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FXUS02 KWBC 060708

PMDEPD



Extended Forecast Discussion

NWS Weather Prediction Center College Park MD

308 AM EDT Mon May 6 2024



Valid 12Z Thu May 09 2024 - 12Z Mon May 13 2024





...Central Gulf Coast States to Appalachians/Southeast U.S. Heavy

Rainfall Threat into Thursday/Friday...





...Guidance/Predictability Assessment...



The 12 UTC GFS/ECMWF/Canadian model solutions seem best clustered 

for Thursday and Friday in a pattern with good ensemble support and

above normal predictability and continuity, mainly in line with 

the 01 UTC National Blend of Models (NBM). A composite blend offers

good system detail. However, model forecast spread and cycle to

cycle continuity issues now increase rapidly by the weekend aloft 

out West, but especially with wetter weather systems moving through

the East/South and western Atlantic coastal low developments that 

are quite varied and without a clear signal to follow. Accordingly,

WPC products at these longer time frames have been mainly derived 

from more compatible guidance from a 12 UTC GEFS/ECMWF/Canadian 

ensemble means composite and the 01 UTC NBM to maintain max 

product continuity but limited system detail pending new guidance.



...Weather/Hazards Highlights... 

Main lows and associated fronts to focus mainly moderate rainfall 

seem set to work from the Great Lakes/Ohio Valley through the 

Northeast/Mid-Atlantic later this week with complex system/energy 

interactions forging offshore low developments downstream.

Meanwhile, a wavy/trailing frontal system and impusles aloft will 

gradually work across the South to intercept return flow with

deeper instability and moisture. Accordingly, a WPC Marginal Risk 

Excessive Rainfall (ERO) area is now in place from the lower 

Mississippi Valley through the central Gulf Coast states to the 

Appalachians for Day 4/Thursday. A small embedded Slight Risk area

is in place from NE Louisana to central Alabama given slow system 

translation. A favorable pattern will continue for rain and 

thunderstorms across the Southeast with the wavy front where a 

Marginal Risk ERO has been introduced for Day 5/Friday. Downstream 

energy track may lead to additional but uncertain coastal lows, 

while additional rainfall potential back to the south-central U.S.

is highly speculative in guidance at this time for into next week.



Expect cooler than normal temperatures for parts of the West into 

Thursday under upper troughing. Meanwhile, mean upper ridging will 

favor lingering warmth from the far South through the Mid-Atlantic

to threaten record seasonal values Thursday. 90s are still forecast

across the far southern tier, with potential for south Texas 

excessive heat with temperatures over 100F and higher heat indices.

Temperatures broadly cool later week onward across the South and 

East, with warming across broad portions of the West in more 

benign weather pattern underneath a building upper ridge.



Schichtel





Additional 3-7 Day Hazard information can be found on the WPC

medium range hazards outlook chart at:

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



WPC medium range 500mb heights, surface systems, weather grids, 

quantitative precipitation forecast (QPF), excessive rainfall 

outlook (ERO), winter weather outlook (WWO) probabilities, heat 

indices, and Key Messages can be accessed from:



https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif

https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif

https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html

https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml

https://www.wpc.ncep.noaa.gov/#page=ero

https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 

https://www.wpc.ncep.noaa.gov/heat_index.shtml

https://www.wpc.ncep.noaa.gov/#page=ovw











































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