Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 290646
Area Forecast Discussion
National Weather Service State College PA
246 AM EDT Thu Sep 29 2016
A widespread moderate to locally heavy rain event will continue
through tonight. Minor flooding impacts are likely across the
southern half of central PA. Unsettled weather with occasional
lighter rain showers will persist into the weekend with a gradual
drying trend by early next week.
.NEAR TERM /UNTIL 8 AM THIS MORNING/...
130AM: Minor changes to previous near term fcst. The 29/04z HRRR-
TLE shows the highest probs for 0.50-1.00 inch rainfall thru 12z
located over the western Blue Ridge/WV/MD panhandles into the
southern Laurel Highlands and over the Delmarva/Chesapeake Bay.
Radar trends would seem to agree for now with relative min in pcpn
from KCHO-KDMW. Temps should hold fairly steady or drop just a few
degrees with most locations in the mid 50s to around 60F.
.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM FRIDAY/...
Heavy rain event is expected to be ongoing over south-central PA
on Thursday. An enhanced convergence axis/frontal zone is progged
to develop on the east side of an upper low meandering over the
OH/TN Valley, tapping into deep moisture/high PW air off the
Atlantic Gulf Stream via anomalous east/southeast low level jet.
The heavy rain axis is progged to gradually pivot to the southwest
with time oriented within moderate excessive rain outlook area
from southwest PA near the Laurel Highlands southeast into
Northern VA/D.C. area. The strength of the upslope flow and high
PW transport along with some elevated instability should provide
an environment for efficient rainfall processes.
WPC QPF nudge employed this afternoon but overall staying the
course from previous forecasts...despite a downtick in some
deterministic solutions in the 12z cycle. Dry antecedent
conditions may limit more significant flooding/runoff issues.
Still expect minor flooding to result from long duration
continuing throughout Thursday. event...and am maintaining Areal
Flood Watch for Laurel Highlands, South Central Mountains and
southern portions of the Central Mountains for late tonight
through Friday morning. Will continue to highlight potential flood
risk in HWO elsewhere...but heaviest rain should fall across the
southern half of the area.
The upper low is fcst to drift back to the west/NW into the OH
Valley on Friday before slowly moving to the ENE across the Lower
Great Lakes through the weekend. We should continue to see periods
of showers on Friday but rainfall amounts will be much lower and
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
The upper level low will continue to slowly move through the
Eastern Great Lakes region and into Southern Canada which should
pull the moisture to the north. Some lingering showers should
continue through Eastern PA Saturday afternoon. There is some
disparity on the timing of the exit of this low and whether or
not it opens up into a wave. The model guidance still suggests
unsettled conditions over the weekend with a gradual decrease in
the chance for showers by Sunday. Temps still holding close to
seasonal normals as we turn the calendar to October.
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --An increasingly moist easterly flow will overspread central Pa
early this morning, bringing low cigs and rain. Model soundings
and latest SREF output support predominantly IFR cigs through this
evening at the higher terrain airfields, including KBFD, KUNV,
KAOO and KJST. At the lower elevation airfields, predominantly
MVFR cigs are expected today at KIPT, KMDT and KLNS. However,
periodic IFR is likely this morning associated with bouts of
Fri-Sat...Low cigs/showers likely, mainly w mtns.
Sun...AM low cigs possible.
Mon...Showers/cig reductions possible at KBFD.
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Flood Watch through Friday morning for PAZ024>028-033>036-056-