Author Topic: [Alert]PBZ issues Area Forecast Discussion (AFD) at Oct 30, 2:34 PM EDT  (Read 82 times)

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PBZ issues Area Forecast Discussion (AFD) at Oct 30, 2:34 PM EDT

119 
FXUS61 KPBZ 301834
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
234 PM EDT Wed Oct 30 2024

.SYNOPSIS...
High pressure will maintain dry and warm weather into Thursday
afternoon. Showers may produce a generally light but potentially
wetting rain late Thursday and Thursday night with a crossing
cold front. Cooler and dry weather is then expected through
Saturday under high pressure. Periodic rain chances and warmer
temperatures return late Sunday through early next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
KEY MESSAGES:

- Dry and warm weather continues
- Record or near record highs in some locations
-------------------------------------------------------------------
Notable ridging resides over the eastern seaboard back into the Ohio
Valley. 500mb heights are progged to peak in between 588 to 591 dam
range today. A low-level jet also stretches from the southern Plains
through the Great Lakes.

Area-wide high temperatures yesterday were near and above NBM 99th
percentile. Persistence forecasting of continued warm air advection,
clear skies and dry ground today puts us at or near 80 across the
region, with chances to tie or break records at a handful of sites.
Efficient mixing and a notable pressure gradient between low
pressure west of us and high pressure to our east, will result in
gusty SW winds reaching around 25 mph this afternoon.

Continued warm air advection and insulating clouds will combine to
give the region another abnormally warm night Wednesday, where
several sites could set records for their highest low temperatures.
NBM shows 30-40% chance for areas along the Ohio river and in
eastern Ohio to see low temperatures stay at or above 60 degrees.

A high launching pad and similar conditions Thursday will once again
set up the potential to heat efficiently and well above modeling.
The limiting reagent Thursday likely lies in cloud coverage
increasing ahead of our next system moving through the Midwest. At
this time it certainly seems possible that we will once again press
80 degrees region-wide and area climate sites could once again
approach, tie or set records.

Our persistent warm and dry pattern is finally set to crack late
Thursday as a cold front approaches the western portions of the
region. Probabilities of measurable precipitation at 2pm Thursday
from the NBM are still widely 0%, with a sliver of 0-10% near
Zanesville and Coshocton. By 8pm these probabilities rise to
>40% for Zanesville and Coshocton and probabilities slowly fall
as you move east, with cities like Clarion, Washington and
Pittsburgh finding themselves in the 0-10% window.

These factors will set up largely dry and warm conditions for any
trick-or-treaters out. The chance to see any potentially candy-
wetting rain rises as you move into central Ohio, where rain will be
approaching the area near sunset.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
KEY MESSAGES:

- Showers accompany a cold front Thursday night
- Dry and cooler Friday and Friday night
-------------------------------------------------------------------

Showers will accompany the cold front as it crosses the region
Thursday night and Friday morning. Much of the stronger forcing
remains off to the northwest during FROPA as the main shortwave
trough lifts across the western and northern Great Lakes.
However, an area of jet-induced upper divergence will accompany
the front as it crosses, supporting the notion of categorical
PoPs, with showers taking on on a banded structure along the
front. The speed of the front and the lack of convection (<100
J/kg of CAPE) will keep precipitation totals muted. However,
NBM probabilities of 0.10" or more of rain are 50-80% across the
region, suggesting a good chance of a wetting rain for many
areas.

An isolated shower or two may linger in the ridges Friday,
otherwise dry weather and a mostly clear sky can be expected
through Friday night as high pressure builds in. Temperatures
much closer to seasonable levels can be expected as well as
quasi-zonal mid-level flow takes hold in the wake of the front.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
KEY MESSAGES:

- Dry with a warming trend through part of Sunday
- Rain chances return Sunday night through Tuesday, with further
  warming
-------------------------------------------------------------------

Upper ridging over the southeast CONUS will continue to build
in response to a digging upstream trough near the Pacific Coast.
High pressure tracking across the Great Lakes towards New
England is expected to provide dry weather into Sunday morning
with fairly high confidence. Temperatures will be near
seasonable levels, with a slight rise into Sunday.

500mb heights continue a slow rise in our region Sunday night into
Monday night. This period will be marked by the approach and passage
of a warm front, which will bring warmer temperatures and increased
moisture levels into early next week. Ensembles are showing some
generally minor issues with the timing of this process, but the
overall model envelope lends some confidence to chances of light
precipitation during this period, with chances highest north of
Pittsburgh where shortwave disturbances are a bit more likely to
track over the top of the Upper Ohio Valley ridge axis. Temperatures
may also jump to 15 degrees or so above normal again behind the warm
front.

Precipitation chances may reach a minimum Tuesday afternoon/evening
in the warm sector behind the warm front.  Uncertainty then
increases regarding how quickly and strongly the western CONUS
trough ejects across the Plains and towards the Great Lakes.  Faster
scenarios would lead to a cooler solution, but the majority are
currently leaning towards higher heights through Wednesday, keeping
temperatures above normal. As the ridge axis shifts east, with a
possible approaching frontal boundary, southwest flow will increase,
leading to higher rain chances by Wednesday.&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
High probability for VFR through the TAF period under the
influence of high pressure southeast of the region, with cirrus
serving as the main cloud cover. Diurnal mixing each afternoon
will foster occasional wind gusts between 20-25kts, with speeds
up to 30kts possible Thursday afternoon. Enough boundary layer
mixing overnight should preclude llws development, though a few
hours of impact can't be ruled out before mixing recommences
Thursday.

The biggest uncertainty is whether a scattered to broken
4kft-9kft cloud deck forms around KZZV and move ENE between
07z-14z Thursday morning. Probabilities are generally less than
20% for this layer to be at MVFR levels.

.Outlook...
An upper level shortwave and surface cold front will cross the
region Thursday late afternoon into Friday with chances for
rain and restrictions.

Ensembles favor high pressure redeveloping over the region by
Friday afternoon through the weekend to promote VFR and light
wind conditions.

&&

.CLIMATE...
A few locations could approach, or break, record high
temperatures through Thursday.

Record High Temperatures / Forecast High   

Thu October 31:
KPIT: 79/1950, 1976         80
KDUJ: 72/2003               76
KMGW: 80/1896               82   
KHLG: 78/1950, 1933         80
KPHD: 77/1971               80
KZZV: 82/1950               81

&&

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

&&

$$

SYNOPSIS...CL
NEAR TERM...AK
SHORT TERM...CL
LONG TERM...CL
AVIATION...Frazier
CLIMATE...WM

Source: PBZ issues Area Forecast Discussion (AFD) at Oct 30, 2:34 PM EDT

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