Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
349 PM EDT Sun Sep 05 2021

Valid 00Z Mon Sep 06 2021 - 00Z Wed Sep 08 2021

...Expansive heat dome building across much of the West, excessively hot
temperatures in the Desert Southwest...

...Unsettled weather for the Deep South and parts of the East; new wave of
low pressure to spark showers and storms in the Upper Great Lakes on
Tuesday...

...Keeping a watchful eye on the Gulf of Mexico for tropical activity this
week...

The upper level pattern to start the first full week of September features
an intensifying ridge in the West with a pair of upper troughs tracking
across the northeastern quarter of the Lower 48. The hottest temperatures
will be centered over the western third of the country with high temp
departures ranging between 10-20 degrees above normal. Some locations in
the Desert Southwest are under Excessive Heat Warnings due to daytime
highs forecast to range anywhere from 105-115F with some spots even
surpassing 115F. Heat Advisories are also in effect for much of
California's Great Valley and a large chunk of Southern California. By
Tuesday the heat continues to build even more in the Great Basin and
Intermountain West where a handful of daily record high temps could be
tied and/or broken. The large area of high pressure aloft will keep the
West dry as well, meaning little relief is expected to come for ongoing
wildfires. In fact, there are Elevated Risks for favorable fire weather
conditions in the northern Rockies and High Plains. Expect large swaths of
wildfire smoke to blanket much of the West and parts of the Plains with
some Air Quality Alerts posted from the West Coast to the Rockies.

The most active weather is set to occur in the Deep South where a
quasi-stationary frontal boundary triggers daily rounds of showers and
thunderstorms. Locally heavy downpours could lead to areas of flash
flooding with a few severe storms possible. In addition, West Texas and
both southern Arizona and New Mexico may witness hit-or-miss showers and
thunderstorms through Labor Day, with chances of seeing precipitation
decreasing on Tuesday as the ridge out west strengthens. Farther north, a
cold front producing spotty showers and thunderstorms tracks through the
Tennessee Valley, the Mid-Atlantic, and Northeast tonight. High pressure
building in behind the front will make for a dry Labor Day for most of
these areas. The lone exception is northern New England as another cold
front passing through Ontario approaches Labor Day afternoon. Last but not
least, a deepening upper trough spawns a new storm system over the Upper
Midwest Monday night into Tuesday. This area of low pressure will be
responsible for showers and thunderstorms bringing locally heavy rainfall
and some severe weather to the Upper Great Lakes on Tuesday.

The NHC is monitoring a tropical wave near the tip of the Yucatan
Peninsula that is forecast to track into the northern Gulf of Mexico later
this week. There is currently a 30% chance of development and it could
usher in heavy rainfall to parts of the northern Gulf Coast. Interests
from Louisiana to the west coast of Florida should continue to check in on
the latest forecast regarding this tropical disturbance over the next few
days.

Mullinax