Today Through the Fourth Friday (22 to 28 days) Weather Outlook for the U.S. and a Six-Day Forecast for the World: posted August 1, 2024
This article focuses on what we are paying attention to in the next 48 to 72 hours. The article also includes weather maps for longer-term U.S. outlooks and a six-day World weather outlook which can be very useful for travelers.
First the NWS Short Range Forecast. The afternoon NWS text update can be found here after about 4 p.m. New York time but it is unlikely to have changed very much from the morning update. The images in this article automatically update.
Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Thu Aug 01 2024
Valid 12Z Thu Aug 01 2024 – 12Z Sat Aug 03 2024…Dangerous heat engulfs much of the country as one heatwave continues
from the Southern Plains to the Southeast/Mid-Atlantic and another begins
in the West……Severe weather and flash flooding expected for portions of the Midwest
Thursday…… Locally heavy monsoonal shower and thunderstorm chances continue for
the Southwest…Widespread, dangerous heat will unfortunately be the main weather story
for much of the country this week as one heatwave continues for the
Plains, Middle/Lower Mississippi Valley, Southeast, and Mid-Atlantic, and
another heatwave begins over portions of the West. A strong upper-level
ridge will remain in place over the southern-tier of the U.S. the next
couple days, allowing for high temperatures to reach into the low 100s
over portions of the Southern Plains/High Plains, the upper 90s to low
100s for the Lower Mississippi Valley, and the upper 90s for the Southeast
into the southern Mid-Atlantic. High humidity values for areas east of the
High Plains will bring heat indices into the 105 to 110 degree range,
potentially as high as 115 for parts of the Lower Mississippi Valley, with
many areas under heat-related advisories or warnings. The combination of
hot temperatures/high heat indices, as well as very warm morning lows only
dropping into the mid- to upper 70s, will be dangerous to anyone without
access to adequate air conditioning. Temperatures warming into the upper
80s/low 90s with periods of higher humidity will lead to some muggy,
potentially dangerous conditions for portions of New England as well,
particularly on Friday. An approaching cold front will bring relief to
northern portions of the Southern Plains and Middle Mississippi Valley on
Friday, with the expectation the heat wave will begin to wane for most
locations through the weekend.In the West, an upper-level ridge will also begin to build northward,
sending high temperatures across much of the northern tier of the West
10-20 degrees above mid-Summer averages. Forecast highs Thursday are into
the upper 90s/low 100s for the inland Pacific Northwest/northern Great
Basin and mid- to upper 90s for the northern Rockies/High Plains.
Temperatures will get even hotter on Friday, with highs into the low to
mid-100s for most locations. Many near record-tying/breaking highs are
possible. Similar to areas further east, many heat-related advisories and
warnings have been issued as this heat will also reach dangerous levels
for the general public. Smoke from area wildfires will also continue to
plague parts of the region, resulting in hazy conditions and poor air
quality, and the risk for more wildfires will increase as the hot, dry
conditions settle in.An upper-level low/accompanying surface frontal system traversing the
northern side of the ridge over the southern tier of the U.S. will bring
another round of showers and thunderstorms to the Midwest Thursday. High
surface moisture leading to very strong instability will support intense
thunderstorm development through the afternoon across the warm sector
ahead of an approaching cold front, with lingering outflow boundaries from
overnight convection helping to trigger individual and clusters of storms.
Sufficient shear with the passing upper-level wave will lead to the threat
of severe weather, with a Slight Risk (level 2/5) from the Storm
Prediction Center covering Illinois, Indiana, Kentucky, and southwestern
Ohio, mainly for the threat of some damaging winds. The threat for some
intense downpours given the high moisture/strong storms, and potential for
some more widespread, organized clusters of storms, will lead to some
heavier rainfall totals and the risk for flash flooding. Many of these
locations have seen recent heavy rainfall given repeated rounds of
organized storms passing through, leading to wetter antecedent conditions
more sensitive to any additional rainfall. A Slight Risk of Excessive
Rainfall (level 2/4) covers much of same region from northeastern Illinois
southeast through Indiana/western Ohio and into eastern Kentucky. Some
slow moving storms producing heavy rainfall under the passing upper-low
may also lead to some flash flooding, with the Slight Risk extending
northwest into southern Wisconsin. Some more isolated storms will be
possible further east into the Appalachians and Mid-Atlantic Thursday.
Additional storms will be possible across the region Friday as the system
shifts eastward, with a greater chance of storms spreading into the
Appalachians and the Mid-Atlantic. Some isolated severe storms and
instances of flash flooding will be possible. A lingering upper-level
weakness will lead to scattered showers and thunderstorms over Florida and
portions of the Southeast Thursday, with moderate to locally heavy
rainfall possible, especially over the Florida Peninsula. More widely
scattered storms will remain possible Friday.Persistent Monsoonal conditions over the Southwest will continue to bring
daily shower and thunderstorm chances. Sufficient moisture across the
region will lead to the threat for some locally heavy downpours and an
isolated flash flooding, particularly over terrain sensitive areas such as
burn scars. A lingering frontal boundary will lead to some storms over
portions of the southern High Plains as well on Thursday, and a subtle
upper-level wave along the edge of the upper-ridging will bring storm
chances northwestward into portions of California Friday, particularly in
vicinity of the Sierra Nevada. Similar to areas further north, forecast
high temperatures more broadly in the region will be trending hotter and
above average, with 90s and low 100s for most locations outside of the
California Coast, and mid-100s to low 110s for the Desert Southwest.