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000
AGUS76 KRSA 201715
HMDRSA

HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
930 AM PST THU NOV 20 2014

...PRECIP TO SWEEP THROUGH THE AREA TODAY FOLLOWED BY A STRONGER
SYSTEM FRIDAY AND SATURDAY...
...WEAK SYSTEM TO CLIP THE NORTH EARLY NEXT WEEK...

.24 HOUR PRECIPITATION TOTALS (ENDING NOV 20 AT 400 AM PST)...

A WEAKENING NEGATIVELY TILTED UPR TROF MOVED ACROSS THE REGION
YESTERDAY. BEST AMOUNTS WERE OBSERVED ALONG THE COAST FROM THE
GOLDEN GATE NORTHWARD WITH 0.50- TO 1.00-INCH WITH SOME LOCAL
AMOUNTS REACHING 1.25- TO 1.50-INCHES OVER THE FAVORABLE WEST FACING
SLOPES ACROSS THE EEL...LOWER KLAMATH...AND SMITH RIVER BASINS.
INLAND OVER THE SHASTA DRAINAGE...CREST OF THE SOUTHERN OREGON
CASCADES...AND AREA NEAR LASSEN NP TOTALS WERE GENERALLY FROM 0.33-
TO 0.67-INCH.

MOVING SOUTH ACROSS THE HEART OF THE SF BAY AREA DOWN ALONG THE
CENTRAL CA COAST...AND THEN INLAND OVER THE SOUTHERN SACRAMENTO AREA
TO THE CENTRAL SIERRA TOTALS WERE GENERALLY FROM A FEW HUNDREDTHS OF
AN INCH TO 0.25-INCH.

A FEW HUNDREDTHS WERE ALSO OBSERVED OVER EXTREME NW NEV/NE CA AND
THE DRIER LOCATIONS OF THE UPPER KLAMATH BASIN.


.METEOROLOGICAL CONDITIONS (SHORT TERM: THU AM - SUN AM)...

THE NEXT WAVE OF PRECIP IS UPON US THIS MORNING...WITH AN UPPER LOW
SEEN ON WATER VAPOR IMAGERY CENTERED AROUND 200-NM WSW OF CAPE
MENDOCINO...WITH A FRONTAL SYSTEM CURRENTLY MOVING THROUGH THE NORTH
COAST. THIS WIDE BAND OF PRECIP EXTENDS FROM OFF THE WEST COAST EAST
INLAND TO AROUND I-5...AND AS FAR SOUTH AS THE SF BAY. ECHOES CAN BE
SEEN OFFSHORE FROM MONTEREY BAY...AND EXPECT PRECIP TO MOVE IN AS
SCHEDULED THROUGH THE MORNING HOURS. PRECIPITABLE WATER PLUME IS NOT
SUPER IMPRESSIVE WITH THIS SYSTEM...AND GPS IPW SENSORS CONFIRM PWAT
AMOUNTS ALONG THE NORTH COAST SITTING AROUND 0.6-0.8"...LOWER THAN
YESTERDAY`S PEAK OF AROUND 1".

EXPECT THE UPPER TROUGH TO CONTINUE PUSHING THROUGH DURING THE
AFTERNOON AND EVENING HOURS...WITH THE FRONT BRINGING PRECIP INTO
THE NORTHERN AND CENTRAL SIERRA THIS AFTERNOON...AS WELL AS INTO THE
CENTRAL COAST AND SAN JOAQUIN VALLEY. IT DOES FALL APART QUICKLY AS
IT DROPS FURTHER SOUTH AND THE MOISTURE FEED IS CUT OFF DURING THE
EVENING. WHILE PRECIP IS EXPECTED TO COME TO A CLOSE BY MIDNIGHT
OVER THE NORTHERN HALF OF THE STATE...A FEW SHOWERS ARE STILL
POSSIBLE OVER SOUTHERN CA AS THE UPPER LOW TRACKS SOUTH THROUGH THE
SE CA DESERTS EARLY FRIDAY MORNING. IT SHOULD FINALLY EJECT TO THE
SOUTHEAST LATER FRIDAY MORNING. FREEZING LEVELS ARE CURRENTLY
SITTING AT AROUND 8000-FT THIS MORNING...BUT ARE EXPECTED TO FALL TO
AROUND 6500-FT DURING THE AFTERNOON AND EVENING HOURS AS THE UPPER
LOW MOVES THROUGH. THIS FALL WILL LIKELY OCCUR AFTER THE MAIN BAND
MOVES THROUGH...HOWEVER...AND EXPECT THE MAJORITY OF WHAT FALLS
TODAY TO BE LIQUID.

