830
FXUS21 KWNC 071911
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT September 07 2026

SYNOPSIS: Model ensembles continue to favor anomalous mid-level high pressure
across the southern and central Contiguous U.S. (CONUS) and above normal
temperatures across much of the Lower 48, although the risk of extreme heat is
diminishing as we move into the second half of September. 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 heavy precipitation for portions of the Desert Southwest and
Great Basin, Tue-Sat, Sep 15-19.

Flooding possible for portions of the Desert Southwest and Great Basin.

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 THURSDAY SEPTEMBER 10 - MONDAY SEPTEMBER 14:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR TUESDAY SEPTEMBER 15 - MONDAY SEPTEMBER 21: Dynamical model guidance
remains in good agreement regarding elevated chances for subtropical ridging
persisting over the southcentral U.S. into week-2, with the ECENS, GEFS, and
CMCE depicting positive 500-hPa height anomalies early in week-2 across much of
the central and southern CONUS. This lends itself to continued elevated chances
for above normal temperatures for these areas during much of the week-2 period.
The model ensembles forecast falling mid-tropospheric heights and surface
temperatures over a broad region that includes the Northern and Central Plains,
Upper and Middle Mississippi Valley, Great Lakes region, Ohio Valley, central
and northern Appalachians, Upper Mid-Atlantic and Northeast. South of this
region, support for extreme heat hazards continues to dwindle. The
Probabilistic Extremes Tools (PETs) show very little potential for maximum
temperatures to exceed the 95th climatological percentile (the favored
threshold during shoulder seasons), and daily ensemble calculated heat indices
no longer show much signal above 105F. Therefore the slight risk of extreme
heat from previous outlooks was finally discontinued yesterday. However,
temperatures are likely to remain well above normal for much of the Gulf Coast
region including approximately the southern half of Texas, and those sensitive
to heat should continue to exercise caution.



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 Four Corners region. Uncalibrated probabilities from the GEFS and ECENS
both indicate at least a 20% chance of 3-day precipitation totals to exceed
half an inch (with a decent signal for 1-inch) over the region through the
middle of the forecast period.  Similarly, both model PETs indicate at least a
20% chance of 3-day precipitation to exceed the 85th climatological percentile
for much of week-2. Calibrated and uncalibrated solutions also show a broad
area of precipitation across the Southwest early in the period, concentrating
thereafter over New Mexico and Colorado. Therefore, a slight risk of heavy
precipitation is posted for Sep 15-19. Additionally, given the continued
indications of potential heavy precipitation, a flooding possible hazard is
posted for portions of the Four Corners region during the week-2 period. 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 20-40% of normal precipitation and deficits of 1-2 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. The best chance for any
significant precipitation is across southern Missouri near a meandering front
during week-1 and early week-2.

FORECASTER: Anthony Artusa

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