Special Weather Statement, NWS Boise, ID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
303 PM MDT SAT MAY 7 2016

.SHORT TERM...TONIGHT THROUGH MONDAY...UPPER LEVEL LOW PRESSURE
CENTERED OVER SOUTHERN UTAH AND NEVADA CONTINUES TO BRING MOIST
AND UNSETTLED CONDITIONS TO THE FORECAST AREA. NOT AS UNSTABLE OF
AN ATMOSPHERE TODAY BUT THE AIRMASS REMAINS VERY MOIST. SHOWERS
AND THUNDERSTORMS WILL DEVELOP LATE THIS AFTERNOON IN DAYTIME
HEATING. APPEARS TO BE A WEAK SHORTWAVE ROTATING AROUND THE NORTH
SIDE OF THE LOW WHICH SHOULD HELP GENERATE SHOWERS AND
THUNDERSTORMS ACROSS THE FORECAST AREA LATE TODAY. LOCALLY HEAVY
RAIN EXPECTED WITH SOME STORMS. MODELS IN FAIRLY GOOD AGREEMENT
PLACING THE HIGHEST QPF THIS EVENING ACROSS BOISE AND VALLEY
COUNTIES EXTENDING SOUTHWEST INTO SOUTHERN MALHEUR COUNTY. EXPECT
SOME HEAVY SHOWERS TO MOVE ACROSS THE TREASURE VALLEY AGAIN THIS
EVENING BUT NOT THE AREAL COVERAGE AS LAST EVENING. THE LOW WILL
GRADUALLY MOVE NORTHEAST AWAY FROM THE AREA OVERNIGHT AND SUNDAY
WITH DRIER AIR SPREADING ACROSS THE AREA AS FLOW ALOFT BECOMES
NORTHWESTERLY. CHANCE OF SHOWERS AND THUNDERSTORMS LIMITED MOSTLY
TO THE HIGH TERRAIN ON THE IDAHO SIDE SUNDAY AFTERNOON.

A SHORTWAVE TROUGH WILL SWEEP SOUTHEAST ACROSS THE NORTHERN
ROCKIES ON MONDAY AND DRAG A COLD FRONT ACROSS THE FORECAST AREA.
THIS LOOKS LIKE A PRETTY DRY SYSTEM AND WIND WILL BE THE MAIN
IMPACT WITH GUSTY NORTHWEST WINDS MONDAY AFTERNOON. TEMPERATURES
WILL TREND UP A FEW DEGREES ACROSS MOST OF THE AREA SUNDAY THEN
COOLER ON MONDAY WITH THE DRY FRONTAL PASSAGE.

.LONG TERM...MONDAY NIGHT THROUGH THURSDAY...UPPER LEVEL TROUGH WILL
CONTINUE TO DECEND TO THE SOUTHEAST...EXITING THE REGION BY EARLY
WEDNESDAY. SLIGHT CHANCE OF SHOWERS IN THE MOUNTAINS NORTH OF THE
SNAKE RIVER PLAIN THROUGH TUESDAY NIGHT. IN THE TROUGH/S
WAKE...HEIGHTS WILL RISE AND WILL SEE A DRYING AND WARMING TREND AS
THE FLOW TURNS NEARLY ZONAL. TEMPERATURES WILL WARM TO 10-15 DEGREES
ABOVE NORMAL BY THE END OF THE PERIOD.

THURSDAY NIGHT THROUGH SUNDAY...RIDGING FRIDAY WILL KEEP THINGS DRY
FOR THE ENTIRE AREA. BY FRIDAY NIGHT MODELS START TO DIVERGE QUITE A
BIT. THE GFS WANTS TO BRING IN AN UPPER LOW WHILE THE ECM HOLDS OFF
ON BRINGING THIS IN UNTIL SATURDAY. BECAUSE OF THESE DIFFERENCES
IN MODELS...CONFIDENCE IS QUITE LOW PAST FRIDAY NIGHT. FRIDAY
LOOKS TO BE AROUND 10 DEGREES ABOVE NORMAL WHILE SATURDAY STARTS
TO COOL DOWN BUT REMAINS ABOVE NORMAL.

&&

.AVIATION...MAINLY VFR. AS OF 20Z...SHOWERS AND ISOLATED
THUNDERSTORMS SOUTH AND EAST OF A KSNT-KBOI-KREO LINE. WILL BECOME
SCT-NUM ACROSS THE REGION LATER THIS AFTERNOON. ISOLATED
THUNDERSTORMS WILL CONTINUE THROUGH 06Z...WITH LOCAL MOUNTAIN
OBSCURATION AND BRIEF IFR CONDITIONS IN HEAVY SHOWERS. SURFACE
WINDS...VARIABLE 10 KTS OR LESS EXCEPT GUSTS UP TO 25 KTS NEAR
THUNDERSTORMS. WINDS ALOFT AT 10K FT MSL...EAST 5-15 KTS...TURNING
NORTH 10-20 KTS BY 00Z.

&&

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

&&

WWW.WEATHER.GOV/BOISE
WWW.FACEBOOK.COM/NWSBOISE
WWW.TWITTER.COM/NWSBOISE

SHORT TERM...TL
LONG TERM....AB/JC
AVIATION.....AB

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BOISE ID
625 PM MDT SAT MAY 7 2016

IDZ013-014-080100-
BOISE MOUNTAINS ID-UPPER TREASURE VALLEY ID-
625 PM MDT SAT MAY 7 2016

...SPECIAL WEATHER STATEMENT...

AT 622 PM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR
ARROWROCK DAM...OR 11 MILES SOUTHWEST OF IDAHO CITY...MOVING SOUTHWEST
AT 15 MPH.

WINDS IN EXCESS OF 30 MPH AND HEAVY RAIN WILL BE POSSIBLE WITH THIS
STORM. SMALL HAIL IS ALSO POSSIBLE.

THIS STRONG THUNDERSTORM WILL BE NEAR...
  ARROWROCK DAM AROUND 640 PM MDT.
  LUCKY PEAK SPRING SHORES MARINA AND ALDAPE SUMMIT AROUND 650 PM
  MDT.
  BOISE...GARDEN CITY...MERIDIAN AND LUCKY PEAK RESERVOIR AROUND 700
  PM MDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

WHEN SAFE TO DO SO...PLEASE RELAY STORM REPORTS TO THE NATIONAL
WEATHER SERVICE IN BOISE IDAHO VIA LOCAL LAW ENFORCEMENT...OR NWS
BOISE FACEBOOK AND TWITTER ACCOUNTS.

&&

LAT...LON 4382 11598 4370 11578 4339 11597 4362 11636
TIME...MOT...LOC 0022Z 030DEG 10KT 4368 11596

JC