774 
FXUS65 KBOI 150954
AFDBOI

SOUTHWEST IDAHO/SOUTHEAST OREGON AREA FORECAST DISCUSSION 
NATIONAL WEATHER SERVICE BOISE IDAHO
355 AM MDT THU MAY 15 2003 

COLD FRONT THROUGH BOISE AROUND 2 AM BROUGHT LATE EVENING AND EARLY 
MORNING GUSTY WINDS OF 23-33 MPH TO THE LOWER TREASURE VALLEY 
INCLUDING ONTARIO AND WEISER RIVER/VICINITY. THE FRONT ALSO CHANGED 
THE BOISE-CALDWELL TEMPERATURE DIFFERENCE FROM 7F WARMER AT 1AM...TO 
1F COOLER AT 3AM...INTO THE MID 50S AT 3 AM.  ASSOCIATED UPPER 
TROUGH SEEN ON SATELLITE OFF THE OREGON-WA COAST SHOWS ABUNDANT COLD 
AIR CU WITH TROUGH...AND A POSSIBLE VORT NEAR 48N 138W SLIDING 
NEARLY DUE EAST ABOUT 40 KTS.  SATELLITE TRENDS AND RUC SHIFT TROF 
AND VORT EAST WITH BEST MOISTURE FOR SHOWERS ONLY CLIPPING NRN 
ZONES...WHILE THE SURFACE OBS AND FORECAST CHARTS SHOW PRESSURE RISE 
CENTER OVER OREGON WITH RUC BUILDING SFC HIGH PRES OVER SW IDAHO BY 
NOON. COLD AIR ADVECTION COMBINED WITH TIGHTENING SFC PRES GRADIENT 
AND WINDS ALIGNED WITH SNAKE RIVER VALLEY MEAN GREAT MIXING 
AFTERNOON WINDS GUSTING TO AROUND 30 MPH FOR SE OREGON/GREATER WINDS 
ALOFT/ AND 20-25 MPH FOR SW IDAHO. ISOLATED SHOWERS EXPECTED TO 
REMAIN NORTH OF BOISE WITH UPPER TROF PASSAGE.

FOR TONIGHT...THE VORT SLIDES EAST ACROSS THE N ID PANHANDLE 
LIMITING SHOWER POTENTIAL TO FAR N ZONES BEFORE MIDNIGHT AS COOL 
MARINE HIGH PRESSURE BUILDS THRU ID FOR BREEZY WEST WINDS GRADUALLY 
DIMINISHING AFTER SUNSET. DRY WESTERLY FLOW AT THE SURFACE AND ALOFT 
CONTINUES FRIDAY WITH MOISTURE LIMITED TO N ID. COOLING TREND 
CONTINUES WHILE /GOOD/ AFTERNOON MIXING IS AGAIN EXPECTED FOR 
LOCALLY BREEZY SURFACE FLOW AGAIN FRIDAY AFTERNOON. 

ON SATURDAY THE NEXT DISTURBANCE IN THE WESTERLY FLOW BRINGS A 
LITTLE MOISTURE TO NORTHERN ZONES...GIVES A SLIGHT COOL DOWN AND 
ENHANCES THE SFC WESTERLY WINDS FOR A BREEZY TO LOCALLY WINDY 
AFTERNOON.  ON SUNDAY A STRONGER DISTURBANCE CROSSES THE AREA FOR A 
WINDY AFTERNOON AGAIN AND A FEW SHOWERS ACROSS NORTHERN ZONES. THIS 
IS THE COOLEST DAY AS THE UPPER TROF DIGS IN THROUGH THE END OF THE 
WEEK AND WEEKEND.  THE COLD AIR IN PLACE COMBINES WITH CLEARING FOR 
MONDAY MORNING. THE TRACK OF THE SURFACE HIGH IS CURRENTLY FORECAST 
NORTH OF BOISE FOR EASTERLY SFC WINDS...LIMITING FREEZE POTENTIAL 
ALTHOUGH FROST IS POSSIBLE ACROSS THE SHELTERED COLDEST SPOTS OF THE 
VALLEY.

DRY UPPER RIDGE EXPECTED TUESDAY THROUGH THURSDAY WITH HIGHS FINALLY 
BACK ABOVE NORMAL FOR THE MIDDLE OF THE WORKWEEK.

.BOI...NONE.

$$
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VM