Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
252 PM EDT Fri May 25 2018


Prelim Day 1 QPF Discussion
Valid May 26/0000 UTC thru May 27/0000 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1

..Northern California---Great Basin into the Northern Rockies...

There continues to be good model agreement with the inland push of
the strong closed low off the north central California coast this
morning---inland across northern to central California tonight and
into the Great Basin Saturday.  An active precip pattern likely to
the north and northeast of this closed low in a region of well
defined upper difluence from northern California---southern to
eastern Oregon---central to northern NV--much of ID into northwest
MT.  PW values across these regions will remain 1-2 standard
deviations above the mean---supporting potential for widespread
moderate to locally heavy precip totals.  WPC qpf did not deviate
from the model consensus of the heaviest precip potential from
northeast California into eastern Oregon---far northwest NV and
western ID.  A broad marginal risk area was maintained in this max
qpf area in the Excessive Rainfall Outlook.

...South Florida..

Showers likely to re-develop tonight across south Florida as
tropical moisture continues to be drawn northward on the eastern
side of Alberto.  This will be the beginning of a multi-day heavy
precip event for South Florida---expanding farther to the north
after day 1 into central to north Florida.  With pw values rising
to 2-3 standard deviations above the mean---confidence is high on
additional heavy precip totals this period from the Keys into
South Florida.  See the latest NHC advisories for additional
updates on this system.

...MS Valley eastward to the east coast...

A broad elongated mid to upper level trof will become established
thru the MS Valley this period.  With pw values along and to the
east of this trof expected to remain above average this
period---widespread scattered convection likely.  Confidence is
rather low with the details of qpf across most areas from the MS
Valley eastward thru the Great Lakes and south across the eastern
third of the nation. the href and in house hi res means used
primarily to mitigate the range of qpf solutions offered in the
latest guidance.  Areal average moderate precip totals depicted
with the likelihood of locally heavy totals where convection does
organize.

...Southern Ontario---southern QB---northern NY state into
northern New England...

A stationary front is expected to remain draped west to east from
north of the Upper Lakes---eastward across southern QB and into
northern New England.  Showers should remain active along this
boundary day 1 where pw values will pool to much above average
levels.  Areas near this boundary from northern NY state into
northern New England will possibly see multiple bands of
precip---with moderate to locally heavy precip values likely
across these areas

Oravec