Wildfire in California, June 23, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
230 PM PDT SAT JUN 23 2007

.SHORT TERM...
UPPER LOW OFF VANCOUVER ISLAND WILL MOVE EASTWARD ACROSS THE PACNW
SUNDAY AND INTO THE NORTHERN ROCKIES MONDAY. ONE SHORTWAVE THIS
AFTERNOON AND ANOTHER EJECTING AHEAD OF UPPER LOW SUNDAY WILL HELP
MAINTAIN A VERY TIGHT THERMAL GRADIENT ACROSS THE GREAT BASIN AND
SIERRA THROUGH SUNDAY. SOME MOISTURE IN THE H7-H5 LEVEL WILL BRUSH
NORTHEAST CALIFORNIA AND NORTHWEST NEVADA TONIGHT AND SUNDAY.
HOWEVER MOST OTHER AREAS WILL REMAIN CRITICALLY DRY DESPITE A
GENERAL DROP IN TEMPERATURES. SEE FIRE WEATHER DISCUSSION BELOW FOR
MORE DETAIL ON CRITICAL FIRE WEATHER THREAT THROUGH SUNDAY. LAKE
WIND ADVISORIES TO BE EXTENDED THROUGH SUNDAY.

CONDITIONS WILL BE MORE STABLE MONDAY AS WEAKNESS IN UPPER LEVEL
WIND FIELD IS LEFT IN WAKE OF EXITING UPPER LOW TO THE NORTH. THIS
COMBINED WITH SURFACE HIGH PRESSURE BUILDING INTO THE GREAT BASIN
WILL RESULT IN LIGHT NORTHEAST GRADIENT. SO LIGHT WINDS AND DRY
AIRMASS WILL RESULT IN RELATIVELY QUIET WEATHER CONDITIONS MONDAY.
TEMPERATURES SUNDAY AND MONDAY WILL BE CLOSE TO NORMAL. THERE ARE
INDICATIONS THAT LONGWAVE PATTERN WILL FAVOR TROUGHINESS IN THE EAST
PACIFIC NEXT WEEK. WEAK SHORTWAVE OFF THE CALIFORNIA COAST WILL
EJECT TUESDAY IN RESPONSE TO ENERGY/REDEVELOPMENT OF TROUGH FROM THE
GULF OF ALASKA INTO THE EAST PACIFIC. PERSISTENT SOUTHWEST FLOW WILL
LIKELY INTERRUPT DESTABILIZATION PROCESS ALONG THE MONO/MINERAL
COUNTY CONVERGENCE ZONE. MODELS HAVE ALSO BEEN TRENDING TOWARDS LESS
INSTABILITY. THEREFORE THE LOW POPS WERE REMOVED. THE 12Z RUN OF THE
GFS DID SHOW SOME DESTABILIZATION OVER SOUTHERN OREGON TUESDAY IN
RESPONSE TO EJECTING SHORTWAVE. THIS COULD BE CLOSE TO AFFECTING
AREAS NEAR THE OREGON BORDER AND WILL NEED TO BE MONITORED. HIGH
TEMPERATURES TUESDAY ARE EXPECTED TO RETURN TO 5 DEGREES ABOVE
NORMAL LEVELS. HOHMANN
&&

.LONG TERM...WEDNESDAY THROUGH SATURDAY...
MODELS IN DECENT AGREEMENT WITH ANOTHER LOW MOVING INTO THE GULF OF
ALASKA EARLY NEXT WEEK AND DEEPENING AS IT MOVES SLOWLY SOUTH ALONG
THE ALASKAN COAST THROUGH THE WEEK. HEIGHTS REMAIN HIGH THROUGH
THURSDAY...THEN MODELS DIFFER IN SOUTHWARD EXTENT OF COOLER AIR ON
FRIDAY. THE GFS IS THE WETTEST AND COOLEST...HINTING AT LOWS IN THE
LOW TO MID 80S ON FRIDAY. THE EURO KEEPS THE COOLER AIR A LITTLE
FURTHER NORTH. NEITHER MODEL SHOWS THE WEAK LOW DEVELOPING OFF THE
SRN CA COAST AND JUST KEEPS THE AREA UNDER DRY AND STABLE SOUTHWEST
FLOW WEDNESDAY AND THURSDAY WHICH WOULD INHIBIT THE DEVELOPMENT OF
CONVECTION. THEREFORE DECIDED TO REMOVE POPS ON WEDNESDAY. RIGHT NOW
THE BEST DAY FOR PRECIP LOOKS TO BE AHEAD OF A STRONGER SHORTWAVE
OVER NWRN ZONES ON FRIDAY OR FRIDAY NIGHT. KEPT POPS AS IS BRINGING
IN ISOLATED POPS FRIDAY NIGHT AND EARLY SATURDAY...BUT LATER SHIFTS
CAN WATCH SYSTEM AND SEE IF ANY WEATHER IS NEEDED EARLIER ON FRIDAY
AS GFS HINTS AT. GUSTY AFTERNOON/EVENING WINDS WILL RETURN TO THE
AREA BY WEDNESDAY AFTER A BREAK EARLY IN THE WEEK. WINDS WILL
INCREASE THURSDAY AND FRIDAY AS GRADIENT TIGHTENS WHICH MAY BRING
ANOTHER PERIOD OF LAKE WIND ADVISORIES AND FIRE WEATHER CONCERNS.
BENINATO
&&

