Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 221100
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
300 AM PST MON DEC 22 2014

.SYNOPSIS...

DRY CONDITIONS AND MILD TEMPERATURES ARE ANTICIPATED THROUGH
WEDNESDAY AS HIGH PRESSURE BUILDS. A STRONG COLD FRONT WILL PUSH
THROUGH THE REGION LATE WEDNESDAY INTO CHRISTMAS DAY WITH GUSTY
WINDS, RAIN, AND SNOW.

&&

.SHORT TERM...

SEASONABLY WARM TEMPERATURES CONTINUE TODAY THROUGH WEDNESDAY
WITH HIGH PRESSURE ANCHORED OFF THE CALIFORNIA COAST. WINDS HAVE
BEEN AIDING IN MIXING AS THE PRESSURE GRADIENT REMAINS RELATIVELY
TIGHT FROM THE SIERRA INTO CENTRAL NEVADA. THIS GRADIENT WILL
SLOWLY RELAX AS JET ENERGY DIPS INTO TEXAS. STILL, ANOTHER
SLIGHTLY BREEZY DAY CAN BE EXPECTED ESPECIALLY FOR SOUTHERN
MINERAL COUNTY WHICH MORE EASILY BECOMES BREEZY WITH NORTHERLY
FLOW. LOCATIONS SOUTH OF HAWTHORNE WILL EXPERIENCE GUSTS GENERALLY
AROUND 35 TO 40 MPH TODAY WITH AREAS OF BLOWING DUST POSSIBLE.
CONDITIONS BECOME FAIRLY BENIGN BY TUESDAY WITH SLOWER WINDS
RESULTING IN LESS MIXING AND SLIGHTLY COOLER TEMPERATURES.

CHRISTMAS EVE...THE FOCUS FOR THE SHORT TERM FORECAST IS QUICKLY
SHIFTING TO WEDNESDAY AS A MUCH COLDER SYSTEM DROPS OUT OF THE
NORTHERN PACIFIC. DUE TO THE STRONG THERMAL GRADIENT, WINDS WILL
BECOME GUSTY DURING THE DAY ON WEDNESDAY. EXPECT GUSTS AROUND 50
MPH FOR MUCH OF THE FORECAST AREA. HAVE ADDED BLOWING DUST FOR
LOCATIONS EAST OF THE VIRGINIA RANGE FROM NORTHERN WASHOE COUNTY
THROUGH MINERAL AND EASTERN MONO COUNTIES.

ASIDE FROM WINDS, THERE WILL BE THE POTENTIAL FOR SNOW DOWN TO
MANY WESTERN NEVADA VALLEY FLOORS. ENDED UP LOWERING SNOW LEVELS
TO AROUND 5000 FEET AS THE FRONT BARRELS THROUGH WEDNESDAY
EVENING INTO EARLY CHRISTMAS DAY. SINCE MOST OF THE PRECIPITATION
IS PROJECTED TO FALL BEHIND THE FRONT, THE CHARACTER WILL BE
MOSTLY SNOW WITH THE POSSIBILITY THAT HEAVIER RATES WILL DRAG SNOW
LEVELS DOWN BELOW 4500 FEET. AN INCH OR TWO IS POSSIBLE DOWN TO
5000 FEET WITH A DUSTING TO AN INCH POSSIBLE DOWN TO 4500 FEET FOR
WESTERN NEVADA.

UNCERTAINTY WITH CHARACTER AND AMOUNTS IS STILL RELATIVELY HIGH
SINCE SHORT TO MID RANGE MODELS CONTINUE TO DIFFER FROM ONE
ANOTHER AND FROM ONE RUN TO THE NEXT. THIS IS KEEPING FORECASTER
CONFIDENCE IN THE LOW TO MEDIUM RANGE. HOWEVER, THERE ARE
INDICATIONS IN THE DETERMINISTIC GFS AND ECMWF THAT THERE WILL BE
A MORE WESTWARD SHIFT IN PRECIPITATION FIELDS SINCE THE UPPER LOW
IS NOW PROJECTED TO MOVE THROUGH NORTHERN CALIFORNIA RATHER THAN
DOWN THE CASCADES OUT OF OREGON. THIS COULD MEAN THAT THE SIERRA
WILL BE FAVORED MORE FOR PRECIPITATION RATHER THAN WESTERN NEVADA
WHICH WOULD BE AT LEAST PARTIALLY SHADOWED. ENSEMBLE MEANS ARE
SLIGHTLY MORE WESTWARD AS WELL, SO THIS BEARS WATCHING. IF THIS
SCENARIO VERIFIES, THEN TRAVEL OVER SIERRA PASSES COULD BE MORE
IMPACTED THAN PREVIOUSLY THOUGHT AS A FEW INCHES OF ACCUMULATION
WOULD BE POSSIBLE.

