Area Forecast Discussion
Issued by NWS Reno, NV

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
000
FXUS65 KREV 182328
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
328 PM PST THU DEC 18 2014

.SYNOPSIS...
A COUPLE WEAK STORMS WILL BRING CHANCES FOR RAIN AND SNOW FRIDAY
THROUGH SATURDAY MAINLY NORTH OF HIGHWAY 50. HIGH PRESSURE WILL
THEN BUILD SUNDAY THROUGH THE FIRST PART OF NEXT WEEK. A COOLING
TREND IS POSSIBLE LATE NEXT WEEK.

&&

.SHORT TERM...
FEW CHANGES MADE OVERALL WITH THE MODELS IN REASONABLY GOOD
AGREEMENT WITH THE WEAKENING SYSTEM ARRIVING FRIDAY MORNING.
EXPECT ANOTHER MILD NIGHT TONIGHT WITH SOME ABUNDANT MID AND HIGH
CLOUD COVER AHEAD OF THE SYSTEM.

THE BULK OF THE SYSTEM ARRIVES FRIDAY MORNING AND ALL THE MODELS
SHOWING IT SPLITTING AND WEAKENING AS IT ARRIVES. WHAT LITTLE JET
ENERGY IS LEFT IS FORECAST TO REMAIN IN OREGON WITH ONLY THE WEAK
LEFT OVER LOW-LEVEL FRONT MAKING IT AS FAR SOUTH AS I-80. THERE IS
ENOUGH MOISTURE TO SQUEEZE OUT SOME RAIN AND SNOW OVER THE SIERRA
FROM TAHOE NORTH. EXPECT LITTLE SPILLING OVER INTO WESTERN NEVADA
EXCEPT NEAR THE OREGON BORDER CLOSER TO THE FORCING WITH THE WEAK
UPPER JET. SNOW LEVELS WILL REMAIN NEAR 6000-6500 FEET AROUND I-80
AND 4500-5000 FEET NEAR THE OREGON BORDER. LIGHT SNOW AMOUNTS OF
UP TO A COUPLE INCHES ARE POSSIBLE ABOVE THIS LEVEL WITH HIGHER
AMOUNTS TO 6 INCHES NEAR THE SIERRA CREST.

AS THIS SYSTEM PULLS AWAY FRIDAY NIGHT, EXPECT A DECREASING CHANCE
OF SHOWERS BUT CLOUD COVER WILL CONTINUE TO KEEP OVERNIGHT TEMPS
MILD. ON SATURDAY, THE PACIFIC JET REORGANIZES AND IS DIRECTED
INTO WASHINGTON. HOWEVER, A MOIST PACIFIC PLUME WILL EXTEND SOUTH
INTO NORTHERN CALIFORNIA AND NEVADA. SOME DECENT ISENTROPIC LIFT
IS SHOWN WITH WARM AIR ADVECTION SATURDAY. THE BEST CHANCE WILL
OCCUR NEAR THE OREGON BORDER WITH CHANCES TAPERING TO NOTHING
SOUTH OF HIGHWAY 50. SNOW LEVELS WITH THIS ONE WILL BE MORE
PROBLEMATIC AS MODEL SOUNDING SHOW ISOTHERMAL PROFILES HOVERING
NEAR FREEZING. THIS COULD KEEP SNOW LEVELS NEAR THE VALLEY FLOORS
IN THE SURPRISE VALLEY BEFORE RAPIDLY RISING TO ABOVE 8000 FEET
WITH THE PASSAGE OF THE WARM FRONT.

AFTER THIS WAVE PASSES SATURDAY NIGHT, THE RIDGE WILL AMPLIFY JUST
OFF THE COAST BRINGING A WARMING AND DRYING TREND. WITH ABUNDANT
CLOUD COVER AGAIN SATURDAY NIGHT BEFORE THE SYSTEM EXITS, TEMPS
COULD AGAIN BE MILD. WARM TEMPS COULD FOLLOW SUNDAY THAT MAY BE
10-15 DEGREES ABOVE NORMAL AS RIDGE TOP (10,000 FOOT) TEMPS RISE
ABOVE FREEZING. WALLMANN

.LONG TERM...MONDAY THROUGH THURSDAY/CHRISTMAS DAY...
AN UPPER RIDGE WILL RULE THE EASTERN SIERRA AND WESTERN NEVADA
MONDAY AND TUESDAY. THIS WILL BRING LIGHT VALLEY WINDS AND HIGH
TEMPERATURES NEAR TO SLIGHTLY ABOVE (4-7 DEGREES) AVERAGE. THE LIGHT
WINDS AND STABLE CONDITIONS WILL ALLOW POLLUTANT BUILDUP FOR THE
VALLEYS, ESPECIALLY FOR THE RENO-SPARKS AREA. HOWEVER, THE LACK OF
SNOW COVER AND A RELATIVELY MILD AIRMASS SHOULD ALLOW FOR A SOMEWHAT
DEEPER MIXED LAYER IN THE AFTERNOONS (MORE ROOM FOR THE POLLUTANTS
TO RISE UP AWAY FROM THE SURFACE).

ON WEDNESDAY AND WEDNESDAY NIGHT (CHRISTMAS EVE), ATTENTION TURNS TO
THE POTENTIAL FOR AN INSIDE SLIDER-TYPE SYSTEM. THESE TYPES OF
SYSTEMS ARE OF SPECIAL INTEREST TO LOCATIONS EAST OF THE SIERRA IN
WESTERN NEVADA AS THEY CAN BRING SOME OF THE HEAVIEST SNOWFALL
RATES/AMOUNTS SEEN IN THE WESTERN GREAT BASIN (DESPITE THEIR
TYPICALLY LIMITED MOISTURE).

TO TALK FIRST ABOUT WHAT WE FEEL CONFIDENT IN, THERE WILL BE A
STRONG COLD FRONT THAT MOVES THROUGH CHRISTMAS EVE INTO VERY EARLY
CHRISTMAS MORNING. CHRISTMAS DAY LOOKS CHILLY WITH HIGH TEMPERATURES
FALLING TO AT LEAST 5-10 DEGREES BELOW AVERAGE (A 15-25 DEGREE DROP
FROM WEDNESDAY`S HIGH). ALSO, GIVEN SUCH A STRONG FROPA AND GOOD
MIXING PRIOR TO THE FRONTAL PASSAGE, IT IS LIKELY TO BE QUITE BREEZY
CHRISTMAS EVE, ESPECIALLY BY AFTERNOON AND EVENING.

THE REAL UNCERTAINTIES WILL BE IN WHETHER WE GET A BAND OF MODERATE
TO HEAVY SNOW ALONG THE FRONT OR NOTHING MORE THAN ISOLATED TO
SCATTERED LIGHT SNOW (OR RAIN CHANGING QUICKLY TO SNOW) SHOWERS. A
SECOND UNCERTAINTY IS JUST HOW COLD IT WILL GET BEHIND THE FRONT ON
THURSDAY. A LOT OF THAT DEPENDS ON SNOWFALL, AS A COUPLE INCHES OF
SNOW ON CHRISTMAS EVE WOULD KNOCK HIGHS ON CHRISTMAS DOWN FROM THE
30S TO THE 20S FOR MOST AREAS.

RIGHT NOW, MODELS ARE FIGHTING BETWEEN AN UPPER LOW OVER FAR WESTERN
NEVADA (BULLSEYE FOR HEAVY SNOW) OR A GLANCING BLOW WITH AN UPPER
LOW OVER IDAHO (MAYBE A FEW LIGHT SHOWERS). THERE ARE SIGNIFICANT
IMPACTS IF THE WESTERN SOLUTION VERIFIES AND IT WILL PROBABLY TAKE
UNTIL EARLY NEXT WEEK FOR MODELS TO ZERO IN ON A SOLUTION SO STAY
TUNED. SNYDER


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

$$

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






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.