Area Forecast Discussion
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368
FXUS61 KPBZ 190255
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1055 PM EDT Thu Apr 18 2019

.SYNOPSIS...
Conditions should be mostly dry until a low pressure system impacts
the region early Friday morning and into the weekend.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
1055 PM update: Reduced POPs across eastern Ohio over the next few
hours as regional radars show precipitation much farther west,
extending along a cold front from approximately Toledo Ohio southward
through Cincinnati. The progression of the rain and cold front will
be rather slow to make it into the PBZ CWA since an upstream low over
the lower Ohio River Valley will deepen in response to an amplifying
upper level trough. This will essentially "hold back" the frontal
passage until the low ejects eastward later in the day Friday.

Previous discussion...

Compared to yesterday`s model runs, both synoptic and high-
resolution models are showing the front arriving slower locally than
previously forecast. Instead of a late morning/early afternoon
passage, it now appears it will be a late afternoon/evening passage.
This timing should be more conducive to allowing a strong/severe
thunderstorm threat, but the NAM and GFS both show a capping
inversion between 5-10 kft that should help to limit overall
instability. High resolution models and the GFS are suggesting a
potential dry slot in advance of the cold front, and depending on how
this plays out, additional surface heating may allow for surface
temperatures to warm enough to overcome the inversion. Wind shear
will be sufficient to help organize any storms that do develop.
Southwesterly winds will keep temperatures as warm as the upper 50s
and lower 60s overnight, with temperatures "only" rising into the
upper 60s and lower 70s ("only" compared to today`s values, though
still well above normal) because of additional cloud cover. After the
cold front`s passage, temperatures should be dropping towards more
normal values, although lows in the mid 40s to lower 50s will still
be 5 to 10 degrees above normal.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
The upper trough responsible for the surface front will close off
into an upper low across eastern Kentucky Saturday morning and move
very little during the next 24 hours. This should keep likely showers
in the forecast Saturday, with scattered showers continuing Saturday
night and Sunday. Temperatures will be near normal through the
weekend.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The upper low will finally move east Sunday night, bringing a brief
end to showers across the region. While the GFS/ECMWF diverge in
their upper level pattern by Tuesday night (trough vs ridging), both
models do show several shortwaves moving through the longwave
pattern through the week, and this should keep scattered showers in
the forecast. While the week won`t be a total washout, each day
should have a chance for showers. Temperatures will be about 10
degrees above normal through the period.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
VFR conditions through a large portion of the forecast. Llvl wind
shear development tonight with jet through the ern flank of TN
Valley, to Mid OH Valley low pres. Surface wind gusts will increase
again Friday morning and conditions will deteriorate late Friday
with eventual restrictions and rain and possible thunderstorms as low
pressure crosses.

.Outlook...
Restrictions and showers are likely through the weekend as strong
low pres traverses the region.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.

&&

$$



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