FXUS65 KREV 042149
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
149 PM PST SAT FEB 4 2012

.SHORT TERM...
RIDGE OVERHEAD TO REMAIN NOW INTO MONDAY BEFORE A SPLITTING SYSTEM
ARRIVES FOR TUESDAY. MODELS ARE IN GOOD AGREEMENT FOR THE NEXT 48 HOURS
BUT CONTINUE TO DIFFER WITH THE SPLITTING TROUGH TUESDAY. AT THIS
POINT, WILL LEAN TOWARD THE CONSISTENT EC SINCE IT HAS THE SUPPORT
NOW OF THE GFS AND GEFS. THIS SOLUTION IS MAINLY DRY FOR OUR AREA
WITH MORE ON THAT BELOW.

AT LEAST FOR THE NEXT 48 HOURS UNDER THE RIDGE, THE FLOW ALOFT
WILL BE VERY WEAK. STILL EXPECT ONY A FEW HIGH CLOUDS FOR INTO
SUNDAY NIGHT WITH LIGHT WINDS. ANY WINDS WILL BE DRIVEN BY THE
SURFACE GRADIENT WHICH WILL BE STRONGEST OVERNIGHT DUE TO
RADIATIONAL COOLING. TEMPERATURES WILL CONTINUE TO HOLD STEADY AND
NEAR NORMAL THROUGH MONDAY.

BY MONDAY AFTERNOON INTO MONDAY NIGHT, CLOUDS WILL INCREASE AHEAD
OF THE SPLITTING TROUGH. THEREFORE A MILDER NIGHT IS EXPECTED
MONDAY NIGHT. THEN EC AND GFS KEEP THE SOUTHERN END OF THE SPLIT
OFFSHORE AS IT MOVES SOUTHEAST TUESDAY. THE EC IS COMPLETELY DRY
EVEN FOR THE SIERRA. THE GFS HAS ENOUGH MOISTURE TO BRING A FEW
LIGHT SHOWERS TO THE SIERRA WITH SNOW LEVELS NEAR 6000 FEET. THE
NAM IS AN OUTLIER SHOWING MOISTURE MAKING IT INTO WESTERN NEVADA
WITH A 1/2 TO 3/4 INCH QPF. GIVEN THE UNCERTAINTY, LEFT THE
FORECAST FOR TUESDAY ALONE EXCEPT TO HAVE A BETTER CHANCE OF
PRECIP IN THE AFTERNOON COMPARED TO THE MORNING. WITH ABUNDANT
CLOUD COVER NO MATTER THE SOLUTION AND WEAK WINDS ALOFT OVER THE
AREA, TEMPERATURES WILL REMAIN NEAR NORMAL. WALLMANN

.LONG TERM...WEDNESDAY THROUGH SATURDAY...
COOLED DOWN HIGHS NEXT SATURDAY A FEW DEGREES, OTHERWISE LITTLE TO
NO CHANGE TO THE EXTENDED GRIDS. UPPER RIDGE TO BUILD IN WEDNESDAY
THROUGH FRIDAY WITH HIGHS RISING TO 5-10 DEGREES ABOVE AVERAGE FOR
THURSDAY AND FRIDAY.

THE ONLY THING OF NOTE TO DISCUSS WILL BE THE POSSIBLE APPROACH OF A
ELONGATING/SPLITTING DISTURBANCE MOVING INTO THE WESTERN CONUS AND
BRITISH COLUMBIA NEXT FRIDAY NIGHT AND SATURDAY. THE PROBLEM WITH
GETTING ANYTHING INTO OUR REGION WILL BE THE MEAN RIDGE OVER THE
WEST, WHICH WILL TEND TO TEAR APART AND WEAKEN ANY ENERGY TRYING TO
MAKE IT INLAND. THE ECMWF DOES NOT EVEN LET ANY ENERGY GET TO US
WITH THE SOUTHERN PART OF THE SPLIT GOING SOUTH WELL OFF THE
CALIFORNIA COAST WITH JUST SOME MID AND HIGH CLOUDS AT BEST BY
FRIDAY NIGHT AND SATURDAY. THE GFS IS MORE PROGRESSIVE AND BRINGS A
WEAK DISTURBANCE IN FOR LIGHT PRECIPITATION.

FOR NOW, I DO NOT BUY THE GFS AS IT TENDS TO BE TOO PROGRESSIVE AND
THE 12Z CANADIAN ENSEMBLE SPAGHETTI PLOTS SEEM TO SUPPORT THE IDEA
OF AN EARLY SPLIT OFF THE COAST SIMILAR TO THE 12Z OPERATIONAL
ECMWF. HOWEVER, EVEN THE ECMWF COOLS TEMPS ALOFT AND BRINGS IN
INCREASING HIGH MOISTURE/CLOUDS FRIDAY NIGHT AND SATURDAY. THEREFORE,
I COOLED DOWN HIGH TEMPS (ESPECIALLY RIDGES) ON SATURDAY AND ALLOWED
DRY RIDGE HUMIDITIES FROM EARLIER IN THE WEEK TO RISE WITH THE
COOLING ALOFT. SNYDER
&&

.AVIATION...
VFR CONDITIONS AND LIGHT WINDS WITH HIGH PRESSURE OVER THE SIERRA
AND WESTERN NEVADA THROUGH MONDAY. LOW CHANCE OF FOG AT TRUCKEE LATE
TONIGHT AND SUNDAY MORNING. HOWEVER, IT COULD JUST BE PATCHY NEAR
THE TERMINAL SO CONFIDENCE IS TOO LOW TO INCLUDE IN THE TERMINAL
FORECAST (ALTHOUGH I MAY GO WITH A BCFG TO COVER PATCHY FOG).
SNYDER
&&


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

$$

HTTP://WEATHER.GOV/RENO



Back to Main Forecast Discussion Page