Special Weather Statement, NWS Reno, NV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
257 AM PDT WED AUG 21 2013

.SYNOPSIS...
LOW PRESSURE OFF THE CENTRAL CALIFORNIA COAST WILL MOVE SLOWLY
ACROSS NORTHERN CALIFORNIA THROUGH THURSDAY. VERY MOIST AND
UNSTABLE AIR MASS WILL LEAD TO STRONG THUNDERSTORMS CAPABLE OF
PRODUCING HAIL AND VERY HEAVY RAINFALL TODAY. ON THURSDAY THE
BEST CHANCE FOR THUNDERSTORMS MOVES NORTH OF INTERSTATE 80. FROM
FRIDAY THROUGH EARLY NEXT WEEK, DRY CONDITIONS AND NEAR NORMAL
TEMPERATURES ARE EXPECTED.

&&

.SHORT TERM...
AFTER SEVERAL DAYS OF REASONABLY GOOD MODEL AGREEMENT AND
FAVORABLE MOISTURE AND INSTABILITY PARAMETERS IN PLACE, HAVE
DECIDED TO ISSUE A FLASH FLOOD WATCH FROM RENO-TAHOE NORTHWARD
ACROSS NORTHEAST CA AND NORTHWEST NV. IN WESTERN NV, THE EASTERN
EDGE OF THE WATCH EXTENDS INTO A SMALL PORTION OF THE WEST CENTRAL
NV BASIN INCLUDING PYRAMID LAKE, AND FROM LYON COUNTY NORTHWARD
TO THE BLACK ROCK DESERT. SO FAR THIS SUMMER, PORTIONS OF
INTERSTATE 80, NV HIGHWAY 447, AND POOR DRAINAGE AREAS ACROSS
STREETS AND INTERSECTIONS IN RENO, SPARKS AND FERNLEY HAVE BEEN
IMPACTED BY FLOODING DUE TO INTENSE RAINFALL RATES EXCEEDING 2
INCHES PER HOUR. AT THESE RAINFALL RATES, EVEN THUNDERSTORMS
LASTING ONLY 15-30 MINUTES HAVE PRODUCED SOME CONCERNS IF THEY
AFFECTED A FLOOD PRONE LOCATION.

PRECIPITABLE WATER VALUES NEAR 1 INCH COMBINED WITH CAPE VALUES
NEAR 1000 J/KG AND THE UPPER FORCING ASSOCIATED WITH THE LOW WILL
NOT ONLY BRING THE THREAT OF HEAVY RAIN, BUT ALSO HAIL AND STRONG
WIND GUSTS. A FEW CELLS MAY REACH SEVERE CRITERIA THIS AFTERNOON
AND EVENING.

FOR TONIGHT, THUNDERSTORM ACTIVITY IS LIKELY TO CONTINUE MAINLY
NORTH OF SUSANVILLE AND GERLACH AS DEFORMATION ZONE SETS UP OVER
THAT AREA. SOME SHOWERS COULD REDEVELOP FARTHER SOUTH TO NEAR I-80
OVERNIGHT WHERE THE AIR MASS IS LIKELY TO REMAIN QUITE MOIST FROM
THE AFTERNOON AND EARLY EVENING ACTIVITY.

AS THE LOW MOVES NORTH THURSDAY, THE BEST FORCING AND INSTABILITY
SHIFTS NORTHWARD TO NORTHEAST CA-NORTHWEST NV WHERE ANOTHER ROUND
OF STORMS WITH HEAVY RAIN OR MARGINALLY SEVERE HAIL AND WIND GUSTS
ARE AGAIN POSSIBLE. SINCE THERE IS SOME UNCERTAINTY WITH THE
NORTHWARD MOVEMENT OF THE LOW, HAVE CONTINUED A POSSIBILITY OF
THUNDER SOUTHWARD TO NEAR HIGHWAY 50 IN THE AFTERNOON, THEN
PUSHING EAST OF RENO-TAHOE BY EARLY EVENING. AS DRIER AIR SWINGS
INTO THE REGION BEHIND THE LOW, WEST WINDS WILL INCREASE WITH
GUSTS TO 30 MPH FROM LATE AFTERNOON THROUGH THE EVENING.

