436
FXUS21 KWNC 191836
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT September 19 2026

SYNOPSIS: A stalled frontal boundary is expected to settle across the Florida
Peninsula and drift slowly northward, increasing the risk of periodic heavy
rain there for all of week-2. No other hazards are posted in a generally
deamplifying mid-level pattern, but a few situations need to be monitored.
Unseasonably hot weather is possible early in part of the south-central U.S.
while rainfall is expected to increase over the Plains could be more beneficial
than hazardous. Farther west, low pressure over the Gulf of Alaska could
enhance precipitation and winds over parts of southern Alaska, and the
continuing active tropical season in the East Pacific enhances the odds for one
or more systems to affect Hawaii, although no specific threat is identified at
this time. Above-normal precipitation is also expected over the Southwest
again, but amounts are not expected to reach hazards thresholds during week-2.

HAZARDS

Slight risk of heavy precipitation for the Florida Peninsula and some adjacent
areas, Sun-Sat, Sep 27-Oct 3.

DETAILED SUMMARY

FOR TUESDAY SEPTEMBER 22 - SATURDAY SEPTEMBER 26:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SUNDAY SEPTEMBER 27 - SATURDAY OCTOBER 03: Dynamical models depict quick
deamplification of the mid-level ridge over the south-central Contiguous U.S.
(CONUS), but 500-hPa heights remain somewhat above normal across most of North
America through week-2. The weakening ridge axis wavers across the central or
interior western CONUS all week, but is expected to have moved little or
retrograded slightly by the end of week-2. Downstream from the ridge axis, weak
to moderate surface high pressure is expected to settle across the interior
eastern CONUS and remain in place most of week-2. Meanwhile, a mid-level trough
remains favored along or just off the East Coast. The ensemble means are not in
good agreement on the strength of this system early week-2, with the European
ensemble (ECENS) stronger than the Canadian ensemble (CNENS) mean, and the GEFS
mean weaker still. A compromise of these depictions is favored, but the
differences in model depictions don`t affect sensible weather over the CONUS
much. The mid-level trough induces lower surface pressure off the East Coast,
and a frontal boundary is expected to set up southward along the mid-level
trough axis, then southwestward across the Florida Peninsula around the fringes
of eastern CONUS high pressure. Like other aforementioned features, this front
is expected to weaken but maintain some identity through week-2. Model
consensus places the front across South Florida and forecasts a slow northward
drift over the course of week-2, in turn expanding its influence northward with
time. Continuous heavy precipitation throughout the week is not expected, but
the front is expected to locally enhance convective activity, resulting in
areas of heavy rain at times across the Florida Peninsula through all of
week-2. The threat is focused on South Florida early and expands northward as
the front drifts in that direction. Rainfall totals may be enhanced by abundant
tropical moisture along and south of the front, particularly if there is any
interaction with tropical disturbances.



Despite the anticipated deamplification of the mid-level ridge over or near the
southern Plains, 500-hPa heights are expected to remain broadly above normal
across most of the CONUS, allowing unseasonably high temperatures to linger in
the southeastern Great Plains and adjacent Lower Mississippi Valley early in
the period. Temperatures or heat indices there may approach hazards thresholds
in early week-2, but the declining 500-hPa heights and the time of year are
expected to preclude any extreme heat from developing.



Model consensus forecasts above-normal precipitation across the southwestern
CONUS for week-2 as a whole, but the heavy amounts and potential flooding
during the prior week are not expected to persist into week-2, precluding any
widespread heavy precipitation threat. However, isolated locations may be
affected by heavy rains and localized flash flooding, especially considering
the wet antecedent conditions.



Early in week-2, significant rainfall is expected to reach eastward out of the
southwestern CONUS across the Plains. This rain is more likely to be beneficial
than hazardous, as antecedent conditions are acutely dry across the southern
half of the Plains.



A mid-level trough is expected to move into the Gulf of Alaska early week-2 and
remain approximately in place through week-2, with fluctuations in intensity.
This is expected to induce and maintain low surface pressures south of Alaska,
which would enhance precipitation totals across Southeast Alaska and possibly
coastal areas farther west at times. Most models show above-normal
precipitation for the week along with periods of gusty winds in variable
locations, but conditions are expected to remain below hazards thresholds. Some
models imply the potential for one or most former tropical cyclones to become
entrained into the mid-level trough, potentially enhancing precipitation totals
and winds at times. However, with no specific threat identified by any subset
of the models, there is too much uncertainty to justify heavy precipitation or
wind hazards due to this potential



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 threatening the
island chain at this time. Refer to products from the National Hurricane Center
for more detailed information, including any tropical cyclone development.

FORECASTER: Rich Tinker

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