Graphic for MPD #0069

Mesoscale Precipitation Discussion 0069
NWS Weather Prediction Center College Park MD
730 PM EST Mon Feb 19 2024

Areas affected...northern and central California

Concerning...Heavy rainfall...Flash flooding possible

Valid 200029Z - 200500Z

Summary...Isolated flash flood potential continues across northern
and central California through 05Z or so.

Discussion...Areas/bands of heavy rainfall (and occasional
embedded deep convection) continues across the discussion area -
especially along an axis from San Francisco northeastward through
Yuba City, Chico, and higher terrain near Lassen County, CA. 
Areas of 0.25-0.5 inch/hr rain rates continue to be reported
beneath stronger convection, and occasional reports of water over
roadways have also been received.  The convection continues amid
broadly cyclonic flow aloft southeast of a closed mid-level low
centered near 42N, -130W.  Difluence aloft combined with strong
low-level warm advection, orographic lift, and 250-750 J/kg SBCAPE
continue to support ongoing convection, and individual cell
motions (parallel to southwesterly steering flow aloft) have
enabled localized training/repeating along with local rainfall
totals near an inch in spots over the past 3-6 hours.

The ongoing scenario should continue to support isolated flash
flood potential for at least the next 3-5 hours.  Synoptic
features supporting the potential have changed very little through
the day and should remain nearly steady state for a few more
hours.  The loss of daytime heating could act as a catalyst for
weakening instability/updraft strength at some point this evening,
though orographic lift and ascent associated with the Pacific
upper low should act to overcome waning instability and still
result in spots of locally heavy rainfall.  Local totals exceeding
1 inch are possible through 05Z on a spotty basis.

Cook

ATTN...WFO...EKA...MFR...MTR...REV...STO...

ATTN...RFC...CNRFC...NWC...

LAT...LON   41912247 41042100 38951999 37772102 37132221
            37982278 39292383 40762436 41662417
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Last Updated: 730 PM EST Mon Feb 19 2024