656
FXUS61 KCTP 171025
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
625 AM EDT Mon Jun 17 2024

.SYNOPSIS...
*Long duration and potentially dangerous heat wave this week
*High temperatures 90+ degrees into next weekend

&&

.NEAR TERM /THROUGH TONIGHT/...
A long duration heat wave will begin later today, as an
anomalous 500mb subtropical ridge builds over the region. Warm
mid level temps should largely suppress convection, but can`t
rule out (10-20% chance) an isolated shower or t-storm this
afternoon along the spine of the Alleghenies, where the elevated
heat source could aid in breaking the cap. Slightly higher POPs
near 30% have been placed along the NY border late today. This
is associated with an approaching MCV over SE Michigan.
The latest HRRR indicates convection will wane later this
morning as it tracks along the north shore of Lk Erie. However,
regeneration is possible this afternoon, as the mid level vort
max tracks across upstate NY.

Any convection should fade with loss of heating after sunset.
Mostly clear skies, light wind and surging low level moisture
appears likely to result in patchy late night valley fog across
the Central Mtns based on latest NAMNest and SREF prob
charts. See no reason to deviate from NBM min temps, which range
from 65-70F.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
The heat and humidity are progged to ratchet up slightly Tuesday
and Wednesday, as the center of the subtropical high lifts north
over PA. Current guidance suggests heat indices will reach
95-100F in valley locations across Central PA Tuesday afternoon.
Upon coordination with neighboring offices, have issued a Heat
Advisory Tuesday afternoon.

Scattered, pulse-type convection remains possible under the
heat dome Tuesday afternoon, primarily along the spine of the
Alleghenies. The threat for PM convection looks even more
limited on Wednesday as temps continue to warm aloft. The heat
wave rolls on through midweek with highs 90-95 forecast with max
HX approaching 100F. Additional heat headlines may be needed.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Medium range guidance continues to show that a prolonged heat
wave will occur throughout the extended forecast period.
A 595-600 dm 500 mb ridge will be situated over Central
Pennsylvania and temperatures will easily reach the 90s across
most of the region each day. Temperatures will ramp up each day
giving us our hottest days for the second half of the week. Heat
indices will be in the upper 90s and low 100s, with the
Thursday-Friday timeframe. Some models indicate the potential
for a few showers or thunderstorms each afternoon across the
northern tier, but coverage should be very limited and elevation
driven.

Ensembles show the ridge beginning to flatten out a little by
Saturday which would allow for a slightly higher chance of
showers or storms, particularly across the northern half of the
area.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Main change for the 12Z TAF package is to add a tempo group
for a very brief period of fog for around 12Z Tuesday. As
the airmass becomes a bit more humid, very light wind fields
could result in some fog.

Otherwise looking at VFR conditions today into this evening, as
high pressure remains over the area.

Winds were gusty at times since Sunday afternoon, but will
weaken a bit more here this morning, as radar VAD winds have
been on the decrease since Midnight.

The strong June sun and mixing may kick winds up at times later
this afternoon.

Highest chance of any showers or storms today will likely be
near the lower Great Lakes.

Not much change to conditions the next several days. If the
dewpoints come up later in the week, then there could be
some patchy fog.

Outlook...

Tue-Fri...Predominantly VFR, with building heat. Density
altitude concerns possible.

&&

.CLIMATE...
A period of much warmer than average temperatures is expected
across much of central Pennsylvania next week, with record high
temperatures being challenged. The record high temperatures for
some sites across central PA are outlined below:

 Jun 18 Jun 19 Jun 20 Jun 21

Harrisburg      97/1957     98/1994     98/1931     98/1923
Williamsport    97/2018     96/1929     101/1923    97/1933
State College   94/1923     94/1931     94/1953     94/1988

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon to 8 PM EDT Tuesday for PAZ004>006-
010>012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066.

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/Steinbugl
LONG TERM...Bauco/Tyburski
AVIATION...Martin
CLIMATE...NPB