179
FXUS21 KWNC 041715
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT April 04 2026

SYNOPSIS: Mid-level low (high) pressure across the western (eastern) contiguous
U.S. (CONUS) increases chances for heavy precipitation across most of the
Plains, the Mississippi and Tennessee Valleys, much of the Ohio Valley, and the
Great Lakes Region during the first half of week-2. Heavy rain appears most
likely across northeastern Texas, eastern Oklahoma, and the adjacent Lower
Mississippi Valley, and a high risk of heavy precipitation is posted there.
Flooding is possible across and near the high risk area. Around the middle of
week-2, pressure gradients between a surface low pressure moving out of the
Plains and higher pressure to the east and could be sufficient to induce strong
winds at times from the east-central and southeastern Great Plains
northeastward through the Great Lakes and Northeast. Unusually strong trade
winds and possible Kona Low activity may bring additional heavy precipitation
to Hawaii during the first half of week-2.

HAZARDS

High risk of heavy precipitation over parts of the southeastern Great Plains
and adjacent Lower Mississippi Valley, Sun, Apr 12.

Moderate risk of heavy precipitation from the Southern Plains northeastward
across much of the Mississippi Valley, adjacent parts of the Ohio and Tennessee
Valleys, and the Great Lakes, Sun-Mon, Apr 12-13.

Slight risk of heavy precipitation for much of the Plains, the Mississippi
Valley, much of the Ohio Valleys, the Tennessee Valley, and the Great Lakes,
Sun-Tue, Apr 12-14.

Slight risk of high winds from the east-central and southeastern Great Plains
through the Great Lakes and Northeast, Tue-Fri, Apr 14-17.

Flooding possible over parts of the southeastern Great Plains and adjacent
Lower Mississippi Valley.

DETAILED SUMMARY

FOR TUESDAY APRIL 07 - SATURDAY APRIL 11:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SUNDAY APRIL 12 - SATURDAY APRIL 18: Models are in good agreement
establishing mid-level ridging over the eastern CONUS and upstream troughing
across the interior West late week-1. This trough slowly lifts northeastward,
with one or more vorticity centers potentially moving through the system during
the first half of week-2. The predicted strength of the trough is similar to
yesterday, slowly weakening as the period progresses, at which point models
start to diverge. This pattern elevates the chances for heavy precipitation
across a large part of the central and interior eastern CONUS. Isolated high
wind gusts are possible in stronger thunderstorms, but model support for more
widespread high winds has shifted to the middle of week-2, especially in the
dynamical European model (ECMWF). Low surface pressure is expected to develop
over the Plains and move northeastward into southern Canada. Areas of high
pressure are expected both ahead of this system and in its wake, potentially
creating enough of a pressure gradient to produce strong winds. This supports a
slight risk of high winds effective later in the period than yesterday`s hazard
(around the middle of week-2).



By the start of week-2, increased low-level Gulf moisture is forecast to
overspread most areas between the Rockies and the Appalachians as surface high
pressure centered over the western Atlantic extends into the southeastern
CONUS. Farther west, the mid-level trough is expected to induce lower surface
pressure over the central CONUS, setting the stage for surface low pressure
center(s) and associated frontal complex(es) to pass through the region. The
influx of low-level moisture into a region of cyclonic mid-level flow and
wavering frontal boundaries increases the odds for heavy precipitation over a
large part of the central and interior northeastern CONUS during at least the
first half of week-2. Guidance has consistently forecast the heaviest amounts
over northeastern Texas, eastern Oklahoma, and the adjacent Mississippi Valley
early week-2. Although amounts are not expected to be excessive, the
consistency with which guidance has favored moderate to heavy amounts across
this region justifies a high risk of heavy precipitation there for the first
day of the period (Sun, Apr 12). There is somewhat more divergence among the
guidance elsewhere regarding the location, timing, and intensity of heavy
precipitation, but most tools generally agree that one or more rounds of
locally heavy rain are possible along a swath from Texas through the Great
Lakes Region, supporting a moderate risk of heavy precipitation there extending
through Mon, Apr 13. There is considerably more uncertainty to the west and
east of this primary threat area, but the situation could trigger heavy
precipitation as far west as the Great Plains and Upper Mississippi Valley, and
as far east as the central Gulf Coast, the western Appalachians, and the Great
Lakes Region at times during the first half of week-2. This potential supports
a slight risk of heavy precipitation across this broad area for the first part
of week-2 (Sun-Tue Apr 12-14). Continuous heavy precipitation throughout this
region and time period seems unlikely, but the synoptic situation is favorable
for the development of periodic, locally heavy rain from heavy thunderstorms to
affect different parts of this region at varying times, whenever there is a
combination of unusual strong low-level moisture influx, a focusing frontal
boundary, and surface instability. The Probabilistic Extremes Tools (PETs)
derived from the GEFS, European ensemble (ECENS), and Canadian ensemble (CMCE)
are not particularly bullish on the potential for heavy precipitation, with
only the ECENS showing any areas with a greater than 40 percent chances for
3-day precipitation totals above the 15th percentile climatological threshold
(centered over Texas and adjacent locales). However, at least a couple inches
of rain are depicted on the deterministic European (ECMWF) and AIGFS models as
well as the ECENS and CMCE means across different parts of the slight risk
area, with the heavier amounts mostly centered over northeastern Texas, eastern
Oklahoma, and adjacent Arkansas and Louisiana. A few tools show at least some
risk of additional heavy precipitation later week-2 over the southern reaches
of the slight risk region, but there is too much uncertainty and model
disparity to justify posting any additional heavy precipitation risks at this
time.



Any heavy week-2 precipitation falling in the high risk region will be on top
of heavy amounts expected during the next few days. According to the National
Water Center (NWC), this will increase the potential for flooding in this area
during week-2 even though drought has been entrenched for the past few months
in many portions of the southern Great Plains and Lower Mississippi Valley. The
area at risk of flooding extends farther north than the area at high risk of
heavy precipitation due to somewhat increased support for heavier amounts
there.



The PETs for high winds are not impressive, but the probabilities for wind
gusts over 39 mph approach 40 percent in the ECENS and CMCE around the middle
of week-2 mostly from the east-central and southeastern Great Plains into the
Mississippi Valley Tue Apr 14. Thereafter, the high wind risk expands
northeastward through the Great Lakes and Northeast Wed-Fri Apr 15-17. The
ECMWF forecasts spotty wind gusts exceeding 50 mph, with the greatest threat
shifting farther northeast with time.



No hazards are issued over Alaska, but flooding can occur this time of year
with little or no notice during river ice breakup season. Check with the Alaska
Pacific River Forecast Center for the latest conditions or advisories.



Across Hawaii, Kona Low activity brought heavy rainfall and flooding during
mid-March, and strong trade winds have helped keep precipitation totals above
normal for the past few weeks. Ensemble guidance shows a mid-level trough to
the north of the island chain early week-2, which may trigger additional heavy
precipitation. PETs from the GEFS and ECENS show increased chances (20 to 40
percent) for 3-day amounts exceeding the 85th percentile early week-2, with
declining chances for heavy precipitation thereafter. Any heavy precipitation
during week-2 will be falling on saturated ground, potentially triggering
additional localized flooding.

FORECASTER: Rich Tinker

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