-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 152331
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
731 PM EDT Sun Apr 15 2018

.SYNOPSIS...
Rain, will overspread the region by this evening and continue
overnight ahead of a cold front. Behind the front, showery
precipitation and colder temperatures will dominate through the
early part of the week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
445pm update...only minor changes to previous forecast. Updated
PoPs for the evening hours in line with latest hires guidance
and radar trends. Temperatures were also slightly adjusted to
better portray current conditions.

Previous discussion...
Elected to expand the Flash Flood Watch to encompass eastern
Ohio and the northern WV panhandle. Model consensus of a band of
1.5 to 2.5 inch QPF, perhaps locally higher, was getting harder
to ignore. The western counties fall under the right entrance
region of a 120-140 knot upper jet during the late afternoon and
evening as the trough tilts. Layered frontogenesis and
deformation will also be present, along with anomalously high
PWAT values of 1.3 to 1.4 inches. Although flash flood guidance
values are fairly high in this area, felt that rain rates may
support at least isolated flooding concerns. The watch is
maintained over the original eastern counties as well where a
period of training heavy showers is also possible.

The cold front will arrive in the western counties this evening
and depart to the east during the predawn hours. Steadier rain
will end, to be followed by more showery precipitation as the
upper low makes its way into the Ohio Valley.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
The upper low will swing across the region behind the boundary
on Monday. Periodic shortwaves will then rotate through in the
troughing pattern through Tuesday, producing showery
precipitation. A mix with and change to snow is still figured
first along the higher ridges Monday, and then areawide Monday
night into Tuesday morning. Boundary layer warming should allow
rain to become dominant again in the lowlands Tuesday afternoon.
Any snow accumulation should be minor given the time of year and
the antecedent warm conditions. Below normal temperatures will
persist.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Precipitation will linger into Tuesday evening north of
Pittsburgh, with a brief period of dry weather late Tuesday
night into Wednesday in advance of low pressure moving into the
region from the Plains. The low should pass just north of the
area Thursday morning, sweeping a cold front through. While a
flake can`t be ruled out north of I-80 with the initial
precipitation, at this point it appears that all precipitation
Wednesday night and Thursday would fall as rain. Before
precipitation ends Friday, all locations will have a chance for
snow Thursday night into Friday morning. High pressure building
across the Great Lakes should then keep weather dry into the
weekend. Temperatures will be below normal through the extended
forecast.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
MVFR to local IFR conditions and showers should continue
tonight with a crossing cold front. A low level jet in place
should also result in gusty SE wind through this evening until
it departs overnight. A wind shift to the west, with gust of
20-25kt are expected after FROPA through the rest of the TAF
period. An upper low crossing the Upper OH Valley region should
maintain MVFR and sct showers Monday.

OUTLOOK...
Restrictions are expected through Tue under upper troughing.
Restriction potential returns with a Thu cold front.
-- End Changed Discussion --

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...Flash Flood Watch until 4 AM EDT Monday for MDZ001.
OH...Flash Flood Watch until 4 AM EDT Monday for OHZ039>041-048>050-
     057>059-068-069.
PA...Flash Flood Watch until 4 AM EDT Monday for PAZ020-021-029-031-
     073>076.
WV...Flash Flood Watch until 4 AM EDT Monday for WVZ001>004-012-021-
     509>514.

&&

$$