< Day 2 Outlook
WPC Day 3 Excessive Rainfall Outlook
Risk of 1 to 6 hour rainfall exceeding flash flood guidance at a point
Updated: 2014 UTC Mon Aug 20, 2018
Valid: 12 UTC Aug 22, 2018 - 12 UTC Aug 23, 2018
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
434 PM EDT Mon Aug 20 2018
Valid 12Z Wed Aug 22 2018 - 12Z Thu Aug 23 2018
...MARGINAL RISK FOR EXCESSIVE OVER NEW ENGLAND...CENTRAL
PLAINS...AND THE SOUTHWESTERN U.S....
...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.
Instability looks quite limited per the 12Z GFS/ECMWF, so the
Marginal Risk was maintained for now.
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.
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. 12Z guidance converged a bit on a
QPF max just north of the KS/OK border which has been fairly wet
over the past week. Maintained a Marginal Risk.
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt