939
FXUS65 KVEF 150921
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
221 AM PDT SUN SEP 15 2019
SYNOPSIS
TODAY WILL BRING ONE MORE DAY OF ABOVE NORMAL
TEMPERATURES BEFORE A LOW PRESSURE SYSTEM DROPPING DOWN FROM THE
PACIFIC NORTHWEST MOVES ACROSS THE SOUTHERN SIERRA AND GREAT BASIN
ON MONDAY BRINGING VERY WINDY CONDITIONS AND SIGNIFICANTLY COOLER
TEMPERATURES. ANOTHER WEATHER SYSTEM WILL FOLLOW A SIMILAR TRACK
AND BRING MORE WIND TO THE REGION WEDNESDAY THROUGH FRIDAY.
DISCUSSION
TODAY THROUGH NEXT SUNDAY.
ABOVE-AVERAGE TEMPERATURES CONTINUE TODAY, THOUGH CLOUD COVER AND
WIND SPEEDS ARE EXPECTED TO PICK UP THIS EVENING. THE ZONAL FLOW
THAT HAS BEEN BRINGING HOT, BUT PLEASANT, CONDITIONS TO OUR AREA
WILL BEGIN TO BREAK DOWN TODAY AS WE PREPARE FOR AN INCOMING DIGGING
TROUGH FROM THE PACIFIC NORTHWEST.
INITIALLY, IMPACTS FROM THIS INCOMING WEATHER SYSTEM INCLUDE A
WIDESPREAD INCREASE IN CLOUD COVER, AN INCREASE IN PRECIPITATION
CHANCES FOR MOHAVE COUNTY, A WIDESPREAD GRADUAL UP-TICK IN WIND
SPEEDS THROUGH THE AFTERNOON AND EVENING, AND AN EVENTUAL STARK DROP
IN TEMPERATURES. A SOUTHERLY FLOW WILL SET UP AS THE TROUGH
APPROACHES, AND WITH THIS FLOW WILL BE AN ASSOCIATED MILD MOISTURE
FLUX INTO MOHAVE COUNTY. THIS MOISTURE WILL BRING THE CHANCE OF
ISOLATED SHOWERS AND THUNDERSTORMS INTO NORTHWESTERN ARIZONA THIS
AFTERNOON AS WELL AS MONDAY AFTERNOON. WITH REGARD TO WINDS, WE WILL
BEGIN TO SEE IMPACTS ALONG THE EASTERN SIERRA SLOPES AND POSSIBLY
DOWN THE OWENS VALLEY SUNDAY EVENING AND THROUGH THE OVERNIGHT
HOURS. THOUGH, AS THESE INCREASED WIND SPEEDS SPREAD NORTH AND EAST
TO ENCOMPASS MUCH OF THE SOUTHERN GREAT BASIN, SPEEDS LOOK TO PEAK
MONDAY AFTERNOON AND EVENING WITH WIDESPREAD GUSTS 40-45 MPH. DUE TO
THE POSSIBLE DOWNSLOPE WIND EVENT IN THE SIERRA, WIND GUSTS IN
EXCESS OF 60 MPH ARE POSSIBLE MONDAY. AS A RESULT OF THESE FORECAST
SPEEDS, WE HAVE ISSUED A HIGH WIND WATCH FOR THE EASTERN SIERRA
SLOPES AND OWENS VALLEY ON MONDAY. IMPACTS TO THE OWENS VALLEY ARE
WITH LOW CONFIDENCE AT THIS TIME. RAP FORECAST SOUNDINGS INDICATE
THE PRESENCE OF A POSSIBLE INVERSION, THOUGH SHEAR LOOKS LIMITED -
BOTH COMPONENTS NECESSARY FOR A HIGH CONFIDENCE FORECAST OF
DOWNSLOPE WINDS REACHING THE VALLEY. WILL CONTINUE TO MONITOR
POTENTIAL IMPACTS TO THE OWENS VALLEY AS WE GET CLOSER. THANKFULLY,
AT THIS TIME, WIND SPEEDS LOOK TO DROP OFF LATE MONDAY NIGHT.
AS THIS DIGGING TROUGH EXITS OUR AREA THROUGH TUESDAY, AN ASSOCIATED
COLD FRONT WILL PLUMMET TEMPERATURES ACROSS THE REGION. FORECAST
HIGHS WILL HAVE AN 8-12 DEGREE DROP BETWEEN SUNDAY AND TUESDAY WITH
MANY AREAS SEEING BELOW-90 DEGREE AFTERNOON TEMPERATURES.
ANOTHER TROUGH IS EXPECTED TO DIG FROM THE PACIFIC NW INTO OUR AREA
THURSDAY AND INTO THE WEEKEND. IMPACTS ASSOCIATED WITH THIS INCLUDE
PERSISTENT HIGH TEMPERATURES IN THE UPPER-80S TO LOWER-90S AND A
RETURN OF BREEZY CONDITIONS.
FIRE WEATHER
ABOVE-AVERAGE TEMPERATURES CONTINUE TODAY, THEN A
STRONG LOW PRESSURE SYSTEM WILL BRING GUSTY WINDS TO INYO COUNTY
SUNDAY AFTERNOON, SPREADING ACROSS MOST OF SOUTHERN NEVADA MONDAY. A
RED FLAG WARNING IS IN EFFECT FOR INYO COUNTY CALIFORNIA ZONES FROM
3 PM SUNDAY UNTIL 9 PM PDT MONDAY. HIGH DOWNSLOPE WINDS GUSTING TO
AT LEAST 60 MPH WILL BE POSSIBLE ALONG THE EASTERN SIERRA SLOPES AND
ADJACENT AREAS OF THE OWENS VALLEY EARLY MONDAY AFTERNOON THROUGH
EARLY MONDAY EVENING. A RED FLAG WARNING IS IN EFFECT FOR THE
SOUTHERN NEVADA ZONES FROM 11 AM MONDAY MORNING UNTIL 9 PM PDT
MONDAY EVENING. A BELT OF STRONG SOUTHWEST WINDS GUSTING NEAR 40 MPH
IS FORECAST FOR THE SOUTHERN GREAT BASIN. THESE STRONG WINDS WILL BE
ACCOMPANIED BY MINIMUM RH VALUES IN THE SINGLE-DIGITS TO LOWER-TEENS.
AVIATION...FOR MCCARRAN
EXPECT SOUTHERLY WINDS INCREASING TO 10
TO 15 KNOTS THIS AFTERNOON, WITH GUSTS 20 TO 25 KNOTS POSSIBLE
OVERNIGHT. SOUTHERLY WINDS WILL PEAK MONDAY, WITH GUSTS OF 30 TO 35
KNOTS POSSIBLE. THERE WILL BE A CHANCE OF THUNDERSTORMS EACH DAY IN
THE PEACH SPRINGS CORRIDOR, BUT NOT AT THE TERMINAL, WHERE NO
OPERATIONALLY SIGNIFICANT CLOUDS ARE EXPECTED THROUGH THE PERIOD.
FOR THE REST OF SOUTHERN NEVADA, NORTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA...SOUTHERLY WINDS GUSTING 15 TO 25 KNOTS ARE EXPECTED
AREAWIDE TODAY, WITH CHANCES FOR THUNDERSTORMS LIMITED TO MOHAVE
COUNTY. MONDAY WILL BE THE WINDIEST DAY FOR MOST AREAS, WITH
SOUTHWEST WINDS GUSTING TO 20 TO 30 KNOTS SOUTHEAST OF INTERSTATE 15
AND 30 TO 40 KNOTS NORTHWEST OF INTERSTATE 15. THERE WILL ALSO BE A
RISK OF DOWNSLOPE WINDS ON THE EASTERN SLOPES OF THE SIERRA, WITH
GUSTS OF 40 TO 50 KNOTS POSSIBLE. CHANCES FOR THUNDERSTORMS WILL BE
OVER MOHAVE COUNTY AGAIN, WITH CHANCES POSSIBLY SPREADING INTO
EASTERN CLARK AND LINCOLN COUNTIES AS WELL AS THE SIERRA AND NEARBY
AREAS.
SPOTTER INFORMATION STATEMENT
SPOTTERS ARE ENCOURAGED TO REPORT
ANY SIGNIFICANT WEATHER OR IMPACTS ACCORDING TO STANDARD OPERATING
PROCEDURES.
DISCUSSION/FIRE WEATHER...VARIAN
AVIATION..................MORGAN
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