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[Printable]
736
FXUS65 KREV 212155
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
255 PM PDT TUE OCT 21 2014

.SYNOPSIS...
AFTERNOON TEMPERATURES WILL WARM THE REST OF THE WEEK. MOISTURE
AHEAD OF A LOW PRESSURE SYSTEM IN THE PACIFIC WILL PRODUCE RAIN
OVER NORTHEAST CALIFORNIA AND NORTHWEST NEVADA THURSDAY. THE LOW
WILL MOVE INLAND ON FRIDAY NIGHT AND SATURDAY BRINGING A PERIOD OF
GUSTY WINDS AND THE POTENTIAL FOR RAIN AND MOUNTAIN SNOW.

&&

.SHORT TERM...

LOW PRESSURE IN THE GULF OF ALASKA IS DIRECTING THE JET AND A
NARROW ATMOSPHERIC RIVER ACROSS THE PACIFIC. HIGH CLOUDS WILL
THICKEN OVER THE NEXT 24-36 HOURS, WITH INCREASING CHANCES OF
RAIN THURSDAY OVER NORTHEAST CALIFORNIA. WITHIN THE MAIN MOISTURE
PLUME PRECIPITABLE WATER VALUES ARE ABOVE 1.5 INCHES, WITH MODELS
SUGGESTING VALUES AS HIGH AS 1.75 INCHES AS IT REACHES THE
NORTHERN CALIFORNIA COAST. HOWEVER FORCING MECHANISMS IN THE
MODELS ARE NOT OVERLY STRONG, SO MOST OF THE PRECIPITATION MAY GET
SQUEEZED OUT ALONG THE COASTAL RANGES.

BEST CHANCE FOR RAIN IS OVER WESTERN LASSEN AND PLUMAS COUNTIES
THURSDAY AND INTO THURSDAY NIGHT. SINCE THE JET WILL REMAIN OVER
OREGON, NORTHEAST CALIFORNIA WILL BE ON THE WARM SIDE OF THE
SYSTEM WITH SNOW LEVELS ABOVE 8000-9000 FEET. RAINFALL TOTALS
AROUND 0.50 INCH ARE POSSIBLE DUE TO UPSLOPE FLOW WEST OF A LINE
FROM SUSANVILLE TO PORTOLA. RAIN SHOULD REACH THE SURPRISE VALLEY
AND NORTHERN WASHOE COUNTY WHERE 0.10-0.20 INCH OF RAIN MAY OCCUR.
IF ANY TYPE OF WAVE OR SOURCE OF ENHANCED LIFT ACCOMPANIES THE
LOW, PRECIPITATION TOTALS COULD EASILY BE DOUBLE THE AMOUNTS
LISTED ABOVE.

ON THURSDAY AFTERNOON THE GULF OF ALASKA LOW IS FORECAST TO TRACK
SOUTH ALONG 140W. THIS WILL TURN THE FLOW TOWARD THE SOUTH AND
LIFT THE MOISTURE PLUME NORTHWARD. RAIN MAY START TO DIMINISH
THURSDAY EVENING OVER LASSEN, PLUMAS AND NORTHERN WASHOE AND
SHOULD END BY FRIDAY MORNING. BRONG

.LONG TERM...FRIDAY THROUGH TUESDAY...

ON FRIDAY, TROUGH APPROACHING THE WEST COAST WILL BRING A DRIER
SOUTH FLOW TO THE REGION. MOISTURE BAND OVER NORTHEAST CALIFORNIA
AND NORTHWEST NEVADA IS PROJECTED TO QUICKLY RETREAT NORTH OF THE
OREGON BORDER DURING THE MORNING. FOR MUCH OF THE REGION, CLEARING
SKIES ARE LIKELY DURING THE AFTERNOON WHICH WILL ALLOW TEMPERATURES
TO REACH THE LOWER 80S FOR MOST OF WESTERN NV, ALONG AND EAST OF
HIGHWAY 95.

