Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center

 
 

 

Follow the Weather Prediction Center on Facebook Follow the Weather Prediction Center on Twitter
NCEP Quarterly Newsletter
WPC Home
Analyses and Forecasts
   National High & Low
   WPC Discussions
   Surface Analysis
   Days ½-2½ CONUS
   Days 3-7 CONUS
   Days 4-8 Alaska
   QPF
   PQPF
   Flood Outlook
   Winter Weather
   Storm Summaries
   Heat Index
   Tropical Products
   Daily Weather Map
   GIS Products
Current Watches/
Warnings

Satellite and Radar Imagery
  GOES-East Satellite
  GOES-West Satellite
  National Radar
Product Archive
WPC Verification
   QPF
   Medium Range
   Model Diagnostics
   Event Reviews
   Winter Weather
International Desks
Development and Training
   Development
WPC Overview
   About the WPC
   Staff
   WPC History
   Other Sites
   FAQs
Meteorological Calculators
Contact Us
   About Our Site
 
USA.gov is the U.S. Government's official web portal to all federal, state, and local government web resources and services.
 
WPC Met Watch

 
Mesoscale Precipitation Discussion: #0488 (2022)
(Issued at 642 PM EDT Tue Jul 12 2022 )

MPD Selection
 


Graphic for MPD #0488
Mesoscale Precipitation Discussion 0488
NWS Weather Prediction Center College Park MD
642 PM EDT Tue Jul 12 2022

Areas affected...Northern Virginia...Southern Central
Maryland...District of Columbia...

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

Valid 122245Z - 130245Z

SUMMARY...Very intense short-term rain rates aligning for
favorable training/repeating resulting in possible localized flash
flooding through late evening.

DISCUSSION...Severe weather scenrio continues to unfold across the
Mid-Atlantic with very strong thunderstorms and high wind gusts. 
This is also resulting in intense moisture convergence with these
cells within a very moist and unstable environment.  The mass
loading into the cells have resulted in numerous reports of 1"/30
minutes with each individual cell.   In the short-term, the
overall speed has limited flooding concerns in all but the most
prone areas, ie urban settings.

However, larger scale synoptic setup has favored the cell moving
across DC toward Annapolis MD in a very favorable placement to the
right entrance region of the jet, but the speed max is exiting
toward the northeast.   Upstream across WV a secondary subtle
speed max is starting to round the base of the upper trof.  This
has reduced the forward speed of the cold front crossing the
central Applachians resulting in a weak kink or wave around W MD. 
As such, the outflow boundary from the initial storm as oriented
favorably west to east for increased west-southwesterly flow ahead
of the approaching speed max/synopic ascent.  As a result oblique
but sufficient isentropic ascent for additional similar but
slightly less intense thunderstorms have formed generally parallel
to the mean flow suggesting increased training potential across
Northern VA into southern central MD.  Given potential of
backbuilding/training as supported by recent runs of the HRRR, an
axis 2-4" totals are possible likely from Rockingham, VA toward
Prince William and across into Charles county this evening.  This
crosses a few areas of lowered FFG due to recent heavy rainfall
increasing the potential for flash flooding to occur.   

Gallina

ATTN...WFO...AKQ...LWX...

ATTN...RFC...MARFC...NWC...

LAT...LON   38947703 38677651 38197659 38057776 38027883
            38317921 38817892 38937793


Last Updated: 642 PM EDT Tue Jul 12 2022
 

NOAA/ National Weather Service
National Centers for Environmental Prediction
Weather Prediction Center
5830 University Research Court
College Park, Maryland 20740
Weather Prediction Center Web Team
Disclaimer
Credits
Glossary
Privacy Policy
About Us
Career Opportunities
Page last modified: Thursday, 12-May-2022 19:44:52 GMT