Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
236 AM EDT Thu Apr 05 2018


Prelim Day 1 QPF Discussion
Valid Apr 05/1200 UTC thru Apr 06/1200 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1

...Pacific Northwest into the northern Rockies...

An impressive surge of moisture pushes into coastal
Oregon/Washington later this morning ahead of a cold front.
Precipitable water values of 0.75-1.00" (+2 to +2.5 standard
deviations) will support widespread light to moderate amounts,
generally 0.25 inches to 0.50 inches, but a bit lighter in the
valleys and about 2-3 times that in the Olympics/Cascades. The
nose of a 110kt jet streak should push into southwestern Oregon by
early afternoon coinciding with larger PW anomalies (southward to
NorCal) of about +2 to +3 standard deviations.

The ARW2.5 and ARW5 cores tended to fit pretty well with the 00Z
global model runs over much of the region.  As a result, we tended
to give more weight to a consensus of the ARW and employed them in
order to provide better horizontal resolution.  A quick look at
the HREF mean (or blended means) showed it was still a viable
solution.  The end result was a QPF that was not too different
from continuity across the Pacific Northwest into the Northern
Rockies. 

Much like on the day shift, followed the idea of expanded QPF area
over northern ID into MT/WY given the rising PW values, a ~120kt
jet out of SW Canada, and the surface front along/east of the
Divide with modest upslope potential.


...Florida...

Some lingering showers are possible along the southeast coast of
the Florida peninsula this afternoon and evening near a weakening
cold front.  Hi-res models still target extreme southern portion
of the peninsula given northeast winds behind the front (sinking
into the Florida Straits) and sea breeze development. Isolated
local maxima may approach 0.5 inches but the heaviest rainfall and
best coverage of precipitation should be off shore.

...Southern Plains...

Southerly flow should be developing over the southern plain during
the afternoon and evening.  These winds will tap some moisture and
start to draw it northward which leads to showery precipitation
breaking out over parts of the Southern Plains. Initially, the
model agreement is not particularly good, but once the H85 flow
accelerates to around 30 kts and the nose of the 1.00 inch
precipitable water value reaches northeast Texas/northwest
Louisiana between 06/06Z and 06/12Z.

Bann