ADDITIONALLY, SOLUTIONS ARE COMING IN MUCH WETTER WITH THE MORE
WESTWARD TRAJECTORY. HAVE UPPED QPF ALONG THE SIERRA AND NORTHERN
ZONES QUITE A BIT WITH AT LEAST 0.5" LIQUID TOTALS FOR SOME
LOCATIONS. THE GFS HAS COMPLETELY CHANGED FROM A VERY DRY SOLUTION
TO OVER AN INCH OF QPF WHILE THE EC IS MORE MODEST AROUND O.66";
WILL CONTINUE TO FAVOR THE MORE CONSISTENT EC. BOYD

.LONG TERM...CHRISTMAS THROUGH MONDAY...

COLD FRONT WILL PUSH TO THE EAST ON CHRISTMAS DAY WITH A VERY CHILLY
NORTH WIND AND A FEW LINGERING SNOW SHOWERS. AFTERNOON HIGHS WILL
LIKELY STAY IN THE 30S FOR THE NEVADA VALLEYS WITH UPPER 20S TO MID
30S FOR THE SIERRA. MOUNTAIN TOP TEMPERATURES WILL BE IN THE SINGLE
DIGITS TO TEENS. THOSE TRAVELING CHRISTMAS MORNING SHOULD BE
PREPARED FOR SLICK AND SNOW COVERED ROADS.

MODELS CONTINUE TO SHOW A BLOCKING PATTEN DEVELOPING IN THE EASTERN
PACIFIC ALONG 140W. RUN TO RUN MODEL CONSISTENCY IN PLACEMENT OF THE
BLOCK AND ASSOCIATED FEATURES IS POOR. LATEST 00Z RUNS SHOW A HIGHLY
AMPLIFIED RIDGE ALONG 140W, WITH A COUPLE COLD SYSTEMS DROPPING INTO
THE REGION FROM WESTERN CANADA. THIS COULD LEAD TO PERIODS OF LIGHT
SNOW SHOWERS NORTH OF HIGHWAY 50 FOR THE WEEKEND. THERE IS THE
POTENTIAL FOR THE RIDGE TO BE PINCHED NORTHWARD, OPENING THE DOOR
FOR WARMER SYSTEMS TO PUSH INTO THE SIERRA AND WESTERN NEVADA OFF
THE PACIFIC. BRONG

&&

.AVIATION...

DECREASING WINDS TODAY WITH HIGH PRESSURE BUILDING INTO NORTHERN
CALIFORNIA. MODERATE TO STRONG RIDGE WINDS MAY HOLD ON THROUGH 00Z
TUESDAY, WITH BUMPY APPROACHES AND DEPARTURES.

NEXT SYSTEM WILL ARRIVE ON WEDNESDAY WITH POTENTIAL FOR A STRONG
WIND EVENT. LATEST MODELS SHOW SURFACE GUSTS TO 50 KTS AS LOW
PRESSURE MOVES INTO NORTHERN CALIFORNIA, ALONG WITH GOOD MOUNTAIN
WAVE SIGNATURES. A COLD FRONT WILL MOVE INTO THE AREA ON CHRISTMAS
EVE, WHICH MAY BRING A ROUND OF LOW LEVEL WIND SHEAR AND A PERIOD OF
MODERATE TO HEAVY SNOW INTO EARLY CHRISTMAS MORNING. BRONG

&&


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

$$

FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)





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