086
FXUS65 KBOI 210259
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
859 PM MDT SUN APR 20 2025
DISCUSSION
A WEAK TROUGH IS CURRENTLY BRINGING LIGHT
SHOWER/VIRGA ACTIVITY ACROSS E-CENTRAL OREGON AND SOUTHWEST
IDAHO. COVERAGE IS EXPECTED TO DECREASE LATE TONIGHT, WITH THE
EXCEPTION OF SOUTH-CENTRAL IDAHO. LIGHTNING HAS BEEN DETECTED IN
NORTHERN NV THIS EVENING, WITH A 15% PROBABILITY OF STRIKES
OCCURRING IN SOUTH-CENTRAL IDAHO. BREEZY NORTHWEST WINDS WILL
TAPER OVERNIGHT BUT SHOULD RETURN BY LATE MONDAY MORNING IN THE
WAKE OF THE TROUGH. NO UPDATES TO THE CURRENT FORECAST
EXPECTED.
AVIATION
MAINLY VFR. SCATTERED LIGHT SHOWERS OR VIRGA CAPABLE
OF 20-30 KT OUTFLOW WINDS, ENDING BEFORE MON/12Z. A 15% CHANCE
OF LIGHTNING NEAR THE ID-NV BORDER. PERIODS OF MVFR AND MTN
OBSCURATION AT/NEAR KMYL WITH PRECIP. SNOW LEVELS: 4500-6000 FT
MSL TONIGHT. SURFACE WINDS: W TO NW 5-15 KT. GUSTS OF 20-30 KT
DECREASING OVERNIGHT. WINDS ALOFT AT 10KFT MSL: 15-30 KT.
KBOI...VFR. VIRGA OR LIGHT RAIN SHOWERS, ENDING BEFORE MON/08Z.
WINDS W TO NW 5-12 KT, OCCASIONAL GUSTS UP TO 20-25 KT TONIGHT.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...A TROUGH OF LOW
PRESSURE IS DIVING TO THE SOUTHEAST OUT OF THE GULF OF ALASKA
THIS AFTERNOON. A SHORT-WAVE EMBEDDED IN THE TROUGH IS RIDING
UP AND OVER THE OR/WA COAST, AND A FRONTAL SYSTEM IS TAKING
SHAPE ALONG THE CASCADES. THIS FRONTAL SYSTEM IS FORECAST TO
FURTHER DEVELOP AND TRACK EASTWARD THROUGH OR AND ID THIS
EVENING AND OVERNIGHT. ENOUGH INSTABILITY AND MOISTURE WILL
ACCOMPANY THE FRONT TO GENERATE SHOWER ACTIVITY IN BOTH CENTRAL
AND SOUTH CENTRAL IDAHO. GUIDANCE SUGGESTS A 10-15% CHANCE OF AN
ISOLATED THUNDERSTORM AS WELL ALONG AND NEAR THE NEVADA BORDER,
INCLUDING THE MAGIC VALLEY. THE MOST SIGNIFICANT IMPACT OVER
THE NEXT 24 HOURS WILL BE AN INCREASE IN WIND ALONG AND BEHIND
THE COLD FRONT, ESPECIALLY MONDAY AFTERNOON. WINDS WILL APPROACH
ADVISORY CRITERIA FOR THE CAMAS PRAIRIE AND MAGIC VALLEY OF
IDAHO FOR A FEW HOURS BETWEEN NOON AND 6PM MDT MONDAY.
BROAD NORTHWEST FLOW WILL SETTLE IN BEHIND THE SHORT-WAVE TROUGH
AND FRONT FOR TUESDAY, WITH PRECIPITATION CHANCES REMAINING
NORTH OF THE AREA. TEMPERATURES WILL LINGER NEAR AVERAGE.
LONG TERM...WEDNESDAY THROUGH SUNDAY...A WARMING TREND WILL BE
UNDERWAY WEDNESDAY/THURSDAY/FRIDAY ASSOCIATED WITH AN SHORTWAVE
RIDGE BUILDING ALOFT. SOUTHEASTERLY WINDS WILL RETURN BRIEFLY ON
THURSDAY AND FRIDAY. THE SHORTWAVE RIDGE MOVES EAST QUICKLY, WITH A
DISAGREED UPON SOLUTION FOR WHAT FOLLOWS LATE
FRIDAY/SATURDAY/SUNDAY. THE GFS HAS A STRONG, OCCLUDING UPPER-LEVEL
LOW PRESSURE SYSTEM AND ASSOCIATED SURFACE LOW PRESSURE SYSTEM
SLOWLY MOVE ONSHORE INTO THE PACIFIC NORTHWEST. EURO AND CANADIAN
BRING A MUCH WEAKER, MUCH FURTHER SOUTH REACHING LONGWAVE
TROUGH. THESE SOLUTIONS BRING LARGE UNCERTAINTY AND DIFFERENCES,
PARTICULARLY IN QPF. NEEDLESS TO SAY, HARD TO DETERMINE THIS
FAR OUT. POPS REFLECT THE CERTAINTY THAT THIS TROUGHING SYSTEM,
REGARDLESS OF INTENSITY, WILL BRING A CLOUDY/RAINY WEEKEND.
PRECIPITATION CHANCES LATE FRIDAY THROUGH SUNDAY RANGE FROM
15-50%, WITH THE HIGHEST CHANCES FOUND IN THE WEST-CENTRAL
MOUNTAINS. THUNDERSTORMS SEEM VAGUELY POSSIBLE DURING THIS
PERIOD. BREEZY NORTHWEST WINDS COME FOLLOWING A COLD FRONT
FRIDAY INTO SATURDAY. BREEZY WINDS WILL CONTINUE THROUGH SUNDAY.
TEMPERATURES WARM FROM AROUND NORMAL ON WEDNESDAY TO 5-10
DEGREES ABOVE NORMAL THURSDAY/FRIDAY, DROPPING BACK DOWN TO
AROUND NORMAL COME SATURDAY AND SUNDAY.
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...SH
AVIATION.....SH
SHORT TERM...MC
LONG TERM....CH
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