High Wind in Nevada, April 15, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
945 AM PDT SUN APR 15 2007

.UPDATE...
UPPER LOW MOVING ACROSS DESERT SOUTHWEST WITH IMPRESSIVE TROWEL AND
UPSLOPE EVENT TO NORTHWEST SIDE OF SYSTEM. THERE HAVE BEEN REPORTS
OF UP TO 6 INCHES OF SNOW IN MAMMOTH AND BOTH RADAR AND REPORTS
INDICATE MODERATE TO OCCASIONALLY HEAVY SNOW CONTINUE ALONG THE EAST
SLOPES OF THE SIERRA FROM ABOUT MARKLEEVILLE TO SOUTH OF MAMMOTH.
SYSTEM IS EXPECTED TO CONTINUE MOVING EAST TODAY AND BE LOCATED OVER
ARIZONA THIS EVENING. LIFT SHOULD DIMINISH AS DEFORMATION AXIS
SHIFTS EAST ALTHOUGH UPSLOPE FLOW WILL KEEP SOME LIGHT PRECIPITATION
GOING INTO THE EVENING WITH CLOUDS NOT BREAKING UNTIL MONDAY
MORNING. BAND OF PRECIPITATION EXTENDED FURTHER NORTH INTO WESTERN
NEVADA ALTHOUGH SNOW LEVELS WERE ABOVE MOST VALLEY FLOORS. THERE
COULD BE A FEW INCHES IN THE HIGHER ELEVATIONS BUT TRAVEL ISSUES
SHOULD BE MINIMAL. SNOW ADVISORY THROUGH THIS AFTERNOON HAS BEEN
ISSUED FOR MONO COUNTY. TRAVEL ALONG HIGHWAY 395 WILL BE DIFFICULT
AT THE HIGHER PASSES WHERE SNOW TIRES AND CHAINS WILL BE NEEDED.
HIGH TEMPERATURES WERE ALSO LOWERED TODAY. HOHMANN
&&

.AVIATION...UPDATED
VFR CONDITIONS EXPECTED NORTH OF I-80 THROUGH SATURDAY NIGHT WITH
ONLY ISOLATED -SHRA/-SHSN. SOUTH OF I-80 SHOWERS WILL BE MORE
NUMEROUS THIS MORNING THEN DECREASE DURING THE AFTERNOON AND EVENING
AS UPPER LOW MOVES INTO WESTERN AZ. SNOW WILL BE WIDESPREAD ALONG
TWEB ROUTE 402 TO KBIH AS UPPER LOW MOVES ACROSS AREA. WIDESPREAD
IFR CONDITIONS IN SNOW/MT OBSCUREMENT WILL CONTINUE THROUGH THE
AFTERNOON. CLOUDS WILL HANG ALONG THE EASTERN SIERRA TONIGHT WITH A
DECREASE IN SNOW. MT TOPS WILL REMAIN OBSCURED UNTIL MONDAY MORNING.
HOHMANN
&&

.SHORT TERM...EARLIER DISCUSSION
UPPER LEVEL LOW OVER SOUTHERN CALIFORNIA WILL CONTINUE TO MOVE TO
THE EAST INTO THE DESERT SOUTHWEST OVER THE NEXT COUPLE DAYS. WITH
THE TROUGH AXIS ALREADY TO THE EAST OF THE AREA...WINDS HAVE
SWITCHED OUT OF THE NORTH-NORTHEAST ACROSS MUCH OF THE AREA. THIS
FLOW IS FAVORABLE FOR UPSLOPE CONDITIONS ON THE NORTHEAST AND
EASTERN SLOPES OF THE SIERRA...NAMELY IN MONO COUNTY. WITH LOW
LEVELS FAIRLY SATURATED WITH WRAP AROUND MOISTURE ON THE BACK SIDE
OF THE LOW...WE ARE ALREADY SEEING SOME UPSLOPE ENHANCEMENT THIS
MORNING IN MONO AND MINERAL COUNTIES...AS WELL AS FARTHER NORTH ON
THE CARSON RANGE AND IN LASSEN COUNTY, CA. IR IMAGERY IS SHOWING
THIS WELL OVER THE CENTRAL SIERRA...AS RADAR ISNT TOO HELPFUL IN
THIS SITUATION DUE TO LOW-TOPPED NATURE OF THE SHOWERS. SNOW LEVELS
WILL REMAIN AROUND 6000 FEET TODAY...WITH 2 TO 4 INCHES OF SNOW
EXPECTED IN MONO AND MINERAL COUNTIES. COULD SEE SOME HIGHER
LOCALIZED ACCUMULATIONS ON NORTH...NORTHEAST FACES...WITH TERRAIN
ENHANCEMENT FROM THE UPSLOPE FLOW.

