PBZ issues Area Forecast Discussion (AFD) at Nov 5, 10:26 AM EST745
FXUS61 KPBZ 051526
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
1026 AM EST Tue Nov 5 2024
.SYNOPSIS...
Another very warm and dry day. Some climate sites will
approach or reach record highs. The risk for showers returns on
Wednesday, but rainfall should be light.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:
- Daily high temperatures for a number of climate sites will
likely be broken or tied.
- An increase in low-level moisture will help to keep fire
weather potential low, but gusty winds remain a concern.
-------------------------------------------------------------------
Wind gusts have picked up earlier and slightly stronger than
expected across the region with several area airports gusting
>25mph. KPIT gusted to 31mph at the 10AM observation. No other
major changes were made at this time, with some minor tweaks to
temperatures. Previous discussion below:
Eastern CONUS ridge will remain parked just to the east of the
region this morning. Minor height rises are expected before
heights slowly fall this afternoon as the entire system drifts
toward the east. With the amplification this morning, another
brief period of warm air advection is expected with the strong
southwesterly flow aloft. This will once again push high
temperatures to well above normal levels. We should get close to
maximizing high temperatures again. Mondays high was 1 degree
below the NBM 99th percentile. Not highly confident we can reach
those levels today as we may maximize the warm air advection in
the morning and also could see cu develop with daytime heating.
Latest NBM probs show a 50 to 60% chance of max T>80 today
generally from PIT south. Will nudge temperatures closer to the
75th pct today which will put most sites right at record levels.
Gusty winds are also expected today as the stronger winds aloft
will mix down to the surface. NBM probs of gusts >30mph are 30
to 50% across the region, with 60 to 70% on the ridge tops. The
main concern with the stronger winds is fire weather. We should
see surface dewpoints increase throughout the day which will
keep RH values elevated. However, with such dry conditions and
lots of dead fuels available, a fire will spread quickly.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
KEY MESSAGES:
- Rain chances return with a late Wednesday cold front.
- High pressure will bring cooler and dry conditions later on
Thursday
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A weakening shortwave trough will slowly cross the region
Wednesday morning. A surface cold front, behind the first
shortwave, will be pushed eastward by a second shortwave trough
which will stream northeastward. The surface boundary likely
won't push through the area until Wednesday evening. With the
deepest moisture and strongest forcing expected with the morning
wave, this would be the best time period for showers. Rainfall
with this system, unfortunately, looks to be light. Latest NBM
probs for rainfall >0.10 inches are mainly 30 to 50% Wednesday
morning, and then decrease quickly in the afternoon.
With the increase in cloud cover and showers, temperatures
Wednesday will be cooler, but still well above normal.
The cold front should stall just south of the region on Thursday
as another ridge slowly builds over the Upper Ohio Valley. A
lingering shower is possible Thursday morning, with the best
chances over northern WV. Cloud cover should slowly decrease
from north to south Thursday and cooler air will overspread the
region. Highs on Thursday will still be 5 to 10 degrees above
normal.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
- Forecast uncertainty increases through the long term.
-------------------------------------------------------------------
Our late week forecast largely hinges on the amplitude and movement
of a western trough digging into the Four Corners region.
Ensemble analysis is showing timing, depth and positional
differences for this trough, meaning that at this time there is
low confidence in the overall pattern.
More clusters are now moving towards a general consensus for the
development of a closed low out west allowing for the amplification
of ridging in the eastern CONUS. This would imply another stretch of
above normal warmth and dry conditions. Clustered members suggest
the possible development of rex blocking over the western or
central CONUS, which could act to slow the eastward movement of
any troughing and allow our period of warmth and dry conditions
to be an extended one. If the western trough were to be weaker,
then less amplification and quicker movement in the wave packet
could allow for more muted warmth and a quicker return to a
cooler and wetter pattern. However, at this time the probability
of this solution has seemingly diminished some.
With high variability and low confidence in the pattern, no
major changes to the extended forecast have been made at this
time.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
VFR expected today with variable mid and high clouds in SW flow
ahead of an approaching trough.
Strong winds aloft above the nocturnal inversion will once
again result in LLWS potential for ports overnight once the
boundary layer decouples early this evening. Showers and
potential cig restriction will increase over the course of
tomorrow morning ahead of an approaching front. Latest NBM
guidance points towards a 60-70% and 30-40% chance of MVFR and
IFR cigs respectively during the afternoon and into the evening.
.Outlook...
Showers and potential restrictions could continue Wednesday
night into Thursday morning in cool NW flow, before high
pressure returns VFR conditions through Saturday.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...AK
NEAR TERM...22
SHORT TERM...22
LONG TERM...AK
AVIATION...88
Source:
PBZ issues Area Forecast Discussion (AFD) at Nov 5, 10:26 AM EST---------------
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