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< 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: 0835 UTC Tue Aug 21, 2018
Valid: 12 UTC Aug 22, 2018 - 12 UTC Aug 23, 2018
Day 2 Excessive Rainfall Forecast
Forecast Discussion
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
447 AM EDT Tue Aug 21 2018
Day 2
Valid 12Z Wed Aug 22 2018 - 12Z Thu Aug 23 2018 


...Northern New England...
Maintained a Marginal Risk over northern New England as moist flow 
from the Atlantic Ocean gets drawn inland by a developing low 
pressure moving into Canada from the eastern Great Lakes 
Wednesday. Plenty of confluent flow at the low levels being drawn 
into the hilly terrain of northern New England is expected. Was 
tempted to remove the Marginal risk given the fact that that the 
models continue to show limited instability, but opted to maintain 
the Marginal Risk for at least one more cycle to evaluate the 
latest hi-res window QPF and global/mesoscale guidance 

...Southwest U.S....
Moisture being drawn northward across AZ shifts east a bit 
centering on the four corners. Ample moisture (generally 1.5 
standard deviations above normal) and instability will allow heavy 
thunderstorms. However, weak forcing suggests widely scattered 
heavy rain with the Marginal Risk maintained for now.

...Central Plains...
Convection forming over the Central/Southern Plains early 
Wednesday morning will taper off at the time of convective minimum 
over parts of Kansas or Oklahoma, followed by an additional round 
of convection forming during the latter portion of Wednesday and 
the early-hours of Thursday morning as 850 mb winds ramp up in a 
low-level jet of 25 to 35 knots. Maintained the Marginal risk 
without modification since the model consensus was for the heavier 
rainfall to occur over areas south and east of areas where Flash 
Flood Guidance was lowered by recent rainfall.


Day 2 threat area:

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