497
FXUS65 KREV 192232
AFDREV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
232 PM PST TUE NOV 19 2024
SYNOPSIS
* A STORM SYSTEM ARRIVES LATE TONIGHT INTO WEDNESDAY WITH INCREASING
SNOW/RAIN CHANCES ACROSS NE CA AND WIDESPREAD GUSTY WINDS.
* ANOTHER SIGNIFICANT STORM SYSTEM HITS THE REGION LATE FRIDAY INTO
SATURDAY WITH STRONG GUSTY WINDS, AND INCREASED RAIN AND SNOW
CHANCES.
* THE WET AND STORMY PERIOD MAY CONTINUE AS ANOTHER ROUND OF BREEZY
CONDITIONS, AND RAIN/SNOW CHANCES ARRIVES FOR SUNDAY INTO MONDAY.
DISCUSSION
THE FIRST IN A SERIES OF PRE-WINTER STORMS SYSTEMS ARRIVES LATE
TONIGHT AND CONTINUES THROUGH WEDNESDAY. THIS SYSTEM IS
SIGNIFICANT DUE TO THE MODERATE TO STRONG LEVEL ATMOSPHERIC RIVER
(AR) POURING LOW AND MID LEVEL MOISTURE, AND PRECIPITATION, INTO
THE WESTERN US.
* AS THIS STORM SYSTEM SWEEPS INTO THE REGION, IT WILL DO SO
MOSTLY DURING THE DAYLIGHT HOURS. THEREFORE, SNOW LEVELS WILL
START TO RISE TO 6500’ TO 7500’ ACROSS NORTHEAST CA, AND
8500’-9000’ OVER THE SIERRA FRONT WHICH WILL CONFINE ANY
SNOWFALL TO THOSE HIGHER ELEVATIONS. STORM TOTAL SNOW AMOUNTS
COULD REACH A FOOT ACROSS HIGHER ELEVATION AREAS OF THE NORTHERN
SIERRA WEST OF HWY-395 IN LASSEN COUNTY. THE VARIABILITY OF
SNOW LEVELS, AS WELL AS HEAVIEST PRECIPITATION TIMING, STILL
BRING A 50-70% CHANCE FOR AT LEAST 2+ INCHES OF ACCUMULATED
SNOWFALL OVER HIGHER SIERRA PASSES. LOWER ELEVATIONS DURING THE
DAY INTO THE EVENING WILL SEE MOSTLY LIGHT TO MODERATE RAIN AND
RAIN SHOWERS WITH LIQUID TOTALS RANGING 0.10" TO 0.30" AROUND
THE LAKE TAHOE BASIN, TO A FEW HUNDREDTHS ACROSS FAR WESTERN NV.
MUCH OF THE BASIN AND RANGE WILL BE SHADOWED FROM ANY
SIGNIFICANT PRECIPITATION.
* HIGHER SIERRA RIDGES WILL ALSO SEE WIND GUSTS PEAKING 80-90 MPH
LATE MORNING WEDNESDAY THAT CONTINUES INTO THE AFTERNOON. THESE
GUSTY CONDITIONS WILL EVENTUALLY MIX INTO THE LOWER VALLEYS
DURING THIS PERIOD WITH GUSTS TO 30-40 MPH. WIND PRONE AREAS
LIKE THE I-580 CORRIDOR THROUGH THE WASHOE VALLEY WILL SEE GUSTS
TO 50 MPH. THESE STRONGER WIND GUSTS ALSO BRING CRITICAL FIRE
WEATHER CONDITIONS TO PARTS OF THE REGION AS WELL. MORE
DETAILED INFORMATION IS CONTAINED BELOW IN THE FIRE WEATHER
SECTION.
