TRUDGING EAST WED. CWFA MORE UNDER INFLUENCE OF SOUTHERN
STORM TRACK AND NV LOW CENTER TONIGHT/WED MORNING BEFORE INFLUENCE
SHIFTS TO NORTHERN TRACK WED NIGHT/THU. AFTERNOON SATELLITE AND AREA
RADAR IMAGERY SHOWING SPIRALING VORT BANDS EXTENDING FROM LOW CENTER
MOVING OVER CWFA. AT 20Z 1 VORT BAND SOUTHEAST ORE...2ND AND
STRONGER VORT SPOKE SOUTHWEST MT TO NORTH CENTRAL NV WHILE POSSIBLY
3RD VORT SPOKE FORMING NORTHERN UT. AIR MASS SOUTHEAST ORE/SOUTHERN
ID QUITE UNSTABLE AS PER GOES SOUNDER/LIGHTNING CHARTS...THOUGH
STORM SPOTTERS MAGIC VALLEY REPORTED JUST SMALL HAIL AND SOME RAIN
WITH BAND OF CONVECTION WHICH MOVED THROUGH THAT AREA AROUND 19Z.
THESE SOUTHWEST ROTATING VORT SPOKES TO CONTINUE SHOWERS/
THUNDERSTORMS OVER CWFA THIS EVENING CONTINUING AFTER MIDNIGHT
EASTERN ZONES AS H5 LOW CENTER DRIFTS EAST INTO NORTHERN UT AND EAST
OF REGION WED. SOME RESIDUAL SHOWERS EARLY WED MORNING BEFORE DRIER
AIR MASS SOUTHEAST ORE ZONES SHIFTS EAST INTO SOUTHWEST ID ZONES.
ASSOCIATED SURFACE LOW CENTER MAGIC VALLEY SLOWLY SHIFTS EAST WED
WITH STRONG PRESSURE GRADIENT/H85-H7 NORTHERLY WINDS FOR BREEZY/
WINDY CONDITIONS TONIGHT/WED FROM BKE-BOI WITH SLIGHTLY LESS WINDS
MAGIC VALLEY. WED 140W H5 TROUGH MOVES THROUGH WESTERN CANADA
AFFECTING NORTHERN HALF OF ID WEAKENING OVER CWFA FOR JUST SOME
CLOUDS. WED NIGHT/THU WEAKENING TROUGH CONTINUES MOVING EAST OF
REGION WITH WEAK SURFACE HIGH PRESSURE BUILDING OVER CWFA FOR SLOW
WARMING.

FLAT/DIRTY RIDGING CONTINUES OVER PACIFIC NORTHWEST FRI/SAT AS PER
EXTENDED MODELS CONTINUING DRY/SLOW WARMING TREND. MODELS DIVERGE
GREATLY BEGINNING SUN WITH MOST MODELS KEEPING SOME RIDGING OVER
REGION WHILE ECMWF DEVELOPS TROUGH. PER COORDINATION WITH
SURROUNDING OFFICES WILL KEEP DRY FORECAST IN PLACE OVER CWFA WITH
AFFECTS OF S/WVS MOVING THROUGH NORTHERN FLOW BRANCH AFFECTING
NORTHERN ID.  BUT CON)FIDENCE IS LOW WITH VARYING MODEL SOLUTIONS.
PARKER

.BOI...NONE.