THE THIRD AND STRONGEST SYSTEM IS STILL SET TO ARRIVE IN THE NORTH
FRIDAY AFTERNOON...RIGHT ON THE HEELS OF THE UPPER LOW`S EXIT. THIS
SYSTEM IS DRIVEN BY A WARM AIR ADVECTIVE PATTERN... WITH THE REGION
IN A FAVORABLE POSITION RELATIVE TO THE STRONG 150-KT UPPER JET AND
FUELED BY A BROAD 1.5" PWAT PLUME DIRECTED AT THE NORTH COAST.
MODELS SHOW VERY STRONG ISENTROPIC LIFT OVER THE NORTH COAST FROM 0-
12Z FRIDAY NIGHT...AND IN A BAND FROM THE RUSSIAN/NAPA BASINS EAST
INTO THE NORTHERN SIERRA FROM 06-18Z SATURDAY. WINDS ARE ALSO QUITE
FAVORABLE...WITH 850-MB WINDS EXPECTED TO HIT 40-50-KTS OUT OF THE
SW OVER THE NORTH COAST...AND 30-40-KTS OUT OF WEST INTO THE
NORTHERN SIERRA. WHILE MODELS HAVE BACKED OFF SLIGHTLY ON PRECIP
EXPECTED OVER THESE AREAS DURING THAT TIME...FEEL THAT THE DYNAMICS
ARE STILL MORE THAN AMPLE TO PRODUCE MODERATE TO LOCALLY HEAVY
PRECIP...AND WOULD NOT BE SURPRISED TO SEE THE FORECAST TOTALS
INCREASE OVER THE NEXT COUPLE OF UPDATES.

FREEZING LEVELS ON FRIDAY INTO SATURDAY MORNING WILL REMAIN FAIRLY
HIGH DUE TO THE NATURE OF THE PRECIP PATTERN...GENERALLY ABOVE 9000-
FT. BY SATURDAY NIGHT...SHOULD SEE THEM TAKE A DIP DOWN TO AROUND
5000-6000-FT OVER THE NORTH COAST AND TO AROUND 7000-FT OVER THE
NORTHERN SIERRA. UNFORTUNATELY FOR SNOW PACK...BY THE TIME THE Z
LEVELS FALL...ONLY SHOWERY PRECIP SHOULD REMAIN.

THROUGH THE MORNING HOURS ON SATURDAY...THE MAIN SLUG OF PRECIP IS
EXPECTED TO MOVE DOWN INTO THE CENTRAL COAST AND CENTRAL AND
SOUTHERN SIERRA...AS WELL AS INTO NORTHERN NEVADA. THE PIECE MOVING
INTO THE CENTRAL COAST SHOULD JUST RESULT IN LIGHT SHOWERS...WHILE
THE INLAND PIECES IN THE SIERRA AND OVER NEVADA SHOULD PRODUCE MORE
MODERATE TOTALS. A FINAL S/WV MOVING THROUGH THE WESTERLY FLOW
PATTERN SHOULD PRODUCE ANOTHER UPTICK IN SHOWERS OVERNIGHT OVER THE
NORTH COAST AND UPPER KLAMATH BEFORE WEAKENING AND PUSHING EAST
SUNDAY MORNING.


.METEOROLOGICAL CONDITIONS (LONG TERM: SUN AM - WED AM)...

NOT THE BEST AGREEMENT AMONGST THE MEDIUM RANGE MODELS WITH THE
PLACEMENT OF THE UPR RIDGE THE KEY FOR THE EARLY TO MIDDLE OF THE
WEEK TIME PERIOD. CONFIDENCE OF PRECIP NEXT WEEK IS FAIRLY LOW AT
THIS POINT. CURRENTLY...WPC FAVORS A COMBINATION OF THE EC AND
NAEFS...WHILE DISCOUNTING THE GFS/GEFS.