ON FRIDAY, DRY SOUTHWEST FLOW WILL PREVAIL WITH A WEAK LATE DAY
ZEPHYR BREEZE. DAYTIME TEMPERATURES WILL BE CLOSE TO SEASONAL
NORMALS AROUND 90 FOR WESTERN NV AND NEAR 80 DEGREES IN THE TAHOE
BASIN. MJD

.LONG TERM...SATURDAY THROUGH TUESDAY...

A TROUGH DEVELOPING ALONG 130 WEST LONGITUDE AND RIDGE OVER THE
SOUTHERN PLAINS SHOULD KEEP A DRY SOUTHWEST FLOW OVER THE SIERRA AND
WESTERN NEVADA THIS WEEKEND AND INTO EARLY NEXT WEEK.  AFTERNOON
HIGHS WILL STAY WITHIN A FEW DEGREES OF NORMAL FOR LATE AUGUST, MID
80S TO LOW 90S FOR WESTERN NEVADA AND MID 70S TO LOW 80S FOR THE
EASTERN SIERRA.  WINDS WILL KICK UP IN THE AFTERNOONS AND EVENINGS
WITH PEAK GUSTS AT 25-30 MPH.

A FEW MODEL AND ENSEMBLE RUNS CONTINUE TO EITHER BUILD THE RIDGE A
BIT STRONGER TO THE WEST OR TRY TO DIG THE TROUGH A BIT DEEPER INTO
NORTHERN CALIFORNIA FOR EARLY NEXT WEEK.  THIS COULD LEAD TO A LOW
CHANCE OF SHOWERS NORTH OF SUSANVILLE TO GERLACH OR EAST OF HIGHWAY
95.  WILL CONTINUE TO MAINTAIN A DRY FORECAST WITH MOST OF THE
GUIDANCE SUPPORTING THE LITTLE TO NO PRECIPITATION.  BRONG

&&

.AVIATION...

LOW PRESSURE OFF THE CENTRAL CALIFORNIA COAST WILL BRING ANOTHER
ROUND OF SHOWERS AND STRONG THUNDERSTORMS TO THE EASTERN SIERRA,
WESTERN NEVADA AND NORTHEAST CALIFORNIA AFTER 20Z.  MAIN THREATS ARE
HEAVY RAIN, HAIL AND STRONG OUTFLOW WINDS OF 40-50 KTS. THE CHANCE
FOR A STORM DIRECTLY IMPACTING KRNO, KCXP, KMMH, KTVL AND KTRK IS
40-50 PERCENT TODAY.

AS THE LOW LIFTS NORTH FOR THURSDAY THREAT OF SHOWERS AND
THUNDERSTORMS WILL BE LIMITED TO AREAS NORTH OF KTVL-KNFL.  BRONG

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH FROM 2 PM PDT THIS AFTERNOON THROUGH THIS
     EVENING NVZ002>005.

CA...FLASH FLOOD WATCH FROM 2 PM PDT THIS AFTERNOON THROUGH THIS
     EVENING CAZ070>073.

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RENO NV
550 AM PDT WED AUG 21 2013

CAZ070>073-NVZ001>005-221300-
SURPRISE VALLEY CALIFORNIA-LASSEN-EASTERN PLUMAS-
EASTERN SIERRA COUNTIES-GREATER LAKE TAHOE AREA-MONO-
MINERAL AND SOUTHERN LYON COUNTIES-GREATER RENO-CARSON CITY-
MINDEN AREA-WESTERN NEVADA BASIN AND RANGE INCLUDING PYRAMID LAKE-
NORTHERN WASHOE COUNTY-
550 AM PDT WED AUG 21 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE EASTERN SIERRA...
NORTHEAST CALIFORNIA AND WESTERN NEVADA.

