Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 221612
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1012 AM MDT TUE JUL 22 2014

.DISCUSSION...FORECAST IS ON TRACK FOR SCATTERED SHOWERS AND
THUNDERSTORMS MOVING NNE INTO EASTERN OREGON THIS AFTERNOON AND
INTO WESTERN IDAHO EARLY THIS EVENING. GIVEN THE STRONG UPPER
LEVEL WINDS AND UNSTABLE ATMOSPHERE IN THE LATE AFTERNOON WE
EXPECT SOME OF THESE STORMS TO CONTAIN GUSTY WINDS AND SMALL HAIL.
THE CORE OF THESE STORM WILL PRODUCE HEAVY RAIN...BUT GIVEN THE
FAST MOVEMENT TOWARD THE NNE AT 40 TO 45 MPH THE HEAVY RAIN IS
NOT EXPECTED TO LAST VERY LONG AT ANY ONE LOCATION. WE MADE SOME
MINOR UPDATES TO INCREASE THE POPS...MAINLY ON THE IN WESTERN
IDAHO THIS EVENING.

&&

.AVIATION...VFR. ISOLATED SHOWERS AND THUNDERSTORMS THIS
MORNING...BECOMING SCATTERED TO NUMEROUS AFTER 21Z AND CONTINUING
THROUGH THE NIGHT. LOCAL MVFR CONDITIONS IN HEAVY SHOWERS. SURFACE
WINDS VARIABLE 10 KNOTS OR LESS...EXCEPT GUSTS TO 40 KNOTS NEAR
THUNDERSTORMS. WINDS ALOFT WILL BE SOUTHWEST 15 TO 20 KNOT UP
THROUGH 10K FEET MSL.


&&

.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH WEDNESDAY...WE REMAIN IN SW FLOW ALOFT
WITH A MOIST ATMOSPHERE AND ABOVE-AVERAGE SHEAR AND INSTABILITY.
THIS COMBINATION LED TO A GREAT DEAL OF LIGHTNING YDAY...
ESPECIALLY IN SE OREGON. CHANCES ARE GOOD THAT WE WILL HAVE A
SIGNIFICANT CONVECTIVE EVENT AGAIN TODAY. WE HAVE INCREASED POPS
AND THUNDERSTORM COVERAGE OVER MOST OF THE AREA...ESPECIALLY FOR
LATE THIS AFTERNOON AND TONIGHT. SPC HAS US IN A /SEE TEXT/
AREA...MEANING WE ARE NEAR THEIR THRESHOLD FOR SEVERE WEATHER. A
VORT MAX LOCATED NEAR 33 N 127 W AS OF 2 AM MDT WAS MOVING NE.
THIS WILL ACCELERATE LATER TODAY AS IT HEADS TOWARD THE AREA. LIFT
ASSOCIATED WITH THIS VORT MAX WILL AID THUNDERSTORM DEVELOPMENT
LATE THIS AFTERNOON AND THIS EVENING. THIS VORT MAX IS ASSOCIATED
WITH A JET MAX OF AROUND 90 KTS AT 300 MB. THIS WILL PROVIDE AMPLE
SHEAR TO MAINTAIN LONG-LIVED AND ORGANIZED THUNDERSTORMS. PW
VALUES ARE BETWEEN 0.75 AND 1.00 INCH ACROSS THE AREA...SO STORMS
WILL PRODUCE HEAVY RAIN IN THE CORES...ALONG WITH HAIL AND GUSTY
WINDS. STORM MOTION WILL BE NORTHEAST AROUND 40 MPH...INCREASING
THE CHANCE FOR STRONG WINDS BUT DECREASING THE CHANCES FOR FLASH
FLOODING. THE CONVECTION WILL CONTINUE WELL INTO THE NIGHT...
ALTHOUGH IT WILL DECREASE IN AREAL COVERAGE AND INTENSITY AFTER
MIDNIGHT. A RED FLAG WARNING HAS BEEN ISSUED FOR MOST OF THE FIRE
WEATHER ZONES BECAUSE OF THE ANTICIPATED LIGHTNING. SEE BELOW FOR
DETAILS. WED...AS A STRONG TROUGH MOVES BY TO OUR NORTH...WE WILL
FIND OURSELVES IN A DRY SLOT AND MOST OF THE CONVECTION WILL BE TO
OUR NORTH AND WEST. HOWEVER...WE STILL HAVE SLIGHT CHANCE TO
CHANCE POPS AND A SLIGHT CHANCE OF THUNDERSTORMS IN THE NRN
QUARTER OF THE CWA. TEMPS WILL BE NEAR NORMAL TODAY AND WED.

LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...AN UPPER LEVEL TROUGH
WILL MOVE NORTHEAST ACROSS WASHINGTON WEDNESDAY NIGHT...THEN ALONG
THE CANADIAN BORDER AND EAST OF THE ROCKIES BY THURSDAY NIGHT.
FOLLOWING THIS SYSTEM WESTERLY FLOW ALOFT WILL BRING MUCH COOLER...
DRIER...AND MORE STABLE AIR ACROSS OUR AREA. HIGH TEMPERATURES ON
THURSDAY WILL BE AROUND 10 DEGREES BELOW NORMAL WITH MOSTLY SUNNY
SKIES. A WARMING TREND WILL COMMENCE ON FRIDAY AND TEMPERATURES WILL
RETURN TO NEAR NORMAL ON SATURDAY THEN ABOVE NORMAL ON SUNDAY AND
MONDAY AS THE FOUR CORNERS UPPER LEVEL HIGH REBUILDS OVER THE
NORTHERN INTERMOUNTAIN REGION. HIGH TEMPERATURES ON MONDAY ARE
EXPECTED TO BE NEAR 100 DEGREES IN THE LOWER VALLEYS.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...RED FLAG WARNING FROM 3 PM THIS AFTERNOON TO MIDNIGHT MDT
     TONIGHT IDZ400-401-420-423.
OR...RED FLAG WARNING FROM 3 PM MDT /2 PM PDT/ THIS AFTERNOON TO
     MIDNIGHT MDT /11 PM PDT/ TONIGHT ORZ636-637-646.

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...JB
AVIATION.....JA
PREV SHORT TERM...SP
PREV LONG TERM....JT


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