INITIALLY...A S/WV TROF WILL MOVE TOWARD THE PACNW WITH THE UPR
RIDGE PUMPING UP OFFSHORE BETWEEN 130W AND 140W. THIS WILL BRING
LIGHT PRECIP TO FAR NORTHERN AREAS NEAR THE CA/ORE BORDER AND INLAND
OVER FAR NORTHERN NEV. THIS SYSTEM WILL SHIFT INLAND AND THEN DIVE
SE ACROSS THE EASTERN GREAT BASIN ON ITS WAY TO THE SOUTHERN ROCKIES.

NEXT SLUG OF MOISTURE WILL ADVECT FROM THE NEAR THE HAWAIIAN ISLANDS
AND FOLLOW THE PERIPHERY OF THE UPR RIDGE ON ITS WAY TOWARD THE
PACNW...CLIPPING FAR NORTHERN CA. A WARM FRONT MOVING OVER THE
CA/ORE BORDER AREA WILL BRING LIGHT PRECIP TO THIS AREA ON
MONDAY...WHILE INTO TUESDAY A S/WV TROF DIVING SOUTH ALONG THE WEST
COAST OF ALASKA/BC WILL MOVE TOWARD THE PACNW. THIS WILL PUSH THE
MOISTURE PLUME SOUTH TOWARD NORTHERN CA...AND AN INCREASE IN PRECIP
OVER THE CA/ORE BORDER AREA LATER TUESDAY INTO EARLY WEDNESDAY.

ALL OF THIS DEPENDS ON THE EC/NAEFS GETTING THE OVERALL PATTERN
CORRECT. IF THE GFS TURNS OUT TO BE THE MODEL TO FOLLOW...THE UPR
RIDGE AXIS WILL BE CLOSER TO THE COAST WITH DRY CONDITIONS
PREVAILING AND SYSTEMS DIVING IN FROM THE NORTH MOVING OFF FARTHER
TO THE EAST OF THE AREA.


.HYDROLOGICAL CONDITIONS...

SMALL RISES HAVE BEEN OBSERVED AND WILL CONTINUE IN MANY OF THE
NORTH COAST RIVERS OVER THE NEXT 24 HOURS.  LARGER RISES WILL COME
OVER THE WEEKEND FOR NORTHERN CA COAST AND SACRAMENTO VALLEY RIVER
LOCATIONS DUE TO THE HEAVIER RAIN EXPECTED FRIDAY MORNING THROUGH
EARLY SUNDAY MORNING.

HOWEVER, ALL RIVER LEVELS ARE EXPECTED TO STAY WELL BELOW MONITOR
STAGE THROUGH THE FORECAST PERIOD.


MORE INFORMATION ON THE CNRFC WEBSITE AT HTTP://WWW.CNRFC.NOAA.GOV

DRK/JM/DRK/BW

$$





000
AGUS76 KRSA 191702
HMDRSA

HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
900 AM PST WED NOV 19 2014

...SERIES OF STORMS TO MOVE THROUGH THE REGION THIS WEEK WITH
HEAVIEST PRECIP EXPECTED FRIDAY NIGHT AND SATURDAY...

.24 HOUR PRECIPITATION TOTALS (ENDING NOV 19 AT 400 AM PST)...

THE LEADING EDGE OF PRECIP BEGAN TO MOVE ONSHORE NORTH OF THE GOLDEN
GATE JUST BEFORE THE END OF THE PERIOD. SCATTERED LIGHT AMOUNTS WERE
RECORDED ACROSS SONOMA...NAPA...AND MARIN COUNTIES WITH TOTALS A FEW
HUNDREDTHS OF AN INCH AT BEST.


.METEOROLOGICAL CONDITIONS (SHORT TERM: WED AM - SAT AM)...

