156
FXUS21 KWNC 111814
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT October 11 2026

SYNOPSIS: Cold surface high pressure is expected over the eastern Contiguous
U.S. (CONUS) early in week-2, increasing the chances for much below normal
temperatures in parts of the Northeast, upper Mid-Atlantic, and Appalachians
the first day of the period (Oct 19). The first frosts and/or freezes of the
season are possible in parts of coastal and southern New England, the northern
Mid-Atlantic, and much of the Appalachians before temperatures quickly
moderate. Farther west, heavy rainfall is possible across the central and
western Gulf Coast region, where a southerly fetch of moist tropical air may
interact with a lingering frontal boundary. Over Alaska, mid-level troughing
and cyclonic flow is expected much of week-2 in the Gulf of Alaska, supporting
periods of above-normal precipitation and high winds from the south-central
Mainland through Southeast Alaska, but conditions are expected to remain below
hazard thresholds.

HAZARDS

Slight risk of much below normal temperatures for southern New England, parts
of the northern Mid-Atlantic, and much of the Appalachians, Sun, Oct 19.

Slight risk of heavy precipitation along the central and western Gulf Coast and
adjacent sections of eastern Texas and central Louisiana, Sun-Thu, Oct 19-23.

DETAILED SUMMARY

FOR WEDNESDAY OCTOBER 14 - SUNDAY OCTOBER 18:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR MONDAY OCTOBER 19 - SUNDAY OCTOBER 25: The hazards perspective largely
remains on track since yesterday. As week-2 begins, the latest 0z European
ensemble (ECENS) and GEFS means show a 500-hPa trough moving away from the
northeastern CONUS, with an upstream 500-hPa ridge extending from the western
and central CONUS into southern Canada. Between these features, a cold surface
high is expected across the eastern CONUS, accompanied by subnormal
temperatures. This has the potential to bring the first frosts and/or freezes
of the season to some of the higher latitudes of the eastern CONUS, and a
slight risk for much below normal temperatures is posted in these regions for
day 8 (Oct 19), avoiding parts of Upstate New York and interior New England
where near- to below-freezing temperatures have already occurred. ECENS
Probabilistic Extremes Tool (PET) shows chances for minimum temperatures below
the 15th climatological percentile range from 20 percent along the spine of the
Appalachians to more than 40 percent across central and eastern Maine. The
ECENS PET also shows chances for subfreezing temperatures topping 20 percent in
many areas from West Virginia and western Virginia northward, with odds
exceeding 50 percent across upstate New York and most of New England.
Thereafter, mid-level ridging quickly builds in from the west, quickly
increasing temperatures. The GEFS shows the cold air lingering in the east a
little longer, and holds the strongest signal farther to the south. On day 8
(Oct 19), the GEFS PET shows at least a 30 percent chance for minimum
temperatures below the 15th percentile extending as far west as the lower Great
Lakes, the Ohio Valley, and part of the Lower Mississippi Valley, with odds
exceeding 50 percent across the southern Mid-Atlantic and South Atlantic
regions. The GEFS PET also holds on to higher chances for subfreezing
temperatures farther south and west, with chances topping 40 percent as far
south and west as the highest elevations near the northern Tennessee/North
Carolina border. The official outlook favors a compromise of these two
forecasts, leaning toward the ECENS faster timing but extending farther south
to where the GEFS shows significant chances for subfreezing temperatures. In
any case, the mid-level ridge to the west quickly builds into the northeastern
CONUS, accompanied by increasing surface temperatures and ending the increased
potential for cold weather.



Farther west, as surface high pressure moves eastward out of the eastern CONUS,
southerly low-level flow is expected to bring an anomalous push of tropical
moisture northward into the central and western Gulf Coast States. This
moisture-laden air has the potential to interact with a weak frontal boundary
lingering across this region, increasing the chances for heavy rainfall. The
ECENS and GEFS PETs both show marginally enhanced chances (over 20 percent) for
3-day rainfall totals to exceed the 15th climatological percentile and 1 inch
along and near the Gulf Coast from Texas through southern Louisiana, extending
northward at times into eastern Texas and central Louisiana. There is a lot of
uncertainty regarding the timing, location, and evolution of any heavy
precipitation that develops, with significant model divergence. The latest 12z
and 0z runs of the dynamical European model (ECMWF) show this area receiving
over 2 inches of rain through the middle of week-2, with amounts topping 5
inches in a few spots. Other models are more muted, however, including the 0z
ECENS which only shows .75 to 1.5 inches and confines that to the immediate
coastline. The dynamical European Artificial Intelligence Forecast System
(ECMWF-AIFS) drops 1 to 2 inches of rain on many locations as well, but are not
in agreement on where the heaviest amounts fall, nor how far north heavy rain
may occur. Meanwhile, the AIGFS shows only a few tenths of an inch at best, and
the dynamical GFS confines heavy amounts to a relatively small part of
southeastern Texas. Despite the uncertainty, a sufficient number of tools
highlight increased chances for heavy rain to support posting a slight risk of
heavy precipitation for much of the northern and western Gulf Coast, extending
inland as far as eastern Texas and central Louisiana, although a few models
bring heavier amounts farther north. The PETs and most models show lesser
amounts after the middle of week-2, so the slight risk of heavy precipitation
is removed then.



Over Alaska, mid-level troughing remains favored late week-1 centered over the
Gulf of Alaska, and the ensemble means today show the potential for a weakened
500-hPa trough to remain in place throughout the period, or potentially reload
farther to the west. In either case, a fairly weak cyclonic mid-level flow is
maintained over the Gulf of Alaska, which favors unsettled weather from the
south-central Mainland through Southeast Alaska. Given how high precipitation
normals are in this region during October, it seems unlikely that amounts will
reach hazards thresholds, and the weak nature of this system does not favor
high winds reaching hazards thresholds either. But there is the potential for
any tropical cyclones that develop in the active western Pacific to recurve
northward and become incorporated into the extratropical westerlies, resulting
in a more amplified mid-level pattern with precipitation enhanced by the
incursion of tropical moisture. No hazards are posted at this time, but the
mid-level pattern over the northern Pacific will continue to be monitored.

FORECASTER: Rich Tinker

$$