Heavy Rain in California, July 5, 2004

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
225 PM PDT MON JUL 5 2004

.SHORT TERM...FOR THE CENTRAL CALIFORNIA INTERIOR...TEMPS WILL
BE NEAR THE CENTURY MARK IN THE SJ VLY AND LOWER FOOTHILLS LATER
THIS AFTN. AND IT WILL BE THE FIRST TIME SINCE JUNE 16TH THAT
THERMOMETER READINGS CLIMB TO 100 DEGREES OR HIGHER IN THESE
LOCALES. BLAME IT ON A STRONG (591DM) RIDGE OF HIGH PRESSURE
ALOFT THAT IS CENTERED OVER CA TODAY. THE MODELS FORECAST THIS
RIDGE TO STRENGTHEN A LITTLE MORE AND REMAIN PARKED OVER THE
STATE DURING THE NEXT 24 HRS. THAT MEANS RESIDENTS OF THE SJ VLY
AND LOWER FOOTHILLS WILL HAVE TO ENDURE ANOTHER EQUALLY HOT DAY
TOMORROW WITH MAX TEMPS AGAIN UP AROUND THE CENTURY MARK.

WHILE THE ATMOSPHERE APPEARS TO BE RELATIVELY STABLE...A FEW
CUMULUS BUILDUPS MAY BREAK THRU THE INVERSION CAP BY LATE THIS
AFTERNOON OR EARLY EVENING...PARTICULARLY NEAR THE SIERRA CREST
BETWEEN YOSEMITE N.P. AND KINGS CANYON. THIS IS WHERE THE 18Z
MESO-ETA FORECASTS CAPES OF AROUND 1000 JOULES/KG AND THETA-E
TEMPS ABOVE 332K LATE THIS AFTERNOON. THE MODELS FORECAST A
SLIGHT INCREASE IN MID LEVEL MOISTURE ACROSS THE CENTRAL CA
INTERIOR TUESDAY. THIS WOULD PROVIDE A MORE FAVORABLE ENVIRONMENT
FOR ISOLD TSTM DEVELOPMENT DURING THE HOTTEST PART OF THE DAY.
THE MESO-ETA SUPPORTS THIS IDEA AND FORECASTS CAPE VALUES AT
OR ABOVE 1500 JOULES/KG NEAR THE SIERRA CREST BY 00Z WED WITH
THETA-E TEMPS ABOVE 334K.

DURING MIDWEEK...THE PATTERN WILL TRANSITION TO A SOMEWHAT COOLER
ONE AS THE HIGH PRESSURE RIDGE SHIFTS EAST AND AN UPPER LEVEL
TROUGH APPROACHES THE CA COAST. IN THE WEDNESDAY-THURSDAY TIME
PERIOD...GRADIENTS WILL BECOME MORE STRONGLY ONSHORE AND PREVAILING
WINDS ALOFT WILL BE FROM THE SOUTHWEST RATHER THAN THE SOUTHEAST.
THIS WOULD SHIFT DEVELOPMENT OF ISOLD PM TSTMS EAST OF THE SIERRA
CREST BY THURSDAY AND BRING A SHALLOW PUSH OF MARINE AIR INTO THE SJ
VLY. TEMPS WILL TREND TO NEAR NORMAL ACROSS THE CWA BY THURSDAY.

.LONG TERM...FOR THURSDAY NIGHT THROUGH MONDAY...MEDIUM RANGE MODELS
IN GOOD AGREEMENT FOR BEGINNING OF PERIOD WITH WEAK UPPER TROUGH
OVER THE WEST IN THE WAKE OF NW UPPER LOW EJECTING NORTHEAST. SOME
MODEL DISCREPANCY DEVELOPS TOWARD THE END OF THE PERIOD WITH
PROSPECTS OF UPSTREAM ALEUTIAN UPPER LOW. GFS HAS BEEN THE MOST
AGGRESSIVE WITH STRENGTH AND PROXIMITY TO WEST COAST.
HOWEVER...LATEST MODEL RUN INDICATES PERHAPS GFS COMING A LITTLE
MORE IN LINE WITH CONSENSUS OF UPPER LOW FARTHER OFFSHORE. EITHER
WAY...WILL NOT HAVE ANY SIGNIFICANT IMPACT THROUGH THE PERIOD.
SYNOPTIC PATTERN WILL PRODUCE SLIGHTLY BELOW NORMAL AFTN HIGHS TO
START THE PERIOD...WITH A GRADUAL RISE TO NEAR NORMAL TO END THE
PERIOD. HIGH SIERRA AFTN TSRA ACTIVITY WILL END ON SATURDAY AS
MODERATE SW FLOW ALOFT WILL PROVIDE MORE STABLE ENVIRONMENT BY
SUNDAY.

&&

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

&&

DURFEE/DCH