Valid Saturday June 14, 2025 to Friday June 20, 2025
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM
EDT June 06 2025
Synopsis: Mid-level high pressure is favored
over the eastern half of the Contiguous U.S. (CONUS) early in week-2, leading
to the development of potentially hazardous heat over portions of the Midwest,
Ohio Valley, and Mid-Atlantic. Soon thereafter, this area of mid-level high
pressure and hazardous heat is predicted to concentrate over the Central Plains
and Midwest. Surface high pressure over the North Atlantic favors abundant Gulf
moisture to move over the Great Plains, leading to elevated heat indices and
also fueling potentially heavy rainfall along the Gulf coast and also over
portions of the coastal Southeast, Great Plains and Mississippi Valley.
Mid-level low pressure over the Pacific Northwest at the outset of week-2 has
the potential to bring periods of high winds to much of the northwestern CONUS
through the middle of the forecast period.
Hazards
- Moderate risk of extreme heat for parts of the Central Great Plains and
Midwest, Sun-Tue, Jun 15-17.
- Slight risk of extreme heat for a larger portion of the Central Great
Plains and Midwest, Sat-Wed, Jun 14-18.
- Slight risk of extreme heat for the Mid-Atlantic, Sat, Jun 14.
- Slight risk of episodic high winds for the northwestern CONUS, Sat-Mon, Jun
14-16.
- Slight risk of heavy precipitation for much of the eastern Great Plains and
Mississippi Valley, Upper Great Lakes, and the Gulf and South Atlantic coasts,
Sat-Mon, Jun 14-16.
- Possible flooding for much of the Middle to Lower Mississippi Valley and
eastern Central and Southern Plains.
Detailed
SummaryFor Monday June 09 - Friday June 13:
WPC Days 3-7 U.S.
Hazards For Saturday June 14 - Friday
June 20: Model ensembles are in fairly good agreement with regard to a
persistent mid-level ridge over areas east of the Rockies, with widespread 6-12
dm positive 500-hPa height anomalies early in week-2, with a predicted
consolidation of the ridge over the north-central CONUS shortly thereafter.
This favors anomalously warm temperatures which, when combined with high
humidity (70 deg F or greater dew points) due to advection of Gulf moisture,
results in potentially hazardous heat for much of the middle of the CONUS. Heat
index values of 100-105 deg F fall just a bit short of hazardous thresholds for
mid-June, but this is offset slightly by the longer (expected) duration of this
event. The Probabilistic Extremes Tools (PETs) indicate at least a 20% chance
of maximum temperatures exceeding the 85th percentile and at least 90 deg F for
much of the Central Plains eastward across the Middle Mississippi Valley
beginning on June 14th and extending through most of the forecast period.
Similar thresholds are briefly reached for the Mid-Atlantic on June 14,
therefore a slight risk of extreme heat is posted for these regions for the
respective time periods indicated. The Mid-Atlantic heat event is considered
marginal and is predicted to wane after the 14th of June, as the Midwestern
ridge shifts westward and 500-hPa heights fall over the Northeast and
Mid-Atlantic regions. Though slight risks of extreme heat are posted for both
areas, even though air temperatures may fall a bit short of hazardous
thresholds for mid-June, this heat event is expected to be the first of the
season, last most of the week (for the Central Plains and Midwest), and be
accompanied by high levels of humidity. In addition to these factors, dry soils
and a slight amplification of the ECENS 500-hPa raw height anomalies late in
week-2 favor a moderate risk of extreme heat for a smaller portion of the
Central Plains and Midwest, June 15-17. This differs from the GEFS solution
starting around day 12, which favors a weakening ridge predicted to retrograde
to the Rocky Mountain states. The ECENS scenario is thought to be more likely
than the GEFS scenario. Across the southern CONUS, temperatures are likely to
be quite hot but hazard criteria are not likely to be met outside the regions
discussed above.
Ensemble means from the GEFS, ECENS, and CMCE for 500-hPa height anomalies
depict an amplified trough situated over the West Coast during week-2, although
this feature is favored to weaken throughout the forecast period. Associated
with this is weak surface low pressure over the Great Basin, which along with
strong surface high pressure over the North Pacific sets up a tight pressure
gradient and resultant enhanced surface winds across the northwestern CONUS.
This is supported by the Probabilistic Extremes Tools (PETs) from the ECMWF,
which broad-brushes at least a 20% probability of 3-day maximum wind speeds
exceeding the 85th climatological percentile for the first few days of the
outlook period over this region. The CMCE and GEFS PETs are less bullish but
still show some signal over these areas for at least a portion of the forecast
period. Therefore a slight risk of high winds is posted for the Pacific
Northwest, Great Basin, and Northern California for Jun 14-16.
A strong Bermuda high is favored by the ensembles throughout week-2,
setting up moist southeasterly flow off the Gulf and into the central CONUS.
The models also indicate weak troughing east of the Rockies which is
anticipated to pair up with the Gulf moisture and lead to significant daytime
heating and potentially heavy precipitation for much of the eastern Great
Plains, Mississippi Valley, Upper Great Lakes, and the Gulf and South Atlantic
Coasts. This enhanced rainfall signal is well-supported by the ECMWF and GEFS
PETs, which both indicate at least a 20% chance of 3-day precipitation totals
exceeding the 85th percentile and at least 1 inch of precipitation for at least
the first several days of the forecast period. Given this, a slight risk of
heavy precipitation is posted for the regions noted above for Jun 14-16.
Additionally, the Middle Mississippi Valley has been plagued by surplus
precipitation and subsequent flooding during the spring and the ground has not
had time to drain much, so new or renewed flooding is a concern, warranting the
posting of a possible flood hazard for the region. Just north of the primary
flood region of the Middle to Lower Mississippi Valley and eastern portions of
the Central and Southern Plains is a relatively dry region (Iowa, northern
Illinois, and far northern Missouri), which has reported low soil moisture
(lowest one-third of the historical distribution) over the past 30-days. This
region of relatively dry soils is being monitored for a potential ROD (Rapid
Onset Drought) designation.
Ice-bound rivers are slow to break up in the North Slope of Alaska. There
is no associated hazard posted at this time but this situation will be closely
monitored in the coming days and weeks as conditions can quickly change,
leading to the potential for ice jams, aufeis (a sheet-like mass of layered ice
that forms from successive flows of ground or river water during freezing
temperatures), and associated flooding.
Forecaster: Anthony
Artusa
$$
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.
Resources
Week-2 Probabilistic Extremes Tool
GFS Ensemble Forecasts