Area Forecast Discussion
Issued by NWS State College, PA
FXUS61 KCTP 301943
Area Forecast Discussion
National Weather Service State College PA
343 PM EDT Thu Mar 30 2017
Low pressure approaching from the Ohio valley will slide
across the Mid-Atlantic Friday and Friday night. Another low
pressure system, following the same track, will likely affect
Pennsylvania late Monday into Tuesday. A third low is likely to
track west of PA through the Great Lakes during the later half
of next week.
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
Dry slot entering far wrn PA is headed this way, but the llvl
serly flow make keep us more-cloudy than not, esp in the E. A
rumble of thunder is possible in the wrn mtns this aftn before
the forcing moves past. Temps across the nrn tier just as
expected and near freezing in places. Just about every precip
type has been falling in the nrn tier and temps will take
another few hours to warm up significantly, and will do so just
as the forcing moves past. But, until then, there may be a thin
coating of SN/PL on the grass. ground/road temps are warm enough
to keep any problems away - esp since the late-March sun will
still be helping through the late aftn. A minor lull in SHRA is
expected for much of the evening over most of the area.
.SHORT TERM /MIDNIGHT THROUGH 6 PM FRIDAY/...
A strong 40+KT lljet develops tonight in advance of the primary
low center moving into nrn OH. Thus, moisture transport
increases again after a minor lull during the evening. More
showers will develop right overhead tonight but temps should not
be a problem by then. Primary low moving into NW PA on Friday
will diminish in favor of a secondary low developing over
central VA. The new low slides just to the SE of the local CWA.
But, the instability around the low and just NW of it will
probably cause some TSRA on Friday. QPF is still O/O of 1-2
inches. However, this should only make some of the rivers in the
east make it up to/over their respective caution stages. Most
of that water is coming from upstream. Overall, the rainfall
will be spread out over the next 36 hours. So, local flooding is
not enough of an issue to make for a flood watch.
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
An active split flow jet stream pattern across North America
will bring multiple chances for precipitation to the region
during much of the long term period. A slower moving longwave
trof looks to develop across the eastern Great Lakes and middle
Atlantic region late next week.
Any early showers Friday night should give way to slowly improving
conditions Saturday, as main surface low exits the coast and a
drier northwest flow takes hold. Some breaks in the cloud cover
should occur Saturday afternoon, esp across the Lower Susq
Valley where drying downslope flow will be enhanced. Max temps
Saturday should return to near seasonal norms.
Fair and mild weather appears likely Sunday, as high pressure
ridge builds across the state. However, the next potent and
moisture laden southern stream wave heads our way for Mon night
and Tuesday, bringing a likelihood of a widespread rain. A brief
break is likely around next Wednesday, then another round of
significant rainfall appears possible by the later half of next
week when all med range guidance tracks the aforementioned
upper trof/closed low northeast through the Great Lakes.
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
Dry slot moving into wrn PA at 3 PM seems to be the warm sector.
However, the SE flow over the area will make it tough to
displace the cool air. Some reports of PL/SN across the nrn
tier. The temps should warm slightly over the next few hours and
precip become more-spotty. TSRA dying as it moves eastward along
the Mason-Dixon Line. Expect it to diminish further quickly.
Other cluster of TSRA over wrn PA is likely to reach the wrn
highlands as well. Thus, it could reach BFD. However, it is
still cool and stable there. Will not mention TS there just yet.
A general lull in precip will continue as the warm sector moves
in. The se flow at the sfc looks to continue so, all MOS
guidance continues to lower cloud cover later tonight and
showers return from the west, esp in the N. Also, an area of
instability develops over DC and moves up into MDT/LNS around
sunrise. Have mentioned prob30 of TS there for 12-18Z/31st.
Widespread showers should affect the area on Friday.
Sat: MVFR cigs N/W. VFR elsewhere.
Sun: VFR/No sig wx.
Mon: VFR early then rain/low cigs vis spreading W-E.
Tues: MVFR in -SHRA.