BREEZY CONDITIONS ARE LIKELY FRIDAY AFTERNOON, THE POTENTIAL
INCREASES FOR STRONGER WIND GUSTS FRIDAY NIGHT INTO EARLY SATURDAY
MORNING AS THE MAIN TROUGH REACHES THE SIERRA. 700 MB WIND SPEEDS
UP TO 60 KT ARE INDICATED FOR EARLY SATURDAY MORNING, WITH LEE
SIDE MOUNTAIN WAVE ACTIVITY SPREADING INTO THE HIGHWAY 395
CORRIDOR FROM SOUTHEAST LASSEN THROUGH THE RENO-CARSON CITY REGION
AND INTO MONO COUNTY. AT THIS TIME WE INCREASED GUST POTENTIAL TO
45 MPH, BUT THERE COULD BE STRONGER GUSTS DEPENDING ON WHEN THE
TROUGH AND UPPER LEVEL JET REACHES THE SIERRA.

FOR SATURDAY, MUCH COOLER TEMPERATURES ARE EXPECTED ALONG WITH A
ROUND OF PRECIPITATION AS UPPER TROUGH AND SURFACE COLD FRONT PASS
THROUGH. WHILE SOME OF THE PREVIOUS MODEL RUNS WERE INDICATING A
SPLITTING TROUGH, THE LATEST DATA TRENDED BACK TO A MORE PROGRESSIVE
PATTERN. ALTHOUGH THE TIMING OF THIS TROUGH VARIES AMONG MODEL
GUIDANCE, THERE IS A BIT MORE CONSENSUS FOR THE MAIN PRECIPITATION
BAND REACHING WESTERN LASSEN COUNTY LATE FRIDAY NIGHT, THEN MOVING
ACROSS THE REST OF THE SIERRA AND WESTERN NEVADA DURING THE DAY
SATURDAY. A PERIOD OF HEAVIER RAIN AND HIGHER ELEVATION SNOW IS
MOST LIKELY FROM THE TAHOE BASIN NORTHWARD INTO LASSEN COUNTY WHEN
THE TROUGH IS TAPPING DECENT PACIFIC MOISTURE. AS THE SYSTEM MOVES
FARTHER INLAND, THIS MOISTURE TAP WILL WEAKEN, RESULTING IN
LIGHTER RAIN AMOUNTS FROM RENO-CARSON CITY EASTWARD. LIGHTER
SHOWERS WILL REMAIN POSSIBLE ACROSS THE REGION SATURDAY NIGHT.

BELOW NORMAL TEMPERATURES ARE EXPECTED SUNDAY AS WEAK RIDGE REBUILDS
OFF THE WEST COAST, WITH SURFACE WINDS SHIFTING TO THE NORTH. A FEW
SHOWERS MAY LINGER IN AREAS NORTH OF A SUSANVILLE-FALLON LINE, WHILE
DRIER NORTHWEST FLOW ALOFT SHOULD END THE PRECIPITATION THREAT FOR
THE SIERRA AND FAR WESTERN NV.

FOR NEXT MONDAY AND TUESDAY, A SLOW WARMING TREND IS EXPECTED AS LOW
AMPLITUDE RIDGE AXIS MOVES EAST ACROSS THE GREAT BASIN. ANOTHER
SHORTWAVE APPROACHING THE WEST COAST WILL SPREAD HIGH CLOUDS ACROSS
MUCH OF THE REGION, WITH A SLIGHT POSSIBILITY OF LIGHT RAIN REACHING
EXTREME NORTHEAST CA AND NORTHWEST NV BY TUESDAY. MJD

&&

.AVIATION...

VFR CONDITIONS WITH GENERALLY LIGHT WINDS WILL PREVAIL THRU
WEDNESDAY WITH AREAS OF HIGH CLOUDS OVERHEAD. INCREASING PACIFIC
MOISTURE WILL BRING A BAND OF RAIN MAINLY NORTH OF
SUSANVILLE-GERLACH LINE BY THURSDAY, WITH LIGHTER RAIN SHOWERS
POSSIBLY SPREADING SOUTHWARD TO NEAR INTERSTATE 80. AT THE MAIN
TERMINALS, CIGS/VSBY WILL LIKELY REMAIN HIGH ENOUGH FOR CONTINUED
VFR CONDITIONS ON THURSDAY. MJD

&&

.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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