PBZ issues Area Forecast Discussion (AFD) at Nov 15, 3:16 PM EST495
FXUS61 KPBZ 152016
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
316 PM EST Fri Nov 15 2024
.SYNOPSIS...
Intermittent drizzle and or light rain will continue today,
along with extensive cloud coverage. Dry conditions will resume
Saturday along with seasonable temperatures.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Patchy dense fog will linger through midday.
- Another day with limited diurnal range in temperature.
------------------------------------------------------------------
Wind is expected to veer to the WNW with speeds gradually
increasing over the next couple of hours. Localized areas of
gusts up to 15 knots possible.
Due to increased wind, expect the local, patchy fog to gradually
lift resulting in improved visibility conditions by early
afternoon. The sky is expected to remain overcast through
tomorrow morning which will also result in a limited diurnal
range in temperatures over the course of the day.
Patchy drizzle and/or light showers chances will continue overnight,
with the highest probabilities northwest of Pittsburgh and across
the ridges.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
KEY MESSAGES:
- Drying and warming trend begins Saturday and lasts through the
weekend
-------------------------------------------------------------------
Conditions will become dry by tomorrow morning. Due to the
developing northwesterly flow, clouds are expected to persist
through late tomorrow morning as a high pressure moves into the
area. The northwesterly conditions are expected to ease midday
tomorrow allowing for a potential break in the clouds.
Late tomorrow night into Sunday morning, expect clouds to return as
a trough moves in behind the exiting high. The flow will shift out
of the southwest helping with the warm air advection. This will help
drive temperatures back into the upper 50s to lower 60s on Sunday
afternoon.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
KEY MESSAGES:
- Rain returns Tue/Wed with additional chances through late week
- High uncertainty remains with a late week system
-------------------------------------------------------------------
Ensembles show fairly high consistency Monday into Tuesday with
significant uncertainty thereafter.
By Monday, sfc low pressure coincident with a mid-level
shortwave will eject out of the southern Plains and into the
Upper Midwest and across the Great Lakes on Tuesday. This should
bring a round of rainfall preceding a cold front through the
area on Tuesday. High temperatures will run 10-15 degrees above
average Mon/Tue, putting much of the area in the lower 60s
(upper 50s north of Pittsburgh).
Breakdown in the forecast occurs in the Wednesday through
Friday timeframe. Generally, models show a more potent
wave/closed low developing over the central US by Wednesday and
diving over the East by Thursday/Friday. Strengthening low
pressure at the surface would bring an initial round of
precipitation followed by wrap-around moisture with a fetch of
cold air advection.
Greatest uncertainty stems from the timing, strength, and
placement of the trough which will depend on the strength of the
downstream ridge over the East Coast. Ensembles currently favor
two clustered scenarios: a more amplified ridge and therefore
weaker/slower trough progression (slightly favored by ENS), or
less amplified ridge with quicker, deeper troughing (favored by
more GEFS/GEPS membership). Ensemble forecast elements across
these days show this bimodal variance, favoring either a colder
or warmer solution. This bimodal distribution makes a
deterministic forecast particularly difficult for the time
period, since NBM mean values fall between the two solutions and
are meteorologically unlikely. For now, have hedged slightly
toward the colder solution, given favored ensemble membership.
This does introduce the possibility of rain/snow (gasp) into the
forecast for the Thursday/Friday timeframe, but this will
obviously be temperature dependent. The 25-75th percentile range
in temps on Thursday is roughly 20 degrees. Stay tuned for more
details...
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
A weak surface trough/wind shift is working its way across the
Upper Ohio Valley this afternoon. Slow improvement in ceiling
and visibility is occurring mainly behind this as marginally
drier air flows in. HLG and ZZV have reached MVFR as a result,
while the rest of the terminals remain at IFR or LIFR conditions
with low stratus and mist.
Continued modest improvement is forecast to continue across the
region, with slow improvement to MVFR conditions during the late
afternoon/early evening hours. HREF probabilities do show a
notable but patchy north-to-south resurgence of IFR ceiling
probabilities after 00Z, likely due to lingering moisture and
boundary-layer cooling. Ended up maintaining IFR ceilings longer
at FKL/DUJ and bringing back IFR at least in TEMPO form for
several terminals to the south of I-80 - but confidence in this
forecast aspect is moderate at best. IFR ceilings could end up
being more persistent or widespread than currently depicted. In
any case, there is high confidence of at least MVFR ceilings at
all TAF sites to at least 14Z or so.
Past the mid-morning hours, approaching high pressure and height
rises will work with daytime mixing to start to lift ceilings
once again. Given the persistence of a subsidence inversion
aloft, kept MVFR ceilings in place at all sites through the end
of the TAF period in accordance with HREF probabilities -
although ZZV has a decent chance of achieving low-end VFR by
18Z.
Outlook....
Hi-res modeling suggests 50-70% probability of MVFR cigs
lingering into Saturday evening and exhibiting a gradual
reduction in MVFR cig likelihoods through Sunday morning from
the southwest to the northeast.
Confidence is high that VFR will develop areawide by Sunday
afternoon before the next weak disturbance crossing Monday
offers increased rain/restriction probabilities that favor
northwest PA.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...88
NEAR TERM...Lupo
SHORT TERM...Lupo
LONG TERM...Rackley
AVIATION...CL
Source:
PBZ issues Area Forecast Discussion (AFD) at Nov 15, 3:16 PM EST---------------
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