PBZ issues Area Forecast Discussion (AFD) at Mar 23, 6:50 PM EDT997
FXUS61 KPBZ 232250
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
650 PM EDT Sun Mar 23 2025
.SYNOPSIS...
Shower chances will continue to remain elevated late this
evening into early Monday ahead of a cold front. Drier weather
and gusty conditions are expected Monday, although afternoon
showers are possible north of Interstate 80. Generally
seasonable temperatures continue with several low probability
shower chances through mid week.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
KEY MESSAGES:
- Precipitation returns later this afternoon, overspreading the
region ahead of a cold front.
- Rain totals will range from 0.10 to 0.40 inches across the
region; the axis of localized higher amounts will likely be
south of Pittsburgh.
- Gusty conditions expected in the wake of the front.
-------------------------------------------------------------------
Light rain is currently tracking through eastern Ohio late this
evening. Despite reflectivity returns on the radar over western
Pennsylvania, dry air aloft is causing evaporation and no
precipitation is reaching the ground. The PIT 12Z sounding
depicted a sufficient dry layer between 2kft to 15kft that needs
to saturate before light rain occurs.
The best time frame for accumulating rain is expected between
9pm tonight to 1am tomorrow morning. Probability of rainfall
totals >= 0.25 inches is elevated (above 60%) for areas south of
I-70, where deeper moisture is noted on GOES-16 water vapor. A
noted dry slot, that is tracking through northern
Illinois/Indiana and will eventually reach our region, is
expected to keep precipitation amounts north of Pittsburgh
between 0.1 to 0.2 inches. With wet-bulbing, there may be a
brief period of rain/snow mix near I-80 before dawn.
Between 4am to 6am Monday, rain will likely be focused east of
Pittsburgh as the cold front advances into eastern Ohio.
In the wake of the cold front, expected gusty conditions
(25-30mph gusts) associated with a tight pressure gradient.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
KEY MESSAGES:
- Drier overall Monday, with gusty wind.
- Monday afternoon showers possible north of I-80.
- Low shower chances Tuesday.
-------------------------------------------------------------------
A surface low will slowly meander across Lake Huron on Monday,
while the upper trough starts to swing our way across the
southern Lakes. Precipitation should have largely ended, save
for perhaps a few lingering showers near the ridges. Low-level
flow generally remains out of the southwest in most model
solutions, limiting cold advection. It still appears that
temperatures will actually be a bit warmer on Monday as compared
to today, given the likely higher level of afternoon sunshine.
The arrival of the upper trough by evening allows flow to veer more
westerly and brings an increase in moisture mostly north of
Pittsburgh, allowing for scattered rain and snow showers. Very
little accumulation is foreseen. Limited moisture penetration
into the dendritic growth zone and falling inversion heights should
limit snow rates, and the warm ground will also be a hindrance.
Deep mixing will allow for efficient transport of wind to the
surface, leading to peak gusts in the 30 to 40 MPH range in the
lowlands. The southwest flow should keep higher gusts to our
east for the most part. Still, cannot rule out the eventual need
for a Wind Advisory in eastern Tucker County. Neighbor
collaboration and uncertainty regarding 850mb flow precluded
issuance at this time.
The mean trough slowly moves east but continues to impact our
weather Tuesday, with temperatures a few degrees cooler than Monday.
Model trends still favor keeping most precipitation south of the
region Tuesday, although scattered rain and snow showers remain
possible into Tuesday night. Some light accumulation is possible
along the ridges during the nighttime hours.
Temperatures on Tuesday will be a bit cooler as meager cold
advection ensues.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
KEY MESSAGES:
- Showers end Wednesday.
- Brief dry period under high pressure Wednesday night/Thursday.
- Shower chances return for Friday and the weekend.
- Temperatures remain seasonable through midweek before a likely
warming trend.
------------------------------------------------------------------
Upper troughing remains in place at the start of this period with
high confidence. Model clusters show increasing confidence in the
axis of the trough moving off of the Atlantic Coast by 00Z Friday,
albeit with slight variances in speed. Uncertainty then increases
from there, as there is disagreement among the various ensemble
members regarding how quickly and strongly 500mb ridging then builds
back towards the Upper Ohio Valley.
Continued, decreasing chances for rain/snow showers seem
appropriate for Wednesday in the lingering troughing, before
drier weather appears likely for Wednesday night/Thursday with
crossing surface high pressure. Daily precipitation chances then
return for Friday and the weekend, tied to uncertainty with
shortwaves rotating through the upper flow, although overall,
precipitation becomes more likely next weekend. Current
expectation is that most, if not all, of this potential
precipitation would be in the form of rain as opposed to snow.
While a return to, and then a rise above, seasonal norms is the most
likely outcome, the uncertainty regarding flow evolution is playing
havoc with ensemble temperature spreads towards next weekend. To
illustrate: at Pittsburgh on Saturday, the spread between the 10th
percentile max temperature (61 degrees) and the 90th percentile
temperature (85 degrees) reaches 24 degrees on the current NBM
run.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
A swath of generally light rain associated with an approaching
low pressure system will continue to overspread the region
through 05z before exiting east by 12z ahead of the mid-level
shortwave. Thermal profiles will support rain, but slightly
cooler air and low dewpoints may allow for wet-bulbing of air
temperature at FKL/DUJ to briefly introduce a snow mix shortly
after onset.
Initial restrictions will be tethered to visibility drops in
heavier rain as the system begins top-down moistening of a
previously dry atmosphere. Near to shortly after the passage of
the main precipitation swath, there is high confidence (near
100%) of 6-7 hours of MVFR cigs with localized IFR possible at
FKL/DUJ. Rapid transition of a surface pre-frontal trough while
the upper axis remains to the west means a quick erosion of
MVFR/IFR cigs between 11z-16z due to strong system dry slotting.
Prior to the late day arrival of the cold front (evident by a NW
wind shift), strong pressure gradients and deeper mixing will
aid 25 to 35kt southwest wind gusts for area terminals.
Outlook...
VFR is favored (90% probability) through mid week as the region
generally sits within the dry slot of a fairly stagnant upper
trough and some influence of surface high pressure to the
southwest. Embedded shortwaves within the upper trough pattern
may initiate low probability precipitation/restriction chances
that favor FKL/DUJ and the higher terrain, but model variability
remains high on these features.
A late week into weekend pattern shift to eastern CONUS ridging
may come with a transition period featuring increasing
precipitation and restriction chances.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...CL
LONG TERM...CL
AVIATION...Frazier
Source:
PBZ issues Area Forecast Discussion (AFD) at Mar 23, 6:50 PM EDT---------------
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