< Day 2 Outlook
WPC Day 3 Excessive Rainfall Outlook
Risk of 1 to 6 hour rainfall exceeding flash flood guidance at a point
Updated: 2040 UTC Tue Aug 14, 2018
Valid: 12 UTC Aug 16, 2018 - 12 UTC Aug 17, 2018
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
438 PM EDT Tue Aug 14 2018
Valid 12Z Thu Aug 16 2018 - 12Z Fri Aug 17 2018
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE EASTERN
...Eastern Great Lakes to Tennessee...
12Z models have become more progressive with a modest low moving
across the Lower Peninsula of Michigan Wednesday. Ample lift from
the mid-level shortwave sits underneath ample right entrance
forcing aloft. In advance of the frontal zone, precipitable water
value anomalies jump into the 2 to 2.5 standard deviation range
accompanied by a significant uptick in low-level jet speeds (30 to
40 knots). The Slight Risk was shifted east (essentially
surrounding Lake Erie) based on the 12Z global model consensus.
...Arizona into New Mexico...
High precipitable water continues to lift north out of the Gulf of
California/Sea of Cortez in a monsoonal pattern. Diurnal heating
over the region should force convection over the higher terrain of
AZ/NM initially although the weak 700-mb winds suggest the
activity may struggle to push off the mountains into the lower
elevations. Expanded the Marginal Risk into western NM on account
of the 12Z consensus.
...Central and Southern Great Plains...
A broad Marginal Risk area was maintained which extends over
sections of the Central to Southern Plains. The Central Plains
portion is a continuation of activity congregating underneath the
upper low ejecting out of South Dakota. Steep lapse rates
underneath the low center should force scattered to locally
organized convection as it drops south and east. An uncertain
amount of related convection will develop farther south of this
wave where ample instability will be present over KS/OK. The 12Z
GFS/EMCWF are farther south and warranted maintenance of the
Marginal Risk into eastern OK.
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt