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FXUS21 KWNC 091809

PMDTHR

US Hazards Outlook

NWS Climate Prediction Center College Park MD

300 PM EDT April 09 2024



SYNOPSIS: Mid-level low pressure is forecast to develop across the west-central 

contiguous U.S. (CONUS) late in week-1 and persist into the first half of 

week-2. This favors a series of surface lows tracking across the Great Plains 

to the Great Lakes. This pattern combined with enhanced moisture flow from the 

Gulf of Mexico increases the chances for heavy precipitation over parts of the 

Southern Plains, Middle and Lower Mississippi, Ohio, and Tennessee Valleys, 

along with possible flooding across northeastern Texas and the Lower 

Mississippi Valley. Additionally these surface lows may bring periods of heavy 

upslope snow to portions of the Rockies and High Plains depending on track and 

cold air availability.



HAZARDS



Moderate risk of high winds across portions of the Northern and Central 

Rockies, Northern and Central Plains, and the Upper Mississippi Valley, Wed, 

Apr 17.



Slight risk of high winds across portions of the Interior West and central 

CONUS, Wed-Fri, Apr 17-19.



Slight risk of periodic heavy precipitation across portions of the Southern 

Plains and Lower Mississippi, Ohio, and Tennessee Valleys, Wed-Sat, Apr 17-20.



Slight risk of heavy snow across portions of the Northern and Central Rockies 

and High Plains, Wed-Thu, Apr 17-18.



Possible flooding across portions of northeastern Texas, extreme southeastern 

Oklahoma, and much of the Lower Mississippi Valley.



DETAILED SUMMARY



FOR FRIDAY APRIL 12 - TUESDAY APRIL 16: 

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



FOR WEDNESDAY APRIL 17 - TUESDAY APRIL 23: At the end of week-1 and into the 

outset of week-2, the 0z GEFS, ECMWF, and Canadian ensembles are in good 

agreement regarding surface low pressure tracking from the Great Plains into 

the Great Lakes. This system is forecast to bring periods of heavy 

precipitation and possibly thunderstorms to portions of the south-central 

states, and wintry weather to the northwest of the storm track over the parts 

of the Rockies and High Plains. Behind this system, gusty winds are also 

anticipated across much of the Interior West and central CONUS, with an 

increased surface pressure gradient in the ensembles supporting a moderate risk 

for high winds across portions of the Northern and Central Rockies, Northern 

and Central Plains, and the Upper Mississippi Valley on day-8 (Apr 17).  







As this initial system departs, continued mid-level troughing over the 

west-central CONUS favors the development of additional surface low pressure 

systems over the same region. A slight risk of heavy precipitation is 

highlighted across portions of the Southern Plains and Lower Mississippi, Ohio, 

and Tennessee Valleys, Wed-Sat, Apr 17-20 where the GEFS and ECMWF 

Probabilistic Extremes Tools (PETs) depict at least a 20 percent chance of 

3-day precipitation totals exceeding the 85th climatological percentile and 

1-inch. 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 forecast heavy 

precipitation during week-2, where there are some locations already 

experiencing flood conditions. 







On the backside of these systems, heavy snow is possible, with the uncalibrated 

ECMWF depicting elevated probabilities for snowfall totals upwards of 6-inches 

early in the period across portions of the Northern and Central Rockies and 

High Plains. There is also some support from the GEFS snow water equivalent 

(SWE) PET, which shows some of these areas having at least a 20 percent chance 

SWE exceeds the 85th percentile and a half-inch. Therefore, a slight risk for 

heavy snow is posted across these aforementioned areas from Apr 17-18, 

coinciding with the highest confidence based on the daily pattern evolution in 

the models.







Elevated wind speeds are forecast across a large portion of the Interior West 

and central CONUS early in week-2. Although the highest confidence is on day-8 

(Apr 17) related to the initial system, any other systems are likely to result 

in similar high wind events. Therefore, a broad slight risk of high winds 

remains highlighted across much of these areas through Apr 19, with blizzard 

conditions possible across parts of the Rockies and High Plains that receive 

snowfall. The National Interagency Fire Center (NIFC) indicates the greatest 

potential for wildfires for day-7 across much of the Great Plains and Four 

Corners, and this should persist into week-2 as additional systems eject out of 

the trough.







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

Basin and Rockies 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, 

the ECMWF PET depicts some of this anomalous cold extending into parts of the 

Great Plains and Middle Mississippi Valley, with some areas having at least a 

20 percent chance of minimum temperatures falling below the 15th climatological 

percentile and 40 deg F. However, there is little support from other models of 

temperatures reaching these thresholds, precluding the addition of a related 

hazard.







Across Alaska, the week-2 mean pattern is predicted to be dominated by positive 

500-hPa height anomalies across much of the state, with increasing northerly 

flow and troughing over the Arctic favoring increased chances for near- to 

below-normal temperatures. Surface low formation is possible over the Gulf of 

Alaska during week-2, although not anticipated to support widespread hazards at 

this time.



FORECASTER: Thomas Collow 



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