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000
FXUS61 KCTP 031131
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
731 AM EDT Mon Aug 3 2020

.SYNOPSIS...
An upper level trough over the midwest will push slowly east
over the next few days. This weather feature will help to
steer tropical storm Isaias north along the east coast today and
Tuesday. A widespread heavy rain is expected tonight through
Tuesday across the eastern Third to half of the state.

High pressure is likely to build in from the Great Lakes the
second half of the week. However, a stalled frontal boundary
will linger just south of Pennsylvania.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
09Z surface analysis shows a weak, stalling front stretching
from Southern NJ to Central VA. low level moisture streaming
NNE along the spine of the Central Appalachians and Allegheny
Plateau was producing widespread stratocu and altocu clouds and
nothing more than a brief light shower possible this morning.

8/3 00Z HREF and latest runs of the HRRR suggest that showers
will spread into the Scent Zones and Lower Susq Valley (along
with the far NW part of our CWA) between 21-23Z today.

Given the meager amounts of CAPE (though high amounts of Precip
Wtr between 1.5-2.0 inches across the SE third of the state)
there will be occasional moderate showers at times.

Min temps to start today will be from the upper 50s in the
normally cooler areas of NW PA and 65-70F across much of the
central and eastern ridge/valley region. Highs this afternoon
will be in the upper 70s over the northern and western mtns and
generally the low to mid 80s elsewhere.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Focus will shift to potential heavy rainfall impacts associated
with TS Isaias later tonight into Tuesday. The latest blended
QPF from WPC/NBM indicates 2-4" are possible across the
eastern/southeastern zones through Tuesday night with higher
amounts possible closer to the I-95 corridor. The axis of
heaviest QPF has shifted a little to the west with the recent
guidance blends/WPC.

Continued with the same areal coverage of the flash flood watch
from tonight through Tuesday evening in collaboration with WFOs
LWX and PHI.

Fortunately, we are going into this event with relatively dry
ground in most places - although the eastern part of the CWA has
been the "wettest" relative to moderate drought locations in
the central and western parts of the CWA. Some locally heavy
rain in this area was also observed last night and early this
morning. High rainfall rates, however, could work against the
dryness.

Latest ECENS and NAEFS support fair and seasonable conditions
Wednesday, as a cold front behind Isaias is progged to move east
of forecast area by dawn.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Medium range guidance is in decent agreement later this week,
all of which indicate a pair of shortwaves affecting the region
Thursday and Friday, spawning waves of low pressure along
stalled frontal boundary running from the Ohio Valley to Mid
Atlantic. Will maintain just a slight chance of showers along
the southern tier for the first wave Thursday, then a better
chance of showers with the stronger wave Friday.

Latest ECENS and NAEFS show high pressure and drier air mass
working into the state next weekend. Have therefore undercut the
NBM and Superblend POPs, but retain mention of widely scattered
diurnal convection. Temperatures should begin near seasonal
normals Thu-Sat, then expect a return to above normal
temperatures by late next weekend, as surface high passes east
of Pa and return southwest flow ensues.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
12Z TAFS sent.

As of 6 AM, most of the lower clouds are out of the area. Nice
sunrise. Still some lake effect showers along the NY border.

Expect winds to shift more to the southwest, and CIGS to lift
by mid morning.

For now, went with a dry fcst for most of the day. Low level
moisture less than on Sunday, and we had very little activity
after sunrise yesterday. Also no one feature to focus widespread
showers on.

The main concern will be the potential for heavy rainfall
impacts associated with TS Isaias later tonight into Tuesday
evening.

Outlook...

Tue...Moderate to heavy rain with MVFR/IFR restrictions likely
across the central and eastern airspace.

Wed-Thu...Trending drier/VFR with just an isolated shower or
t-storm possible.

Fri...Local impacts from sct showers/tstms.

&&

.CLIMATE...
July 2020 was a remarkably warm and dry month in Central PA.

*Average Temperature*
-Warmest month on record at Harrisburg & State College (82.2F
 at MDT, breaking the old record of 81.8F set in July 1999;
 77.0F at STC, breaking the old record of 76.5F set in 1955).
-T-3rd warmest month at Williamsport (78.2F, tied with July 1921
 and behind 1955 with 79.1F and 1901 with 78.9F)

*Average Maximum Temperature*
-3rd warmest month on record at Harrisburg (92.2F behind 1999
 with 93.5F and 1966 with 93.2).
-5th warmest month on record at Williamsport (90.0F; record of
 93.0F set in 1955 with other warmer Julys in 1988, 1934, and
 1921).

*Average Minimum Temperature*
-Warmest month on record at Harrisburg & State College (72.2F at
 MDT, shattering the old record of 70.7F last year; 67.5F at
 STC, breaking the old record of 66.6F set in 2012)
-2nd warmest month on record at Williamsport (66.4F behind 1901
 with 71.1F)

*90 degree days*
-2nd most on record at Williamsport with 19, behind 1955 with
 25.
-T-2nd most on record at Harrisburg with 22, behind 1966 with 23
 and tied with 1999.

*Precipitation*
-Driest July since 2007 at Williamsport (1.86")
-Driest July since 2002 at Harrisburg (1.35")
-5th driest July at State College (1.38")

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from this evening through Tuesday evening
for PAZ035-036-056>059-063>066.

&&

$$
SYNOPSIS...Lambert
NEAR TERM...Lambert
SHORT TERM...Lambert/Steinbugl
LONG TERM...Fitzgerald
AVIATION...Martin
CLIMATE...