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FXUS02 KWBC 070700

PMDEPD



Extended Forecast Discussion

NWS Weather Prediction Center College Park MD

300 AM EDT Tue May 7 2024



Valid 12Z Fri May 10 2024 - 12Z Tue May 14 2024





...Guidance/Predictability Assessment...



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

valid for Friday and Saturday in a pattern with good 12 UTC cycle 

ensemble support and near to above normal predictability and 

continuity, generallly in line with the 01 UTC National Blend of 

Models (NBM). A composite blend offers good system detail, with

the most forecast spread relating to moderate coastal genesis and 

development up off the East Coast. 12 UTC guidance trended toward 

better clustering compared to the more varied 18 UTC GFS/GEFS. The 

12 UTC guidance cycle best fits latest Machine-Learning guidance.

Latest 00 UTC guidance remains in line, but the ECMWF is delayed.



Forecast spread and model cycle to cycle continuity issues 

increase more significantly over the weekend into next week over 

the West in developing split flow and especially with amplitude and

extent of digging of northern stream energies down into the north-

central and/or eastern U.S.. WPC products at these longer time 

frames were mainly derived from more compatible guidance from the 

12 UTC ECMWF/NAEFS ensemble means and the 01 UTC NBM along with 

WPC applied manual edits to maintain max WPC product continuity, 

albeit with less than ideal system detail given growing uncertanty.

The latest 00 UTC models remains varied with run to run issues.



...Weather/Hazards Highlights...



A main parent low and frontal system working toward the Northeast 

Friday will help focus generally moderate rainfall, with activity 

aided and prolonged Saturday as uncertain downstream energy 

tranference leads to coastal low genesis. Additional but uncertain

upstream northern stream systems may periodically offer bouts of 

mainly lighter rains from the north-central U.S. to the Great 

Lakes/Northeast Sunday-next Tuesday. 



Meanwhile to the south, a cooling and trailing/wavy front will 

moderate lead warmth while working through the Southeast to the 

Gulf of Mexico and northern Mexico. A WPC Day4/Friday Excessive 

Rainfall Outlook Marginal Risk area is in place for parts of the 

Southeast given lingering deep moisture/instability and favorable 

upper jet/diffluence support. This slowing front and a reinforcing 

front/upper impulses are expected to periodically focus 

predipitation from the southern Rockies/Plains out through the Gulf

of Mexico and Florida over the weekend into next week. Guidance 

remains varied at these longer time frames, but latest signal 

trends suggest the main areas to monitor for any runoff issues may 

be the Florida Peninsula and the western Gulf Coast.



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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