Area Forecast Discussion
Issued by NWS Boise, ID

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000
FXUS65 KBOI 240312
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
912 PM MDT WED JUL 23 2014

.DISCUSSION...VIGOROUS UPPER LEVEL TROUGH SPINNING OFF THE PACIFIC
NORTHWEST COAST IS SLOWLY SHIFTING INLAND. THIS TROUGH HAS PUSHED
ALL THE MONSOONAL AIR NORTHEAST OF OUR FORECAST AREA AS THE
THUNDERSTORM THREAT HAS ENDED. COLD FRONT WILL MOVE THROUGH BOISE
AROUND 05Z...TWIN FALLS BY 09Z WITH GUSTS TO 35MPH WITH FRONTAL
PASSAGE. OUR REGION WILL REMAIN IN A DRY SLOT WITH STIFF
SOUTHWESTERLY AND THEN WESTERLY FLOW ALOFT AS THIS TROUGH PASSES
BY TO THE NORTH. TEMPERATURES THURSDAY WILL BE AROUND 15 DEGREES BELOW
NORMAL. EXPECT DRY WEATHER WITH MOSTLY SUNNY SKIES...BREEZY
CONDITIONS ESPECIALLY DURING THE AFTERNOON AND EVENINGS AND A
RETURN TO SMOKY CONDITIONS FROM ALL THE NEW FIRE STARTS. UPDATED
FORECAST TO LOWER THUNDERSTORM COVERAGE WITH THE INTRUSION OF DRY
AIR.

&&

.AVIATION...VFR...EXCEPT LOCAL MVFR CONDITIONS DUE TO SMOKE NEAR
WILDFIRES. ISOLATED SHOWERS AND THUNDERSTORMS GENERALLY NORTH OF A
KBKE-KMYL LINE UNTIL 06Z. WEST-NORTHWEST SURFACE WINDS 10-20 KNOTS
WITH GUSTS TO 30 KNOTS DUE TO A COLD FRONT...WITH WINDS DIMINISHING
BY 12Z. COLD FRONT WILL REACH KBOI BY 05Z...AND KTWF/KJER BY 09Z.
WINDS ALOFT SOUTHWEST 20-30 KNOTS AT 10K FEET MSL.

&&

.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH FRIDAY...EXPECT STRONG STORMS
/POSSIBLE A FEW SEVERE STORMS AS WELL/ THIS AFTERNOON AND EVENING
ACROSS OUR NORTHERN ZONES. ANOTHER SHORTWAVE...EMBEDDED IN THE
SOUTHWESTERLY FLOW AHEAD PACIFIC NORTHWEST TROUGH...WILL BE THE
FOCUS FOR THUNDERSTORM DEVELOPMENT AS IT TRACKS ALONG OUR NORTHERN
ZONES THIS EVENING. SHORTWAVE...AT 20Z...IS LOCATED OVER CENTRAL
OREGON AND HAS ALREADY INITIATED SCATTERED THUNDERSTORMS ACROSS
NORTHEAST OREGON. EXPECT THIS SHORTWAVE TO MOVE EAST-NORTHEAST
ACROSS NORTHEAST OREGON BETWEEN 23Z-01Z INTO NORTH-CENTRAL IDAHO
BETWEEN 00Z-03Z. THERE IS ALREADY STRONG 0-6 KM SHEAR AND CLOSE TO
500 J/KG MU CAPE IN PLACE THIS AFTERNOON WHICH SUGGEST STRONG
STORMS WOULD BE POSSIBLE TONIGHT. GIVEN A SLIGHTLY DRIER BOUNDARY
LAYER AND PLENTY OF SURFACE HEATING FROM BAKER CITY TO
MCCALL...GUSTY WINDS AND HAIL WILL LIKELY ACCOMPANY THE STRONGER
CELLS. MUCH COLDER...DRIER AND BREEZY ON THURSDAY IN THE WAKE OF A
COLD FRONTAL PASSAGE. FRONT REACHES BAKER AROUND 01Z
TONIGHT...BOISE AROUND 05Z TONIGHT AND TWIN FALLS AROUND 09Z.
NORTHWEST WINDS WILL INCREASE WITH PASSAGE OF THE FRONT OVERNIGHT
AND REMAIN BREEZY ACROSS SW IDAHO THROUGH THURSDAY AFTERNOON.
FRIDAY REMAINS ABOUT 4-7 DEGREES BELOW NORMAL WITH ZONAL FLOW OVER
THE REGION.

LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...ZONAL WESTERLY FLOW
THROUGH SATURDAY THEN FOUR CORNERS HIGH WILL REESTABLISH AND RIDGE
OVER PACNW WILL BE DOMINANT FEATURE FOR REST OF THE EXTENDED
FORECAST PERIOD.  TEMPS WILL RETURN TO NEAR NORMAL BY FRIDAY AND
THEN RETURN TO 5-10 DEGREES ABOVE NORMAL FOR SUNDAY...TEMPS WILL
REMAIN 8-10 DEGREES ABOVE NORMAL FOR MONDAY THRU WEDNESDAY.  AS FOR
THREAT OF PRECIPITATION...ZONAL FLOW IS DRY AND MODELS ARE CONSISTENT
IN BRINGING SOME MONSOON MOISTURE NORTHWARD INTO OUR AREA MONDAY THRU
WEDNESDAY...SO WILL STAY WITH CURRENT FORECAST AND KEEP A MENTION OF
A CHANCE OF SHOWERS MAINLY AFTERNOONS AND EARLY EVENINGS FROM MONDAY
THROUGH WEDNESDAY.

&&

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

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...KA
AVIATION.....BW
PREV SHORT TERM...JDS/LC
PREV LONG TERM....RD/AB


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