FXUS65 KREV 301611 AAA
AFDREV

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RENO NV
811 AM PST MON NOV 30 2009

.UPDATE...
QUICK UPDATE THIS MORNING TO ADD PATCHY FREEZING FOG FOR MONO
COUNTY. REMNANT MOISTURE COMBINED WITH QUITE COLD TEMPS THIS
MORNING HAS ALLOWED FOG TO FORM MAINLY OVER THE LAKES OF MONO
COUNTY. GOOD SOLAR RADIATION SHOULD BURN OFF THE CLOUD COVER
QUICKLY THIS MORNING. NORTHEAST FLOW ALOFT HAS KEPT FOG PRONE
AREAS AROUND TAHOE AND TRUCKEE CLOUD-FREE THIS MORNING. JORDAN

&&

.PREVIOUS DISCUSSION... /ISSUED 231 AM PST MON NOV 30 2009/ 

SHORT TERM...A WEAK RIDGE OF HIGH PRESSURE JUST OFF THE WEST COAST 
HAS BEGUN TO SETTLE INTO PLACE AND IS EXPECTED TO REMAIN THROUGH THE 
WEEK. THE SURFACE PRESSURE GRADIENT CAUSING THE GUSTY WINDS ALOFT 
WILL RELAX COMPLETELY BY MIDDAY TODAY BRINGING WIND GUSTS AT 
RIDGETOPS DOWN. WITH NO UPPER OR MIDLEVEL SUPPORT WINDS SHOULD 
REMAIN LIGHT ACROSS THE REGION AT ALL ELEVATIONS THROUGH TUESDAY. 
THE LACK OF WINDS WILL MAKE IT DIFFICULT FOR VALLEY LOCATIONS TO 
BREAK THE INVERSION AND THEREFORE KEEP TEMPERATURES FROM REACHING 
THEIR MAX POTENTIAL. A SHORTWAVE DISTURBANCE IS EXPECTED TO PASS TO 
OUR NORTHEAST TUESDAY EVENING WHICH WILL REORIENT THE FLOW OUT OF 
THE NORTH. THIS WILL DROP TEMPERATURES SLIGHTLY ON WEDNESDAY AND 
INTRODUCE SOME UPPER LEVEL MOISTURE TO NORTHERN NEVADA. PW VALUES 
REMAIN AROUND ONE QUARTER INCH WITH THIS MILD SHORTWAVE PUSH...SO 
ANY PRECIP IS UNLIKELY. LABELLE

LONG TERM...THURSDAY THROUGH SUNDAY...
THERE CONTS TO BE CONSIDERABLE SPREAD IN MODEL SOLNS WITH REGARD TO 
REGIONAL DETAIL ESPECIALLY BY THE WEEKEND. ON THE OTHER HAND THERE 
SEEMS TO BE BETTER AGREEMENT IN LARGER SCALE FEATURES INCLUDING 
AMPLIFICATION OF RDG FM THE EPAC INTO THE GULF OF ALASKA DURING THE 
FIRST HALF OF PD FOLLOWED BY UPR RDG GETTING PINCHED OFF AS SRN 
STREAM ENERGY UNDERCUTS RDG AND WORKS INTO THE WEST COAST BY LATE IN 
THE WEEKEND INTO NEXT WEEK. ONE OF THE BIGGEST UNCERTAINTIES RESTS 
WITH THE EXTENT OF COLD AIR PROGGED TO WORK SWD INTO THE WRN U.S. IN 
RESPONSE TO BLDG UPSTREAM RDG. THE OP GFS/CANADIAN ARE MOST 
AGGRESSIVE AT PUSHING COLD AIR INTO CA-NV WHILE THE ECMWF PLACES 
MORE EMPHASIS ON INCOMING MOISTURE AND ENERGY FM THE CNTRL 
PAC...ESSENTIALLY BRINGING COLD AIR DOWN INTO THE PACNW/NRN ROCKIES 
BUT THEN MODIFYING IT GREATLY BY THE TIME IT WORKS MUCH FURTHER SWD 
WHERE A STG AND MOIST WLY FLOW WOULD BE IN PLACE. THERE IS A LOT OF 
UNCERTAINTY HOW THE MOISTURE AND COLD AIR WL PLAY OUT WITH THE 
SIERRA/WRN NV RIGHT IN THE MIDDLE. AND THAT IS HOW THIS FCST WAS 
SCRIPTED THIS MRNG. POPS WERE GRADUALLY INCREMENTED OVR THE WEEKEND 
INTO THE PRELIM DAY 8 WITH TEMPS COOLED TO VALUES RIGHT IN THE 
MIDDLE OF THE MOS ENSEMBLE EXTREMES. IF THERE IS ANY TREND TO BE 
SEEN FOR LATE WEEKEND INTO EARLY NEXT WEEK IT WOULD BE COLDER/LESS 
WET NORTH AND MILDER/MORE WET SOUTH. IN SUMMARY...A MUCH MORE 
UNSETTLED WEATHER PATTERN IS SHAPING UP FOR NEXT WEEK WITH 
CONFIDENCE GROWING THAT THERE WL BE IMPACTS...ESPECIALLY JUST BYND 
THIS FCST PD. HOHMANN

AVIATION...
VFR CONDS WITH LIGHT SFC WINDS. 

KTRK...AIRMASS REMAINS VERY DRY WITH WK ELY GRADIENT. POTENTIAL FOR 
FREEZING FOG IS VERY LOW THIS MRNG AND NOT MUCH HIGHER TUE MRNG. ANY 
DEVELOPMENT WOULD BE SHALLOW...FORMING AFT 12Z AND NOT LASTING MUCH 
BYND 16Z. HOHMANN

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&

$$

HTTP://WEATHER.GOV/RENO