779
FXUS65 KBOI 101631
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1031 AM MDT SAT MAY 10 2025
DISCUSSION
ANOTHER MILD START THIS MORNING WITH A BROAD AREA
OF MID-HIGH CLOUD COVER, SOME OF IT INITIATING FROM SOUTHWEST
FLOW OVER THE NORTHERN SIERRA MTNS. PARTS OF THE WESTERN MAGIC
VALLEY ARE ALREADY HEATING UP FAST THIS MORNING (82F AT TWF AS
OF 10AM). AS S-CENTRAL IDAHO AND NORTHERN NV CONTINUE TO HEAT
AND DESTABILIZE EXPECT TO SEE ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS BY EARLY AFTERNOON. THE SHEAR ENVIRONMENT REMAINS
WEAK IN THIS AREA SO EXPECT CELLS TO BE SHORT-LIVED. HOWEVER,
GIVEN THE DRY AIR AT LOW LEVELS EVEN INNOCUOUS LOOKING SHOWERS
COULD DELIVER A PUNCH OF 60 MPH OUTFLOW WINDS TO THE AREAS FROM
THE ID/NV BORDER INTO THE WESTERN MAGIC VALLEY AND CAMAS
PRAIRIE. ON A LARGER SCALE, THE SOUTHWEST FLOW ALOFT WILL BRING
BREEZY CONDITIONS WITH GUSTS OF 25-40 MPH TO MOST AREAS THIS
AFTERNOON, THOUGH SOME SITES WILL BRIEFLY TOP THOSE SPEEDS (KTWF
ALREADY HITTING 45 MPH GUSTS THIS MORNING). HAVE MADE MINOR
UPDATES TO THE WINDS FOR THIS MORNING.
AVIATION
MAINLY VFR. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS IN THE MAGIC VALLEY LATE THIS AFTERNOON/EVENING,
EXPANDING TO THE REST OF SW IDAHO LATE THIS EVENING AND
OVERNIGHT. SMALL HAIL AND OUTFLOWS UP TO 50 KT POSSIBLE FROM
STRONGER STORMS. SURFACE WINDS: VARIABLE/SE LESS THAN 10 KT,
BECOMING SW 10-20 KT WITH GUSTS TO 30 KT THIS AFTERNOON.
STRONGEST WINDS IN THE HIGHER TERRAIN. SURFACE WINDS BECOMING
SE-SW 5-15 KT TONIGHT. WINDS ALOFT AT 10KFT MSL: SW 20-30 KT.
KBOI...VFR. LIGHT WINDS THROUGH MID AFTERNOON. WINDS SHIFTING TO
S-SW 8-15 KT WITH GUSTS UP TO 25 KT LATE THIS AFTERNOON, THEN
BACK TO SE 7-13 KT BY MID EVENING. A 50% CHANCE OF BRIEF OUTFLOW
GUSTS TO 30 KT TONIGHT.
SUNDAY OUTLOOK...AN APPROACHING COLD FRONT WILL PRODUCE A 20-50%
CHANCE OF SHOWERS, HIGHEST CHANCE IN THE MOUNTAINS, AND A 10-20%
CHANCE OF THUNDERSTORMS. FRONT WILL MOVE THROUGH SUNDAY EVENING
WITH CONTINUED SHOWERS ACROSS THE NORTH. SURFACE WINDS: SW
10-25 KT WITH GUSTS 25-45 KT, SHIFTING TO THE W-NW AND
DECREASING BEHIND THE FRONT. AREAS OF BLOWING DUST DUE TO GUSTY
WINDS.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH MONDAY NIGHT...A DEEPENING UPPER-
LEVEL LOW APPROACHING THE WESTERN CANADIAN COAST TODAY WILL
AMPLIFY THE RIDGE OVER THE INTERMOUNTAIN WEST, TIGHTENING THE
PRESSURE GRADIENT AND LEADING TO BREEZY SOUTHERLY WINDS ACROSS
THE REGION. WITH THE ADDED DOWNSLOPE FLOW AND WARMING AIR MASS,
VALLEY TEMPERATURES WILL CLIMB TO NEAR-RECORD LEVELS IN SOME
AREAS, WITH HIGHS REACHING THE LOW 90S.
