Flash Flood Warning 15, NWS Hanford, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
208 PM PDT SUN JUL 20 2008

.DISCUSSION...KHNX 88D INDICATING A FEW HIGH BASED LIGHT SHOWERS
REMAIN OVER THE NORTHERN MOST PORTIONS OF OUR CWFA.
ELSEWHERE...SKIES HAVE CLEARED OUT FROM THE SOUTH THEN
SUBSEQUENTLY CUMULUS HAS BUILT UP AS THE RESULT OF INSTABILITY
IN A FAIRLY MOIST AIRMASS. 18Z WRF RUN INDICATING HIGH CAPES
REMAINING EAST OF OUR CWFA...BUT THERE REMAINS ENOUGH INSTABILITY
AND MID LEVEL MOISTURE TO KEEP MENTION OF A SLIGHT CHANCE TO LOW
CHANCE OF THUNDERSTORMS ACROSS THE MOUNTAINS AND KERN DESERTS
THROUGH THIS EVENING. TEMPERATURES HAVE BEEN RUNNING WELL BELOW
YDAY AS THE RESULT OF THE INCREASED MID LEVEL CLOUD COVER TODAY
WITH THE MOST PRONOUNCED COOLING IN THE CENTRAL AND SOUTH SAN
JOAQUIN VALLEY WHICH ALSO WAS IMPACTED BY AN INTRUSION OF LOW
LEVEL MARINE AIR OVERNIGHT WHERE TEMPERATURES HAVE BEEN RUNNING
AROUND 10 DEG F BELOW YDAY. SOME RECOVERY IS EXPECTED ON MONDAY AS
RH PROGS INDICATE SKIES CLEARING OUT TONIGHT AND P-GRADS HAVE BEEN
DECREASING TODAY.

WRF/GFS CONTINUE TO INDICATE A DRY UPPER LOW CURRENTLY DEPICTED BY
WV NEAR 37N/127W TO TRACK SLOWLY NORTHEAST TONIGHT AND MONDAY THEN
CROSS NORCAL MONDAY NIGHT. BEFORE THE LOW MOVES INLAND...OUR AREA
WILL STILL BE AFFECTED BY THE SURGE OF TROPICAL MONSOONAL
MOISTURE. 18Z WRF INDICATING CAPES OF 400 TO 800 J/KG ACROSS THE
KERN DESERTS AND 200 TO 400 KG OVER THE MOUNTAINS MONDAY AFTERNOON
WITH LI/S BELOW ZERO. WILL THEREFORE KEEP MENTION OF A SLIGHT
CHANCE OF THUNDERSTORMS FOR THESE AREAS FOR MONDAY AFTERNOON AND
EVENING. AFTER THE LOW PASSES BY TO OUR NORTH...HEIGHTS AND
THICKNESSES LOWER SOME ALLOWING FOR TEMPERATURES TO LOWER BY A FEW
DEG F FROM MONDAY. RH PROGS ARE INDICATING A MUCH DRIER AIRMASS
BUILDING INTO OUR AREAS AS WELL AS THE TROUGH ASSOCIATED WITH THIS
UPPER LOW PUSHES THE MONSOONAL MOISTURE WELL TO THE EAST OF OUR
AREA.

