Valid Saturday May 03, 2025 to Friday May 09, 2025
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
SummaryFor Monday April 28 - Friday May 02:
WPC Days 3-7 U.S.
Hazards 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 today’s 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 50’s near the Great Lakes to around 80
degrees F near the Nation’s 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
$$
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.
Resources
Week-2 Probabilistic Extremes Tool
GFS Ensemble Forecasts