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FXUS21 KWNC 291937

PMDTHR

US Hazards Outlook

NWS Climate Prediction Center College Park MD

300 PM EDT April 29 2024



SYNOPSIS: Weak mid-level high pressure over the southern Contiguous U.S. 

(CONUS) supports increased potential for excessive heat to portions of the 

Southern Plains at the beginning of the week-2 period. Meanwhile, a mid-level 

low pressure system predicted over the Northern Plains early in week-2, 

enhances the likelihood for heavy precipitation for portions of the Northern 

Plains and Upper Mississippi Valley. Surface low pressure east of the Central 

Rockies is favored to bring a risk of high winds to portions of the western and 

central CONUS. Central Florida has been experiencing persistent dryness.With 

little additional precipitation forecast for the region during either week-1 or 

week-2 there are higher chances for rapid onset drought (ROD).



HAZARDS



Slight risk for excessive heat for portions of the Southern Plains, Tue-Fri, 

May 7-10.



Slight risk for heavy precipitation for portions of the Northern Plains and 

Upper Mississippi Valley, Tue-Wed, May 7-8.



Slight risk for high wind for portions of the Great Basin, Central and Southern 

Rockies, Desert Southwest, and the Central and Southern Plains, Tue-Fri, May 

7-10.



Risk for rapid onset drought for portions of Central Florida.



DETAILED SUMMARY



FOR THURSDAY MAY 02 - MONDAY MAY 06: 

https://www.wpc.ncep.noaa.gov/threats/threats.php



FOR TUESDAY MAY 07 - MONDAY MAY 13: There is poor consensus among ensemble 

model solutions regarding the 500-hPa height anomalies for week-2. Nonetheless 

there is common ground with regard to some key synoptic features that have 

implications for potentially extreme weather during the week-2 forecast period. 

Both the GEFS and ECMWF depict weak positive height anomalies over the Southern 

Plains for most of week-2. As we get towards the middle of May such anomalous 

ridging leads to the potential for excessive heat. The ECMWF and GEFS 

Probabilistic Extremes Tools (PETs) indicate at least a 20% probability of 

maximum temperatures exceeding the 85th percentile climatologically, and 95F 

for much of the Southern Plains, and >100F for portions of the Rio Grande 

Valley for May 7-10, resulting in a slight risk for excessive heat for portions 

of the Southern Plains as far north as the Texas Hill Country for the days 

highlighted above.







A second feature that is well-depicted in model solutions is persistent surface 

low pressure in the lee of the Rockies for most of the forecast period. When 

paired with surface high pressure over the North Pacific, a broad tight 

pressure gradient is depicted over much of the southwestern CONUS, which would 

favor high winds for the region. This is supported by the GEFS and ECMWF wind 

PETs, which give at least a 20% probability of wind speeds exceeding the 85th 

percentile for portions of the western and central CONUS roughly from the 

Sierra Nevadas east to western Kansas and Oklahoma, thus a slight risk for high 

wind is posted for portions of the Great Basin, Central and Southern Rockies, 

Desert Southwest, and the Central and Southern Plains for May 7-10.







Both the GEFS and ECMWF also depict a passing shortwave trough moving along the 

Northern Tier early in the forecast period. This trough may pair up with the 

aforementioned surface low pressure, bringing potentially heavy precipitation 

to the Northern Plains. The GEFS and ECMWF PETs both indicate at least a 20% 

probability of 3-day precipitation totals exceeding the 85th percentile and at 

least a half inch at the onset of week-2 centered over the Dakotas. Solutions 

from these two models differ with regard to the timing of the heaviest 

rainfall, with the ECMWF moving the shortwave east more quickly than the GEFS. 

Although models indicate the system moving through the region fairly quickly, 

the uncalibrated ECENS shows 3-day precipitation totals exceeding one inch. 

Additionally, with the potential for thunderstorms a slight risk for heavy 

precipitation is posted for portions of the Northern Plains and Upper 

Mississippi Valley for May 7-8.







In the Southeast, above-normal temperatures and near- to below-normal 

precipitation is forecast during weeks-1 and 2. In parts of the central Florida 

peninsula soil moisture levels are declining due to limited precipitation in 

recent weeks and months. Recent weeks have seen areas of abnormal dryness (D0) 

developing and expanding across both of these regions. As we approach the 

middle of May, increasing sun angles and temperatures in the 80-90 Deg F could 

lead to further drying of soils and potentially lead to drought conditions 

across this region. Therefore, an area of rapid onset drought (ROD) is posted 

for portions of central Florida.







In Alaska, as we move into the middle of May snowmelt season is underway and 

frozen rivers will begin to break up in the near future.This leads to the 

potential for river flooding related to ice-jams. We continue to monitor the 

situation but currently there are no indications of impending major river 

break-ups so no flooding-related hazards are posted at this time.



FORECASTER: Danny Barandiaran 



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