035
FXUS21 KWNC 251847
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT April 25 2025

SYNOPSIS: At the outset of week-2 surface low pressure is forecast to move from
New England into southern Quebec, with a trailing cold front extending across
the east-central contiguous U.S. (CONUS) and the Southern Plains. This front is
forecast to become stationary, which favors enhanced chances of heavy
precipitation and thunderstorms across portions of the south-central CONUS
continuing through most of week-2. Broad mid-level high pressure is forecast to
develop across the CONUS later in week-2, favoring increased chances for
above-normal temperatures over many areas.

HAZARDS

Moderate risk of heavy precipitation for much of Oklahoma and Texas, Sat-Wed,
May 3-7.

Slight risk of heavy precipitation for portions of the Southern and Central
Plains, Sat-Fri, May 3-9.

Possible flooding for the Southern Plains.

Possible flooding for the Lower Mississippi River.

DETAILED SUMMARY

FOR MONDAY APRIL 28 - FRIDAY MAY 02:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SATURDAY MAY 03 - FRIDAY MAY 09: At the beginning of week-2, as surface low
pressure departs New England and moves into southern Quebec, an associated
trailing cold front is predicted to extend across the east-central CONUS and
the Southern Plains, serving as a focus for continued increased chances of
localized enhanced precipitation and thunderstorms. As the baroclinic zone
stalls, the heavier precipitation amounts are favored over portions of the
Southern and Central Plains, where a slight risk of heavy precipitation is
posted for May 3-9. The GEFS and ECENS Probabilistic Extremes Tools (PETs)
indicate at least a 20 percent chance of rainfall amounts exceeding the 85th
climatological percentile and 1-inch across the highlighted risk area. A
moderate risk (40-60% chance) is introduced today over much of Oklahoma and
Texas from May 3-7, primarily based on higher probabilities in the ECENS PET,
good model run consistency in ECENS precipitation forecasts, and the 12Z GEFS
showing increasing potential for heavier amounts.



A possible flooding hazard remains posted across the Lower Mississippi River
given the potential for new and renewed rises in water levels during week-2
tied to any additional rainfall over the region associated with the stationary
front, as well as runoff from rainfall upstream. Main channels are already very
high, and thus are unlikely to have large responses to additional
precipitation. Regardless, tributaries and streams across this region
(including the Southern Plains) will continue to be susceptible to renewed
flooding or flash flooding if additional rainfall occurs. A risk of possible
flooding is introduced for northern Texas and Oklahoma in todays outlook,
where there are the most vulnerable top soils to flooding where there is a
moderate risk of heavy precipitation highlighted during the period. Late spring
is the peak time for flash flooding in Texas, due in part to slow-moving
thunderstorms.



Though no wind hazards are posted today, one area of concern is the Southwest,
in advance of a mid-level, southern stream trough. Typically during the spring,
as the deserts heat up, stronger winds rounding the base of approaching
mid-level troughs are mixed down to the surface resulting in very gusty winds
that occasionally produce significant damage. The ECENS and GEFS PETs depict
wind speeds of at least 20 mph in parts of the Southwest, which may be
underdone given the inherent nature of ensemble smoothing and challenges of
wind predictability.



A cold front moving off the Northeast coast early in week-2 favors a reduction
in temperatures over the Great Lakes and Northeast. High temperatures are
forecast to range from the upper 50s near the Great Lakes to around 80 degrees
F near the Nations Capital. The National Blend of Models (NBM) does not show
any widespread areas of record or near-record temperatures anywhere over the
CONUS during at least the first half of week-2. A general trend toward more
broad ridging and a pattern typical of late-Spring is forecast to emerge over
much of the CONUS later in week-2.



Troughing forecast across Alaska favors increased chances for increased onshore
flow and above-normal precipitation over the southeastern part of the state,
though forecasted precipitation amounts of 1-2 inches fall short of hazards
thresholds. Below-normal temperatures predicted over many areas may favor a
slight delay in seasonal river ice breakup. However, as temperatures continue
to warm, the eventual river ice breakup may lead to ice jams and associated
upstream flooding in the coming weeks.

FORECASTER: Anthony Artusa

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