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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 201207
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
807 AM EDT Thu Jun 20 2019

.SYNOPSIS...
A low pressure system will push across the state later today 
and tonight. A pleasant and dry weekend is in store. 
Temperatures will trend a little cooler than normal for Friday 
and Saturday with warmer weather returning next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Trouble with the weather...trying to forecast it. System 
looking like it will come in two or three pieces today. Not all 
the pieces are aligning for a terrible weather day. However, we
are still under slight risks of both excessive rainfall and 
severe thunderstorms. 

The low spinning through nrn OH at 08Z will slide east a little
today, but it does not seem to be the only low on the map.The
recent CAM runs point to the heavy rain this morning being along
the NY border. Showers and isolated thunderstorms over nrn OH
should continue to move into PA through the morning. The clouds
and rain from this part of the system could keep the threat of 
severe wx lower than fcst today, cutting CAPES/tenps. Shear is 
already going to be weak to moderate at best. Wind shift with 
the "deepest" low does come through in peak heating. But, the 
frontal zone it drags along behind it lays out west-to-east in 
the evening and only creeps through slowly after dark.

PWATs are still very high. Many areas have had heavy rain these
past 3-4 days. But, the storm motion this afternoon/evening 
should be 20-30 MPH. This is the main thing which could cut 
down the threat for flooding a bit. The threat for wind gusts
will be mainly in the afternoon and early evening, before dark.
The multiple fronts/boundaries and low LCLs could contribute to
a few spinning cells and an isolated tornado is possible.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
Showers and thunderstorms will last into the middle of the night
as the frontal boundary drags it's feet going through the CWA.
The upper trough axis does not cross the entire area until early
Friday morning. The residual showers could still contain some
thunder.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Breezy and drier/less humid conditions will arrive Friday on 
the backside of the departing system. Expect a break from the 
rain for 2-3 days with pleasant conditions through the weekend 
before a surge in humidity returns showers and storms to the 
forecast next week.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Generally IFR conditions for much of CWA this morning, with some
improvement already over the SW. Vsby will improve and ceilings
will gradually rise to MVFR then to VFR from the SW to NE over
the next several hours. 

But, very humid and unsettled conditions will again bring areas
of showers/tstms starting late morning and continuing through
the evening hours. Best chance for a more organized line of
convection will be early to mid afternoon over eastern sections,
but any thunderstorm will be capable of very heavy rainfall
along with local IFR restrictions and gusty winds. 

A low pressure area slides across PA tonight. Showers will taper
off, but lower ceilings will return to NW half overnight.
Friday will bring improving conditions with widespread VFR
conditions. 


.Outlook...

Fri...AM low cigs possible W Mtns. Then VFR.

Sat-Sun...No sig wx expected.

Mon...Ceiling restrictions poss in rain showers.

&&

.CLIMATE...
Astronomical summer (solstice) begins Friday, June 21st at
1154AM EDT (1554 UTC).

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from noon EDT today through late tonight for 
PAZ004>006-010>012-017>019-024>028-033>037-041-042-045-046-
049>053-056>059-063>066.

&&

$$
SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Steinbugl
AVIATION...RXR
CLIMATE...