AWUS01 KWNH 152313
FFGMPD
CAZ000-ORZ000-160915-

Mesoscale Precipitation Discussion 0067
NWS Weather Prediction Center College Park MD
713 PM EDT Sat Mar 15 2025

Areas affected...Southwest Oregon...Far Northwest CA...

Concerning...Heavy rainfall

Valid 152315Z - 160915Z

SUMMARY...Persistent solid, relatively unwavering moist onshore
flow to bring average .25"/hr & up to .5"/hr rates; resulting in
localized totals of 4-5" in Coastal Range of SW Oregon and 2-3"
across lower slopes of southern Oregon Cascades.=20

DISCUSSION...GOES-W WV suite shows classically anti-cyclonically
curved strong upper-level jet with axis starting to near the
Oregon coast in the next hour or so.  A highly sheared
vorticity/shortwave center along the northwest edge of the axis
will slide northeast into WA and leading nose of enhanced low to
mid-level moisture plume will reach the south-central to southwest
Oregon coastline.  Winds will veer to SWly and increase from
40/45kts to 50-60kts by 03z.  Visible imagery loop shows moisture
axis as well defined mid-level clouds with a line of enhanced, but
still shallow verticality that extends from near the ridge apex at
126W to 39N136.5W and 35.5N141W aligned with both the enhanced
moisture and surface to boundary layer convergence/confluence
axis.  Very slow eastward advancement of the axis will retain
consistency in placement between N Coos to S Curry county in
Oregon for the next 9-12hrs. IVT values of average of 500 will
peak toward 750 kg/m/s throughout the late evening into early
morning hours.  Combine this with favored orographic ascent will
allow for current .15-.25"/hr rates to increase to .33" to
occasionally .5"/hr rates in the SW OR boreal rain forest for that
duration.

This should result in localized 4-5" totals across SW Oregon,
while downstream, the moisture will be slightly reduced having
wrung out on the Coastal Range, but rates of .25-.33"/hr across
the Southern Oregon Cascades may allow for spots of 2-3" totals by
12z.  This will be fairly focused and solid, given the location is
fairly accepting of these rainfall totals, increased run-off
should feed rivers but not likely result in rapid
run-off/inundation. As such, will leave this Atmospheric River as
Heavy Rainfall tag at this time.

Gallina

ATTN...WFO...EKA...MFR...PQR...

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

LAT...LON   44932234 44342219 43732228 43082226 42512226=20
            42642271 42482332 41762335 41632368 41912437=20
            42562454 43202456 43962431 44422419 44622389=20
            44412352 44242311 44732266
            
$$
--- SBBSecho 3.20-Linux
 * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (618:250/1)