####018003915#### AGUS76 KRSA 091519 HMDRSA HYDROMETEOROLOGICAL DISCUSSION NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA 930 AM PDT MON MAR 9 2009 ...COOL WITH SOME PRECIPITATION MAINLY ACROSS NEVADA AND SHOWERS ACROSS THE CA/OR BORDER TODAY... .24 HOUR PRECIPITATION TOTALS (ENDING MAR 9 AT 500 AM PDT)... GENERALLY LIGHT PCPN FELL ACROSS THE NRN CNRFC AREA...WITH BASIN AMOUNTS EXCEEDING 0.10 INCHES OVER THE W SLOPE OF THE OR CASCADES...PORTIONS OF THE ERN FEATHER BASIN IN THE NRN SIERRA...AND NRN NV FROM AROUND WINNEMUCCA NWD. THE LOWER MAD RIVER BASIN ALONG THE CA N COAST ALSO RECEIVED CLOSE TO 0.10 INCHES. .METEOROLOGICAL CONDITIONS... THE MAIN AREA OF PRECIPITATION THIS MORNING LIES IN A ENE-WSW LOW LEVEL CONVERGENT BOUNDARY ACROSS NRN NEVADA TRAILING BACK TOWARD THE LAKE TAHOE REGION. A N-S UPPER JET DOWN THE COAST OF THE PACIFIC NORTHWEST IS DRIVING COLD AIR INTO THIS SYSTEM..MAINTAINING THE FRONTAL BOUNDARY...AND ALSO GENERATING A FEW SHOWERS INTO THE SRN OREGON CASCADES AND OVER THE COASTAL WATERS OF NW CA. THE AIRMASS REMAINS QUITE DRY THOUGH WITH TOTAL PRECIPITABLE WATER ESTIMATES LESS THAN 0.2 INCHES ON THE RENO AND ELKO SOUNDINGS TAKEN AT 5AM THIS MORNING. DESPITE THE LOW MOISTURE CONTENT OF THE AIRMASS..THIS SYSTEM HAS BEEN FAIRLY EFFICIENT IN PRECIPITATING SOME OF THIS MOISTURE AS WINNEMUCCA REPORTED 0.16 INCHES OF LIQUID EQUIVALENT PRECIP IN THE 11PM-5AM 6-HOUR PERIOD EARLIER THIS MORNING. THE BROADER SCALE UPPER TROUGH HAS ALSO LIFTED A DEEPENED MARINE LAYER OVER COASTAL SRN CA AND HAS SQUEEZED OUT A FEW HUNDREDTHS OF DRIZZLE/LIGHT RAIN INTO THE MID/UPPER ELEVATIONS OF THE COASTAL MTNS. EXPECT SIMILAR CONDITIONS WILL CONTINUE INTO THE EVENING HOURS BEFORE DIMINISHING. THE MAIN ORGANIZED PRECIP BOUNDARY ACROSS NRN NEVADA WILL CONTINUE TO SLIDE SOUTHEAST TODAY AS THE MAIN UPPER TROUGH DIGS SE INTO WRN UT BY LATE EVE...WHILE LIGHT SHOWERS WILL CONTINUE TO LINGER OVER THE SRN OREGON CASCADES. PRECIPITATION IS EXPECTED TO WIND DOWN ALL AREAS AFTER TUESDAY MORNING IN A WEAKER NORTHWEST FLOW PATTERN. A WEAK UPPER LOW CURRENTLY VISIBLE ON WATER VAPOR SATELLITE IMAGERY IN THE ERN PAC NEAR 43N 139W IS FORECAST TO GET PICKED UP IN THE NORTHWEST FLOW AND DRIFT TOWARD THE COAST OF CENTRAL CA BY WEDNESDAY. LATEST MODELS SHOW A LOT OF SPREAD ON THE TRACK OF THIS WEAK FEATURE WITH THE 00UTC ECMWF PROBABLY A REASONABLE COMPROMISE...POSITIONING THE LOW NEAR PT. CONCEPTION BY 12UTC THURSDAY. DESPITE THE UNCERTAINTY IN THE TRACK...THE MODELS DO AGREE THAT THIS SYSTEM WILL REMAIN WEAK..LACKING IN MOISTURE..AND NOT EXPECTED TO PRODUCE MUCH IF ANY PRECIPITATION. CURRENT QPF FOLLOWED HPC ON KEEPING THE AREA DRY FOR NOW FOR THE PERIOD LATE WEDNESDAY INTO THURSDAY MORNING WHEN THE LOW IS DUE TO ARRIVE. DAY 1 QPF (MON 09/12Z TO TUE 10/12Z): 0.1-0.3 INCHES MAINLY NE AND EAST CENTRAL NEVADA HIGHER TERRAIN. OTHERWISE LIGHTER AMOUNTS GENERALLY 0.1 INCHES OR LESS ACROSS NRN NEVADA TRAILING BACK TOWARD THE NRN/CENTRAL SIERRA NEVADA CREST..MAINLY LAKE TAHOE REGION EAST. ALSO 0.1 INCHES OR LESS INTO THE SRN OREGON CASCADES TOWARD THE FAR NORTH COAST OF CA. A FEW HUNDREDTHS OF AN INCH IN THE COASTAL WEST SLOPES OF SRN CA. DAY 2 QPF (TUE 10/12Z TO WED 11/12Z): A FEW HUNDREDTHS OF AN INCH EARLY IN THE PERIOD AROUND CRATER LAKE IN SRN OREGON AND EXTREME NE NEVADA. OTHERWISE DRY. DAY 3 QPF (WED 11/12Z TO THU 12/12Z): DRY. .HYDROLOGICAL CONDITIONS... ALL CALIFORNIA AND NEVADA RIVERS STAGES REMAIN STEADY OR ARE RECEDING SLOWLY AS DRIER WEATHER CONTINUES. ALL RIVERS ARE EXPECTED TO REMAIN WELL BELOW MONITOR LEVELS THROUGH THE WEEK. MORE INFORMATION ON THE CNRFC WEBSITE AT HTTP://WWW.CNRFC.NOAA.GOV AH/ME/AM $$