Scientific Forecaster Discussion
fxus61 kctp 191518
Area forecast discussion
National Weather Service State College PA
1118 am EDT Fri Jul 19 2019
----dangerous heat and humidity expected today through Sunday---
We will be dealing with hazy, hot and very humid conditions
until early next week when some relief is in sight. Dangerous
heat will build today into Saturday and continue into Sunday.
Heat indices will peak on Saturday afternoon, easily exceeding
100 over southern and especially southeastern areas.
Near term /through tonight/...
heat still on tap...but...
today's hi forecast has dropped a bit over the northwest due to cloud
cover. Lots of angst about whether/not to drop the heat advy for
that area. Have decided that canx the advy for that area for
today could cause more confusion, esp considering the advy is
expected to run into tmrw, and that we have been shouting about
the heat for the last week. It will be hot and humid and well
above what folks in the alleghenies are used to. So, it's okay.
We will just let it run. The bust potential is high for all
three days for the wwas we have running, considering the sct
convection and cloud cover poss, mainly over the north. The
elevation and full Leaf/transpiration across the mountains is
also a big deal. Have also lowered pops slightly without as much
cape there. Forcing and lift is still expected as the old mesoscale convective system
inches into the nrn tier.
heat will build in today, along with high humidities. Highest
heat indices will be through the se, corresponding with the
excessive heat warning. However widespread heat indexes, ranging
from the upper 90s through the northwest, to around 100 through
most of central PA, to upwards of 108 near Harrisburg. Along
with the heat and humidity, a boundary will drop across New York
and linger in the mid Atlantic. That will bring with it a
marginal risk of severe storms from Storm Prediction Center. Latest guidance keeps
the convection through the northern tier of the commonwealth,
though some isolated/scattered convection is possible. The warm
air aloft will also weaken any convection formation. Any
convection that does occur could tamper temperatures but as
stated it should remain through the north. Temperatures will be
warm tonight, ranging from the low 70s through the northwest to the
upper 70s through the southeast.
Short term /Saturday/...
*excessive heat advisories and warnings Saturday
*heat indexes from 106 through central PA to 113 through the
Excessive heat peaks this Saturday. Expect it to range from 103
to 113 Saturday with the stream of moisture to our north. Very
warm mid level temps will continue to tamper any storm growth
though, mesoscale convective system activity remains possible. With 21.5c at 850mb that
will mean Max t's in the upper 90s f through the lower
Susquehanna. The nights will bring little respite as lows will
range from around 70s along the New York border, to the upper
70s along the Mason Dixon.
Long term /Saturday night through Thursday/...
*heat indexes in from 100 to 106 Sunday afternoon.
*Excessive heat advisories and warnings through the eastern
portion of central PA into Sunday.
The biggest change has been in the pattern into Sunday. The
front continues to stall and looks to not move through until
Sunday evening. The upper trough coupled with the front along
with the surface heat dome in place will mean convection to
become possible Sunday aft into Sun night. With highs in the
mid to upper 90s through the se, along with the stalling front,
the heat dome will remain entrenched through the south. This
will allow for heat indexes to reach excessive heat warning
criteria again Sunday. As the front drops down across the region
Sunday into Monday, a cool down is expected. Along with it a
break in the oppressive humidity as the mean upper level trough
is nearby. Monday could still be muggy over the southeast where
scattered tstms will continue, but overall trend will be that
temperatures of 10-20f above normal over the weekend will
retreat back to near July normals during the work week.
Aviation /15z Friday through Tuesday/...
keeping on with mentions of vcsh in bfd for this aftn, but
current cooling cloud cover could curtail convection.
Alliterally. Lake breeze and lift along the ridge southeast of the Lake
May already be allowing some showers to form. The MVFR clouds
extend into ipt and unv as well, but the deck should be rising
as we warm a little.
While the high heat and humidity makes it easier to hit home
runs, it also means that takeoffs and landings will take more
Dying cluster of storms may again try to move into the nrn tier
late tonight. Still skeptical on that.
Sat-sun...mainly VFR with isolated to widely scattered PM
Mon...still a chance of showers and storms as cfropa occurs Mon
or Mon PM.
Tues...no sig wx.
heat advisory until 8 PM EDT Saturday for paz004>006-010>012-
Excessive heat warning until 8 PM EDT Saturday for paz028-036-
Heat advisory from 8 PM Saturday to 8 PM EDT Sunday for paz028-
Excessive heat warning from noon to 8 PM EDT Saturday for
Heat advisory until noon EDT Saturday for paz019-025>027-034-
Excessive heat warning until 8 PM EDT Sunday for paz059-066.