SHOWERS WILL TAPER OFF THIS AFTERNOON/EVENING...AS AN UPPER LEVEL
RIDGE BUILDS IN FROM THE WEST. THIS RIDGE WILL BRING IN SOME
SUBSIDENCE...AS WELL AS GIVING US MORE OF A WESTERLY FLOW ALOFT BY
MONDAY. TEMPERATURES WILL SHOOT UP INTO THE HIGH SIXTIES ACROSS THE
WESTERN NV VALLEYS ON MONDAY AFTERNOON...WITH FIFTIES IN THE SIERRA
LOCATIONS.

TUESDAY...A SHORTWAVE TROUGH WILL DROP OUT OF THE GULF OF ALASKA AND
INTO NORTHERN CALIFORNIA BY LATE TUESDAY. UK/EURO LOOK DEEPER THAN
GFS...BUT TIMING LOOKS TO BE IN GOOD AGREEMENT. THIS WILL BRING A
CHANCE FOR RAIN AND SNOW ACROSS THE NORTHERN ZONES FOR TUESDAY AND
TUESDAY NIGHT. STRONG WINDS WILL BE A CONCERN FOR THIS SYSTEM...AS
THE GRADIENT LOOKS TO TIGHTEN UP WELL AHEAD OF THIS SYSTEM. MAY SEE
WIND ADVISORIES TUESDAY FOR WESTERN NV VALLEYS...AS WELL AS THE LEE
SIDE OF THE SIERRA. COLD FRONT WILL PUSH THROUGH LATE TUESDAY...
BRINGING IN COLDER TEMPS ACROSS THE REGION. HOON

.LONG TERM...WEDNESDAY THROUGH SATURDAY...
AN UNSETTLED WEATHER PATTERN WILL CONTINUE THROUGH THE PERIOD AS A
BROAD UPPER TROUGH REMAINS OVER THE PACIFIC NORTHWEST AND NORTHERN
ROCKIES WITH A BLOCKING RIDGE OVER THE CENTRAL CONUS INTO CANADA.
SHORT WAVE ENERGY WILL DEEPEN THE TROUGH AT TIMES...KEEPING
TEMPERATURES BELOW SEASONAL NORMALS AND PRODUCING SHOWERS AT TIMES.

THE MEDIUM RANGE MODELS ARE IN AGREEMENT ON THE LARGE SCALE FEATURES
BUT VARY IN THE STRENGTH OF THE TROUGH WITH THE GFS GENERALLY WEAKER
THAN THE EUROPEAN AND CANADIAN MODELS. THE ECMWF HAS BEEN THE MODEL
OF CHOICE WITH ITS CONSISTENCY AND BETTER HANDLING OF THE MAIN
FEATURES. IT IS UNUSUAL HOWEVER TO FIND NONE OF THE GFS ENSEMBLE
MEMBERS MATCHING THE STRENGTH OF THE WEDNESDAY TROUGH SHOWN BY THE
OTHER MODELS.

THERE WILL BE A BREAK IN THE SHOWERS WEDNESDAY NIGHT AND THURSDAY AS
ONE SHORT WAVE PULLS AWAY TO THE EAST AND BEFORE THE NEXT VORT MAX
APPROACHES FROM THE NORTHWEST THURSDAY NIGHT AND FRIDAY. SHOWERS
WITH THIS FEATURE PERSIST THROUGH FRIDAY THEN END BY SATURDAY
MORNING. RIDGING SHOULD BEGIN TO STRENGTHEN OVER THE EASTERN PACIFIC
FOR THE WEEKEND. RC
&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...LAKE WIND ADVISORY TODAY FOR NVZ002-004.

CA...SNOW ADVISORY THROUGH 4 PM FOR CAZ073
     LAKE WIND ADVISORY TODAY FOR CAZ072.
&&

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