PBZ issues Area Forecast Discussion (AFD) at May 12, 1:28 PM EDT598
FXUS61 KPBZ 121728
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
128 PM EDT Mon May 12 2025
.SYNOPSIS...
Low pressure is expected to move slowly across Mississippi
today, Kentucky on Tuesday, and Ohio on Wednesday. Increasing
clouds and moisture will lead to showers and thunderstorms
through Wednesday. Another low moving across the Great Lakes
Thursday and Friday will bring more thunderstorm possibilities.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Clouds increasing from south to north.
- Showers moving in this afternoon and continuing through
tonight.
-------------------------------------------------------------------
A closed upper low across the Mississippi Valley will slowly
begin to meander northeast today overspreading height falls
locally as a southeast to northwest oriented mid-level ridge
slides off to the east. Dry conditions should prevail into the
early afternoon hours with little moisture to be had locally,
but deep layer flow out of the south will pump in better
moisture as the column saturates top down and clouds will
thicken and lower.
Expect that precip chances will ramp up after 2-3pm this
afternoon, but initial returns will encounter said dry air and
struggle to reach the ground. Broad ascent with height falls,
lobes of mid-level vorticity, and increased low level
convergence on the nose of an 850 mb jet will eventually support
a shield of rain this evening and continuing into the overnight
hours. The best deep layer moisture through tonight is forecast
to be across western Pennsylvania and northern West Virginia
where the highest PoPs and amounts will lie while areas of
eastern Ohio are favored to see more scattered showers and even
some dry periods possible.
Went between NBM Mean and 90th MaxT in the far north and
lowered Tds to between mean and 10th percentile. Expect
thickening mid to high clouds today with showers possible in the
south by midday but I-80 corridor to stay dry with partial
sunshine. Temperatures will be warmest in the north where lower
80s expected, but readings will only peak out in the middle 70s
in the south and then will likely cool later in the afternoon as
precipitation creates some wet bulbing.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
KEY MESSAGES:
- Locally heavy rain possible this afternoon and tonight over
Preston and Tucker Counties WV and area wide Tuesday
especially over the ridges
- Showers and thunderstorms linger on Wednesday
----------------------------------------------------------------
Upper low crosses Tennessee tonight and Kentucky on Tuesday
before reaching Ohio on Wednesday. Deep south to southeast flow
is expected during the period with increasing moisture and
precipitable water values in the 1 to 1.5" range. While showers
can occur at any time, expect a typical increase in coverage and
intensity with diurnal heating each afternoon and evening.
WPC has a marginal risk in Preston and Tucker Counties WV
Today, and across the forecast area Tuesday with a slight risk
in eastern Tucker County. NBM 72 hour PQPF 25th percentile is
0.25-0.50" most areas but 0.75-1.00" over the ridges. 75th
percentile ranges from 0.75-1.00" most areas but 1.50-3.00" over
the ridges with highest amounts over eastern Tucker County WV.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
KEY MESSAGES:
- Thursday night into Friday has the potential for strong to
severe thunderstorms
- Temperatures 15-20F above normal especially Thursday/Friday
-------------------------------------------------------------------
Ridge building ahead of strong trough in Upper Mississippi River
Valley will bring warmer day with more sunshine and less shower
threat on Thursday. 850 mb temperatures over lower Ohio Valley
could warm into 20-24C range with +16C over the forecast area,
resulting in middle 80s highs. It appears that the warm sector
will be capped most of the day Thursday upstream, allowing very
unstable conditions with SBCAPE of 2,000-4,000 j/kg to build up
over Indiana and Western Ohio.
Models have been relatively persistent at pushing strong warm
advection across area late Thursday night and Friday morning.
That is when the strongest moisture transport is shown to push
through Upper Ohio River Valley and so round of weakening
thunderstorms that still could be strong to severe is likely.
SPC post-processing GEFS based severe shows highest
probabilities of severe staying west of area on Thursday and
then south and east of area on Friday which appears reasonable.
While deep low moves from Great Lakes to Ontario on Saturday, a
fast moving trough moves beneath it and across the Ohio Valley
bring another chance of showers and thunderstorms to the
forecast area. Heights begin to rise on Sunday as the trough is
likely headed across the northeast and New England and would
expect a drying trend although timing differences in the
ensembles suggest showers are still possible.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Mid and upper level cloud coverage will continue to spread north
across the region this afternoon low pressure creeps up out of
the south, which will eventually lead to periodic showers (and
possible TSRA) through midweek. Precipitation will spread from
south to north later this afternoon and into the evening. Latest
NBM probabilities show between 60%-70% chances of of MVFR cigs,
and around 25%-30% chance of eventual IFR cigs overnight (best
chances north of KPIT). Wind will be relatively light.
Outlook...
The mentioned low over the Ohio River Valley will maintain
periodic shower and isolated thunderstorm chances through
Wednesday favoring the afternoon and evening hours. Area
restrictions may be more closely tied to surface boundary
positioning and prior rainfall, creating more spotty and
fluctuating cig heights.
Drier weather with VFR is likely Thursday under brief shortwave
ridging before the next low pressure system arrives Friday.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Craven
NEAR TERM...MLB
SHORT TERM...Craven
LONG TERM...Craven
AVIATION...88
Source:
PBZ issues Area Forecast Discussion (AFD) at May 12, 1:28 PM EDT---------------
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