778
FXUS21 KWNC 021832
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT June 02 2026

SYNOPSIS: Mid-level high pressure forecast over southern Canada is expected to
bring above-normal temperatures for much of the lower 48, with a lingering
potential for extreme heat conditions over parts of the Great Plains,
Mississippi Valley, and Great Lakes heading into next week.  The combination of
unseasonable late spring warmth and inadequate rainfall amounts supports the
continuation of a Rapid Onset Drought (ROD) risk over portions of the
Mississippi and Ohio Valleys and Great Lakes.

HAZARDS

Slight risk of extreme heat for portions of the Northern and Central Plains,
Upper and Middle Mississippi and Ohio Valleys, and Great Lakes region, Wed-Thu,
Jun 10-11.

Slight risk of high winds for portions of coastal California and the Pacific
Northwest, Wed-Fri, Jun 10-12.

Slight risk of heavy precipitation for portions of the coastal Southeast, and
Florida, Wed-Thu, Jun 10-11.

Rapid Onset Drought possible for parts of the Upper and Middle Mississippi
Valley, Ohio Valley, and Great Lakes region.

DETAILED SUMMARY

FOR FRIDAY JUNE 05 - TUESDAY JUNE 09:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR WEDNESDAY JUNE 10 - TUESDAY JUNE 16: At the start of week-2, there
continues to be agreement between the GEFS and ECMWF ensemble mean 500-hPa
height forecasts favoring a deamplifying ridge center to the south of Hudson
Bay, with a large coverage of positive height departures overspreading much of
the entire CONUS. As the anomalous ridge center weakens and shifts eastward to
the Canadian Maritimes, these ensemble mean solutions are now beginning to
favor more of a split flow pattern taking shape over the eastern U.S and
western Atlantic, with the ECMWF depicting a closed mid-level low that
temporarily cuts off from the mean circulation.  Additionally, more mid-level
troughing is featured upstream in both the GEFS and ECMWF, where lowering
heights over the West Coast looks to better isolate the ridge axis across the
central CONUS early in the period. Over time, the ECMWF still maintains a
comparably more progressive pattern than the GEFS, namely with an anomalous
500-hPa ridge center initially favored over the eastern Pacific that shifts
eastward into the northwestern CONUS and southwestern Canada.  Taken together,
there is continued forecast confidence for above-normal temperatures and
possible extreme heat conditions over the north-central CONUS in proximity to
the anomalous ridge center over southern Canada, with heat risks possibly
emerging over the West Coast later in week-2. Bookending mean troughs over the
western and eastern CONUS supports the potential for more unsettled weather
early in week-2, with cooler mean temperature solutions being favored over the
southeastern CONUS relative to previous model guidance.



A slight risk of extreme heat remains posted for the north-central CONUS where
the GEFS and ECMWF Probabilistic Extreme Tools most agree in percentile space,
and show increased chances (20-40%) for daytime temperatures exceeding the 85th
climatological percentile. The highlighted slight risk area remains valid
through Jun 11 and captures the strongest positive temperature departures
favored along with modest support for the heat index values potentially
reaching 100 (105) deg F across the Northern Plains and Upper Mississippi
Valley (Central Plains and Middle Mississippi Valley). Due to the potential for
troughing underneath the ridge center, its coverage is reduced to exclude more
of the Ohio Valley. Similar to yesterday, the ECMWF PET continues to feature
growing heat signals over the West Coast and the Interior West towards the
middle of the period tied to the encroaching ridge center from the eastern
Pacific. While the GEFS and GEFSAI favors the emergence of above-normal
temperatures over the West Coast, an accompanying heat risk continues to be
less supported in the raw and calibrated tools, precluding any corresponding
temperatures hazards in being issued in the updated outlook. However, this
potential will continue to be closely monitored in upcoming hazard outlooks.



Over the past several weeks, precipitation has been quite limited over portions
of the Great Lakes region and Middle and Upper Mississippi Valley following a
wet spring in these regions. The U.S. Drought Monitor shows an expansion of
abnormally dry conditions into portions of Minnesota, Wisconsin, eastern Iowa,
northern Illinois, and adjacent Indiana in its latest update. Although near to
slightly above-normal precipitation is favored during week-2, the lack of total
precipitation forecast combined with favored above-normal temperatures to drive
increased evaporation rates supports the continuation of Rapid Onset Drought
(ROD) risk over this part of the country.



With better model agreement favoring more troughing over the West coast early
in the period, a slight risk of high winds is added to the outlook over parts
of coastal California and the Pacific Northwest for early week-2 (Jun 10-12).
This hazard is supported by both the GEFS and ECMWF PETs, which have come into
better agreement depicting increased chances for wind speeds exceeding the 85th
percentile, as well as mean surface patterns favored in the ensemble which
depict periods of strengthening pressure gradients along parts of the West
Coast.



Over the western Atlantic, there is growing guidance support for cyclonic
surface flow and the potential coastal low development tied to the troughing
favored underneath the ridge center over southeastern Canada. While this
development is rather novel in the guidance, a more coherent precipitation
response is depicted in some of the tools late in week-1 that persists into
early week-2. Uncalibrated precipitation tools show the greatest signals for
precipitation exceedance mostly offshore of the lower eastern Seaboard, however
there is support in the GEFS PET for a heavy precipitation risk which extends
inland over the coastal Carolinas southward to the Florida Peninsula. Given
this, and the prevailing pattern favored, a slight risk of heavy precipitation
is added to the outlook, valid for Jun 10-11.  Should any heavy precipitation
be realized, localized flash flooding is possible within the highlighted area.



Over the eastern Pacific, the National Hurricane Center (NHC) continues to
monitor two areas for formation in the eastern Pacific, with one located to the
south of Mexico (40% chances for development during the next seven days).
Should any development occur next week associated with the area south of
Mexico, a northwestward track nearing the Gulf of California could bring
enhanced moisture and increased precipitation into the lower Four Corners. The
ECMWF ensemble does favor an increase in precipitable water extending poleward
from western Mexico associated with this scenario late in week-2, however no
corresponding hazards are posted given a lack of support in the precipitation
tools as well as general high uncertainty at this lead.



In Alaska, river ice breakup season is ending, but many rivers north of the
Brooks Range remain icebound. 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: Nick Novella

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