563
FXUS21 KWNC 171916
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT June 17 2025

SYNOPSIS: Strong mid-level high pressure continues to be predicted across the
northeastern quadrant of the contiguous U.S. (CONUS) from late in week-1 until
at least the middle of week-2. There is good agreement in model guidance and
associated tools indicating enhanced chances for extreme heat for this region.
A high risk of extreme heat is posted for the Ohio Valley, Great Lakes region,
Northeast, and Mid-Atlantic, for Jun 25. Broader areas are highlighted across
the northeastern CONUS including the Mid-Atlantic with slight and moderate
risks of extreme heat. A front is predicted to extend from the Upper
Mississippi Valley to the Central Plains, bringing potentially heavy
precipitation and isolated strong thunderstorms to parts of the Upper Midwest
early in the period.

HAZARDS

High risk of extreme heat for the Ohio Valley, Great Lakes, Northeast, and
Mid-Atlantic, Wed, Jun 25.

Moderate risk of extreme heat for parts of the northeastern CONUS including the
Mid-Atlantic and South Carolina, Wed-Thu, Jun 25-26.

Slight risk of extreme heat for portions of the eastern CONUS, Wed-Sat, Jun
25-28.

Slight risk of heavy precipitation for parts of the Upper Midwest, Wed-Thu, Jun
25-26.

DETAILED SUMMARY

FOR FRIDAY JUNE 20 - TUESDAY JUNE 24:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR WEDNESDAY JUNE 25 - TUESDAY JULY 01: Multiple ensemble means show greater
positive 500 hPa height anomalies over the northeastern CONUS on Jun 25 with a
longer favored duration of this pattern compared to yesterday. Therefore, the
high risk of extreme heat is continued for the onset of week-2 in addition to
the moderate risk being expanded spatially and the slight risk extended in
time.



In general, the ECENS Probabilistic Extremes Tool (PET) has a greater signal
for extreme heat than the GEFS. Due to the week-2 consolidation tool favoring
the ECENS over the GEFS, the extreme heat hazards are primarily based on the
ECENS. A high risk of extreme heat is designated for the Ohio Valley, Great
Lakes region, Northeast, and Mid-Atlantic, Jun 25, primarily based on where the
ECENS PET shows at least a 60% chance of maximum temperatures exceeding the
85th climatological percentile, and at least a 20% chance of exceeding the 95th
percentile. A moderate risk area (40 to 60% chance) is posted for parts of the
northeastern CONUS including the Mid-Atlantic and South Carolina, June 25-26,
while a broader area is highlighted with a slight risk (20 to 40% chance)
across parts of the eastern CONUS, Jun 25-28. The National Blend of Models
(NBM) shows some of these areas nearing or breaking record temperatures both in
the maximum and minimum temperatures. Anticipated high dewpoints are likely to
support heat index values exceeding triple digits (deg F) across the
Mid-Atlantic and mid 90s (deg F) elsewhere in the highlighted risk areas.
Minimum heat index values could reach or exceed 80 (deg F) in some areas. Lower
temperatures are anticipated for high elevation areas.



Mid-level troughing is predicted across the northwestern CONUS, supporting a
front developing ahead of it, from the end of week-1 into the beginning of
week-2. This front may bring enhanced precipitation to the upper Midwest, and a
slight risk of heavy precipitation is posted for this region, Jun 25-26. The
greatest rainfall totals are expected to occur at the end of week-1 with
potential of heavy rainfall extending into the beginning of week-2. The PETs
indicate at least a 20% chance of 3-day accumulated rainfall totals exceeding
the 85th percentile and one inch. Enhanced warm moist flow from the Gulf may
provide favorable conditions for localized severe thunderstorms in the
highlighted risk area.



The National Hurricane Center (NHC) currently indicates Tropical Storm Erick as
of 9am CST located offshore of Central America and Mexico. This disturbance
combined with possible low formation over Baja California and the Southwest may
bring enhanced moisture to parts of the Southwest which could bring localized
enhanced rainfall and thunderstorms to the area. There is no specified
precipitation hazard due to high uncertainty regarding specific details, but
this potential will continue to be monitored.



Ice-bound rivers are beginning to break up in the North Slope of Alaska.
Flooding is possible by the end of week-1 and into week-2 across much of the
region as a result of ice jams, aufeis, snow melt, and associated flooding. A
flood risk is not designated for today due to conditions anticipated to start
to wane during the week-2 period.

FORECASTER: Melissa Ou

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