THE FIRST IN A SERIES OF STORMS IS UPON THE REGION THIS MORNING...
WITH THE MAIN FRONTAL BAND CURRENTLY DRAPED THROUGH NORTHERN CA. THE
LEADING EDGE IS MOVING NE INTO THE SHASTA BASIN RIGHT NOW...WITH THE
REST OF THE PLUME EDGING INTO THE NORTHERN SIERRA. WIDESPREAD LIGHT
SHOWERS CAN BE SEEN ALL THE WAY SOUTH THROUGH THE SACRAMENTO
VALLEY...DOWN TO NEAR STOCKTON. QUITE A BIT OF MID LEVEL MOISTURE IS
MOVING THROUGH SOUTHERN CA AS WELL...WHERE WIDESPREAD VIRGA AND A
FEW ISOLATED LIGHT SHOWERS ARE BEING REPORTED IN THE SAN JOAQUIN
VALLEY AND SRN SIERRA FOOTHILLS...AS WELL AS THROUGH THE CENTRAL
COAST.

MAIN BAND OF MOISTURE CONTINUES TO SIT JUST OFF THE WEST
COAST...WHICH SEEMS TO BE THE LIMITING FACTOR WITH PRECIP SO FAR.
WHILE PWAT AMOUNTS OF NEARLY 1.25" ARE BEING PICKED UP OFF THE
COAST...AMOUNTS ARE CLOSER TO 0.5-0.7" OVER THE CENTRAL VALLEY.
STILL EXPECT PRECIP TO CONTINUE THROUGH THE DAY...WITH ANOTHER BRIEF
UPTICK IN INTENSITY THIS AFTERNOON AS THE S/WV PUSHES THROUGH THE
NORTH COAST. THAT SHOULD PUSH THROUGH DURING THE EVENING HOURS AND
GIVE THE REGION A BRIEF BREAK BEFORE THE NEXT SYSTEM ARRIVES ON ITS
HEELS. FREEZING LEVELS EXPECTED TO REMAIN ABOVE 8000-FT TODAY.

AN UPPER LEVEL LOW DIVING OUT OF THE GULF OF ALASKA WILL MOVE INTO
THE AREA THURSDAY MORNING...BRINGING THE NEXT WAVE OF PRECIP TO
NORTHERN CA. SHOWERS ARE EXPECTED TO PICK UP ACROSS THE SMITH BASIN
THURSDAY EARLY THURS MORNING...THEN SPREAD SOUTH DOWN THE NORTH
COAST THROUGH THE AM HOURS. SOUTHERLY FLOW SHOULD INCREASE DURING
THE AFTERNOON...CAUSING AN UPTICK IN PRECIP OVER THE SHASTA
REGION...BEFORE TURNING SW AND BRINGING PRECIP TO THE NORTHERN AND
CENTRAL SIERRA. CONDITIONS AREN`T FAVORABLE FOR ANY HEAVY PRECIP
DURING THIS TIME...BUT IT SHOULD STILL BE SOMETHING.

THE UPPER LOW IS EXPECTED TO DIG SOUTH WITH THE ASSOCIATED TROUGH
PUSHING INTO SOUTHERN CA. WHILE IT ORIGINALLY LOOKED LIKE THERE
WOULD ONLY BE A FEW SPRINKLES ALONG THE CENTRAL COAST AND SOME NORTH
SLOPE ACTION OVER THE SRN CA MTNS...MODELS ARE TRENDING FURTHER WEST
W THE TROUGH RESULTING IN WIDESPREAD LIGHT PRECIP OVER SRN CA
THURSDAY NIGHT. THIS SHOULD QUICKLY PUSH EAST FRIDAY MORNING AS THE
UPPER LOW MOVES INTO ARIZONA.