SOUTHWESTERLY FLOW ALOFT WILL INCREASE THROUGH THE DAY, DRAWING
IN LIMITED MID- AND UPPER-LEVEL MOISTURE AND ENHANCING BREEZY
CONDITIONS, PARTICULARLY OVER HIGHER TERRAIN. ALTHOUGH OVERALL
MOISTURE REMAINS MODEST, VERY STEEP LOW-LEVEL LAPSE RATES AND A
DRY SUB-CLOUD LAYER WILL FAVOR EFFICIENT EVAPORATIVE COOLING,
INCREASING THE POTENTIAL FOR STRONG DOWNDRAFT WINDS. THE MOST
FAVORABLE AREA FOR THUNDERSTORM DEVELOPMENT APPEARS TO BE A
NARROW CORRIDOR FROM SOUTHERN TWIN FALLS COUNTY THROUGH THE
CAMAS PRAIRIE AND INTO THE SAWTOOTH MOUNTAINS, WHERE CHANCES ARE
AROUND 60%. A FEW STORMS MAY ALSO FORM OVER THE BAKER
MOUNTAINS. THE STRONGER CELLS COULD PRODUCE ISOLATED WIND GUSTS
OF 50 TO 60 MPH.
LATE TONIGHT INTO EARLY SUNDAY, MOISTURE SHIFTS WESTWARD AS THE
UPPER LOW DROPS SOUTHWARD ALONG THE PACIFIC NORTHWEST COAST.
WHILE INSTABILITY WILL WANE WITH THE LOSS OF DAYTIME HEATING,
STRONGER SHOWERS MAY STILL PRODUCE BRIEF GUSTY WINDS UP TO 45
MPH ACROSS SOUTHWEST IDAHO.
BY SUNDAY AFTERNOON AND EVENING, THE LOW REACHES THE OREGON
COAST, FURTHER INCREASING SOUTHWESTERLY FLOW ALOFT. THIS WILL
BRING WIDESPREAD WINDY CONDITIONS TO OPEN TERRAIN IN SOUTHEAST
OREGON AND SOUTHWEST IDAHO, WITH GUSTS OF 40 TO 50 MPH POSSIBLE
NEAR THE NEVADA BORDER—POTENTIALLY LEADING TO AREAS OF BLOWING
DUST. THUS, A WIND ADVISORY HAS BEEN ISSUED. THUNDERSTORMS WILL
LIKELY REDEVELOP OFF THE HIGHER TERRAIN SUNDAY EVENING, WITH
STRONG OUTFLOW WINDS BEING THE PRIMARY CONCERN.
CLOUD COVER AND COOLING ALOFT WILL KNOCK 7 TO 12 DEGREES OFF
DAYTIME HIGHS ON SUNDAY COMPARED TO SATURDAY, AHEAD OF A COLD
FRONT EXPECTED LATER IN THE DAY. AS THE UPPER LOW MOVES INLAND
ON MONDAY, SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS THE
REGION. HIGH TEMPERATURES WILL FALL ANOTHER 10 TO 15 DEGREES,
SETTLING 5 TO 8 DEGREES BELOW NORMAL FOR EARLY JUNE.
LONG TERM...TUESDAY THROUGH SATURDAY...A DEEP UPPER LOW WILL BE
OVER THE REGION TUESDAY BEFORE EXITING EASTWARD WEDNESDAY NIGHT.
DURING THIS PERIOD WE'LL SEE COOLER TEMPERATURES, GUSTY WINDS, AND
WIDESPREAD PRECIPITATION. PRECIPITATION CHANCES ARE HIGHEST TUESDAY:
30-40% IN LOWER ELEVATIONS AND 60-70% IN MOUNTAINS. SOME INSTABILITY
BOTH AFTERNOONS WILL BE ENOUGH FOR AN ISOLATED TO SCATTERED THUNDER
RISK. MOST OF THE AREA WILL SEE WIND GUSTS UP TO 30 MPH BEFORE THE
UPPER LOW EXITS WEDNESDAY NIGHT. A BRIEF WARMING AND DRYING TREND
DUE TO AN UPPER RIDGE WILL BEGIN THURSDAY AND END EARLY FRIDAY AS
THE NEXT SYSTEM WORKS INTO THE AREA. SOME MODEL DISAGREEMENT EXISTS
ON THE TRACK AND STRENGTH OF THIS LOW, BUT MOST SHOW AT LEAST SOME
PRECIPITATION.
BOI WATCHES/WARNINGS/ADVISORIES
ID...WIND ADVISORY FROM NOON SUNDAY TO MIDNIGHT MDT SUNDAY NIGHT
IDZ015-029.
OR...WIND ADVISORY FROM NOON MDT /11 AM PDT/ SUNDAY TO MIDNIGHT MDT
/11 PM PDT/ SUNDAY NIGHT ORZ061-063.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...DG
AVIATION.....ST
SHORT TERM...JDS
LONG TERM....JM
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