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000
FXUS61 KPBZ 150309 AAA
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
1109 PM EDT Sun Apr 14 2024

.SYNOPSIS...
Showers and thunderstorms will move across the area tonight with
a cold front. Some storms could be severe. A brief bout of dry
weather expected Monday before rain chances return on Tuesday
with moderating temperatures into next week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
KEY MESSAGES:

- Severe Thunderstorm Watch until 10 PM for much of the area
- Localized flash flood potential where training occurs
-----------------------------------------------------------------

1110 PM Mesoscale Update...
After coordination with the Storm Prediction Center, and
surrounding NWS offices, let the Severe Thunderstorm Watch
expire on time at 11pm. Convection continues to show an overall
weakening trend, looking at satellite cloud top temperatures and
radar VIL loops. There could be a marginal severe storm over the
next hour, with a local warning possible. Overall, storms will
lose the low level jet support, with instability also
diminishing.

1005 PM Mesoscale Update...
Convection has been showing signs of becoming less intense.
Overall, regional VIL loop values have been slowly decreasing,
though a few individual cells remain strong to severe. Models
show MU CAPE diminishing through the night, with a southward
push to the low level jet as well. Overall, expect a gradual
diminishing trend to the storms overnight, but will still need
to monitor with instability in place.

905 PM Mesoscale Update...
Cancelled the severe thunderstorm watch behind the current line
of thunderstorms. Some redevelopment to the west has been
occuring over the last hour, though the cells have not been as
strong as the activity to the east.

00Z PIT sounding still shows very dry air at the surface. MU
CAPE was measured near 900 j/kg, with 45kt of effective shear.

8 PM Mesoscale Update...
Thunderstorms continue to form along a band of enhanced
instability, pwats and elevated K index values. South of this
area, warm air aloft has precluded additional development. The
surface cold front/trough was analyzed across NW PA-Nrn OH. The
latest mesoanalysis shows MU CAPEs around 1000 j.kg across NW
PA. LAPS data shows a K index maximum of 36 where the current
band of convection has set up. Values below 30 were seen across
SW PA into central OH. Vertical development of the CU field west
of this area has been shallow. Will leave watch as is for now
due to uncertainty in additional convective development.

Most of the severe weather reports received this evening have
been 1-1.5 inch hail. Well developed storm cores have been
observed on radar with these storms. Shear values have remained
near 40-50kt, though high LCLs have kept the tornado potential
low, despite rotating storms. Expect a slow diminishing trend
through the evening as instability gradually wanes.

A localized flash flood potential has also developed as some of
these storms have trained over the same locations.

Expect a southward shift in this activity as the trough drops
slowly southward across the region. The western extent of the
convection remains in question, with more limited moisture in
that region.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
KEY MESSAGES:

- Dry weather returns Monday with moderating temperatures.
- Rain chances return for the latter half of Tuesday.
-------------------------------------------------------------------

With the only minimal uncertainty being driven by the progression of
the upper trough into Monday, confidence is high that the cold front
will clear the area by Monday morning and, aside from some low
probability shower chances south of I-70, the day should otherwise
be dry. Ensembles aren`t very bullish on a notable push of colder
air in the wake of the front as an 850 mb ridge quickly builds
counteracting weak cold advection in residual northwest flow; most
of the day should feature a rather sunny sky with increasing
subsidence drying out the boundary layer and temperatures are
expected to remain above normal with still a 70-90% chance of
exceeding 70 degrees mainly south of I-80.

Brief upper ridging slides overhead on Tuesday reinforcing the dry
weather for the first half of the day, but clouds increase from the
southwest with increasing moisture aloft ahead of an approaching
shortwave traversing and flattening the ridge and reintroducing
showers for the second half of the day. We should see a brief break
overnight Tuesday night before trailing low pressure arrives.
Amounts with this batch look light with even NBM 90th percentile
values only near 0.1-0.2" through Wednesday morning.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
KEY MESSAGES:

- Temperatures remain above average.
- Rain chances continue into mid-week.
- Temperatures return closer to normal by the end of the week.
-------------------------------------------------------------------

Above normal temperatures and rain chances continue to be the theme
into mid-week as southerly return flow promotes warm advection
kicking highs above average with ensemble probability for >70F in
excess of 70% through Thursday.

What`s left of the ridging breaks down into Wednesday as an upper
trough and surface low pressure dig across the Midwest with
diffluent flow aloft promoting broad ascent. Primary ensemble
uncertainty stems from the progression of the trough and surface
low, but consensus tracks it through the Great Lakes to our north as
it occludes and returns rain to our region by Tuesday with a leading
shortwave passing through. Rain chances continue into Thursday as
the warm front approaches with the cold front following behind as
early as Wednesday night or more likely more toward early Thursday
morning. We`ll dry out briefly behind the front, but ensembles push
a secondary reinforcing trough through by late week which then
favors temperatures dipping back down towards normal to close out
the week and low confidence rain chances as early as Friday morning,
but more likely into Friday afternoon and evening. Still early
to talk rainfall totals, but ensemble spread sits from 0.2" on
the reasonable low end to near 1" on the high end through
Friday.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
A band of redeveloping thunderstorms have set up across west
central/NW PA in a band of favorable instability, moisture and
shear. Expect this activity to shift slowly southward with a
southward moving surface cold front/trough, and become more
disorganized, and less severe as instability slowly wanes. MVFR
to IFR restrictions are expected as this activity affects
individual storms. Have included TEMPO groups for some ports
where it remains uncertain how far westward thunderstorm
development occurs, where warm air aloft has prevented
convection.

General VFR is expected behind the front as high pressure
gradually builds over the region. Mixing has resulted in strong
wind gusts today, and these should also gradually diminish
through this evening after the storms end.

.Outlook...
VFR is expected under high pressure Monday and most of Tuesday.
Restriction potential returns late Tuesday and Wednesday with
approaching low pressure. Restrictions are possible into
Thursday under a subsequent upper trough.

&&

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

&&

$$

SYNOPSIS...MLB/Shallenberger
NEAR TERM...WM
SHORT TERM...MLB/Shallenberger
LONG TERM...MLB/Shallenberger
AVIATION...WM