CNRFC Hydrometeorological Discussion
AGUS76 KRSA 282004
HMDRSA
Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
100 PM PDT Thu Mar 28 2024
...LINGERING SHOWERS AND ISOLATED TSTORMS TODAY AS A COLD FRONT
CONTINUES TO MOVE THROUGH CA/NV...
...A LARGE SURFACE/UPPER LOW WILL TRAVEL ALONG THE COAST FRIDAY INTO
THE WEEKEND BRINGING WIDESPREAD PRECIP AND ISOLATED TSTORMS...
.METEOROLOGICAL CONDITIONS (SHORT TERM: THU PM - SUN AM)...
Radar imagery continues to show scattered showers across the region
this afternoon along with some thunderstorms as a cold front passes
through soCal/NV and troughing takes over the west coast. The
surface/upper low continue to inch closer to the coast as well while
the next system develops offshore. Another 0.25-0.75" has fallen
over the Sierra the past 6 hours with 0.10-0.50" along the north
coast and through to Shasta. Forecast overall remains on track for a
surface/upper low to approach the CA coast tonight arriving Friday
morning. The system will draw in some moisture from the southwest
funneling into soCal as the low travels south along the coast into
the weekend. This is expected to produce widespread precipitation
and isolated thunderstorms Friday/Saturday with the heaviest amounts
along the central/srn coastal CA mountains, across coastal soCal,
and over the Sierra. A secondary low is still expected to develop
over NV/UT late Saturday into Sunday producing additional precip
over NV.
There haven't been many changes in the 12z model runs compared to
this morning aside from some subtle shifts in timing/positioning of
the low. QPF change from this morning over the three day period has
generally between 0.10-0.50" up or down depending on location.
Exceptions have been 0.50-1" increase along the Big Sur coastal
mountains. Ensemble spread is just as wide across coastal soCal as
this morning with 24 hr QPF ending Sunday morning at San Diego
ranging between <0.50" to over 3" between the GFS and ECMWF.
The official forecast was a blend of the latest WPC guidance and the
12z GFS/ECMWF along with the previous forecast. QPF through 12z Sun:
1-2.50" CA coast from Sonoma to San Diego, 2-4" Transverse Range, 2-
4.50" central coast mountains, 1.50-3" Sierra, 0.50-1.50" most of
the rest of nrn CA, 0.25-1" down the valleys, and 0.10-0.50" for
ne/se CA.
Freezing levels 3.5-5 kft north of I-80 and 4-11 kft to the south
today with lower freezing levels spreading across the region into
Friday. Mid Friday morning, expecting freezing levels 3.5-6.5 kft
north of Point Conception and 5.5-10.5 kft to the south. Most of the
region will be below 6 kft by Saturday morning with the entire
region down to 4.5-6.5 kft at the end of the period as the low takes
over.
.METEOROLOGICAL CONDITIONS (LONG TERM: SUN AM - WED AM)...
Minor changes to the afternoon forecast issuance after incorporating
the latest WPC QPF and NBM as two areas of low pressure move out of
the area...one over northeast NV and the other crossing the CA/MX
border area. These two features will be the focal points of the
precip on Sunday before tapering off. Coastal southern CA and
northern NV near the I-80 corridor will see the best precip with
0.25- to 0.75-inch. Freezing levels will range from 4000- to about
6000-feet from north to south. After the upr trof moves a bit more
inland...an upr ridge building over the eastern Pacific will nudge
across the Pacific Northwest and northern CA...which will generate
dry north to northeast flow aloft. Freezing levels will bump up to
10000- to 12000-feet.
QPF graphics are available at www.cnrfc.noaa.gov/qpf.php
AS/Kozlowski
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