Thursday, June 29, 2017, 10:00 AM EDT
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Area Forecast Discussion
Valid At
Wed, Dec 31, 7:00pm EST
FXUS61 KCTP 291147

Area Forecast Discussion
National Weather Service State College PA
747 AM EDT Thu Jun 29 2017

High pressure off the eastern seaboard will set up a warmer and
more humid airflow over the next several days. A cold front on 
Saturday will bring a brief break in the humidity.


The eastern US is under a broad upper ridge, but close to the 
southern edge of the main westerlies. A series of weak 
shortwaves rippling through the broad ridge will help advect 
more unstable air out of the midwest into the region. 
Deterministic models develop some modest CAPE and mid level 
lapse rates in the 6-7C/km range by afternoon. At least one
upper jet streak is forecast to slide into the lower lakes 
which will enhance the wind fields with respectable deep level
shear expected to develop across my northern tier by mid day
into the afternoon. Overall an afternoon or evening shower or 
thunderstorm will be possible, with the best chance being north
of I-80. Isolated strong winds and hail will be possible in 
some of the stronger updrafts.

Convection will fade with the loss of heating this evening
leading to a warm-muggy overnight and a break in comfortable 
sleeping weather we have had for the last several nights.


A broad WSW flow will be well established over the area Friday
making for a hazy-warm and humid day. Highs in the 80s to around
90 over the south will be above normal by about 3-6 deg on

The upper ridge will be giving way to increasingly cyclonic 
flow aloft about a large low that will be dropping out of 
central Canada toward the upper Midwest and Gr Lakes. I used a 
blend of MOS POPs to arrive at a forecast of scattered mainly 
afternoon showers and thunderstorms. Near term guidance suggests
mid levels could be a bit on the warm side so the cap might be 
tough to break and I might be a tad pessimistic.


The extended part of the forecast will be influenced mostly by
a broad upper trough that will swing a series of shortwaves 
down into the NERN US. Despite being under the trough into at 
least early next week, the upper heights are forecast to remain
seasonably high as the best energy lifts north of PA.

A weak cold front is forecast to pass through the region
Saturday with the best chance for organized showers and

The GEFS shows some small chance for precip leftover for 
Sunday, but overall it should be a very warm day with a mix of 
sun and clouds. Not sure if we will see a noticeable break in 
the humidity at this point given how weak the airmass 
difference is expected to be.

As we get into next week, differences arise between the GFS/GEFS
and the ECMWF with the EC leaning toward a drier forecast and 
the GFS/GEFS showing a number of fast moving disturbances 
rippling down under the NW flow aloft creating the potential for
daily diurnal convection.

Despite the dominance of the upper trough, temperatures are
expected to be above normal through the end of the extended.


Expect predominately VFR flying through the 29/12z TAF period. 
High level cirrus will give way to sct-bkn cumulus with isolated
to scattered thunderstorm activity possible during the late
afternoon and evening mainly across the northwest 1/2 of the 
airspace. Latest HRRR indicates rain risk through midnight
across the northern airspace. Surface wind gusts 15-20kts from 
170-240 degrees from mid/late morning through the afternoon 
before diminishing around 30/00z. 


Fri...Isold/sct PM Tstm impacts psbl; most likely NW 1/3.

Sat...Tstms likely with MVFR/IFR restrictions. 

Sun-Mon...No sig wx expected.




NEAR TERM...La Corte
LONG TERM...La Corte

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