THE STRONGEST SYSTEM IS EXPECTED TO MOVE INTO THE REGION FRIDAY
AFTERNOON...BRINGING WITH IT COPIOUS MOISTURE AND HIGH INTENSITY
PRECIP. A WIDE PLUME OF 1.25-1.5" PWAT AMOUNTS IS FORECAST TO BE
PUSHED INTO THE REGION BY A STRONG UPPER JET WITH A 150-KT CORE.
EXPECT PRECIP TO BEGIN LATE FRIDAY AFTERNOON ALONG THE NORTH COAST
IN A WAA PATTERN. AS THE UPPER JET BEGINS TO SAG SOUTHWARD INTO SRN
OREGON AND NRN CA DURING THE EVENING HOURS...EXPECT STRONG WESTERLY
FLOW TO RAMP UP AT LOW LEVELS AND BRING MODERATE TO LOCALLY HEAVY
PRECIP TO THE SMITH AND EEL R BASINS...AS WELL AS THE WEST SLOPES OF
THE SRN OREGON CASCADES. THIS STRETCHES FURTHER DOWN THE NORTH COAST
TO AROUND THE RUSSIAN AND NAPA BASINS OVERNIGHT...BRINGING MODERATE
PRECIP TO THOSE REGION AS WELL. EXPECT HEAVIER PRECIP TO BEGIN OVER
THE SHASTA DRAINAGE AND NORTHERN SIERRA OVERNIGHT AS WESTERLY FLOW
TRANSPORTS HIGHER MOISTURE INTO THE REGION.

FREEZING LEVELS ARE EXPECTED TO REMAIN HIGH DURING THIS PERIOD WITH
THE WAA PATTERN IN PLACE. DO NOT EXPECT TO SEE MUCH SNOW...WITH
FREEZING LEVELS GENERALLY AT OR ABOVE 8000-FT. COULD SEE SOME LOCAL
LOWERING IN HIGHER INTENSITY CELLS.


.METEOROLOGICAL CONDITIONS (LONG TERM: SAT AM - TUE AM)...

THE PERIOD BEGINS WITH A S/WV TROF MOVING ONSHORE ACROSS THE PACNW
WITH AN E-TO-W UPR JET NOSING INLAND OVER THE CA/ORE BORDER AREA.
THE ASSOCIATED MOISTURE PLUME WILL HAVE ALREADY SAGGED TO THE
SOUTH...AIMED AT THE SF BAY AREA WITH WESTERLY MID-LEVEL ONSHORE
FLOW. THE FOCUS OF THE PRECIP WILL BE OVER THE I-80 CORRIDOR...WHERE
THE BEST ISENTROPIC LIFT WILL BE CENTERED. THE 19/06Z GFS CONTINUES
TO BE THE WETTEST OF THE MODELS WITH THIS SYSTEM...WITH THE 19/09Z
SREF AND 19/00Z GEM NOT FAR BEHIND. BY SAT MORNING...THE EC IS
RATHER UNIMPRESSIVE IN TERMS OF PRECIP AMOUNTS. THIS IS MOST LIKELY
DUE TO THE FACT THE MOISTURE PLUME BECOMES MORE DISCONNECTED FROM
THE BETTER FORCING TO THE NORTH. THE EC SHOWS THE MOISTURE PLUME
AIMED AT PT CONCEPTION WITH LESSER MOISTURE LINGERING ALONG THE I-80
CORRIDOR IN CA (0.50- TO 0.75-INCH PW)...WHEREAS THE GFS STILL SHOWS
0.75- TO 1.25-INCHES OF PW ALONG THE WEST SLOPE OF THE CENTRAL
SIERRA BACK TOWARD THE SF BAY AREA. FOR NOW...LEANED SLIGHTLY TOWARD
THE GFS/GEM/SREF...BUT DID REMAIN SOMEWHAT CONSERVATIVE WITH AMOUNTS
JUST IN CASE THE EC IS CORRECT EVEN THOUGH IN THE MINORITY.

BY THE AFTERNOON HOURS...THE S/WV TROF WILL MAKE ITS WAY TOWARD THE
NORTHERN ROCKIES WITH THE UPR JET NOSING OVER NORTHERN CA INTO
CENTRAL NEV...BUT BEGINNING TO TAKE ON AN ANTI-CYCLONIC CURVE.
PRECIP WILL BE ON THE DECREASE WITH THE WEST SLOPE OF THE CENTRAL
SIERRA SEEING THE BEST OPPORTUNITY FOR PRECIP WITH CONTINUED ONSHORE
FLOW AND THE UPR JET NOSING OVERHEAD. BY THIS TIME...THE MOISTURE
PLUME WILL HAVE BEEN REDIRECTED OVER SOUTHERN CA.

