710
FXUS21 KWNC 231853
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT June 23 2025

SYNOPSIS: The extreme heat currently affecting the eastern half of the
Contiguous U.S. (CONUS) should be waning at the start of week-2, but conditions
may linger into the first day of the period, when a slight risk of extreme heat
is posted for the I-95 Corridor and the Carolinas. Hot weather is also expected
across much of the Interior West near a strong mid-level ridge axis, and a
slight risk of extreme heat is posted there as well early week-2. Meanwhile,
tropical moisture may enhance a quick start to the Monsoon, leading to a slight
risk of heavy precipitation into mid-week. At the same time, surface low
pressure along with a robust influx of Gulf moisture might trigger heavy
rainfall along the central and eastern Gulf Coast. Farther west, a strong
pressure gradient along most of the immediate West Coast could bring episodes
of high winds to the region before conditions ease later week-2.

HAZARDS

Slight risk of extreme heat in the I-95 corridor and the Carolinas, Tue, Jul 1.

Slight risk of extreme heat in the central Rockies and from the northern
Intermountain West into the northern High Plains, Tue-Wed, Jul 1-2.

Slight risk of heavy precipitation in parts of the central and eastern Gulf
Coast Region, Tue-Fri, Jul 1-4.

Slight risk of heavy precipitation in portions of the Southwest, Tue-Fri, Jul
1-4.

Slight risk of high winds along most of the immediate West Coast, Tue-Fri, Jul
1-4.

Flooding possible in portions of eastern Arizona and western New Mexico.

DETAILED SUMMARY

FOR THURSDAY JUNE 26 - MONDAY JUNE 30:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR TUESDAY JULY 01 - MONDAY JULY 07: The extreme heat wave currently impacting
much of the eastern CONUS is expected to start waning later week-1. Slowly
improving conditions are expected to continue into early week-2, with the
hottest weather pushing eastward while slowly diminishing. Still, from the I-95
Corridor into the Carolinas, extreme heat may linger into the first day of the
period (Jul 1), so a slight risk of extremeheat is posted. According to the
Probabilistic Extremes Tools (PETs) derived from the European ensemble and the
GEFS, these areas have a 20 to 40 percent chance that high temperatures will
top the 85th climatological percentile. High temperatures are expected to
exceed 90 deg. F through this region, with high humidities pushing the heat
index several degrees higher. Extreme heat should finally be removed from the
eastern CONUS on WedJul 2.



Potentially extreme heat is anticipated to cover the central and northern
Rockies as well as the northern Intermountain West and northern High Plains. At
the start of week-2, a 500-hPa ridge axis is forecast to stretch from southern
Canada through or just east of these regions. This should trigger considerably
above-normal temperatures across these areas, and there is a chance that daily
high temperatures will reach hazards thresholds, especially in the lower
elevations, so a slight risk of extreme heat is posted here. The PETs show 20
to locally over 40 percent chances for high temperatures above the 85th
percentile the first day of week-2, but the PETs from the European and
especially the Canadian ensembles quickly diminish the risk thereafter. The
PETs show elevated chances for temperatures to exceed 95 deg. F over many of
the lower elevations in the risk area, with marginal odds for temperatures to
exceed 100 deg. F in a few isolated locations. The PET derived from the GEFS
shows more robust odds for these conditions and keeps them in place farther
into week-2. The stronger mid-level ridge that lingers closer to the Interior
West in the GEFS is driving this depiction. A weakening ridge that may drift
eastward away from the Interior West is the preferred solution since it is
favored by a preponderance of the guidance.



Models depict a precipitation total maximum through at least the middle of
week-2 along and near the central and eastern Gulf Coast as an influx of
tropical moisture interacts with surface low pressure. All three PETs show odds
of 20 to 30 percent for amounts to exceed the 85th percentile in at least part
of this region through midweek, when chances start to decline. The PETs also
indicate 20 to 40 percent chances for 3-day totals to exceed an inch throughout
the area, with 20% odds for 1.5 inches or more indicated in a few spots. Given
the tendency of longer-range models to underestimate moisture influx from the
tropics into the mid-latitudes, and the local precipitation maximum forecast in
this region by all three ensemble means, a slight risk of heavy precipitation
is posted through the middle of week-2.



In the Southwest, robust monsoonal rainfall is expected to begin in the next
several days and continue into week-2. Ensemble means do not bring an
exceptional amount of rain into the region, and PETs also show fairly weak
chances for 3-day rainfall amounts to top 0.5 inch. However, as along the Gulf
Coast, the guidance is probably underestimating the influx of tropical moisture
advecting northward, and PETs derived from the European ensembles indicate a 40
to near 50 percent chance for amounts over the 85th percentile, pointing toward
significant rainfall shortly after monsoonal rains move in. These rains will
fall on some areas that are expected to experience flooding during week-1,
increasing the week-2 flood risk over roughly the southeastern half of the
region, from eastern Arizona to central New Mexico. Most guidance shows
precipitation slowly decreasing toward the end of the period.



Surface high pressure over the Northeast Pacific adjacent to surface low
pressure over the southwestern CONUS and Intermountain West may lead to tight
pressure gradients along much of the West Coast at times. This may be enhanced
by the abnormal heat anticipated in portions of the Interior West early in the
period, which would likely lower surface pressure. As a result, a slight risk
of high winds is posted along most of the immediate West Coast. Most models
keep this setup in place considerably longer than depicted last week, so the
high wind hazard is extended into the middle of week-2 (Jul 4). The
deamplification of the mid-level pattern across the CONUS is expected to lead
to a reduced pressure gradient later in the period, ending the high wind threat.



Numerous wildfires have developed across Alaska during the past few days, and
robust fire activity is expected to continue for at least a few more days. The
smoke generated by these fires is forecast to meander around the state during
week-2, following low-level wind currents. As a result, periods of very poor
air quality and low visibility may occur.

FORECASTER: Rich Tinker

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