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WPC Met Watch

 

Mesoscale Precipitation Discussion: #0219 (Issued at 1228 PM EDT Sat May 04 2024
) MPD Selection

 


Graphic for MPD #0219

Mesoscale Precipitation Discussion 0219
NWS Weather Prediction Center College Park MD
1228 PM EDT Sat May 04 2024

Areas affected...Central Appalachian Mountains & Eastern Slopes...

Concerning...Heavy rainfall...Flash flooding possible

Valid 041630Z - 042130Z

SUMMARY...Risk for scattered upslope slow-moving thunderstorms
capable of 1-1.5"/hr rates/totals may result in localized flash
flooding given complex/steep terrain.

DISCUSSION...Current GOES-E trends denote an area of increasing
clearing over the central Appliachians donwstream of approaching
shortwave.  Favorable surface (in mountain) to mid-level warm air
advection is pressing the warm front north across the Cumberland
plateau into NE KY while solid damming east of the range sharpens
the FGEN across western NC in the eastern upslope regions. 
DPVA/height-falls along and just east of the spine of the terrain
is likely to start backing low level flow more perpendicular to
the orographics enhancing low level moisture flux convergence. 
Combined with broken insolation, temps are starting to increase
and SBCAPE instability is also rising; and with Tds in the mid-60s
values are going to reach near 1000-1500 J/kg.  Due to terrain,
lowest profile reduces total moisture values, but still reaches
near 1.25+ and with strengthening flux to 15-20kts, moisture flux
should allow for efficient low level rainfall production as cell
mature.

Steering flow remains weak to the northeast at 15-20kts but also
parallel to the terrain suggesting training/repeating is possible.
 However, with near zero bulk shear, cells are more likely to be
pulse in nature and liable to collapse in less than an hour
resulting in sub-hourly rates/totals of 1-1.5".  However, given
strength of upslope, some cells may regenerate/back-build along
favored peaks (or just east downslope), allowing for multiple
up/downdraft cycles in similar proximity, in particular where
frontal zone interaction enhances some additional FGEN forcing. 
As such localized totals of 1-2" are probable with perhaps on or
two focused areas recieving 2-3" in 1-2hrs.  As such, scattered
incidents of flash flooding are possible within
higher-slope/complex terrain.

Gallina

ATTN...WFO...GSP...MRX...RLX...RNK...

ATTN...RFC...LMRFC...MARFC...OHRFC...SERFC...NWC...

LAT...LON   38068088 37768046 37448031 36708063 36168094
            35458185 35088292 35308347 35658359 36418307
            37028255 37958140

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Last Updated: 1228 PM EDT Sat May 04 2024



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