780
FXUS65 KREV 190927
AFDREV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
127 AM PST FRI DEC 19 2025
KEY MESSAGES
* WIDESPREAD STRONG WINDS TODAY AND POSSIBLY AGAIN ON SUNDAY.
LIKELY IMPACTS FOR BOTH ROAD AND AIR TRAVEL. LOCALIZED FIRE
WEATHER CONCERNS IN THE EASTERN SIERRA.
* SHOWERS INCLUDING MOUNTAIN SNOW SHOWERS THIS AFTERNOON AND
EVENING. HEAVIER RAINS LIKELY SATURDAY NIGHT THROUGH SUNDAY THAT
COULD LEAD TO LOCALIZED FLOODING CONCERNS.
* ANOTHER STORM OR TWO COULD BRING SIGNIFICANT RAIN AND SNOW
TUESDAY INTO CHRISTMAS DAY, BUT CONFIDENCE REMAINS MIXED.
DISCUSSION
* WELP, IT'S STILL LOOKING RATHER BUSY WEATHER-WISE OVER THE
COMING 7 DAYS WITH A SERIES OF PACIFIC STORMS INCLUDING
ATMOSPHERIC RIVERS. ANYONE WITH HOLIDAY TRAVEL PLANS BY ROAD AND
BY AIR SHOULD KEEP AN EYE ON THE FORECAST AND ADJUST
ACCORDINGLY.
* WIND: TODAY & SUNDAY ARE THE WINDIEST DAYS IN WHAT WILL BE A
BREEZY PERIOD THROUGH MOST OF NEXT WEEK. RATHER IMPRESSIVE ZONAL
JET MOVING THOUGH THE PAC NW & N CALIF COUPLED WITH INCREASING
PRE-FRONTAL GRADIENT WILL YIELD WIDESPREAD STRONG WINDS TODAY.
GIVEN W/SW FLOW ORIENTATION AND 700MB SPEEDS 50-60 KNOTS, WAVE
BREAKING AND DOWNSLOPE ENHANCEMENT IS POSSIBLE TODAY ALONG HWY
395 FROM SUSANVILLE-RENO-MAMMOTH WHERE WE HAVE WIND ADVISORIES
POSTED. LOW HUMIDITY COULD CREATE FIRE WEATHER CONCERNS, AND IT
WON'T BE A PRETTY DAY FOR FLYING EITHER. FOR SUNDAY ANOTHER
PLUME OF HIGH SPEED AIR ALOFT COMES IN WITH AN MODERATE
ATMOSPHERIC RIVER. RRFS SHOWING 700MB WINDS OVER 70 KNOTS. WOW.
SO IF WE END UP BEING MORE SHADOWED ON SUNDAY (MORE T THAN V
FROM THE AR IVT) WE COULD HAVE ANOTHER ROUND OF RATHER STRONG,
IMPACTFUL WINDS REGIONWIDE.
* RAIN: WHILE TODAY WILL GENERALLY BE DRY, HIGH-RES MODELS SHOW
SHOWERS MOVING IN POST-FRONT THIS AFTERNOON INTO THE EVENING.
SHOULD BE MOSTLY RAIN EXCEPT THE SIERRA PEAKS, HOWEVER NBM AND
HREF ARE SHOWING POTENTIAL FOR SNOW P-TYPE AT PASSES IF WE SEE
HEAVIER PRECIP RATES. RAPID P-TYPE CHANGES CAN CATCH TRAVELERS
OFF- GUARD. SATURDAY NIGHT THROUGH SUNDAY IS STILL THE MAIN SHOW
FOR HEAVY RAIN WITH PRONOUNCED ATMOSPHERIC RIVER SIGNAL AND
HIGH RAIN- SNOW LINES (8000'+). QPF IN THE MOUNTAINS IS SIMILAR
TO GUIDANCE 24 HOURS AGO BUT A LITTLE LESS IN LEE-SIDE AREAS OF
W NEVADA (MORE PERIODS OF SHADOWING/WIND PERHAPS?). HIGHEST RISK
OF HEAVY RAINS AND POTENTIAL FLOODING REMAINS THE TAHOE BASIN
INTO NE CALIF WHERE MODELS STALL/PIVOT THE MAIN AR BAND FOR THE
LONGEST TIME. IF THERE WERE AN AREA TO UNDERPERFORM IT WOULD BE
THE EASTERN SIERRA/MONO CO BASED ON FURTHER NORTH TRAJECTORIES
OF THE AR PLUME.
* SNOW: PRECIP NEVER TOTALLY SHUTS OFF IN THE MOUNTAINS BUT DOES
LESSEN IN INTENSITY MONDAY INTO EARLY TUESDAY. STARTING MONDAY
NIGHT THE SNOW LINES DROP ENOUGH WERE WE COULD START SEEING MORE
REGULAR IMPACTS TO TRAVEL OVER THE PASSES. SIMULATIONS SHOWING
ONE OR TWO ADDITIONAL NOTABLE AND COOLER STORMS MOVING IN
TUESDAY EVENING THROUGH CHRISTMAS DAY. LOTS OF VARIABLES HERE
WITH MODELS DIGGING TROUGHS OFF THE COAST WHICH SOMETIMES CAN
RESULT IN A SOUTHWARD SHIFT OF THE HEAVIEST PRECIP, WIDE
BOOM/BUST SCENARIOS, AND AN INCREASED AIRING OF GRIEVANCES NEXT
WEEK. THAT ALL BEING SAID, QPF AND SNOWFALL IN THE NBM 50TH
PERCENTILES HAS GONE UP QUITE A BIT VS 24 HOURS AGO FOR
WEDNESDAY-THURSDAY. POTENTIALLY GOOD NEWS FOR THE SNOWPACK AND
LOCAL "WHITE CHRISTMAS" STATS, BUT NOT SO GOOD NEWS FOR THOSE
TRYING TO GET SOMEPLACE AT THE LAST MINUTE BEFORE CHRISTMAS.