.AVIATION...
VFR CONDITIONS WILL CONTINUE THROUGH SUNDAY. GUSTY SOUTHWEST TO WEST
WINDS WITH GUSTS 30-35KT WILL CONTINUE OVER MUCH OF WESTERN NV AND
EASTERN CA BETWEEN 22Z-04Z. SLIGHTLY WEAKER WINDS EXPECTED FOR
SUNDAY...BUT STILL UP TO 30KT IN THE AFTERNOON. BENINATO
&&

.FIRE WEATHER...
CRITICAL FIRE WEATHER CONDITIONS CONTINUE OVER THE WHOLE AREA THIS
AFTERNOON WITH BREEZY SOUTHWEST WINDS AND VERY LOW HUMIDITIES.
STRONGER WINDS ALOFT HAVE BEGUN MIXING DOWN TO EXPOSED AREAS AND
MIDSLOPES AND WILL CONTINUE INCREASING OVER ALL VALLEY LOCATIONS
THROUGH THIS AFTERNOON. WIND GUSTS OF 40 MPH WILL BE FAIRLY
WIDESPREAD WITH WIND PRONE AREAS GUSTING TO 45 MPH...ESPECIALLY
ALONG THE SIERRA FRONT. MEANWHILE HUMIDITIES WILL CHANGE VERY LITTLE
THROUGHOUT THE AFTERNOON WITH VALUES AROUND 5%. WINDS WILL BEGIN TO
DECREASE AROUND SUNSET TONIGHT BUT HUMIDITY RECOVERIES OVERNIGHT
WILL BE VERY POOR ONCE AGAIN...15-20%. TEMPERATURES TOMORROW WILL
DROP A FEW DEGREES WITH A SLIGHT INCREASE IN HUMIDITIES OVER MAINLY
THE NORTHERN ZONES...HOWEVER IT WILL STILL BE QUITE DRY WITH
CONTINUED BREEZY CONDITIONS EVERYWHERE ELSE. SO CRITICAL FIRE
CONDITIONS ARE EXPECTED MAINLY SOUTH OF INTERSTATE 80 ONCE AGAIN
TOMORROW.

WITH ALL THIS IN MIND AND THE FACT THAT THERE ARE NOW FIRES BURNING
IN THE AREA...WILL EXTEND THE RED FLAG WARNING FOR AREAS SOUTH OF
INTERSTATE 80 THROUGH TOMORROW EVENING INCLUDING THE OVERNIGHT
PERIOD TONIGHT. SO THE RED FLAG WARNING IS IN EFFECT FOR GUSTY WINDS
AND LOW HUMIDITY THROUGH THIS EVENING...THEN VERY POOR HUMIDITY
RECOVERIES OVERNIGHT...WITH GUSTY WINDS AND LOW HUMIDITY DEVELOPING
AGAIN SUNDAY AFTERNOON AND EVENING. FOR AREAS NORTH OF INTERSTATE 80
AND THE TAHOE BASIN...THE RED FLAG WARNING IS IN EFFECT FOR GUSTY
WINDS AND LOW HUMIDITY WITH CONDITIONS EXPECTED TO IMPROVE OVERNIGHT
TONIGHT. JORDAN
&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...RED FLAG WARNING UNTIL 10 PM PDT THIS EVENING FOR NVZ458.
     RED FLAG WARNING UNTIL 9 PM PDT SUNDAY FOR NVZ450-453-459.

CA...RED FLAG WARNING UNTIL 10 PM PDT THIS EVENING FOR CAZ272-278.
     RED FLAG WARNING UNTIL 9 PM PDT SUNDAY FOR CAZ273.
&&

HTTP://WEATHER.GOV/RENO