Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 291008
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
308 AM PDT TUE JUL 29 2014

.SYNOPSIS...
ABUNDANT MOISTURE WILL CONTINUE PUSHING NORTH INTO THE REGION WITH
VARYING CHANCES FOR THUNDERSTORMS THROUGH THE WEEK. AN UPPER LEVEL
DISTURBANCE COULD BRING A FEW STRONGER THUNDERSTORMS THIS AFTERNOON.
TEMPERATURES WILL REMAIN NEAR OR SLIGHTLY ABOVE NORMAL.

&&

.SHORT TERM...

A FEW ADJUSTMENTS TO THE FORECAST TODAY MAINLY TO SPREAD SCATTERED
STORM COVERAGE ACROSS MUCH OF THE FORECAST AREA. WE WILL REMAIN
ON THE WESTERN PERIPHERY OF AN UPPER-LEVEL RIDGE WHICH WILL KEEP
DEEP MOISTURE OVER THE REGION (PWATS >0.75"). THE MAIN UNCERTAINTY
FOR TODAY WILL BE INSTABILITY AND VORTICITY FORCING. LATEST
GUIDANCE SUGGESTS A VORTICITY MAX MOVING ACROSS WESTERN NEVADA
ROUGHLY OVER NORTHERN LYON COUNTY BY LATE MORNING. HOWEVER,
LOCATING THESE FEATURES ON WATER VAPOR SATELLITE PROVES DIFFICULT
WITH THE LARGE MASS OF DEEP MOISTURE ACROSS NEVADA SO CONFIDENCE
IS ONLY MEDIUM IN THE FORCING ASPECT. STORM LAYER WINDS ARE
LARGELY IN THE 10-20 KT RANGE SO COULD SEE HYBRID TYPE STORMS THAT
PRODUCE STORMS WITH HEAVY RAINFALL WITH THE POTENTIAL FOR ISOLATED
DRY LIGHTNING STRIKES. GUSTY OUTFLOW WINDS ARE STILL POSSIBLE
ALTHOUGH LESS LIKELY THAN YESTERDAY AFTERNOON WITH WEAKER DCAPES
AND HIGHER SUBCLOUD LAYER HUMIDITY.

FOR WEDNESDAY, HEAVY RAINFALL AND AREAS OF FLASH FLOODING LOOK TO BE
THE PRIMARY CONCERNS. WE CONTINUE WITH HIGH PWATS WITH BETTER
INSTABILITY PARTICULARLY ACROSS MONO, MINERAL, AND SOUTHERN LYON
COUNTIES. STORM LAYER WINDS WILL AVERAGE AGAIN BETWEEN 10-20 KTS BUT
BECOME ORIENTED MORE NORTH-SOUTH WHICH MAY FAVOR TRAINING ACROSS
HIGHER TERRAIN. BOTH THE EC AND GFS ARE DEPICTING A FAIRLY STRONG
VORTICITY MAX TO PUSH ACROSS WESTERN NEVADA LATE WEDNESDAY AFTERNOON
AND EVENING. THIS COUPLED WITH A MODEST CONVERGENCE/DIVERGENCE
COUPLET ASSOCIATED WITH A WEAK UPPER JET MAY FOCUS THE THREAT FOR
HEAVY RAIN AND FLASH FLOODING PARTICULAR FOR AREAS SOUTH OF HIGHWAY
50 LATE WEDNESDAY AFTERNOON INTO THE EVENING. DID ALSO INSERT
MENTION OF STORMS OVERNIGHT PARTICULARLY OVER PERSHING-CHURCHILL
COUNTIES WITH DYNAMIC FORCING IN PLACE.

BY THURSDAY, THE THREAT TRANSITIONS MORE TOWARDS STRONGER
THUNDERSTORM OUTFLOW WIND GUSTS AND INCREASED POTENTIAL FOR DRY
LIGHTNING STRIKES. THIS WILL BE DUE TO A SWATH OF DRIER AIR THAT
WILL BEGIN TO PUSH ACROSS CALIFORNIA AND WESTERN NEVADA WITH DCAPE
VALUES OVER 1200 J/KG ACROSS MUCH OF THE REGION. SOME DISAGREEMENT
EXISTS HOWEVER WITH HOW QUICKLY THIS DRY AIR MOVES IN WITH THE GFS
MUCH DRIER THAN THE NAM BY THURSDAY AFTERNOON. ASIDE FROM STORM
THREATS, TEMPERATURES WILL REMAIN NEAR SEASONAL AVERAGE WITH LOW TO
MID 90S ACROSS WESTERN NEVADA AND MID 80S ACROSS SIERRA VALLEYS.
FUENTES

.LONG TERM...FRIDAY THROUGH MONDAY...