DURING THE EVENING HOURS...THE UPR RIDGE WILL CONTINUE TO BUILD
OFFSHORE BETWEEN 130W AND 140W. THIS WILL RESULT IN NWLY FLOW ALOFT
ACROSS CA AND NEV WITH A WEAK S/WV TROF MOVING THROUGH THIS FLOW AND
PROVIDING SOME LIGHT PRECIP TO AREAS NEAR THE CA/ORE BORDER AND THEN
NORTHERN NEV.

UPR JET SHIFTS NORTH AND EAST AS THE UPR RIDGE STRENGTHENS FURTHER
OFFSHORE ON SUNDAY. PRECIP WILL BECOME LIGHTER AND SCATTERED OVER
THE FAR NORTH. THE MODELS DISAGREE WITH THE TIMING OF A S/WV TROF
MOVING TOWARD THE PACNW ON MONDAY. THE GFS IS ABOUT 12 HOURS FASTER
THAN THE EC. FOR NOW...FOLLOWED THE EC SOLUTION...WHICH WILL BRING
THE SOUTHERN EXTENT OF THIS SYSTEM DOWN TO THE CA/ORE BORDER AND FAR
NORTHERN NEV AREA. ONLY LIGHT AMOUNTS ARE EXPECTED.


.HYDROLOGICAL CONDITIONS...

SMALL RISES CAN BE EXPECTED IN MANY OF THE NORTH COAST RIVERS OVER
THE NEXT 48 HOURS.  LARGER RISES WILL COME OVER THE WEEKEND FOR
NORTHERN CA COAST AND SACRAMENTO VALLEY RIVER LOCATIONS DUE TO THE
HEAVIER RAIN EXPECTED FRIDAY MORNING THROUGH EARLY SUNDAY MORNING.

HOWEVER, ALL RIVER LEVELS ARE EXPECTED TO STAY WELL BELOW MONITOR
STAGE THROUGH THE FORECAST PERIOD.


MORE INFORMATION ON THE CNRFC WEBSITE AT HTTP://WWW.CNRFC.NOAA.GOV

DRK/JM/DRK/BW

$$





000
AGUS76 KRSA 181701
HMDRSA

HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
900 AM PST TUE NOV 18 2014

...PRECIP TO RETURN TO NORTHERN CA LATE TONIGHT...
...ADDITIONAL WAVES IN A SERIES OF PRECIP EVENTS AFFECTS REGION
THURS AND AGAIN FRI/SAT...

.24 HOUR PRECIPITATION TOTALS (ENDING NOV 18 AT 400 AM PST)...

DRY CONDITIONS WERE OBSERVED WITH AN AMPLIFIED UPR RIDGE SITUATED
ALONG THE WEST COAST.


.METEOROLOGICAL CONDITIONS (SHORT TERM: TUE AM - FRI AM)...

SATELLITE THIS MORNING SHOWS AN UPPER LEVEL LOW SITTING AROUND 500-
NM WEST OF CAPE MENDOCINO...WITH THE MAIN FRONTAL SYSTEM APPARENT
JUST AHEAD. A BROAD PLUME OF PRECIPITABLE WATER PEAKING AROUND 1.25"
IS BRING ENTRAINED INTO THE SYSTEM FROM THE SOUTH. SHORT TERM MODELS
AGREE DECENTLY ON TIMING...BRINGING THE FIRST SHOWERS TO THE COAST
SHORTLY AFTER MIDNIGHT TONIGHT. LOCATION AND INTENSITY...HOWEVER...
ARE MUCH LESS CERTAIN. THE 18/00Z EC DIGS THE TROUGH DEEPER THAN THE
OTHERS...AND SWEEPS THE FRONT ACROSS THE CA COAST FROM THE NRN
BORDER ALL THE WAY SOUTH TO POINT CONCEPTION. IN CONTRAST...THE
18/12Z GFS AND NAM...ALONG W THE 18/09Z SREF REFLECT A SHALLOWER
TROUGH THAT KEEPS PRECIP AROUND THE SF BAY AND NORTHWARD AT ITS
ONSET. HAVE LEANED TOWARDS THE GREATER MODEL CONSENSUS FOR THE
WEDNESDAY PERIOD OF THE FORECAST.

