379
FXUS65 KREV 230843
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
143 AM PDT Mon Sep 23 2024

.SYNOPSIS...

* A dry and mild pattern is expected this week with light winds
  through tomorrow.

* Increased southwest winds are likely Wednesday with areas of
  elevated to localized critical fire weather concerns across
  northeast CA and northwest NV.

* Temperatures will remain around 3-7 degrees above season
  averages this week with the warmest days forecasted tomorrow
  and on Wednesday.

&&

.DISCUSSION...

The latest RAP analysis of the upper air pattern shows a generally
north-northwesterly upper air flow over the CWA being under the
forward portion of a Pacific Northwestern upper air ridge while a
localized upper level low resides off the coast of central CA this
morning. Current satellite imagery and surface observations
report generally light winds across the region with some high
clouds moving into northern portions of area from OR this morning.
Going through the rest of today and into tomorrow, model guidance
shows the upper air ridge progressing eastward over the western
CONUS while the aforementioned low off the CA coast stays in
place. With this setup aloft, dry conditions are expected to
continue along with lighter winds across the CWA. Daytime
temperatures look to be slightly warmer today compared to
yesterday with the warming trend expecting to continue into
tomorrow as above average temperatures are in the forecast with
valley portions of the CWA potentially seeing Tuesday afternoon
highs in the middle to upper 80s.

By late Tuesday, forecast guidance depicts the upper air low
opening off into a trough causing a southwesterly flow over the
CWA on Wednesday. As a result of this pattern development above, a
pretty good pressure gradient looks to develop at the surface
across the CWA ahead of a cold front in the Pacific Northwest.
While the precipitation chances look to stay in OR and WA on
Wednesday, the forecast looks to call for increased surface winds
out of the southwest compared to those earlier in the week
particularly in portions of the CWA closer to the OR border. When
looking at latest NBM wind gust probabilities: Lassen, eastern
Modoc, and northern Washoe Counties see around a 40-60% chance of
gusts of 30 mph or greater during the Wednesday afternoon hours.
With relative humidity values in the middle to upper teens in the
forecast, these areas may see elevated to near critical fire
weather conditions during Wednesday afternoon as a result. As
localized critical fire weather conditions may seem possible for a
few hours, will continue to monitor this going forward in
upcoming forecasts. While Wednesday`s daytime highs across the CWA
appear to be similar to those on Tuesday, cooler lows are in the
forecast for Wednesday night/early Thursday morning with western
NV ranging between the middle 40s and middle 50s while the higher
Sierra elevations look to range between the lower 30s and the
middle 40s.

For the rest of the week and going into the weekend, ensemble
guidance currently shows a mostly zonal flow over the CWA following
the trough`s departure on early Thursday. While daytime temperatures
expect to cool by few degrees on Thursday afternoon, regional
temperatures on Friday and Saturday do look rebound back to around
those expected on Tuesday and Wednesday. Dry conditions also are in
the forecast for the area for the remainder of the week. Over the
weekend, ensemble forecasts do show a weak upper level low
developing off the coast of CA once again on Saturday which may
interrupt the zonal flow aloft. Will continue to monitor this going
forward, but there are some early indications of area temperatures
starting a slight cooling trend coming out of the weekend. -078

&&

.AVIATION...

VFR conditions are expected at all REV TAF sites going through today
with very low (>5%) chances for precipitation across the entire
region. A few high level clouds may develop during this morning over
areas closer to the OR border before skies look to clear up during
the afternoon hours. A few high clouds may develop briefly in the
late afternoon and early evening hours in western NV, but they look
to diminish going into the overnight hours. Winds across the area
are forecast to be generally on the lighter side today as well as
Tuesday. The area forecast then calls for an increase in winds out
of the southwest on Wednesday with portions of the OR closest to the
OR border possibly seeing gusts up to around 25-35 kts during the
afternoon hours. -078

&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

$$