180
FXUS65 KREV 020731
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
1231 AM PDT Tue Jul 2 2024

.SYNOPSIS...

* High pressure brings a prolonged heatwave starting on Wednesday
  through early next week.

* Afternoon highs will be 10-20 degrees above average by the
  weekend resulting in a moderate to major HeatRisk.

* It will remain very dry with typical afternoon breezes, and a
  very low chance, less than 5%, for precipitation in the weekend.

&&

.DISCUSSION...

The theme of the week is summer heat brought to you by an upper
level ridge slowly transiting from the Pacific Ocean into the
Great Basin.

Upper trough slowly moves east into the Rockies allowing an upper
ridge to move inland. This will lead to a warm up over the next
few days as the ridge center reaches the Great Basin by Saturday.
In the meantime, afternoon temperatures will rise a few degrees on
Tuesday. By Wednesday and Thursday (4th of July) afternoon highs
will be around 5 to 15 degrees above normal for early July. The
hottest temperatures of the week are expected between Friday and
Sunday. Afternoon highs will be around 10-20 degrees above normal.
Currently, Sunday is possibly the hottest day of the week. For
reference, normal temperatures in early July for Reno range from
91-94 F, for South Lake Tahoe 78-81 F, and for Truckee 81-84 F.

There is good agreement with ensemble guidance and deterministic
models going through the weekend. So, not really expecting a lot
of change in the forecast. Although, it is looking like a long
stretch of 100 degree days for western NV, 90 degree days for
Truckee and Mammoth Lakes, and upper 80s to around 90 for South
Lake Tahoe and other communities around the lake. Probabilities of
over 105 degrees in western NV are 40-80% over the weekend. For
this reason, an Excessive Heat Watch is in effect from Saturday
through Tuesday. Lake Tahoe communities, Truckee, Mammoth Lakes
and vicinity have a 40-60% chance of reaching 90 degrees, which
could lead to heat advisories if the trend continues.

Temperatures should start a very slow cooling trend Monday and
beyond as the upper ridge slowly moves east towards the Four
Corners area. Therefore, the heatwave should end by the middle of
next week.

No significant winds are expected over the period. Although,
typical afternoon breezes are likely every other day. Not really
expecting any precipitation with the upper ridge overhead
providing subsidence and with PWATs generally around 0.25 inches.
However, some ensemble members of the CMC are showing some light
precipitation in the Eastern Sierra. If anything develops it will
be light and short-lived, and can`t really rule out lightning
with any cell, but the probability is less than 5% for convection
through the period.

&&

.AVIATION...

VFR conditions expected through the period. Skies will be clear or
with a few clouds. Winds will be light and VRB, except in the
afternoon and early evening, where east to north winds with
speeds up to 10 kts and gusts up to 15-20 kts are likely. Density
altitude concerns are very likely areawide starting on Wednesday
and into early next week.

&&

.FIRE WEATHER...

Hot and dry is the main theme of the week and early next week.
Temperatures will be rising over the next few days. Afternoon
highs will be about 10-20 degrees above normal by the weekend.
Minimum relative humidity will be in the single digits over western
NV, northeast CA and the valleys of Mono county, and in the teens
for the higher elevations of the Sierra. Overnight recoveries are
expected to be poor to very poor through the period. At least,
winds are expected to be below any critical thresholds with max
gusts up to 30 mph. Chances for precipitation are below 5% for the
Eastern Sierra this weekend, otherwise it should be dry.

&&

.REV Watches/Warnings/Advisories...
NV...Excessive Heat Watch from Saturday morning through Tuesday
     morning NVZ001-003>005.

CA...None.
&&

$$