MOISTURE AND INSTABILITY REMAIN IN THE FORECAST THROUGH THE WEEKEND
AND INTO NEXT WEEK. THE FOUR CORNERS RIDGE REMAINS IN PLACE WITH A
TROUGH DEVELOPING OFF THE CA COAST THIS WEEKEND. HIGH TEMPERATURES
WILL REMAIN IN THE 90S FOR THE LOWER ELEVATIONS AND 80S IN THE
SIERRA.

SOUTHWEST FLOW ALOFT WILL LIKELY KEEP CONVECTION OUT OF THE NORTHERN
SIERRA AND TAHOE BASIN FRIDAY AND SATURDAY, WITH THE BEST CHANCES
FOR THUNDERSTORMS IN WESTERN NEVADA. BY SUNDAY, THE OFFSHORE TROUGH
STARTS TO TURN THE FLOW TO MORE OF A SOUTHERLY DIRECTION, ALLOWING
FOR THUNDERSTORMS TO RETURN TO THE NORTHERN SIERRA CREST AND TAHOE
BASIN SUNDAY AND MONDAY. OVERNIGHT SHOWERS AND THUNDERSTORMS ARE
ALSO POSSIBLE EACH NIGHT AS THERE WILL BE PLENTY OF AVAILABLE MID
LEVEL MOISTURE AND UPPER FORCING TO KICK OFF NOCTURNAL CONVECTION.

BY FRIDAY AND SATURDAY, PRECIPITABLE WATER VALUES DROP OFF TO AROUND
0.60" UNDER SOUTHWEST FLOW. THIS WILL CAUSE CLOUD BASES TO INCREASE
TO OVER 15K FEET MSL. MODEST STORM MOTIONS AROUND 15KTS WILL ALLOW
FOR INCREASED SUB-CLOUD EVAPORATION AND LESS RAINFALL REACHING THE
GROUND. THIS WILL INCREASE THE CHANCES FOR NEW LIGHTNING FIRES ON
BOTH FRIDAY AND SATURDAY. MODELS ARE SHOWING DEEP INVERTED-V
SOUNDINGS AND DOWNDRAFT CAPE OVER 1500 J/KG, DEMONSTRATING THE
POTENTIAL FOR VERY POWERFUL OUTFLOW WINDS ON BOTH THOSE DAYS.

BY SUNDAY AND MONDAY, AS THE FLOW ALOFT BEGINS TO TURN SOUTH TO
SOUTHEAST, PWATS WILL INCREASE TO AROUND 0.70-0.9", ALONG WITH FOR
SLOWER STORM MOTIONS AND HIGHER POTENTIAL LOCALLY HEAVY RAINFALL.
HOON

&&

.AVIATION...

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED FOR THE ENTIRE
FORECAST AREA TODAY. STORMS WILL DEVELOPING OFF THE HIGH SIERRA
AROUND 18Z AND PUSHING NORTH AND EAST THROUGH THE AFTERNOON AND
EVENING.

HIGHEST CHANCES FOR THUNDERSTORMS ARE NORTH OF KSVE AND NEAR
KMMH/KBAN WITH A 40% CHANCE OF A THUNDERSTORM DIRECTLY HITTING THE
TERMINAL. KRNO, KTRK, KTVL, KNFL, AND KLOL HAVE A SLIGHTLY LOWER
CHANCE AT AROUND 25%. LOCALLY HEAVY RAINFALL, SMALL HAIL, AND GUSTY
OUTFLOW TO 30-40 KT ARE POSSIBLE NEAR THUNDERSTORMS TODAY. SIMILAR
CONDITIONS ARE EXPECTED AGAIN FOR WEDNESDAY. HOON

&&


.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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