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FXUS21 KWNC 111802

PMDTHR

US Hazards Outlook

NWS Climate Prediction Center College Park MD

300 PM EDT April 11 2024



SYNOPSIS: Mid-level low pressure is forecast across the north-central 

contiguous U.S. (CONUS) early in week-2. While chances for frontally focused 

precipitation are still elevated over portions of the east-central CONUS at the 

outset of the period, confidence decreases thereafter as models differ in the 

amplitude of the mid-level low and resultant flow pattern across the East. A 

more southwesterly flow pattern would enhance precipitation chances across much 

of the East, while a more amplified mid-level low and resultant increased 

northerly flow may limit the greatest precipitation potential to the Gulf 

Coast. As surface high pressure builds southward early in week-2, elevated wind 

speeds are possible along its periphery, including over the Upper Mississippi 

Valley, Great Lakes, Southwest, and Central and Southern Rockies and High 

Plains, with upslope snow remaining possible across the Central Rockies.



HAZARDS



Moderate risk of heavy precipitation across portions of the Southern Plains and 

Lower and Middle Mississippi and Tennessee Valleys, Fri, Apr 19.



Slight risk of heavy precipitation across portions of the Southern Plains, 

Lower and Middle Mississippi, Ohio, and Tennessee Valleys, Great Lakes, 

Mid-Atlantic, and Northeast, Fri-Sun, Apr 19-21.



Slight risk of heavy snow across portions of the Central Rockies, Fri, Apr 19.



Slight risk of high winds across portions of the Southwest, Central and 

Southern Rockies, and Central and Southern High Plains, Fri, Apr 19.



Slight risk of high winds across portions of the Northern Plains, Upper 

Mississippi Valley, and Great Lakes, Fri, Apr 19.



Possible flooding across portions of northeastern Texas, extreme southeastern 

Oklahoma, and much of the Lower Mississippi Valley.



DETAILED SUMMARY



FOR SUNDAY APRIL 14 - THURSDAY APRIL 18: 

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



FOR FRIDAY APRIL 19 - THURSDAY APRIL 25: At the end of week-1 and into the 

outset of week-2, the 0z GEFS and ECMWF indicate troughing moving across the 

north-central CONUS, with surface low pressure tracking into eastern Canada. 

The 0z Canadian is quick to weaken this trough and depicts a stronger ridge 

across the East early in week-2, while the 0z GEFS depicts a more amplified 

trough across the region. The ECMWF is in between the two extremes, but leans 

more on the Canadian given its depiction of a weaker trough, and the 12z GEFS 

has trended less amplified with the troughing compared to the 0z run. The model 

differences reduce forecast confidence as the amplitude of troughing over the 

Northeast will dictate the sensible weather. The ECMWF/Canadian solution with a 

weaker trough would promote more southerly flow and an enhancement of 

precipitation chances across much of the East early in week-2. However, the 

more amplified 0z GEFS solution would result in more northerly flow and a 

southward extension of surface high pressure, thus reducing precipitation 

chances.







The ECMWF Probabilistic Extremes Tool (PET) continues to depict at least a 20 

percent chance 3-day precipitation exceeds the 85th climatological percentile 

and 1-inch across much of the east-central CONUS, with the GEFS PET confining 

these elevated probabilities to the central Gulf of Mexico coast. These 

differences are also reflected in the uncalibrated guidance, with the 0z ECMWF 

showing an expansive region with 24-hour precipitation totals above a half-inch 

on day-8, and at least a 20 percent chance for exceeding 1-inch over some 

areas. Given this, along with an uptick in precipitation totals in the 12z 

GEFS, the moderate risk for heavy precipitation remains in place for day-8 (Apr 

19) across portions of the Southern Plains and Lower and Middle Mississippi and 

Tennessee Valleys, with the potential for thunderstorms to enhance 

precipitation totals locally. The slight risk extends farther north into the 

Ohio Valley and along the Eastern Seaboard through Apr 21 to account for the 

wetter ECMWF and Canadian solutions. A possible flood risk area is designated 

for parts of northeastern Texas, extreme southeastern Oklahoma, and much of the 

Lower Mississippi Valley due to antecedent wet conditions anticipated during 

week-1 and potential for additional heavy precipitation during week-2, where 

there are some locations already experiencing flood conditions. 







Increased north to northwesterly winds are possible across the Northern Tier in 

the wake of the departing surface low, with a slight risk of high winds posted 

across portions of the Northern Plains, Upper Mississippi Valley, and Great 

Lakes, Apr 19. The GEFS depiction of a stronger trough across the Northeast 

would also favor increased wind speeds in that region, but holding off on 

expanding the hazard due to the differing flow pattern in the ECMWF and 

Canadian ensembles. Surface high pressure building southward out of Canada 

favors a tight pressure gradient across the Southwest and the central and 

southern Rockies and High Plains, where another slight risk for high winds is 

highlighted Apr 19. This may also lead to continued chances for upslope snow 

across the Central Rockies, with the uncalibrated 0z ECMWF continuing to 

support a slight risk for heavy snow over the region Apr 19. Additionally, the 

National Interagency Fire Center (NIFC) indicates the greatest potential for 

wildfires for day-7 across much of the Four Corners and Southern Plains, and 

this should persist into week-2 given the continued potential for increased 

wind speeds and little precipitation.







A period of below-normal temperatures is possible across parts of the Great 

Basin, Rockies, and Northern Plains early in the period, with some sporadic 

areas of mixed vegetation susceptibility noted across parts of Utah and 

Colorado. Subfreezing temperatures are possible across these areas, but the 

threat of any widespread impacts is marginal, thus no related hazard is posted. 

By the middle of week-2, this anomalous cold may shift across parts of the 

eastern CONUS, with the GEFS PET indicating a more expansive region of 20 

percent or greater chances for minimum temperatures falling below the 15th 

climatological percentile compared to the ECMWF PET. The GEFS depiction would 

possibly result in some vegetation concerns across the Ohio Valley with 

temperatures dropping into the 30s deg F. However, no hazard is issued due to 

the relatively warmer ECMWF solution across this region.







Across Alaska, the week-2 mean pattern is predicted to start with positive 

500-hPa height anomalies, with increasing northerly flow and troughing 

extending southward from the Arctic favoring increased chances for below-normal 

temperatures. Surface low formation is possible over the Gulf of Alaska during 

week-2, although this is not anticipated to support any hazards at this time.



FORECASTER: Thomas Collow 



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