Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 250253
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
853 PM MDT THU APR 24 2014

.DISCUSSION...THUNDERSTORMS CONTINUED IN NORTH ELMORE COUNTY AND
ALONG THE ELMORE/BOISE COUNTY LINE AT 845 PM WHILE NUMEROUS
SHOWERS PERSISTED OVER SE OREGON. A DEVELOPING H7 MID ALTITUDE LOW
CENTER WILL DEVELOP NEAR SW OREGON LATER WHERE WATER VAPOR/IR IS
SHOWING AMPLIFICATION. THIS LOW IS EXPECTED OVER NE OREGON FRIDAY
MORNING WITH NUMEROUS SHOWERS OVER SE OREGON/SW IDAHO IN THE
WIDESPREAD LIFT AHEAD OF THE LOW. A DEEPER TROUGH FARTHER WEST
40N-50N ALONG 135W AT 830 PM WILL DIG INTO THE CA/NV AND IDAHO
REGION AS FRIDAY PROGRESSES. INSTABILITY IS EXPECTED TO INCREASE
WITH THIS FEATURE FOR MORE SPRING TIME THUNDERSTORMS WITH HAIL AND
GUSTY WINDS AND BRIEF HEAVY RAIN. THUNDER AND COOL TEMPS ARE IN
THE FORECAST ALONG WITH WETTING RAIN FOR THE NEXT 24-30 HOURS
/EXCEPT SRN TWF COUNTY THIS EVENING AND BAKER COUNTY FRIDAY
AFTERNOON WHICH MATCHES TIMING OF ABOVE MENTIONED FEATURES. NO
CHANGES THIS SHIFT BUT MAY ADD THUNDERSTORM CHARACTER TO SHORTEST
TERM FORECASTS. FORECAST ON TRACK SO NO UPDATES PLANNED.

&&

.AVIATION...WIDESPREAD SHOWERS WILL CONTINUE THROUGH FRIDAY.
ISOLATED THUNDERSTORMS THROUGH 04Z WILL BE ACCOMPANIED BY LOCAL
HEAVY RAIN...SMALL HAIL...AND BRIEF IFR CONDITIONS. EXPECT AREAS OF
MOUNTAIN OBSCURATION AND MVFR/LOCAL IFR CEILINGS MAINLY 06Z-18Z...
THEN GRADUALLY IMPROVING CONDITIONS IN THE VALLEYS AFTER 18Z.
SURFACE WINDS...LIGHT THROUGH FRIDAY MORNING...THEN WEST TO
NORTHWEST 10-15 KTS AFTER 18Z. WINDS ALOFT...SOUTHWEST UP TO 30 KTS
AT 10K FT MSL.

WEEKEND OUTLOOK...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
THROUGH SUNDAY COULD PRODUCE LOCAL BRIEF MVFR OR LOWER CONDTIONS.
OTHERWISE VFR.

&&

.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH SATURDAY...NUMEROUS SHOWERS AND
ISOLATED THUNDERSTORMS DEVELOPING ACROSS SOUTHEAST OREGON AT 20Z
ASSOCIATED WITH A SHORTWAVE TROUGH MOVING EAST-NORTHEAST ACROSS
SOUTHWEST WASHINGTON. SHOWERS AND THUNDERSTORMS WILL BE SHIFTING
EAST-NORTHEAST INTO SOUTHWEST IDAHO IN THE NEXT HOUR OR TWO. THE
MODELS SHOWING THE BEST INSTABILITY NORTH OF A BURNS-BOISE-
KETCHUM LINE THROUGH 02Z. GUSTY WINDS AND BRIEF HEAVY RAIN HAVE
BEEN REPORTED WITH THE STRONGER CELLS. SMALL HAIL IS ALSO A
POSSIBILITY. CONVECTIVE SHOWERS DIMINISH THIS EVENING HAS THE
SHORTWAVE EXITS THE REGION. MORE WIDESPREAD PRECIPITATION IS
EXPECT BEGINNING EARLY FRIDAY AS THE UPPER TROUGH BUILDS SOUTH
ALONG THE PACIFIC NORTHWEST COAST AND MOVES INLAND FRIDAY
AFTERNOON. THERE WILL BE PERIODS OF MODERATE RAINFALL THROUGHOUT
THE AREA. SNOW LEVELS REMAIN AT OR ABOVE 6000 FEET MSL UNTIL THE
UPPER TROUGH MOVES OVER THE AREA LATE FRIDAY/EARLY SATURDAY.
PRECIPITATION DIMINISHES SATURDAY AFTERNOON AS THE UPPER TROUGH
PASSAGE AND THE UPPER FLOW BRIEFLY SHIFTS TO THE NORTHWEST.

LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...STRONG WESTERLY FLOW
FOR SUNDAY AND MONDAY WILL BRING A WEAKER SHORTWAVE TROUGH INTO THE
PAC NW ON SUNDAY KEEPING A CHANCE OF LIGHT PRECIPITATION TO ALL
ZONES. DRIER CONDITIONS GRADUALLY WORK INTO THE AREA ON MONDAY AS
THAT FEATURE LIFTS TO THE NORTH AND EAST. THE LONG RANGE MODELS AND
THEIR ENSEMBLE MEANS AGREE ON AMPLIFYING THE FLOW PATTERN EARLY NEXT
WEEK...RESULTING IN DEVELOPMENT OF AN UPPER RIDGE OVER THE WESTERN
U.S. THIS INCREASES CONFIDENCE IN A PERIOD OF DRY CONDITIONS
STARTING ON TUESDAY. LESS CERTAINTY IN TEMPERATURE FORECAST AS THE
RIDGE IS FAIRLY NARROW AND THERE REMAINS SOME SPREAD IN THE POSITION
OF THE RIDGE AXIS.

&&

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

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...VM
AVIATION.....JT
PREV SHORT TERM...JDS
PREV LONG TERM....DG/WH



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