A SUBSEQUENT AND WETTER STORM SYSTEM WILL BRING A SECOND SURGE OF
SUBTROPICAL MOISTURE INTO THE WEST COAST FRIDAY INTO SATURDAY THAT
PUSHES PRECIPITATION FURTHER INLAND INTO THE BASIN AND RANGE. THIS
RELATIVELY COLDER SYSTEM WILL BRING A DROP IN SNOW LEVELS THAT
FOCUSES HIGHER STORM TOTAL SNOWFALL FURTHER SOUTH INTO THE EASTERN
SIERRA AND SOME LOWER ELEVATIONS OF MONO COUNTY-MAMMOTH. THE
LATEST EUROPEAN AND NCEP MULTI-MODEL ENSEMBLE SIMULATIONS CONTINUE
TO TREND PRECIPITATION TOTALS A BIT HIGHER WITH THIS SUBSEQUENT
WINTER STORM. THEREFORE, LOOK FOR A BETTER CHANCE FOR HIGHER
SNOWFALL TOTALS ACROSS THE SIERRA AS THE MAJOR PUSH OF MOISTURE
INTO THE REGION WILL OCCUR MOSTLY DURING THE OVERNIGHT HOURS
THURSDAY THROUGH FRIDAY MORNING, AND AGAIN OVERNIGHT FRIDAY INTO
SATURDAY MORNING. THESE WILL BE THE PERIODS TO LOOK OUT FOR
TRAVEL IMPACTS OVER MOUNTAIN PASSES, ESPECIALLY IF WINDS TAPER OFF
SLOWER THAN ANTICIPATED.
THE ACTIVE WEATHER PATTERN HAS THE POTENTIAL TO BRING AN ADDITIONAL
ROUND OF INCREASED RAIN/SNOW CHANCES SUNDAY THAT LOOKS TO CONTINUE
THROUGH MONDAY. THERE WILL, HOWEVER, BE LOWER CERTAINTY WITH
PROJECTED PRECIPITATION TOTALS WITH THIS NEXT SYSTEM.
NONETHELESS, THIS NEXT SYSTEM WILL BE A BIT COLDER THAN IT’S
PREDECESSORS, AND INCREASE THE CHANCES FOR SNOWFALL AT LOWER
ELEVATIONS AS IT PUSHES THROUGH THE REGION.
MORE DETAILED INFORMATION ABOUT WIND AND WINTER WEATHER ADVISORIES
IN EFFECT ACROSS THE REGION ARE AVAILABLE AT
HTTPS://WWW.WEATHER.GOV/REV. IT ALSO WOULD BE ADVISED TO CHECK THE
ROAD CONDITIONS VIA STATE DOT WEBSITES SUCH AS CALTRANS QUICKMAP
(QUICKMAP.DOT.CA.GOV) AND NEVADA 511 (NVROADS.COM) IF YOU PLAN
OVER SIERRA PASSES THIS AFTERNOON AND EVENING. -AMANDA
AVIATION
* VFR CONDITIONS WILL CONTINUE FOR ALL TAF SITES THROUGH THIS
EVENING WITH WIND GUSTS FROM THE S-SW 15-25 KTS FOR SIERRA AND
FAR WESTERN NV TERMINALS. FL100 WINDS WILL ALSO INCREASE TO
30-40 KTS THAT PRODUCES PERIODS OF MOUNTAIN WAVE TURBULENCE THIS
EVENING. THE AIRSPACE WILL BE IMPACTED BY TWO STORMS SYSTEMS
THROUGH THE WEEKEND.
* THE FIRST STORM SYSTEM WILL HIT SIERRA TERMINALS WEDNESDAY
MORNING AFTER 15Z WITH PERIODS OF MVFR CONDITIONS IN LIGHT TO
MODERATE RAIN THROUGH THE DAY. PLAN ON LOW CHANCES (10-15%) FOR
A RAIN/SNOW MIX WEDNESDAY INTO THURSDAY FOR THIS FIRST STORM
SYSTEM AS AN ATMOSPHERIC RIVER PUSHES INTO NORTHERN CA AND THE
SIERRA. WINDS WILL BRING THE HIGHEST IMPACTS WITH W-SW SURFACE
WINDS 20-30 KTS AND FL100 WINDS APPROACHING 50-60 KTS FOR KTRK,
KTVL, KRTS, AND KRNO.
* THE SECOND STORM SYSTEMS FOR FRIDAY INTO THE WEEKEND HOLDS A HIGHER
POTENTIAL FOR WETTING RAINS AND HIGH ELEVATION SNOWFALL. LIQUID
WATER STORM TOTALS ARE NEARING 1-3" FOR ALONG THE SIERRA CREST,
WITH A 50-60% CHANCE OF 2+ INCHES OF SNOW FOR KTRK, KMMH, AND
KTVL. IN ADDITION, LOOK FOR MOUNTAIN OBSCURATIONS DURING PERIODS
OF MVFR/IFR CONDITIONS IN RAIN/SNOW FOR SIERRA AND FAR WESTERN
NV TERMINALS.
