Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
255 PM EDT Sat May 26 2018


Prelim Day 1 QPF Discussion
Valid May 27/0000 UTC thru May 28/0000 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1

...Florida into the Southeast...

No significant changes to the forecast thinking with the heavy to
excessive rainfall potential day 1 associated with the northward
movement of Alberto across the eastern portions of the Gulf of
Mexico.  Heavy rains will continue on the eastern side of Alberto
in the persistent axis of much above average pw values---2.5-3+
standard deviations above the mean---across much of FL.  Models do
show potential for a developing dry slot pushing northeastward off
the eastern Gulf and across portions of FL tonight into Sunday. 
The highest pw values may focus along the east coast of FL where a
few of the hi res runs are indicating potential bands setting up
parallel to the coast late Saturday night into Sunday--with a
lessening heavy rain threat for the western portion of the
peninsula.  Farther to the northeast---the precipitation threat
will be increasing across the Southeast across southern GA into
coastal SC as the higher pw values on the east side of Alberto
continue to stream northward.  For the day 1 time period---the
potential very heavy rains near the center of Alberto will likely
remain offshore given the current official NHC track---with this
core heavy rains a day 2 and beyond threat as the low continues to
push north.

...Mid-Atlantic into the Central Appalachians...

Much above average pw values expected to remain in a east to west
axis across portions of the Mid-Atlantic---extending into the
Central Appalachians.  Initially this is well to the south of the
frontal boundary over the northeast.  With time this front will be
pressing south into the Mid-Atlantic and may become a focus for
heavy to excessive rainfall amounts Sunday.  A predecessor
rainfall band well to the northeast of Alberto is possible along
this front where favorable upper difluence in the axis of much
above average pw values will support heavy to locally excessive
precip totals Sunday.

...Great Basin into the Northern Rockies

The strong Great Basin closed low will be moving only very slowly
eastward day 1. Well defined upper difluence ahead of this closed
low will support fairly well organized comma head deformation
precipitation areas to the north and northeast of this strong
closed low.  This will support widespread moderate to locally
heavy precip totals from the Great Basin into the Northern
Rockies.  The href mean and in house hi res ensemble used
primarily to mitigate any run to run and model to model qpf detail
differences.

Oravec