AS PRECIP MOVES INLAND WED MORNING AND AFTERNOON...EXPECT AN UPTICK
IN RATES OVER THE NORTH COAST...AS WELL AS THE SHASTA DRAINAGE WITH
INCREASING SOUTHERLY WINDS THROUGH THE SACRAMENTO VALLEY. PRECIP
SHOULD MOVE INTO THE NORTHERN SIERRA BY LATE AFTERNOON...ENHANCED A
BIT BY A DIVERGENT UPPER AIR PATTERN. MOISTURE DOES BECOME AN ISSUE
AS THE DAY GOES ON...WITH MODELS STRUGGLING TO DRAG THE MOISTURE
PLUME INLAND ALONG W THE FRONT. DO NOT EXPECT TO SEE IMPRESSIVE
AMOUNTS OVER THE SIERRA...GENERALLY LESS THAN HALF OF AN INCH BY THE
TIME THE STORM EXITS THURS AM.

WEDNESDAY NIGHT AND THURS AM WILL LIKELY JUST SEE RESIDUAL SHOWERS
LEFT BEHIND THE SYSTEM OVER FAR NRN AREAS OF CA AND NV AS WELL AS
THE NORTHERN SIERRA. THE GFS CLEARS OUT MUCH MORE SHARPLY BEHIND
THOUGH...SO EITHER WAY...QPF OVERNIGHT IS EXPECTED TO BE MINIMAL.
FREEZING LEVELS DURING THIS PERIOD ARE NOT FORECAST TO FALL TOO LOW
DUE TO THE ABSENCE OF MAJOR HEIGHT FALLS...AND SHOULD HANG OUT
AROUND 8000-FT DURING THE EVENT.

THE NEXT WAVE WILL ARRIVE QUICKLY ON THE HEELS OF THE FIRST...IN THE
FORM OF AN UPPER LOW TRACKING DOWN THE PACIFIC NORTHWEST COAST AND
INTO NORTHERN CA EARLY THURSDAY MORNING. THE 18/12Z GFS AND NAM
HANDLE THIS SYSTEM QUITE SIMILARLY...WHILE THE 18/00Z EC IS A BIT OF
AN OUTLIER BUT ONLY IN THE DETAILS. EXPECT THE FRONT TO BRING PRECIP
TO THE NORTH COAST THURSDAY MORNING...QUICKLY MOVING SOUTHWARD AND
INLAND BY EARLY AFTERNOON. THE EC PRESENTS A MORE FAVORABLE FLOW
PATTERN FOR THE NORTHERN SIERRA DURING THURS AFTERNOON AND
EVENING...WHILE THE GFS/NAM/SREF CONSENSUS HOLDS MORE OF THE BULK
ALONG THE COAST. A BAND OF PRECIP SHOULD DEVELOP ACROSS NEVADA THURS
NIGHT ALONG THE DIFFLUENT EDGE OF THE TROUGH AS IT CONTINUES
THROUGH...AS WELL AS THROUGH CENTRAL CA. EXPECT PRECIP AS FAR AS THE
N SLOPES OF THE SRN CA MTNS OVERNIGHT AS WELL.

FREEZING LEVELS EXPECTED TO FALL MORE THAN WITH THE PREVIOUS DAY`S
SYSTEM...TO AROUND 6000-7000-FT OVER NORTHERN CA ON THURSDAY.


.METEOROLOGICAL CONDITIONS (LONG TERM: FRI AM - MON AM)...

THE PATTERN ON FRIDAY MORNING SHOWS A S/WV TROF EXITING THE REGION
OVER THE LOWER COLORADO RIVER BASIN WITH SOME LINGERING LIGHT PRECIP
ACROSS THE HIGHER TERRAIN OF SOUTHERN CA AND PORTIONS OF EXTREME
SOUTHERN NEV.

