####018003058#### AWUS01 KWNH 041220 FFGMPD VAZ000-NCZ000-SCZ000-GAZ000-041800- Mesoscale Precipitation Discussion 0218 NWS Weather Prediction Center College Park MD 820 AM EDT Sat May 04 2024 Areas affected...Northeast GA...Upstate SC...Western & Central NC...far South-Central VA... Concerning...Heavy rainfall...Flash flooding possible Valid 041220Z - 041800Z SUMMARY...Slow moving, narrow, but intense updates with occasional collisions/mergers pose a few incidents of widely scattered and localized flash flooding possible this morning. DISCUSSION...GOES-E WV depicts a elonaged shortwave lifting out of eastern AL into N GA with mid-level ridge axis poking through the central Carolinas. Confluent deeper moisture streams from the Gulf and return moisture out of the western Atlantic meld through depth along and just NW of the Fall-line in the central Piedmont from E GA through south-central VA. Enhanced deep layer moisture reaches over 1.5" and nears 1.75" with best solid low level moisture in place along the I-85 corridor from Anderson-Greenwood, SC to Greensboro, NC. While potentially allowing for more efficient rainfall production, the moist environment has limited steeper lapse rates for greater mid-level instability to be tapped. Yet, there appears to be sufficient 500-750 J/kg through a similar axis along the southeast gradient of the moisture axis. The approaching shortwave is providing some broad DPVA along and just northeast of its advancement, but also increasing low level flow from 5-10kts to 10-20kts by mid-morning to focus on increasing confluence downstream into NC/S VA. Deep layer steering is going to be more limited further from the short-wave/deeper into the shortwave ridging... so some stationary nature, even slight retrograding responding to the approaching height-falls can be expected. As such, any thunderstorms that do develop are likely to struggle to maintain strength and may be more pulse-like in nature but will have intense local downdrafts capable of 1.5" in short-duration. Resultant outflow boundaries should allow for collisions and aid to generate the next updraft cycle. As such, locally intense sub-hourly to hourly totals of 1.5-2.5"/hr are possible and with collisions/slow motions may result in localized 3" totals. So while most of the area within the MPD is NOT likely to see intense rainfall, there will be widely scattered (maybe regionally clustered) ares that may see spotty flash flooding conditions, especially if the downdrafts fall on urban centers or traditionally poor drainage areas near the Fall-line and lower eastern slopes of the Appalachians. Gallina ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...CAE...FFC...GSP...RAH...RNK... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 36838010 36567886 35767903 34688010 33408171 32368268 32518353 33348387 33918451 34868355 35478272 36178140 ####018000741#### PENA01 KWNH 041200 @UHPISF000CN MPDSUM@V2.0@0101700060@12040524@@0NMCGPHMPD xP@!' `' ` @ & B7)p&PNAM02@@Cn}|zt{zzzy|{z{{{{{{zyzz{}|@@n@@n@@K0218 @@d&MESOSCALE DISCUSSION SUMMARY GRAPHIC @@d& OF ALL VALID MESOSCALE DISCUSSIONS AT @@d& TIME OF PRODUCT CREATION:@@d& ISSUED 05/04/2024 1220Z @@ dNOAA/NWS/NCEP@@d WEATHER PREDICTION CENTER @@d FOR COLOR VERSION SEE: @@d WWW.WPC.NCEP.NOAA.GOV @