Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
219 PM EDT Sun May 06 2018


Prelim Day 1 QPF Discussion
Valid May 07/0000 UTC thru May 08/0000 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1


...East...

Showers and thunderstorms will exit the VA/NC coasts this evening,
with the activity over the OH/TN/MS Valley gradually weakening
with the loss of daytime heating. The mid/upper level trough will
remain overhead into the day Monday. The cooler temperatures aloft
underneath this trough should allow for scattered convective
development with daytime heating along a low level convergence
axis forecast from the western Carolinas into WV and western VA.
The flow will be rather weak along this corridor, thus anticipate
some slow moving pulse activity. Briefly heavy rains will be
possible, but any individual cell should be short lived, and PWATs
will only be around average. Also may see some shower activity
along another convergence axis closer to the coast. Less
instability forecast here, thus looking more like generally light
shower activity. WPC QPF generally followed a multi model blend,
weighted more towards the 12z HREF guidance.


...Florida...

Convection will continue to expand in coverage this afternoon
ahead of a southward dropping cold front. The heaviest totals
should focus across the central and eastern portion of the state,
with the intensity decreasing with the loss of heating tonight.


...Pacific Northwest---Northern Great Basin into the Northern
Rockies...

Showers and embedded thunderstorms will expand in coverage this
afternoon across northern ID into western MT ahead of a well
defined shortwave. Storms should be quick moving, however
instability increasing to around or above 1000 J/KG will support
at least a few more intense storms, capable of producing briefly
heavy rainfall rates. The 12z HREF does indeed show moderate
probabilities of localized amounts exceeding 1" in an hour. This
rainfall potential along with melting snows will result in rising
stream flows and potential for runoff issues from northern ID into
western MT. The best window for these higher rates is from around
21z - 04z.

During the day Monday isolated to scattered convection should
again break out near this shortwave as it tracks east across MT
and towards the western Plains. Most cells should be quick moving,
and not expecting much organization. Thus areal averaged rainfall
will generally be light, with just some localized heavier totals.

Chenard