Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 050343 AAA
AFDREV

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RENO NV
843 PM PDT MON MAY 4 2015

.UPDATE...
SHOWER COVERAGE HAS DIMINISHED CONSIDERABLY OVER THE PAST COUPLE
HOURS WITH LOSS OF DAYTIME HEATING. WEAK SHORTWAVE ALOFT COUPLED
WITH RESIDUAL MOISTURE MAY BE ENOUGH TO KICK OFF A SHOWER OR TWO
THROUGH THE OVERNIGHT HOURS, SO HAVE RETAINED ~20% POPS. REST OF
FORECAST UNCHANGED.

SCATTERED BUT WELCOME RAINS EARLIER TODAY. RADAR ESTIMATES ARE
CLOSE TO GAUGES IN THE RENO/SPARKS AREA WHERE UP TO ABOUT 0.4"
FELL OVER SPARKS EAST OF PYRAMID HWY. THE HEAVIEST RAINS WERE
NORTH OF SMITH VALLEY AND FROM ABOUT ALPINE COUNTY EAST TO MINERAL
COUNTY WHERE SOME AREAS LIKELY PICKED UP AT LEAST 0.5" OF RAIN.

CS


&&

.PREVIOUS DISCUSSION... /ISSUED 225 PM PDT MON MAY 4 2015/

SYNOPSIS...
WARM TEMPERATURES AND CHANCES FOR SHOWERS AND THUNDERSTORMS WILL
CONTINUE INTO MONDAY EVENING. ANOTHER ROUND OF THUNDERSTORMS IS
POSSIBLE SOUTH OF HIGHWAY 50 TUESDAY. LOW PRESSURE DROPPING OUT OF
THE GULF OF ALASKA WILL BRING MUCH COOLER TEMPERATURES AND MORE
WIDESPREAD SHOWER ACTIVITY FOR MID TO LATE WEEK.

SHORT TERM...
CONVECTION STARTED A LITTLE EARLIER TODAY AND IS CREEPING UP THE
SPINE OF THE SIERRA TOWARD THE SOUTH END OF THE TAHOE BASIN. WE
ARE NOT EXPECTING MUCH MORE THAN TYPICAL THUNDERSTORMS WITH GUSTY
WINDS TO NEAR 40-45 MPH AND SMALL HAIL THROUGH THIS EVENING. WEAK
WESTERLIES SHOULD DEVELOP LATE IN THE AFTERNOON/EARLY EVENING AND
PUSH ANY STORMS OUT OF THE TAHOE BASIN AND INTO WRN NV. THE
STRONGEST STORMS THIS EVENING SHOULD BE CONFINED TO AREAS SOUTH OF
HIGHWAY 50.

LITTLE HAS CHANGED IN THE FORECAST THINKING BEYOND TONIGHT.
MODELS STILL INDICATE A TROUGH DROPPING SOUTH TOWARD THE REGION
TUESDAY. INCREASED SW FLOW ALOFT AHEAD OF THIS TROUGH SHOULD
DECREASE THE CHANCES FOR CONVECTION OVER THE NORTHERN 2/3RDS OF
THE CWA TUESDAY. THE BEST INSTABILITY AND LIGHTEST WINDS ALOFT
WILL REMAIN OVER THE FAR SOUTHERN CWA...GENERALLY ALONG AND SOUTH
OF A LINE FROM BRIDGEPORT TO YERINGTON TO AUSTIN. SO WE HAVE KEPT
MENTION OF CONVECTION CONFINED TO THAT AREA. SINCE THERE IS LITTLE
IN THE WAY OF FORCING AFTER SUNSET FOR THAT REGION...WE WILL LET
ALL SHOWERS DROP OUT BY MIDNIGHT. TEMPS TUESDAY SHOULD BE A DEGREE
OR TWO COOLER THAN MONDAY.

BY WEDNESDAY THE PATTERN BEGINS TO SHIFT TO A MORE WIDESPREAD
SHOWERY SCENARIO AS THE UPPER LOW INCHES CLOSER TO THE REGION. THIS
WILL RESULT IN COOLER DAYTIME HIGHS AND MORE CLOUD COVER. SURFACE
BASED INSTABILITY DOES NOT LOOK AS GOOD FOR WEDNESDAY...BUT THERE
IS SOME COOLING ALOFT WHICH WILL AID IN THE DEVELOPMENT OF CONVECTION.
THE QUESTION IS HOW MUCH WILL BE DEEP CONVECTION (THUNDERSTORMS).
FOR NOW THE GUESS IS MOSTLY ISOLATED THUNDERSTORMS SPRINKLED IN
AMONGST THE SCATTERED SHOWERS FOR THAT DAY. WINDS MAY GUST UP TO
NEAR 30 MPH INITIALLY LATE TUESDAY NIGHT INTO WEDNESDAY MORNING
BEFORE DROPPING A BIT THROUGH THE DAY AS THE UPPER LOW SETTLES A
LITTLE CLOSER TO THE FORECAST AREA. HIGH TEMPERATURES WEDNESDAY
SHOULD BE IN RANGE OF 8-12 DEGREES COOLER THAN TUESDAY...POSSIBLY
BELOW AVERAGE IN THE WRN NV VALLEYS. 20

LONG TERM...THURSDAY THROUGH MONDAY...
THE FORECAST IS ON TRACK FOR A LOW-PRESSURE TROUGH TO BRING
COOLER AND WETTER CONDITIONS FOR THE END OF THIS WEEK (MEDIUM TO
HIGH CONFIDENCE). A COLD FRONT TRAVELING SOUTH OUT OF OREGON
WEDNESDAY NIGHT IS EXPECTED TO REACH HIGHWAY 50 BY SUNRISE
THURSDAY MORNING. THE COOLER AIR MASS THURSDAY SHOULD DROP HIGHS
ABOUT 10 TO 15 DEGREES FROM WEDNESDAY WITH MANY LOCATIONS IN THE
50S AND SOME SIERRA COMMUNITIES IN THE MID TO UPPER 40S. SNOW
AND/OR ICE PELLET ACCUMULATIONS WILL BE POSSIBLE ON ROADWAYS, AND
ANYONE WORKING OR RECREATING OUTDOORS IN THE MOUNTAINS SHOULD BE
PREPARED FOR WINTER-LIKE CONDITIONS.

A LONGER DURATION PRECIPITATION BAND COULD ALSO SET UP ACROSS
WESTERN NV AND SOME PORTION OF THE EASTERN SIERRA. HOWEVER, THIS
REMAINS UNCERTAIN AS MODEL GUIDANCE DIFFERS ON THE TRACK OF THE
UPPER LOW. AT THIS TIME, THE BEST CHANCE FOR THIS BAND TO SET UP IS
DURING THE THU-THU NIGHT PERIOD AND FOR LOCATIONS SOUTH OF HIGHWAY
50 AND FROM HIGHWAY 95 EASTWARD, WITH SOME GUIDANCE SUGGESTING IT
COULD WRAP AROUND THE UPPER LOW AND SPREAD WESTWARD TOWARDS SOME
PORTION OF THE SIERRA EAST SLOPES.

SAT-SUN A WARMING TREND IS EXPECTED AS A TRANSIENT HIGH-PRESSURE
RIDGE MOVES OVER THE SIERRA AND GREAT BASIN.  THE WARMING TREND
MAY NOT LAST THOUGH AS THERE IS POTENTIAL FOR ANOTHER LOW-PRESSURE
SYSTEM TO BRING A RETURN OF COOLER AND WETTER CONDITIONS BY MONDAY
OR TUESDAY. JCM

AVIATION...
SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THE EARLY EVENING...
WITH THE STRONGEST STORMS SOUTH OF HIGHWAY 50. NEAR THE THUNDERSTORMS
GUSTY OUTFLOW WINDS...HAIL AND TURBULENCE ARE LIKELY. THE MOST
LIKELY TERMINAL TO BE AFFECTED BY STORMS THIS EVENING IS KMMH...
BUT STORMS COULD ALSO AFFECT APPROACHES INTO KHTH...KCXP...KMEV
AND KTVL. CONVECTION SHOULD BE OUT OF THE FORECAST AREA BY 5/05
UTC (10PM PDT).

CONVECTION FOR TUESDAY SHOULD BE LIMITED TO AREAS SOUTH OF
BRIDGEPORT TO YERINGTON TO AUSTIN. AN APPROACHING UPPER LOW WILL
BRING SLIGHTLY STRONGER SW FLOW ALOFT TO AREAS NORTH OF THAT LINE
AND LIMIT THE ABILITY FOR STORMS TO DEVELOP.

MORE WIDESPREAD SHOWERY WEATHER WITH INTERMITTENT LOWER CIGS WILL
START LATE WEDNESDAY AS THE UPPER BEGINS TO SETTLE OVER THE REGION.
20

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&

$$

FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)






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