Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 172040
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
240 PM MDT WED SEP 17 2014

.SHORT TERM...AFTERNOON TEMPS ARE APPROACHING FORECAST HIGHS DESPITE
EXTENSIVE HIGH CLOUDINESS FROM UPPER TROUGH OFF THE OREGON COAST. A
LOW HAS FORMED IN THE TROUGH NEAR 39/130 WHICH WILL HELP SPLIT THE
TROUGH AS IT MOVES INLAND THURSDAY.  THE LOW ITSELF WILL GO DOWN THE
CALIF COAST THU AND FRI WHILE THE NORTHERN PORTION OF THE TROUGH
SHEARS EAST INTO MONTANA...LEAVING OUR CWA IN THE COL BETWEEN THEM.
WEAK SURFACE COLD FRONT WILL PRODUCE A SLIGHT CHANCE OF SHOWERS IN
OUR OREGON ZONES LATE TONIGHT AND IN IDAHO ZONES THURSDAY.  MAIN
INSTABILITY FOR THUNDERSTORMS WILL BE IN ERN-MOST IDAHO ZONES
TONIGHT AND THURSDAY BUT INSTABILITY AND VERTICAL SHEAR WILL LIMIT
MENTION TO ONLY A SLIGHT CHANCE.  HOWEVER A BETTER CHANCE WILL EXIST
IN SRN TWIN FALLS COUNTY AND SERN OWYHEE COUNTY THURSDAY AFTERNOON
AND EVENING WHERE MOISTURE MAY BE ENTRAINED FROM WEAKENING TROPICAL
STORM ODILE IN ARIZONA.  MODELS HAVE SURPRISINGLY LITTLE INSTABILITY
ON OUR NRN BORDER THURSDAY EVEN THOUGH THE UPPER TROUGH WILL BE
NEARBY.  DRYING FROM THE WEST LATE THURSDAY NIGHT AND FRIDAY.  TEMPS
WILL BE ABOVE NORMAL AGAIN TONIGHT DUE TO CLOUD COVER.  MAX TEMPS
THURSDAY WILL COOL 8-10 DEGREES FROM TODAY WITH A FEW DEGREES
FURTHER COOLING OF BOTH MIN AND MAX TEMPS FRIDAY.

.LONG TERM...
FRIDAY EVENING THROUGH SUNDAY...EXPECT SOUTHEAST OREGON AND
SOUTHWEST IDAHO TO BE DRY AND MILD. HIGHS WILL RUN AROUND 5 ABOVE
NORMAL. SKIES SHOULD BE MOSTLY CLEAR OR SUNNY. THIS IS DUE TO AN
UPPER LEVEL RIDGE CURRENTLY ABOUT 2000 MILES WSW OF BOISE...THAT
BUILDS NORTHEASTWARD LATE THIS WEEK ACROSS THE PACNW AND EVENTUALLY
SPREADS TO INTERIOR SW CANADA AS WELL FOR THE WEEKEND. THIS LEAVES
OUR AREA OPEN TO INFLUENCE /MOISTURE INSTABILITY AND LIFT/ FROM THE
UPPER LOW MEANDERING FROM OUR W TO S IN THE SHORT TERM. PREFER A
GEFS/EC/GFS BLEND. SO THE LOW NOW IS EXPECTED TO LIFT NNE TO THE NV-
ID BORDER SUNDAY MORNING AND ACROSS SW- TO S-CENTRAL IDAHO SUNDAY
THROUGH MONDAY RESPECTIVELY WITH SCATTERED MAINLY MOUNTAIN SHOWERS
AND ISOLATED THUNDERSTORMS. THEN THROUGH WEDNESDAY...TEMPERATURES
WILL CONTINUE TO BE ABOUT 5-7 DEGREES ABOVE NORMAL AND A SLIGHT
CHANCE OF PRECIPITATION WILL LINGER IN THE WEST CENTRAL MOUNTAINS
FROM THE CUTOFF LOW. MODELS AGREE THAT A TROUGH COMING OUT OF THE
NE PACIFIC WILL MOVE IN BY WEDNESDAY EVENING BRINGING AROUND A HALF
AN INCH OF PRECIPITATION TO MUCH OF SE OREGON/WEST CENTRAL MOUNTAINS/
BOISE MOUNTAINS. COOLER TEMPERATURES WILL ACCOMPANY THE ASSOCIATED
FRONT...BRINGING US TO JUST A FEW DEGREES ABOVE NORMAL.

&&

.AVIATION... DETERIORATING CONDITIONS AFTER 09Z BUT STILL MOSTLY
VFR. VFR HIGH CLOUDS THIS EVENING EXCEPT IN THE IDAHO MOUNTAINS.
IDAHO MOUNTAINS WILL HAVE BKN MID CLOUDS WITH ISOLATED THUNDERSTORMS.
THURSDAY OVER IDAHO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
MAINLY IN THE MOUNTAINS WITH AREAS OF MTN PEAKS OBSCURED WITH
OREGON AND IDAHO VALLEYS GETTING ISOLATED SHOWERS AND THUNDERSTORMS.
SURFACE WINDS STRONGEST OVER OREGON UNTIL SUNSET FROM THE SW 20-30
KTS THEN SW TO W 15-25 KTS. IDAHO SURFACE WINDS SOUTH TO WEST 10-15
KTS SHIFTING TO W AND NW 10-20 KTS THURSDAY. WINDS ALOFT SHIFTING FROM
SW TO WEST 25-35 KTS.

$$

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.

&&

$$

WEATHER.GOV/BOISE

SHORT TERM...LC
LONG TERM....VM/AB
AVIATION.....VM



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