305
FXUS21 KWNC 041754
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT October 04 2025

SYNOPSIS: Prior to week-2, a tropical cyclone (TC) is likely to develop
offshore of southwestern Mexico with a potential  track near the Baja
Peninsula. Due to this potential TC in the East Pacific, there is an increased
chance of heavy rainfall across the Four Corners region and Desert Southwest
through the middle of the forecast period. Enhanced convection near a frontal
boundary may bring a chance of heavy precipitation to the Florida Peninsula. A
Rapid Onset Drought risk remains for parts of the Southern Plains and Lower
Mississippi Valley where above-normal temperatures and limited precipitation is
forecast over the next 2 weeks. Over Alaska, a strong low pressure system may
bring high winds to portions of the Bering Sea and Chukchi Sea coasts.

HAZARDS

Moderate risk of heavy precipitation for portions of the Desert Southwest and
southern Great Basin, Sun-Mon, Oct 12-13.

Slight risk of heavy precipitation for much of the Desert Southwest as well as
portions of the Southern and Central Rockies and southern Great Basin, Sun-Wed,
Oct 12-15.

Slight risk of heavy precipitation for southern portions of the Florida
Peninsula, Sun-Tue, Oct 12-14.

Slight risk of high winds for coastal areas of western Mainland Alaska, the
Alaska Peninsula, and the Aleutians, Sun, Oct 12.

Flooding possible across portions of the Southwest and Four Corners Region.

Rapid Onset Drought (ROD) possible for parts of Texas and Louisiana.

DETAILED SUMMARY

FOR TUESDAY OCTOBER 07 - SATURDAY OCTOBER 11:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SUNDAY OCTOBER 12 - SATURDAY OCTOBER 18: As of 11am PDT on October 4, the
National Hurricane Center (NHC) is continuing to monitor a broad area of
disturbed weather offshore of southwestern Mexico and states that there is a
100% percent chance of a TC forming in this area during the next 48 hours.
Model guidance remains consistent indicating this potential TC tracking
northwestward near the Baja Peninsula. The NHC is also monitoring a second
disturbance south of the Gulf of Tehuantepec, which currently has a lower
chance of forming into a TC (50% in the next 7 days) while moving northwestward
parallel to the Mexican coast. Todays model solutions from the 0z ECMWF and
GEFS are not quite as bullish with respect to TC formation associated with the
second disturbance in week-2, but continue to favor both disturbances to move
generally toward the Gulf of California. Along with mid-level troughing favored
over the eastern Pacific and West Coast, this scenario would transport copious
amounts of tropical moisture into the Desert Southwest and generate potentially
hazardous heavy precipitation. This is well-supported by the ECMWF and GEFS
Probabilistic Extremes Tools (PETs) which both indicate at least 30% chances of
3-day total precipitation to exceed the 85th climatological percentile, with
the ECMWF PET indicating similar chances for at least 1 inch early in week-2.
This signal drops off as the forecast period progresses but still indicates at
least a 20% chance of 3-day precipitation exceeding hazardous thresholds
through the middle of the week extending further north into the Great Basin and
Rocky Mountains. A moderate risk of heavy precipitation is posted for much of
central and northern Arizona as well as adjacent areas of Utah, Colorado, and
New Mexico for Oct. 12-13, as well as a slight risk of heavy precipitation
extending further inland to cover the western slope of the Southern and Central
Rockies as well as much of the Wasatch and Uinta Mountains, for Oct 12-15. A
flooding possible hazard is also posted for portions of the Southwest and Four
Corners Region associated with the moderate risk of heavy precipitation and the
potential for localized flooding and flash flooding, particularly in canyons
and creeks where topography can focus runoff resulting in quickly rising water
levels.



Model ensembles depict a stalled frontal boundary over the Southeast U.S early
in week-2 which combines with plentiful tropical moisture, resulting in
potentially heavy precipitation which is favored to remain mostly offshore but
may affect the Florida Peninsula. Uncalibrated probabilities from both the
ECMWF and GEFS indicate at least a 20% chance of daily precipitation totals to
exceed half an inch early the period while the PETs indicate at least a 20% of
3-day precipitation to exceed the 85th percentile and at least one inch through
the middle of the period. Going with the highest consensus among various
guidance, a slight risk of heavy precipitation is posted over southern portions
of the Florida Peninsula for Oct 12-14. Localized flooding and flash flooding
is also a possibility given the often very high rainfall rates encountered in
tropical squalls, although no associated flooding hazard is posted at this time.



 An amplified 500-hPa trough over the Bering Sea is forecast to result in a
series of deep surface low pressure systems affecting western Mainland Alaska,
the Alaska Peninsula, and Aleutians during early to mid-October. Although the
greatest impact from this synoptic setup is now likely to be in week-1, there
remains good model agreement on a moderately strong pressure gradient lingering
early into week-2. Therefore, a slight risk of episodic high winds remains
posted for western Mainland Alaska along the Bering and Chukchi Sea coasts
along with the Aleutians and Alaska Peninsula. This wind hazard is valid for
the first day of the period (October 12), after which surface pressure
gradients are favored to ease.



Across portions of Texas, Louisiana, and central Mississippi, 30-day
precipitation deficits range from 2 to 5 inches. This antecedent dryness along
with little to no precipitation anticipated during the next week to ten days
and increased likelihood of above-normal temperatures (highs in the mid 80s to
low 90s) results in a rapid onset drought risk for portions of southeastern
Texas, much of Louisiana, and central Mississippi.

FORECASTER: Danny Barandiaran

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