127
FXUS21 KWNC 181735
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 18 2026

SYNOPSIS: An area of mid-level high pressure is expected to bring an elevated
risk of extreme heat over portions of the central and western contiguous U.S.
(CONUS) along with Florida and the Gulf Coast. Some weakening is possible
around the middle of the period, but conditions may reintensify later. Hot and
dry conditions bring an increased risk of rapid onset drought risk to part of
northern Great Plains. In the West, the monsoonal circulation may be relatively
robust at times, but hazardous amounts of rain are not expected. Farther east,
a wavering frontal boundary near the southeastern CONUS supports a heavy
precipitation risk over parts of the Southeast and Carolinas through the middle
of week-2.

HAZARDS

Moderate risk of extreme heat for much of the Great Plains and adjacent parts
of the Mississippi Valley, the southern High Plains, and the Desert Southwest,
Sun-Tue, Jul 26-28.

Slight risk of extreme heat for the California Valley, the Southwest, parts of
the Intermountain West, Much of the Rockies, the Plains and adjacent
Mississippi Valley, the Gulf Coast, and the adjacent Southeast, Sun-Sat, Jul
26-Aug 1.

Slight risk of heavy precipitation for much of the central Gulf Coast, part of
the South Atlantic region, and the eastern Carolinas, Sun-Thu, Jul 26-30.

Rapid onset drought (ROD) possible for part of the northern Great Plains.

DETAILED SUMMARY

FOR TUESDAY JULY 21 - SATURDAY JULY 25:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SUNDAY JULY 26 - SATURDAY AUGUST 01: Heading into the start of week-2,
models are in good agreement featuring an amplified 500-hPa ridging over the
Interior West and High Plains bookended by a pair of mid-level troughs, one
over the northeastern Pacific and the other overspreading much of eastern North
America. Over time, both the European ensemble (ECENS) and GEFS means show the
ridge drifting westward into the Four Corners region, where it remains centered
through the rest of week-2. The Canadian ensemble (CMCE), ECENS, and GEFS means
generally agree on maximum 500-hPa heights around 597 dm early week-2 edging
down to around 594 dm during the middle of the period, then rebounding to near
596 dm late in week-2. Despite the potential for nominally wavering intensity,
however, the ridge remains relatively amplified throughout the period. The
anomalous ridge is expected to take on a somewhat positive tilt over the last
half of the period, with an axis stretching from the middle of the Four Corners
toward the northern High Plains. This mid-level ridge favors an increased risk
of extreme heat across large parts of the western, central, and far
southeastern CONUS. To the northeast of this broad area, a stagnant mid-level
trough is expected to keep extreme heat at bay for most of the eastern CONUS.



Underneath the ridging aloft, an elevated potential for heat risk continues to
be supported by a number of temperature and heat tools for many parts of the
southern, western, and central CONUS. Higher than normal dewpoints are also
favored east of the Rockies under a long fetch of southerly flow near the
surface, helping to drive up heat index values there. A moderate risk of
extreme heat remains posted over the Southern Plains for Jul 26-28, with
coverage expanded northward to include more of the central and northern Great
Plains. These adjustments are based mainly on the expected ridge evolution and
internal heat index tools, which depict nontrivial chances for heat index
values exceeding 110 deg F as far north as southeastern South Dakota and
adjacent Iowa. The best chances for this extreme heat stretches from southern
Kansas through much of Oklahoma and into adjacent Texas. Deep South Texas and
part of the Desert Southwest also have significant chances for heat index
values or absolute temperatures to top 110 deg F, but this is not as unusual
there as it is in the locations farther north. The moderate risk covers the
first few days of week-2, ending as the mid-level ridge weakens slightly. This
modest weakening in both the mid-level ridge and extreme heat risk may only be
temporary, but there is not yet enough confidence in reamplification late
week-2 to keep a moderate risk in place. Surrounding the moderate risk area, a
slight risk of extreme heat remains posted with coverage expanded today to
include some lower elevations of the Intermountain West, all of the Great
Plains, and the adjacent Mississippi Valley. With a slightly stronger and more
persistent mid-level trough depicted across eastern North America, the slight
risk of extreme heat is contained slightly farther south along the East Coast,
including only Florida and southern Georgia, where anomalously high SSTs in
adjacent waters will contribute to heat and humidity. With the mid-level ridge
expected to remain amplified throughout week-2, the slight risk of extreme heat
likewise extends through the entirety of week-2. The Probabilistic Extreme
Tools (PETs) are not as robust with the odds for extreme heat as might be
expected given the nature of the mid-level ridge, but the GEFS PET does
indicate better chances than yesterday. In addition, the extreme heat risk is
based partly on the expected high dew points east of the Rockies, whereas the
PETs only reflect actual temperatures.



Meanwhile, antecedent dryness, anomalous warmth and dryness during week-1, and
the potential for extreme heat during week-2 support an enhanced risk of Rapid
Onset Drought (ROD) across portions of the Northern Plains despite slightly
enhanced chances for above-normal precipitation during the 6- to 10-day period
(Jul 24-28). The anticipated heat is expected to overwhelm any short-lived
relief that may occur during that time frame.



Despite the strong mid-level ridge favored over to prevail across the
southwestern CONUS, the forecast position of the ridge center does not support
the robust advection of monsoonal moisture into the region. There may be
locally heavy convection at times during week-2, but raw model output and the
Probabilistic Extreme Tools (PETs) from all of the ensembles show limited
chances for 3-day precipitation amounts exceeding the 85th percentile over the
Southwest. Any uptick in monsoonal moisture could also produce dry lightning,
resulting in increased wildfire risk where significant precipitation does not
fall.



A wavering frontal boundary is likely to set up near the central Gulf and South
Atlantic regions in conjunction with the mid-level troughing favored over the
eastern U.S. This set-up brings a slight risk of heavy precipitation to parts
of the central Gulf Coast, South Atlantic region, and eastern Carolinas. The 0z
ensemble`s output shows the mean position of this feature to be a little
farther east and south than yesterday, but also maintains this pattern for a
longer period. Therefore, the slight risk of heavy precipitation is suppressed
somewhat to the southeast relative to yesterday, but is extended through day 12
(Jul 30). Continuous heavy precipitation does not appear likely, but the front
will drift far enough west at times to increase the odds for episodic heavy
precipitation. The raw ensemble output and a preponderance of the PETs outputs
show slightly increased chances (less than 30 percent) chances for three day
precipitation amounts to exceed the 85th climatological percentile and 1 inch.
This represents a slightly less enhanced signal compared to yesterday, but
nonetheless, the position and persistence of the quasi-stationary front and
abundant low-level moisture have the potential to induce scattered heavy
rainfall at times.

FORECASTER: Rich Tinker

$$