THE NEXT MOISTURE PLUME WILL ALREADY BE REACHING THE WEST COAST NEAR
THE CA/ORE BORDER...STRETCHING BACK SW TO JUST WEST OF THE HAWAIIAN
ISLANDS. PEAK VALUES OFFSHORE WILL BE AROUND 1.75-INCHES...WHILE
ALONG THE IMMEDIATE COAST VALUES WILL ROUGHLY BE BETWEEN 1.25- AND
1.33-INCHES. AN APPROX 150- TO 155-KT UPR JET WILL INITIALLY NOSE
TOWARD THE PACNW. THERE ARE SOME DIFFERENCES THAT SHOW UP AMONGST
THE MEDIUM RANGE MODELS WITH THE 18/00Z GFS/GEM SLIGHTLY WETTER AS
THEY SAG THE UPR JET A TAD FARTHER SOUTH AS COMPARED TO THE 18/00Z
EC. THE GFS/GEM BRINGS THE UPR JET AXIS SOUTH OF THE CA/ORE
BORDER...WHEREAS THE EC KEEPS THE FEATURE EITHER NORTH OF OR JUST
ALONG THE CA/ORE BORDER. FOR NOW...TOOK A COMPROMISE APPROACH WITH A
SLIGHT LEAN TOWARD THE GFS/GEM.

LOOK FOR WAA/ISENTROPIC LIFT TYPE PRECIP TO RAMP UP ON FRIDAY AND
FROM MAINLY I-80 NORTHWARD. BEST LIFT WITH LOWEST CONDENSATION
PRESSURE DEFICITS IS GENERALLY IN THE 290-K TO 300-K LAYER.
ALSO...OROGRAPHIC FLOW WILL BE ALMOST DUE WEST AT 700-MB FROM APPROX
I-80 NORTHWARD WITH PEAK MAGNITUDES BETWEEN 50- AND 60-KT. THE
GFS/GEM DOES SHOW A SLIGHT SOUTHERLY COMPONENT TO THE MID-LEVEL
FLOW...WHILE THE EC WITH THE UPR JET AXIS FARTHER NORTH ACTUALLY HAS
A SLIGHT NORTHERLY COMPONENT. AS EXPECTED...THE 18/00Z GFS-BASED
RHEA OROGRAPHIC AID IS WETTER THAN THE 18/00Z EC-BASED VERSION
ACROSS THE NORTHERN/CENTRAL SIERRA BASINS. FOR INSTANCE...ACROSS THE
FEATHER RIVER BASIN THE GFS SHOWS 1.40-INCHES WHILE THE EC SHOWS
0.68-INCH. A BIT FARTHER SOUTH OVER THE AMERICAN RIVER BASIN THE GFS
SHOWS 0.90-INCH WITH THE EC AT 0.41-INCH. HEAVIEST PRECIP WILL MOVE
ACROSS THE REGION LATER FRIDAY INTO EARLY SATURDAY.

FOR LATER SATURDAY INTO SUNDAY...THE MOISTURE PLUME WILL SINK TOWARD
THE SOUTH BECOMING DETATCHED FROM THE UPR JET TO THE NORTH. PRECIP
WILL BE ON THE DECREASE ACROSS CENTRAL CA. THE UPR RIDGE WILL BEGIN
TO PUMP UP OFFSHORE GENERALLY BETWEEN 130W AND 140W. NWLY FLOW WILL
DEVELOP OVER CA AND NEV ON SUNDAY. A S/WV TROF MOVING THROUGH THE
FLOW WILL BRING LIGHT PRECIP TO AREAS NEAR THE CA/ORE BORDER AND THE
NORTHERN HALF OF NEV.


.HYDROLOGICAL CONDITIONS...

MINOR RISES ARE EXPECTED ON RIVER NORTH OF INTERSTATE 80 WITH
PRECIPITATION FOR THE UPCOMING WEEK. ALL FORECAST POINTS WILL REMAIN
BELOW CRITICAL STAGES.


MORE INFORMATION ON THE CNRFC WEBSITE AT HTTP://WWW.CNRFC.NOAA.GOV

DRK/JM/DRK/BW

$$





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