331
FXUS21 KWNC 191844
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT September 19 2024

SYNOPSIS: Model solutions indicate increasing tropical convection and the
potential for tropical cyclone (TC) development over the western Caribbean,
resulting in an enhanced chance for heavy precipitation for portions of the
Southeast U.S. Mid-level low pressure over the Aleutian Islands and a series of
surface low pressure systems bring the potential for episodic heavy
precipitation to southeastern Alaska and high winds along the southern and
southeast coasts. Large precipitation deficits over the last few weeks,
combined with expected warm, dry weather results in the risk for Rapid Onset
Drought (ROD) for portions of the Southern Plains and Ozarks.

HAZARDS

Moderate risk of heavy precipitation for northern and central Florida, much of
Alabama and Georgia, and portions of South Carolina, Fri-Sun, Sep 27-29.

Slight risk of heavy precipitation for the Southeast U.S. as well as portions
of the Tennessee and Lower Mississippi Valleys, Fri-Tue, Sep 27-Oct 1.

Slight risk of heavy precipitation for portions of southeastern Alaska,
Fri-Tue, Sep 27-Oct 1.

Slight risk of high winds for Florida, coastal portions of Alabama,
Mississippi, and eastern Louisiana, as well as portions of southern Georgia,
Fri-Sun, Sep 27-29.

Slight risk of high winds for the southern and southeast coast of Alaska,
Fri-Tue, Sep 27-Oct 1.

Risk of Rapid Onset Drought for portions of the Southern Plains and Ozarks.

DETAILED SUMMARY

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

FOR FRIDAY SEPTEMBER 27 - THURSDAY OCTOBER 03: The highlight for the week-2
hazards outlook continues to be the potential for TC activity in the western
Caribbean. Forecast uncertainty remains high regarding the timing and location,
but model ensembles continue to show with fairly high confidence that some sort
of system is likely to form and affect the Gulf Coast. It is still too early to
determine the potential intensity of an emerging storm, but models are
consistently depicting the potential for copious precipitation over much of the
Southeast U.S. during week-2. The GEFS and ECMWF Probabilistic Extremes Tools
(PETs) continue to indicate at least a 20% probability of 3-day precipitation
exceeding the 85th percentile and at least 1 inch for much of the Southeast
U.S. for much of the forecast period. The ECMWF is especially bullish,
extending 3-day 1 inch totals all the way up the Eastern Seaboard and higher
probabilities of exceeding the 85th percentile for the Southeast U.S., as well
as highlighting the potential for over 2 inches for portions of Florida,
Alabama, and Georgia early in week-2. Therefore a moderate risk of heavy
precipitation is posted for northern and central Florida, much of Alabama and
Georgia, and portions of South Carolina for Sep 27-29, and a larger slight risk
of heavy precipitation is posted for the Southeast U.S. as well as portions of
the Tennessee and Lower Mississippi Valleys for Sep 27-Oct 1. A slight risk of
high winds is also highlighted for Florida, coastal Alabama, and southern
Georgia for Sep 27-29.



There is good consensus among multiple model ensembles with regard to an
amplified mid-level trough over the Aleutian Islands in place at the start of
week-2 and a series of surface low pressure systems moving into the
southeastern Alaska coast, bringing periods of heavy precipitation with them.
This is supported by the ECMWF and GEFS PETs, which indicate the potential for
3-day precipitation totals to exceed 3 inches for portions of the panhandle of
Alaska for much of week-2. Uncertainty increases later in the forecast period
so for now a slight risk of heavy precipitation is posted for the southern
coast and Panhandle of Alaska for Sep 27-Oct 1. Todays model solutions feature
stronger surface lows moving onshore, bringing enhanced potential for strong
winds all along the southern coast of Alaska, including the potential for gap
winds along the Alaska Peninsula. Therefore a slight risk of high winds is
posted for the southern and southeast coast of Alaska for Sep 27-Oct 1.



A large area of the Southern Plains, including portions of northern Texas,
eastern Oklahoma and western Arkansas have been experiencing very dry
conditions for the last month, with precipitation deficits exceeding 3 inches
in some locations. This has led to drying soils, a situation likely to be
exacerbated by above-normal temperatures that are expected for the next few
weeks and little precipitation, especially in week-2. Given these conditions
the risk for ROD is highlighted for central and eastern Oklahoma, as well as
portions of northern Texas and western Arkansas.

FORECASTER: Danny Barandiaran

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