041
FXUS21 KWNC 211814
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT September 21 2026

SYNOPSIS: A stationary front and prolonged easterly flow are expected to set up
across the Florida Peninsula and the Gulf, accompanied by an elevated risk for
periods of heavy rain all week-2. Another stalled front may form across
southern portions of the Great Plains and Mississippi Valley may bring some
enhanced rainfall to southern portions of those regions especially early in the
period. No other hazards are posted under a deamplifying zonal mid-level
pattern across the Contiguous U.S. (CONUS), but a few situations need to be
monitored. Unseasonably hot weather is possible early in part of the
south-central U.S. Meanwhile, farther west, low pressure in the Gulf of Alaska
has the potential to bring increased precipitation and winds to parts of
southern Alaska at times, and the continuing active tropical season in the East
Pacific increases the chances that at least one disturbance impacts Hawaii.

HAZARDS

Slight risk of heavy precipitation for the Southern Plains, Lower Mississippi
Valley, Florida Peninsula and the Gulf Coast region, Tue-Mon, Sep 29-Oct 5.

DETAILED SUMMARY

FOR THURSDAY SEPTEMBER 24 - MONDAY SEPTEMBER 28:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR TUESDAY SEPTEMBER 29 - MONDAY OCTOBER 05: Dynamical models generally
indicate a deamplifying mid-level ridge across the central and interior western
CONUS from the end of week-1 into the onset of week-2 before potentially
slightly strengthening by the middle of the period with troughs bookending this
ridge across the Northeast Pacific and eastern CONUS. There are significant
differences regarding the details of these features, regarding how amplified
the trough across the East will be, translating to increased uncertainty
regarding the potential for heavy rainfall. In general, stationary fronts are
anticipated to drape across the Great Plains and Mississippi Valley in addition
to the Gulf Coast and Florida.  Furthermore, any tropical waves or low pressure
systems that interact with the frontal boundary would further enhance rainfall
over at least part of the Gulf Coast and Florida, The ECENS mean 500 hPa trough
across the East is more favorable for more widespread and heavier rainfall
across parts of the southern CONUS compared to the GEFS. The ECENS
Probabilistic Extremes Tool indicates greater than 50% chances of 3-day
accumulated rainfall (Sep 29-Oct 1) exceeding the 85th percentile over the
Southern Plains with greater than 40% chances extending into the Lower
Mississippi Valley. The GEFS PET limits probabilities of 20 to under 30%
chances for these thresholds. The ECENS, GEFS, and CMCE PETs all indicate at
least a 20% chance of portions of the Gulf Coast, Florida and Southern
Plains/Lower Mississippi Valley exceeding one inch of rainfall in a 3-day
period with thunderstorms possible in some areas. Therefore, a slight risk of
heavy rain is continued across the Gulf Coast and Florida for the entirety of
the period, with expansion into southern portions of the Great Plains and
Mississippi Valley, with the greatest chances for heavy rainfall across the
Southern Plains and Mississippi Valley at the beginning of week-2. Rainfall
would be beneficial  in areas where antecedent conditions have been dry.  Some
areas of heavy rain could be slow-moving, potentially triggering isolated flash
flooding, although no particular area appears vulnerable to widespread and
persistent flood conditions.



Anomalously hot temperatures may linger from the end of week-1 into week-2
across the south-central CONUS, especially across southern Texas with lingering
ridging across the central CONUS.  Calibrated heat tools indicate a 20-40%
chance of maximum heat index values exceeding the 90th percentile across this
region. However, in general the mid-level heights are anticipated to be less
favorable of temperature values reaching hazardous criteria in addition to
decreasing sun angles in the autumn. Therefore no heat related hazards are
designated in today`s outlook.





Mid-level troughing is expected to be centered over the Gulf of Alaska
throughout week-2, supporting surface low formation over the region. In general
the models indicate a more favorable pattern for a stronger low and associated
onshore flow to the Gulf of Alaska toward the end of week-2 which may bring
enhanced rainfall and gusty winds to south-central and southeastern Alaska. No
hazards are designated at this time but will be monitored closely in the
upcoming days.





As the active tropical season in the East Pacific, the increase in tropical
cyclone development enhances the odds that at least one system may influence
conditions across Hawaii. Grounds are saturated in many areas due to periods of
heavy rain over the past few months, and any additional episodes of heavy rain
may renew impacts caused by the wetness, such as flooding and possibly
mudslides. At this time, several areas of potential tropical development are
being monitored in the East Pacific, but no specific system is identified for
week-2 hazardous impacts. Refer to products from the National Hurricane Center
for more detailed information, including any tropical cyclone development.

FORECASTER: Melissa Ou

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