Flash Flood in California, August 1, 2003

INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
155 PM PDT FRI AUG 1 2003

MAIN FORECAST CONCERN CONTINUES TO BE THE THUNDERSTORMS AND THE
POTENTIAL FOR HEAVY RAIN THE REMAINDER OF THIS AFTERNOON AND THIS
EVENING. A LARGE CLOUD MASS COVERS MUCH THE EASTERN CA DESERTS AND
THE SIERRA NEVADA THIS AFTERNOON. THUNDERSTORMS HAVE BEGUN
DEVELOPING ALONG THE WESTERN EDGE IN THE INTERFACE BETWEEN THE VERY
MOIST AIR AND THE LESS MOIST AIR FROM KERN COUNTY SOUTHWARD. WITH
PRECIPITAL WATER VALUES AROUND 1.2 INCHES AND RATHER LIGHT STEERING
WINDS WILL CONTINUE WITH FLASH FLOOD WATCH FOR THE KERN COUNTY
MOUNTAINS AND DESERT. HOWEVER...WITH THUNDERSTORMS EXPECTED TO
CONTINUE THROUGH THE EVENING HOURS...WILL EXTEND WATCH UNTIL 9 PM.

UPPER LOW OFF THE SRN CA COAST EXPECTED TO MOVE SLOWLY NORTHWARD
SATURDAY...WHILE UPPER HIGH OVER UT AND NM SHIFTS FARTHER EAST. THE
CORRESPONDING UPPER LEVEL FLOW SHIFTS TO MORE OF A SOUTH DIRECTION
SATURDAY. BUT WITH THE UPPER LOW BRINGING A VORTMAX OVER CENTRAL
CA...AND PLENTY OF MOISTURE REMAINING...CONVECTION MAY NOT BE
LIMITED TO THE SIERRA NEVADA. HAVE ADDED SLIGHT CHANCE POPS TO THE
VALLEY AND FOOTHILL ZONES FOR SATURDAY AND HAVE INCREASED THE POPS
IN THE MOUNTAIN ZONES SLIGHTLY. THE FLOW ALOFT FINALLY BECOMES
SOUTHWESTERLY SUNDAY AS AN UPPER TROUGH IN THE PACIFIC MOVES
NORTHEAST AND SETS ITSELF UP ALONG THE PACNW COAST. THIS WILL SHUT
OFF THE CONVECTIVE THREAT FOR ALL BUT THE SIERRA CREST SUNDAY.

IN THE EXTENDED PERIOD...TUE THRU FRI...LONG RANGE MODELS IN VERY
GOOD AGREEMENT IN THE 4 TO 6 DAY PERIOD WITH LONG WAVE TROUGH
POSITIONED OFF THE WEST COAST AND UPPER LEVEL RIDGE CENTERED ALONG
THE CONTINENTAL DIVIDE. IMPRESSIVE ONSHORE GRADIENTS DURING MIDWEEK
WOULD CONTINUE TO BRING REINFORCING MARINE PUSHES INTO THE SJ VLY IN
ADDITION TO SYNOPTIC COOLING OVER THE HIGHER ELEVATIONS. IN
ADDITION...WESTERLY WINDS MAY BE LOCALLY GUSTY THRU AND BELOW THE
MOUNTAIN PASSES OF KERN COUNTY DURING MIDWEEK AS WELL AS THE WEST
SIDE OF THE SJ VLY. TEMPS LIKELY TO AVERAGE A FEW DEGREES BELOW
NORMAL IN MOST AREAS. THE LATEST RUN OF THE GFS FORECASTS 850 MB
TEMPS TO COOL INTO THE MIDDLE TEENS (CELSIUS) OVER THE NORTHWEST
PORTION OF THE CWA BY TUE AFTN AND WED AFTN. SUPPLEMENTED WITH A
BRISK ONSHORE FLOW...MAX TEMPS COULD CONCEIVABLY BE ONLY 78 OR 79
DEGREES ON DAYS 3 AND 4 IN WESTERN MERCED CO. EVEN IN THE KERN CO
DESERT...TEMPS MAY PEAK JUST UNDER 90 DEGREES IN PLACES LIKE MOJAVE
BY WED. A WARMING TREND WILL BEGIN THURSDAY AND CONTINUE FRIDAY AS
UPPER LEVEL HIGH BUILDS WESTWARD TOWARD CA. BY FRI PM...THE GFS
WARMS 850 MB TEMPS INTO THE LOWER TO MID 20S (CELSIUS) ACROSS
INTERIOR CENTRAL CA...THUS NUDGING TEMPS TO NORMAL OR SLIGHTLY ABOVE
NORMAL BY THE CLOSE OF THE WORK WEEK. THE GFS GIVES NO INDICATION
THAT THE MONSOON WILL RETURN TO CENTRAL CA BY DAY 7...SO WILL KEEP
THE FORECAST DRY THROUGH THE EXTENDED PERIOD.

.HNX...FLASH FLOOD WATCH THIS EVENING FOR THE KERN COUNTY MOUNTAINS
AND DESERTS (ZONES 95, 98-99).

BEAN/DURFEE

CAZ089>099-021230-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
1000 AM PDT FRI AUG 1 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE CENTRAL CALIFORNIA
INTERIOR.

.DAY ONE...TODAY

THERE IS A CHANCE OF THUNDERSTORMS TODAY AND THIS EVENING. ANY
THUNDERSTORMS MAY CONTAIN BRIEF HEAVY RAIN...GUSTY WINDS...AND
DANGEROUS LIGHTNING. THE STRONGEST STORMS ARE EXPECTED TO DEVELOP
OVER THE KERN COUNTY MOUNTAINS AND DESERTS...AND A FLASH FLOOD WATCH
HAS BEEN ISSUED THROUGH 600 PM. REFER TO FFAHNX /WGUS66 KHNX/ FOR
DETAILS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS TO THEIR LOCAL NATIONAL WEATHER SERVICE OFFICE.

JSN