A DRY SOUTHWEST FLOW IS EXPECTED TO PREVAIL OVER CENTRAL CA FOR
THE MIDWEEK PERIOD WITH MEDIUM RANGE MODELS IN GOOD AGREEMENT
INDICATING THE LARGE RIDGE OVER THE SOUTH CENTRAL CONUS
RETROGRADING WESTWARD INTO THE FOUR CORNERS AREA BY THE END OF THE
WEEK. THIS WILL RESULT IN A WARMING TREND ACROSS OUR AREA AS
HEIGHTS AND THICKNESSES RISE...PUSHING TEMPERATURES ABOVE CLIMO.
RH PROGS FROM THE GFS AND ECMWF ARE INDICATING THAT MID/UPPER
MONSOONAL MOISTURE WILL RETURN TO THE SOUTHEASTERN PORTION OF OUR
CWFA BY FRIDAY. HOWEVER....ANOTHER TROUGH IS PROGGED TO PUSH INTO
WESTERN CONUS OVER THE WEEKEND WHICH COULD DEFLECT MOST OF THIS
MOISTURE EAST OF OUR AREA. BECAUSE TIMING UNCERTAINTIES WITH THE
RETURN OF THE MONSOON AND THE TROUGH THAT MAY PUSH IT OUT OF OUR
AREA...WILL KEEP MENTION OF LOW POPS IN THE GRIDS ACROSS THE
MOUNTAINS AND KERN DESERTS FOR FRIDAY THROUGH SUNDAY BUT WILL NOT
MENTION THUNDERSTORMS IN THE FORECAST FOR THIS TIME PERIOD UNTIL
CONFIDENCE IMPROVES.

&&

.AVIATION...ISOLATED MVFR AND IFR IN ISOLATED SHOWERS AND
THUNDERSTORMS IN THE EAST SIDE FOOTHILLS AND ALONG THE CREST OF THE
SIERRA NEVADA RANGE AS WELL AS THE KERN COUNTY MOUNTAINS AND DESERT
THIS AFTERNOON AND AGAIN MONDAY AFTERNOON...OTHERWISE VFR CONDITIONS
WILL CONTINUE ACROSS THE REGION THROUGH 00Z TUESDAY.

&&

.AIR QUALITY ISSUES...
ON MONDAY JULY 21 2008...UNHEALTHY FOR SENSITIVE GROUPS IN KERN
AND TULARE COUNTIES. FURTHER INFORMATION IS AVAILABLE AT
VALLEYAIR.ORG

&&

.HNX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

PUBLIC...DS
AVN/FW...JDB

WEATHER.GOV/HANFORD

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
550 AM PDT SUN JUL 20 2008

CAZ095>099-211300-
KERN COUNTY MOUNTAINS-SIERRA NEVADA FROM YOSEMITE TO KINGS CANYON-
TULARE COUNTY MOUNTAINS-INDIAN WELLS VALLEY-
SOUTHEASTERN KERN COUNTY DESERT-
550 AM PDT SUN JUL 20 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE SOUTHERN SIERRA
NEVADA...THE TEHACHAPI MOUNTAINS AND THE KERN COUNTY DESERTS.

.DAY ONE...TODAY AND TONIGHT

A RENEWED SOUTHERLY WIND FLOW MAY BRING A RETURN OF MONSOON TYPE
MOISTURE INTO THE KERN COUNTY DESERTS...THE TEHACHAPI MOUNTAINS
AND SOUTHERN SIERRA NEVADA. THERE WILL BE A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS OVER THE KERN COUNTY MOUNTAINS AND
DESERTS THIS MORNING...SPREADING NORTH OVER THE SOUTHERN SIERRA
NEVADA BY THIS AFTERNOON AND CONTINUING INTO THIS EVENING. LOCALLY
HEAVY RAIN FROM THUNDERSTORMS COULD CAUSE RENEWED CONCERN FOR
FLASH FLOODING IN THOSE AREAS MOST PRONE.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

HERE WILL BE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS MONDAY
AFTERNOON AND EVENING OVER THE MOUNTAINS OF FRESNO...TULARE AND
KERN COUNTIES AND OVER THE KERN COUNTY DESERTS. LOCALLY HEAVY RAIN
FROM THUNDERSTORMS COULD CAUSE RENEWED CONCERN FOR FLASH FLOODING
IN THOSE AREAS MOST PRONE. OTHERWISE...NO HAZARDOUS WEATHER IS
ANTICIPATED.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION MAY BE NECESSARY FOR THE SOUTHERN
SIERRA NEVADA...THE TEHACHAPI MOUNTAINS AND THE KERN COUNTY
DESERTS.

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT OR
UNUSUAL CONDITIONS TO THE NATIONAL WEATHER SERVICE.

WEATHER.GOV/HANFORD