-CHRIS
AVIATION
* BUCKLE UP, IT'S NOT EXACTLY GOING TO BE A SMOOTH DAY FOR FLYING
WITH STRONG WINDS, MOUNTAIN WAVES, ROTORS, AND LOW LEVEL WIND
SHEAR ALL ON THE TABLE TODAY INTO THIS EVENING.
* STRONG W/SW FLOW WITH RRFS 700MB WINDS TO 60 KNOTS FORECAST
TODAY AND TONIGHT, ASSOCIATED WITH AN UPPER JET AND APPROACHING
COLD FRONT. 80% CHANCE OF SEEING PEAK GUSTS AT LEAST 35 KNOTS AT
MOST AIRFIELDS INCLUDING RNO/CXP/MEV, TRK/TVL, MMH WITH 40-60%
AT NFL/SVE/HTH. HIGH-END GUSTS OVER 50 KNOTS CANNOT BE RULED OUT
IN MORE WIND PRONE AREAS ALONG HWY 395. NBM HAS 40-60% CHANCES
OF 50 KNOT PEAK GUSTS AT RNO AND MMH FOR EXAMPLE. ANOTHER ROUND
OF STRONG WINDS IS LOOKING LIKELY ON SUNDAY AS WELL.
* WITH THAT FRONT TODAY, WE WILL HAVE SHOWERS DEVELOP THIS
AFTERNOON AND EVENING. MAINLY IN THE MOUNTAINS FROM SVE TO
TRK/TVL WITH POTENTIAL FOR MVFR-IFR CONDITIONS IN RAIN. CAN'T
RULE OUT A RAIN/SNOW MIX BUT LOW CONFIDENCE. FOR RNO/CXP/MEV,
LIGHT SHOWERS ARE POSSIBLE (40% CHANCE) BUT VISIBILITY/CEILINGS
LOOK TO REMAIN VFR. MMH MISSES OUT ON THIS ONE, JUST WIND FOR
THEM.
* ADDITIONAL SHOWERS POSSIBLE SATURDAY BUT MAINLY LIGHT
INTENSITY. WINDS SHOULD BE LESS ROBUST AS WELL.
-CHRIS
FIRE WEATHER
* THERE IS CONCERN OVER AREAS OF CRITICAL WIND AND LOW HUMIDITY
IN THE EASTERN SIERRA TODAY, SPECIFICALLY FIRE WEATHER ZONES
CA274 AND NV421.
* LATEST NBM AND HREF GUIDANCE SUGGEST 1-3 HOURS OF CRITICAL
CONDITIONS ESPECIALLY ALONG HWYS 395 & 6 WHERE W/SW WINDS COULD
GUST OVER 50 MPH THIS AFTERNOON (SEE WIND ADVISORY). HUMIDITY
VALUES ALREADY IN THE TEENS AS OF THIS WRITING AND IT'S BEEN
RATHER DRY LATELY WITH WELL ABOVE NORMAL ERC LEVELS.
* NO RED FLAG WARNING AT THIS TIME DUE TO LIMITED SPATIAL EXTENT
AND DURATION OF CRITICAL CONDITIONS HOWEVER WE WILL HIGHLIGHT
THE RISK IN THE FWF AND OUR MORNING BRIEFING EMAIL.
-CHRIS
HYDROLOGY
REPOST OF YESTERDAYS HYDRO SECTION. THIS WILL BE UPDATED WITH THE
DAYTIME DISCUSSION.
* MODERATE TO HEAVY RAINS WILL LEAD TO SIGNIFICANT RISES ON
RIVERS AND STREAMS SUNDAY INTO MONDAY MOST NOTABLY FROM THE
TAHOE BASIN NORTH THROUGH LASSEN COUNTY, BUT NO MAINSTEM RIVER
FLOODING IS CURRENTLY EXPECTED.
* MINOR FLOODING OF URBAN AND POOR DRAINAGE AREAS AND ROCKFALL
ARE POSSIBLE DURING ANY PROLONGED PERIODS OF HIGH INTENSITY
RAINFALL. WATCH FOR ADDITIONAL RISES NEAR CHRISTMAS EVE AND
POSSIBLE FLOODING CONCERNS ESPECIALLY IN DRAINAGES WITH LARGE
MOUNTAIN DRAINAGES BELOW ABOUT 6,000 FEET, LIKE THE SUSAN RIVER
FOR EXAMPLE.
* YOU CAN FIND RIVER FORECASTS UPDATED TWICE DAILY AT:
WWW.CNRFC.NOAA.GOV
-TIM
REV WATCHES/WARNINGS/ADVISORIES
NV...WIND ADVISORY UNTIL 4 AM PST SATURDAY NVZ002-003-005.
LAKE WIND ADVISORY UNTIL 4 AM PST EARLY THIS MORNING NVZ002.
LAKE WIND ADVISORY UNTIL 4 AM PST SATURDAY NVZ004.
CA...WIND ADVISORY UNTIL 4 AM PST SATURDAY CAZ070>072.
LAKE WIND ADVISORY UNTIL 4 AM PST EARLY THIS MORNING CAZ072.
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