406
FXUS21 KWNC 051741
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT September 05 2026

SYNOPSIS: Model ensembles continue to favor increased chances of above normal
temperatures and a chance of extreme heat into week-2 tied to anomalous
mid-level high pressure across the southern and central Contiguous U.S.
(CONUS). A potential surge of moisture from the Gulf of California may result
in heavy precipitation over portions of the Desert Southwest and Great Basin.
Antecedent dryness, combined with little precipitation favored over the next
two weeks supports a Rapid Onset Drought (ROD) risk for portions of the Central
and Southern Plains, Lower and Middle Mississippi, Ohio and Tennessee Valleys.

HAZARDS

Slight risk of extreme heat across much of the Southern and Central Plains, and
the Middle and Lower Mississippi Valley, Sun, Sep 13.

Slight risk of heavy precipitation for portions of the Desert Southwest and
Great Basin, Sun-Thu, Sep 13-17.

Rapid Onset Drought (ROD) risk for portions of the Central and Southern Plains
and the Middle and Lower Mississippi, Tennessee, and Ohio Valleys.

DETAILED SUMMARY

FOR TUESDAY SEPTEMBER 08 - SATURDAY SEPTEMBER 12:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SUNDAY SEPTEMBER 13 - SATURDAY SEPTEMBER 19: Dynamical model guidance
remains in good agreement regarding elevated chances for subtropical ridging
persisting over the south-central U.S. into week-2, with the 0z ECMWF, GEFS,
and Canadian ensembles depicting positive 500-hPa height anomalies early in
week-2 across the central and eastern CONUS. This lends itself to continued
elevated chances for above normal temperatures during much of the week-2
period. The Probabilistic Extremes Tools (PETs) continue to show a greater than
20% chance for maximum temperatures to exceed the 95th climatological
percentile for day 8 across much of the southern CONUS. Uncalibrated apparent
temperatures are forecast to slowly decline from week-1 into week-2 across
portions of the Central and Southern Plains. By day 9, these chances are
significantly reduced for extreme heat across the south-central and
southeastern CONUS. Therefore, a slight risk of extreme heat remains posted for
only Sep 13 for these regions.



Model ensembles indicate a mid-level trough off the West Coast early in week-2.
This may combine with enhanced moisture from the Gulf of California due to
tropical activity over the Eastern Pacific to generate heavy precipitation over
the North American monsoon region. Uncalibrated probabilities from the GEFS and
ECMWF both indicate at least a 20% chance of 3-day precipitation to exceed half
an inch over the region early in the forecast period. Deterministic guidance in
particular continues to show enhanced chances for heavy precipitation into the
southwestern CONUS into the middle of week-2 period. Therefore, a slight risk
of heavy precipitation is posted for Sep 13-17. This region is prone to flash
flooding and caution should be exercised near canyons and creek beds, and
additional rainfall may hamper recovery efforts from recent flooding in the
Grand Canyon.



A Rapid Onset Drought (ROD) risk remains designated for parts of the Southern
Plains and Lower Mississippi Valley and adjacent portions of the Central
Plains, Ohio, Tennessee and Middle Mississippi Valleys, and Southeast U.S. This
area has seen 20% to 40% of normal precipitation and deficits of 1 to 2 inches
over the past 30 days. Near to below normal precipitation and above normal
temperatures remain forecast for this region over the next two weeks increasing
evapotranspiration rates into the middle of September.

FORECASTER: Danny Barandiaran

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