Skip Navigation Links 
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
   Flood Outlook
   Winter Weather
   Storm Summaries
   Heat Index
   Tropical Products
   Daily Weather Map
   GIS Products
Current Watches/

Satellite and Radar Imagery
  GOES-East Satellite
  GOES-West Satellite
  National Radar
Product Archive
WPC Verification
   Medium Range
   Model Diagnostics
   Event Reviews
   Winter Weather
International Desks
Development and Training
WPC Overview
   About the WPC
   WPC History
   Other Sites
Meteorological Calculators
Contact Us
   About Our Site is the U.S. Government's official web portal to all federal, state, and local government web resources and services.
< Day 1 Outlook Day 3 Outlook >
WPC Day 2 Excessive Rainfall Outlook
Risk of 1 to 6 hour rainfall exceeding flash flood guidance at a point
Updated: 2017 UTC Mon May 10, 2021
Valid: 12 UTC May 11, 2021 - 12 UTC May 12, 2021
Day 2 Excessive Rainfall Forecast
Forecast Discussion
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
419 PM EDT Mon May 10 2021
Day 2
Valid 12Z Tue May 11 2021 - 12Z Wed May 12 2021 


21z Update...Areas along the Gulf are still on track to see heavy 
rainfall amounts associated with the frontal boundary. Latest 
guidance has shifted the axis of heaviest amounts a bit further 
eastward through portions of central MS/AL with upwards of 1 to 2 
inches during this time frame with pockets of 2.5+ inches. These 
areas are still sitting at 150 to 600 percent of normal of 
rainfall over the past week. With this being said, have extended 
the Marginal Risk area further eastward for MS and southward 
through southern portions of AL per request of MOB CWA. Have also 
extended the Slight Risk area a bit further eastward for these 
areas as well as southward through southern TX with latest QPF 
guidance showing heavy amounts of 2 to 4 inches for this area.   


Previous Discussion...

Model agreement has gotten better in terms of the speed and 
placement of the front approaching from the only a 
minor expansion was made around the western and southern/eastern 
periphery of the previously-issued risk area.  

The southward moving front over Texas and the central Gulf states 
will slow its progression during this period which results in the 
boundary becoming oriented from west-to-east. With very moist air 
streaming in from the east/southeast over boundary, convection 
will build westward and support training cells along and north of 
this boundary. The signal remains for moderate to heavy rainfall 
across parts of the area, although the GFS had backed off the 
areal coverage and maximum rainfall amounts somewhat from 09/18Z.  
Even so, am not inclined to make significant changes either to the 
QPF or the Excessive Rainfall Outlook given the anomalous amount 
of moisture in place (maximum anomalies in excess of 2 standard 
deviations above climatology) which is sustained by continued 
influx of moisture on low-level southeasterly winds and enough 
instability (1000-1500 J/kg MLCAPE) to result in cells being able 
to produce downpours.

Day 2 threat area:

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
Privacy Policy
About Us
Career Opportunities