.DAY ONE...TODAY AND TONIGHT

SHOWERS AND THUNDERSTORMS WILL DEVELOP IN THE SIERRA...WESTERN
NEVADA...AND NORTHEAST CALIFORNIA. STRONGER STORMS MAY PRODUCE
HEAVY RAIN...HAIL UP TO 1 INCH AND WIND GUSTS TO 60 MPH. A FLASH
FLOOD WATCH IS IN EFFECT FOR NORTHEAST CALIFORNIA...NORTHWEST
NEVADA AND THE LAKE TAHOE BASIN. A FEW STORMS MAY LAST INTO THE
LATE EVENING ESPECIALLY IN THE NORTHERN SIERRA.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A CHANCE OF THUNDERSTORMS WILL CONTINUE ON THURSDAY IN NORTHEAST
CALIFORNIA AND NORTHWEST NEVADA NORTH ON INTERSTATE 80 WITH THE
MOST LIKELY AREA FROM SUSANVILLE NORTH. FRIDAY THROUGH THE MIDDLE
OF NEXT WEEK WILL BE DRY WITH TEMPERATURES NEAR NORMAL.

.SPOTTER INFORMATION STATEMENT...
SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER TO THE
NATIONAL WEATHER SERVICE ACCORDING TO STANDARD OPERATING PROCEDURE.

REPORTS OF SEVERE WEATHER ARE ALSO WELCOME BY POSTING TO THE
NATIONAL WEATHER SERVICE RENO FACEBOOK PAGE...OR ON TWITTER
USING...AT NWSRENO.

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RENO NV
1225 PM PDT WED AUG 21 2013

CAZ072-NVZ002-003-212030-
GREATER LAKE TAHOE AREA-GREATER RENO-CARSON CITY-MINDEN AREA-
1225 PM PDT WED AUG 21 2013

...STRONG THUNDERSTORMS MOVING OVER LAKE TAHOE...

AT 1220 PM PDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE
TRACKING A STRONG THUNDERSTORM NEAR SOUTH LAKE TAHOE...AND MOVING
NORTH AT 20 MPH.

FREQUENT DEADLY LIGHTNING...HEAVY RAIN WITH AMOUNTS NEAR ONE INCH PER
HOUR...SMALL PEA SIZE HAIL...AND GUSTY WINDS TO 45 MPH...WILL OCCUR
WITH THIS STORM.

* LOCATIONS AFFECTED THROUGH 130 PM PDT INCLUDE...CRYSTAL BAY...
  INCLINE VILLAGE...DAGGET PASS...GLENBROOK...KINGSBURY AND SPOONER
  SUMMIT.

IF ON OR NEAR A LAKE...GET OUT OF THE WATER AND MOVE INDOORS OR
INSIDE A VEHICLE NOW. DON'T BE CAUGHT ON THE WATER IN A THUNDERSTORM.
STRONG WIND GUSTS AND LIGHTNING POSE AN IMMEDIATE DANGER TO BOATERS.
GUSTY WINDS WILL CAUSE A RAPID INCREASE IN WAVE HEIGHTS WHICH MAY
CAPSIZE SMALL BOATS.

HIKERS AND CAMPERS SHOULD SEEK SHELTER IN A VEHICLE IF POSSIBLE.
TENTS AND TREES ARE UNSAFE SHELTERS DURING THUNDERSTORMS. STAY AWAY
FROM CREEKS AND STREAMS AS WATER LEVELS MAY RISE RAPIDLY NEAR
THUNDERSTORMS.

&&

LAT...LON 3928 12027 3935 11993 3886 11983 3881 12005
TIME...MOT...LOC 1924Z 166DEG 16KT 3893 11997

SNYDER