Hydrometeorological Discussion
Issued by NWS California-Nevada RFC

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AGUS76 KRSA 291541
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ZCZC RNOWRKHMD 291514
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HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
740 AM PST THU JAN 29 2015

...PRECIP FOR SE CA UP INTO S NEV TODAY AND TOMORROW...
...LIGHT PRECIP NEAR CA/ORE BORDER AND FAR N NEV SUN AND MON...

.24 HOUR PRECIPITATION TOTALS (ENDING JAN 29 AT 400 AM PST)...

WEAK UPPER RIDGING OVER THE WEST KEPT THE REGION DRY OVER THE LAST
24-HRS.


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

UPR RIDGE AXIS IS ALIGNED EAST OF THE AREA FROM THE 4-CORNERS STATES
NNW TOWARD WESTERN CANADA. A COUPLE WEAK UPR LOWS ARE SPINNING JUST
OFF THE WEST COAST. THE FIRST IS LOCATED NEAR CAPE MENDOCINO...WHILE
THE SECOND IS TO THE SW OF THE REGION...WEST OF CENTRAL BAJA. OVER
THE NEXT 3 DAYS...THE SOUTHERN LOW WILL DRIFT TO THE NE AND
STRENGTHEN...WHILE THE NORTHERN LOW IS EXPECTED TO DRIFT SOUTH ALONG
THE CA COAST AND BECOME ENGULFED BY THE OTHER SYSTEM.

MOISTURE IS ALREADY ADVECTING NORTHWARD ACROSS BAJA IN THE SOUTHERLY
FLOW AHEAD OF THE UPR LOW. MID- AND HIGH-LEVEL CLOUDINESS IS ALREADY
STREAMING NORTHWARD ACROSS THE SW PORTION OF THE US. THE 29/12Z KNKX
RAOB SHOWS A NEARLY SATURATED LAYER ABOVE 600-MB. BELOW THIS
LEVEL...THERE IS A DECENT DRY SUB-CLOUD LAYER THAT WILL NEED TO BE
SATURATED BEFORE PRECIP REACHES THE GROUND. 88-D MOSAIC DOES SHOW
SOME WEAK ECHOES MOVING ACROSS SOUTHERN CA NE TOWARD EXTREME
SOUTHERN NEV...BUT MOST LIKELY NONE OF THIS IS REACHING THE GROUND.

THROUGH TODAY INTO FRIDAY...MOISTURE WILL CONTINUE TO INCREASE FROM
THE SOUTH WITH PRECIP BECOMING MORE WIDESPREAD ACROSS SOUTHEAST CA
INTO SOUTHERN NEV. THE UPR LOW WILL BECOME SITUATED OVER EXTREME
SOUTHERN CA NEAR THE US/MEXICO BORDER.

BY SATURDAY...THE UPR LOW WILL DRIFT OFF TOWARD THE SE TOWARD MEXICO
WITH A POSITIVELY TILTED UPR RIDGE MOVING ACROSS THE AREA FROM THE
SW. THIS WILL RESULT IN CONDITIONS DRYING OUT.


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

BY SUNDAY MORNING...HIGH PRESSURE OVER THE EASTERN PACIFIC WILL HAVE
DOMINATED THE PATTERN AGAIN AND DRY CONDITIONS ARE EXPECTED THROUGH
THE DAYTIME HOURS. THINGS BECOME A LITTLE MORE TRICKY AS A WARM
FRONTAL PATTERN SETS UP OVER THE NORTH COAST DURING THE EVENING
HOURS...THOUGH TO WHAT DEGREE REMAINS THE QUESTION. THE 00Z GFS IS
MUCH MORE AGGRESSIVE THAN THE 06Z RUN...FAVORING BRIEF MODERATE
PRECIP OVER THE SMITH BASIN SUNDAY NIGHT. THE 06Z RUN IS INDICATING
JUST LIGHT SHOWERS EARLY MONDAY AM THROUGH AFTERNOON. THE 00Z EC IS
THE SPEEDIEST AND FURTHEST SOUTH...BRINGING LIGHT PRECIP DOWN TO PT
ARENA SUNDAY NIGHT THROUGH MON AFTERNOON. WENT WITH A COMPROMISE
BETWEEN THE 06Z GFS AND THE 00Z EC...TRENDING TOWARDS A SHALLOWER
SYSTEM FAVORING ONLY THE SMITH AND UPPER KLAMATH LATE SUNDAY THROUGH
MON EARLY AFTERNOON...THEN DRIFTING EAST THROUGH NORTHERN NEVADA
MONDAY EVENING.

AFTER THIS SYSTEM MOVES THROUGH...EXPECT THE STORM TRACK TO REMAIN
AIMED WELL TO THE NORTH AS RIDGING AGAIN DOMINATES THE WEST THROUGH
AT LEAST MIDWEEK.


.HYDROLOGICAL CONDITIONS...

PRECIP FORECAST FOR THE COMING WEEKEND WILL HAVE MINIMAL IMPACTS ON
AREA RIVERS. SOME MINOR SNOWMELT IS OCCURING IN HIGH ELEVATION
BASINS WHICH IS CAUSING SOME VERY MINOR RISES.  MOST AREA RIVERS ARE
EITHER FLAT OR RECEDING.

ALL RIVER STAGES ARE EXPECTED TO REMAIN WELL BELOW MONITOR LEVELS
THROUGH THE NEXT FIVE DAYS.



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

JM/DRK/JM/PF

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