214
FXUS21 KWNC 061823
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT June 06 2026

SYNOPSIS: Strengthening mid-level high pressure near the West Coast increases
the risk of a multi-day heat wave for portions of the West during mid-June.
Heat is likely to peak late next week across the Northeast, but an elevated
risk of extreme heat may linger into the beginning of week-2 (June 14).
Following a return of drier weather for the East to start June, an increased
chance of heavy precipitation is forecast to return by mid-June. This heavy
precipitation hazard extends west to the Central and Southern Great Plains.

HAZARDS

Moderate risk of extreme heat for parts of the Pacific Northwest and northern
California, Sun-Tue, June 14-16.

Moderate risk of extreme heat for parts of the Mid-Atlantic, Sun, Jun 14.

Slight risk of extreme heat for parts of the Eastern Seaboard Sun-Mon, Jun
14-15.

Slight risk of extreme heat for parts of the West, Sun-Fri, June 14-19.

Slight risk of heavy precipitation for much of the eastern and south-central
contiguous U.S (CONUS), Sun-Wed, Jun 14-17.

Rapid onset drought possible for parts of northeastern Illinois and
northwestern Indiana.

DETAILED SUMMARY

FOR TUESDAY JUNE 09 - SATURDAY JUNE 13:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SUNDAY JUNE 14 - SATURDAY JUNE 20: The ECENS, GEFS, and CMCE are in
reasonably good agreement and very consistent that a 500-hPa ridge strengthens
later next week over the northeastern Pacific. This mid-level ridge peaks in
strength on day 8 when 500-hPa heights reach 588 dm and 582 dm over northern
California and the Pacific Northwest, respectively. The GEFS-AI favors the
ridge axis closest to the West Coast which leads to 588 dm heights
overspreading the Pacific Northwest which is a sign of a major heat wave and
would be a +180 meter height departure for mid-June. Based on this anomalously
strong 500-hPa ridge for June and a 40% (GEFS) to 60% (ECENS) chance of maximum
temperatures exceeding the 85th percentile according to the Probabilistic
Extreme Tools (PETs), a moderate risk of extreme heat is posted for parts of
the Pacific Northwest from June 14 to 16. In addition, the National Blend of
Models shows near record or record highs of 95 in Portland and 87 at Seattle on
June 15. Although the extreme heat signal is slightly lower for northern
California in the PETs, a moderate risk is also designated for the Sacramento
Valley early in week-2 with the NWS HeatRisk tool having near a 40% chance of
major heat-related impacts. Through early week-2, the preferred ECENS depicts
maximum temperatures of at least heat advisory levels for mid-June and are in
the mid 80s in Seattle, near 90 at Portland, and around 100 in the Sacramento
Valley. Based on the NWS HeatRisk tool and PETs (20-40% chance of either major
heat-related impacts or maximum temperatures exceeding the 85th percentile) a
broad slight risk of extreme heat extends south through the Central Valley of
California and Desert Southwest. Although the ensemble mean solutions depict
the mid-level ridge gradually weakening and retrograding away from the West
Coast, the ECENS and CMCE have positive 500-hPa departures persisting through
late week-2. This supports a continued slight risk for extreme heat though June
19.



On June 14, a moderate risk of extreme heat is posted from Philadelphia
northeast to the greater NYC area where multi-model ensemble means favor a hot,
humid airmass persisting ahead of a cold front. Within the moderate risk area,
heat index values may reach or even exceed 100 degrees F. A slight risk of
extreme heat continues one day later, but an amplifying 500-hPa trough over the
Midwest is expected to result in a cold front providing heat relief due to
lower maximum temperatures associated with a widespread coverage of showers and
thundershowers. Towards the end of week-2, the GEFS depicts a return of
anomalous 500-hPa ridging which could renew the risk of extreme heat. The lack
of support from the ECENS precludes the designation of a slight risk for
extreme heat beyond June 15.



The amplified 500-hPa trough upstream over the Midwest, a slow-moving/stalled
surface front, and anomalously high moisture content increase the chance of
locally heavy rainfall with any convection across much of the East extending
west to the Central and Southern Great Plains. The slight risk of heavy
precipitation, valid June 14-17, generally followed where the multi-model
ensemble means depict a surface front and the PETs have 3-day amounts exceeding
the 85th percentile. Thundershowers are likely to be capable of producing more
than 1 inch per 24 hours. Additional support for heavy precipitation hazard is
the analog tool from the manual 500-hPa height blend showing enhanced
above-normal precipitation probabilities over the designated hazard area. A
broad slight risk area is necessary due to the uncertainty in convective
rainfall at this time lead during June. Given the anomalously high moisture,
any slow-moving thunderstorm could trigger flash flooding.



30-day precipitation has averaged less than 50 percent of normal across much of
the Midwest. The U.S. Drought Monitor, valid June 2, depicts an expanding
coverage of abnormal dryness (D0) across this region and moderate drought (D1)
in northern Illinois and southern Wisconsin. Rapid onset drought (ROD) is
underway with this lack of adequate precipitation, warmer temperatures, and
increasing water demand at this time of year. The ROD hazard, currently
depicted in northeastern Illinois and northwestern Indiana, may be discontinued
on Monday as an increasingly wet pattern is forecast during the next two weeks.



In Alaska, river ice breakup season is ending and even the rivers across the
North Slope are beginning to open. River breakup flooding can occur with little
or no notice as conditions on frozen rivers can change quickly, so please check
with the Alaska Pacific River Forecast Center for the latest conditions and
advisories.

FORECASTER: Brad Pugh

$$