686
FXUS61 KCTP 170026
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
826 PM EDT Tue Jul 16 2024

.SYNOPSIS...
 - The last of the thunderstorms from today will continue to
   move south east into the early hours of tonight.

 - A cold front will push through on Wednesday with another
   round of strong to severe thunderstorms.

 - High pressure will build in from the Great Lakes on Thursday
   and bring mainly fair weather with seasonable temperatures
   through the end of the week.

&&

.NEAR TERM /UNTIL 8 AM WEDNESDAY MORNING/...
A line of convection is still present in the far SE corner of
the lower Susquehanna Valley. These storms will likely move out
of the CWA by 10 PM. With temperatures cooling off as sunset
approaches the environment to support thunderstorms will
continue to wane across the SE. Additional storm development is
not anticipated after the current line of storms exits the
area.

Low temps tonight will remain uncomfortably warm across south
central Pennsylvania. The heat advisory remains in effect
overnight as lows in the lower susq will stay in the mid to
upper 70s. Lack of clouds tonight could again make some patchy
valley fog, but lack of rainfall today will be a tick in the
negative column. Developing morning showers may impinge on the
wrn highlands by sunrise.

&&

.SHORT TERM /8 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
An upper level trough approaching from the Grt Lks will push a
cold front through the region Wednesday, accompanied by a round
of showers/tsra Wed afternoon into Wed evening. Cloud cover and
an early arrival of the fropa should keep the threat of severe
weather low over the northwest part of the forecast area.
However, the pre-frontal heating of the a very moist/unstable
airmass, combined with a belt of relatively strong mid level
flow, will support a threat of severe weather Wed PM across the
southeastern counties. Cloud cover and convection should hold
temps down a bit Wednesday, even across the Lower Susq Valley.
The Heat Advy currently up for that area for Wed will be allowed
to continue as surging dewpoints ahead of the front could still
yield heat indices near 100F across the southeast counties. PWs
of nearly 2" in the SE could help feed very heavy downpours.
But, the fast storm motions and very high FFG (widespread 4.5"/3
hrs values) keep the threat for flash flooding low. The MRGL
risk in the Day2 ERO was collaborated with WPC, mainly in order
to keep continuity with previous forecasts.

Wed PM looks like the cfropa occurs for all but perhaps a few
towns on the MD border. Thus, the SHRA should press mainly or
entirely to the S of the border well before sunrise. Dropping
dewpoints may keep the threat of fog low, but the temps drop
right along with them. Have not added it into the wx grids at
this point. For Thursday guidance converges towards a return
towards fair and seasonable weather with lower humidity during
the day Thursday and through the end of this week as high
pressure builds from the Great Lakes.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
A stalled front is expected to nudge northward into the
weekend, allowing for a return to diurnally driven convection.
Have capped PoPs mainly to a SChc north of the turnpike Saturday
afternoon/evening with the northward extent of SChc creeping
into portions of the Middle Susquehanna Valley Sunday evening
where the front could continue to drift slightly north.

Model guidance does outline mainly dry conditions for the
majority of the day on Monday; however, diurnally driven
convection cannot be ruled out in the afternoon/evening hours
with the best chances mainly south of I-80. Have capped PoPs at
low-end Chc (20-30%) given some uncertainty wrt boundary
placement and how this will impact any potential convection.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Weakening of the mid level winds and time of day has resulted
in the reduction of gusty winds since mid afternoon. This has
allowed storms to reform again across the far southeast part
of the area. This will use a TEMPO group across the far
southeast for a few hours.

Otherwise expect dry weather overnight. Earlier shifts have
more showers in for early Wednesday, along with some lower
CIGS and fog. Not sure this will occur, given how much the
wind dried out the ground today, but with the front still to
the northwest, have some showers in with lower conditions for
a few hours on Wed.

For later in the week, looking at much cooler and drier air.
Thus should see mainly VFR conditions after Wed.

Outlook...

Thu...AM Showers exit southeast; MVFR cigs psbl west bcmg VFR.

Fri-Sun...AM valley fog. Otherwise, no sig wx/VFR.

&&

.CLIMATE...
Daily record max temp of 99F was tied at Harrisburg on 7/15.
Previous record was set in 1995.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM EDT Wednesday for PAZ036-056-057-059-
063>066.

&&

$$

SYNOPSIS...Dangelo/Bowen
NEAR TERM...Dangelo/Bowen
SHORT TERM...Dangelo/Bowen
LONG TERM...Fitzgerald/Tyburski
AVIATION...Martin
CLIMATE...Steinbugl