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fxus61 kctp 211142 

Area forecast discussion
National Weather Service State College PA
742 am EDT sun Jul 21 2019

another hot and humid day is in store, but a cold front will
move through the region bringing an end to the recent heat
wave. Noticeably cooler and less humid air will finally provide
relief from the sweltering heat by the middle of next week.


Near term /through tonight/...
radar shows scattered nocturnal convection moving east over
the northern tier. The activity is forming in an area of
moisture convergence associated with a cold front that will
eventually change the weather pattern for US from the recent
heat and humidity to cooler and drier.

The last couple of nights, the hrrr has been of little use
catching onto the scattered convection, and tonight is no
exception with no rain generated in the model in the County Warning Area at this
hour. The rap is a little better at least depicting some stray
showers over the northern 1/2 or so of the forecast area through
the morning hours.

Another hot and humid day is in store, though with winds
shifting to the north, our northern counties will begin to see
some measure of relief with highs "only" in the mid 80s.

We expect more scattered thunderstorms today, starting over the
north this morning, but more area-wide during the afternoon.
Mid level temps are still progged to be quite warm, but forcing
associated with the cold front and steep mid level lapse rates
should be enough to allow showers to pop as the day warms up.

The oppressive humidity will lead to heat indices in excess of
100 deg over much of the region today, from roughly ipt-unv-aoo
and eastward. Today should be the last day for heat headlines.

The various members of the href suggest that the scattered
showers and storms will continue into the evening, and may even
pick up again later at night in response to the frontal system
becoming influenced by falling heights aloft associated with the
deepening shortwave moving through the Great Lakes.


Short term /Monday/...
Monday looks to be an active day. The frontal system will slow
during its passage and with a deepening upper trough overhead,
at least one wave is expected to form on the front,
potentially helping to focus locally heavy rain.

At this hour I don't have enough confidence to say exactly
where the best rains will fall, but early indications suggest my
southeastern zones where pwats around 2 inches (2-3 sigma) will pool
along and ahead of the wavy front. In general, when warm season
tropical moisture combines with upper forcing more in line with
a cool season system, we usually see problems develop. We are
leaving it for the day shift to evaluate and possibly issue a
Flood Watch to start preparation for the potential heavy rain


Long term /Monday night through Saturday/...
the 00z deterministic NAM and European model (ecmwf) are slower in making the
last of the wavy front and the rain exit my southeastern zones, with
rain lingering much of Monday night. The GFS and Canadian are
faster and bring the drier air in sooner.

What is more certain is that by the end of Tuesday we will see
markedly less humid air moving into the forecast area. This
will be the beginning of a period of pleasant mid Summer days
with temperatures running several degrees cooler than normal,
and with lower dewpoints and humidity.

Models agree with keeping the anomalous eastern upper trough the
dominant feature through the end of the week when some
indications of rising heights returning to the NE are depicted.


Aviation /12z Sunday through Thursday/...
12z tafs sent.

The few showers and storms that formed around 4 am are mainly
gone now.

Hard to believe it is 80 degrees outside the office at 7 am.
We did not get the outflow from any storms last night, as was
the case the night before. Other nights we cooled down to around
70 degrees.

Anyway, expect at least some showers later today, as a cold
front moves toward the area. Left thunder out for now. Used vcsh
for the most part.

Trend for Monday is cooler and wetter.


Mon...widespread showers and tsra impacts possible. sig wx expected.


Ctp watches/warnings/advisories...
excessive heat warning until 8 PM EDT this evening for paz028-
Heat advisory until 8 PM EDT this evening for paz019-025>027-



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