-AMANDA
FIRE WEATHER
* STRONGER SOUTHWEST WINDS AHEAD OF THE INCOMING STORM SYSTEM,
COUPLED WITH DRIER CONDITIONS AND LOW RHS, WILL BRING CRITICAL
CONDITIONS TO PORTIONS OF THE SIERRA FRONT, MONO-MINERAL-
SOUTHERN LYON COUNTIES, AND THE REMAINDER OF THE BASIN AND RANGE
ON WEDNESDAY. WIND GUSTS OF 35-50 MPH AND HUMIDITY RANGING
12-25%, BRING CRITICAL CONDITIONS TO THE REGION LATE MORNING
INTO THE EARLY EVENING, MOSTLY SOUTH OF I-80.
* THEREFORE, A RED FLAG WARNING WAS ISSUED FOR LATE MORNING
THROUGH EARLY EVENING WEDNESDAY. CRITICAL CONDITIONS WILL LESSEN
ON WEDNESDAY EVENING AS WETTING RAINS SPREAD INTO AREAS WEST OF
HWY-395 IN LASSEN COUNTY, AS WELL AS WASHOE, DOUGLAS, AND LYON
COUNTIES. DISSIPATING WINDS AND DECENT RH RECOVERIES ACROSS THE
BASIN AND RANGE IN THE EVENING WILL BRING IMPROVED CONDITIONS
AS WELL. -AMANDA
HYDROLOGY
HEAVY RAINFALL DUE TO AN ATMOSPHERIC RIVER MAKING LANDFALL IN
NORTHERN CA WILL LIKELY CAUSE PONDING IN POOR DRAINAGE AREAS AND
INCREASING FLOWS ALONG RIVERS AND STREAM THROUGHOUT THE AREA LATE
WEDNESDAY THROUGH FRIDAY. IF THE STORM SYSTEMS TREND TOWARD BEING
ON THE WETTER AND WARMER SIDE OF THE FORECAST, MINOR FLOODING
WILL BE POSSIBLE ALONG SMALL CREEKS AND STREAMS IN NORTHEASTERN
CALIFORNIA AND THE SUSAN RIVER. RECENT BURN AREAS WILL ALSO BE A
CONCERN FOR MINOR FLOODING, EXACERBATED BY THE TRANSPORT OF ASH,
SEDIMENT, AND DEBRIS THAT MAY OBSTRUCT DRAINAGE AREAS.
THERE IS CONSIDERABLE UNCERTAINTY IN THE HYDROLOGIC RESPONSE DUE,
NOT ONLY TO THE RANGE IN THE PRECIPITATION FORECAST, BUT ALSO
UNCERTAINTY IN THE VARYING PRECIPITATION TYPE WITH TRANSITIONS FROM
SNOW TO RAIN AND BACK TO SNOW AGAIN FROM WEDNESDAY INTO THE WEEKEND.
ADDITIONAL CONSIDERATION SHOULD BE GIVEN TO THE FACT THAT AT STORM
ONSET SOILS WILL BE DRY WITH GENERALLY LOW STREAMFLOWS, WHICH WILL
DELAY AND MUTE STREAMFLOW RESPONSES INITIALLY. KEEP AN EYE ON RIVER
FORECAST UPDATES AT CNRFC.NOAA.GOV.
-BARDSLEY/AMANDA
REV WATCHES/WARNINGS/ADVISORIES
NV... RED FLAG WARNING FROM 10 AM TO 7 PM PST WEDNESDAY
NVZ420-421-423-429.
LAKE WIND ADVISORY FROM 10 PM THIS EVENING TO 7 PM PST WEDNESDAY
NVZ002.
WIND ADVISORY FROM 10 AM TO 7 PM PST WEDNESDAY NVZ001-003.
CA...WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 PM PST
WEDNESDAY CAZ071.
RED FLAG WARNING FROM 10 AM TO 7 PM PST WEDNESDAY CAZ274.
LAKE WIND ADVISORY FROM 10 PM THIS EVENING TO 7 PM PST WEDNESDAY
CAZ072.
WIND ADVISORY FROM 10 AM TO 7 PM PST WEDNESDAY CAZ073.
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