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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 201723
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
123 PM EDT Sat Apr 20 2024

.SYNOPSIS...
Dry, cool, and breezy conditions are expected through the late
evening. Frost/freeze potential increases during the overnight
hours; Freeze Watch continues for portions of the region.
Building high pressure will return above average temperatures
mid-week.

&&

.NEAR TERM /UNTIL 10 PM THIS EVENING/...
KEY MESSAGES:

-  Breezy conditions will continue for the lower elevations
   through 6pm; higher terrain through midnight.
-  No Hazardous weather.

------------------------------------------------------------------

Sub-advisory wind gusts have been measured at ASOS/AWS stations
early this afternoon. Max wind gusts have ranged from 30mph to
39mph due to tight pressure gradient associated with a passing
shortwave trough. Probability of 46mph gusts (Wind Advisory
criteria) remains low across the region, even in eastern Tucker
County (probability less than 25%).

Hi-Res guidance indicates that the probability of 35mph gusts
will remain elevated through 6pm for lower elevations; higher
terrain through midnight as the pressure gradient gradually
reduces in intensity. Otherwise, dry and quiet weather will
continue today.

Temperatures will continue to trend below average by 5 to 10
degrees with cold advection under northwest flow.

&&

.SHORT TERM /10 PM THIS EVENING THROUGH MONDAY NIGHT/...
KEY MESSAGES:

- Frost/Freeze impacts are expected Sunday and Monday morning.
- Below average temperature and dry weather expected to continue
  through Monday afternoon.
----------------------------------------------------------------

High pressure will continue to build in from the west,
maintaining dry conditions through the weekend.

A Freeze Watch will be upgraded to a Freeze Warning or changed
to a Frost Advisory this afternoon after collaboration with
neighboring offices. The forecast area is now in the growing
season, and latest HREF guidance has between a 60% and 80%
chance of see 32F or low overnight for a number of counties.

Confidence is considered low to medium for a Freeze Warning in
areas south of Pittsburgh due to lingering winds and/or
increase cloud coverage limiting radiational cooling.

&&

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


- The next low pressure system and associated precipitation
  chances is likely for late Tuesday into Wednesday.
- Ridging is favored for the late week period, pointing to
  rising temperature heading into the weekend.
-------------------------------------------------------------------

Though ensemble models vary in trough analysis moving across the
southeast U.S. Monday, the outcome remains the same for the
Upper Ohio River Valley: rising heights aloft and the influence
of high pressure will support dry conditions and seasonable
temperature Monday.

There is fairly high consensus on the next upper level trough
and associated surface low to drop from the north central plains
through the Great Lakes late Tuesday into Wednesday. Ahead of
the system, weak warm advection will support above normal
temperature and increasing cloud cover before the system`s
arrival. Widespread showers and low probability thunderstorms
are then likely as the system crosses the region. Depth of the
upper trough remains the biggest uncertainty during this period,
which will strongly influence the timing of precipitation
passage and degree of cold advection behind the system.

The late week period will be defined by the progression of the
upper trough through the northeast CONUS and the rapidity of
height rises in its wake. Dry weather will be favored given
high confidence of surface high pressure, with the degree of
temperature recovery in the post-cold front passage environment
dictated by said height rises.

&&

.AVIATION /17Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
The forecast remains VFR through tonight. The passage of a
secondary cold front/surface trough has veered wind to the NW.
Gusts of 25 to 35 knots will continue this afternoon in deep
mixing and with a sufficient surface gradient. Scattered to
broken cumulus/stratocumulus will also persist, most numerous
north of I-80, with bases at or above 5k feet. NBM/HREF progs
show that any small chance of MVFR ceilings remains confined to
FKL/DUJ.

Wind gusts will diminish this evening, along with daytime
heating-supported clouds, leaving only some cirrus overnight in
westerly flow aloft. These clouds may thicken a bit overnight
while wind goes largely light and variable under surface
ridging. With a weaker pressure gradient Sunday, wind will not
be nearly as gusty, with peak values likely in the 10 to knot
range out of the northwest. Scattered afternoon VFR cumulus will
again be expected.

.Outlook...
High confidence in VFR conditions through a majority of Tuesday
under the influence of high pressure. Passage of a low pressure
system will bring widespread precipitation and restriction late
Tuesday into Wednesday. Ensemble models favor dry weather and
VFR conditions to end the work week.
-- End Changed Discussion --

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Freeze Watch from late tonight through Sunday morning for
     PAZ007>009-013>016-020>022-029-031-073>078.
OH...Freeze Watch from late tonight through Sunday morning for
     OHZ039>041-048>050-057>059.
WV...Freeze Watch from late tonight through Sunday morning for
     WVZ001>004-510>513.

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...88
LONG TERM...Frazier
AVIATION...CL