Area Forecast Discussion
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FXUS61 KPBZ 221608
Area Forecast Discussion
National Weather Service Pittsburgh PA
1208 PM EDT FRI JUL 22 2016
Hot and humid weather is forecast for today into early next week,
along with intervals of scattered thunderstorms.
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --A line of showers and thunderstorms ahead of a shortwave should
continue to move SE across the area through early afternoon.
Earlier hi res model guidance didn`t handle this so well, but pops
have been adjusted to reflect the current and future placement
based on radar trends. It remains in question how much development
we will have north of the current broken line this afternoon, as
lingering cloud cover may prohibit destabilization. Opted to leave
the chance pops that were inherited for now. If anything does
develop, we will still need to monitor the threat for strong
storms with marginal shear present.
Rain and cloud cover this morning will most likely keep much of
the region from hitting 90 today.
Shower/storm chances should gradually diminish tonight as
instability decreases, though low chances will continue overnight
in proximity to the shortwave trough with it`s advancement to the
I 70 corridor by morning.
-- End Changed Discussion --
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
A weak boundary will stall out over the southern third of the
forecast area by Saturday morning. Models continue to activate
showers and thunderstorms along this boundary through the
afternoon, but a lack of upper- level support and dry air through
the column should limit development. Opted to continue with slight
chance/isolated shower or thunderstorms south of Pittsburgh.
Remaining mid-level moisture will clear the southern border by late
Saturday, ending the low rain chances. Near-surface moisture and
high surface dewpoints will linger, resulting in another warm and
humid night with lows well above average. Surface high pressure will
shift east Sunday as the next system moves through the southern
Canadian Plains. This will return southerly flow, and re-enforce the
warm and humid airmass. A few showers could develop across our
western zones Sunday afternoon as the weak boundary returns north as
a warm front. Heat indices Saturday and Sunday will reach into the
mid and upper 90s for a majority of our forecast area, and approach
100 for a few of our southwestern counties. An HWO mention will be
maintained for this.
Warm and humid conditions will carry into the new work week,
although an increase in clouds will limit high temperatures. A weak,
sweeping cold front will drag across the area Monday, bringing a
chance of rain for all, but the progressive nature of the system
will limit amounts.
.LONG TERM /MONDAY THROUGH THURSDAY/...
Rain chances will quickly dissipate in the wake of the cold front,
Tuesday, bringing a return to dry conditions. The upper-level flow
pattern will temporarily flatten to nearly zonal, as high pressure
builds at the surface. Temperatures will moderate under the zonal
flow aloft, but will remain a few degrees above normal. Consistent
model agreement on the digging of a trough over the cornbelt in the
latter part of next week. This will bring rain chances back to the
forecast Thursday and Friday.
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
A line of thunderstorms with MVFR/local IFR restrictions should
continue to advance across the region this morning with an
approaching shortwave, though coverage should be more scattered
across OH ports.
Additional scattered thunderstorms are expected to develop this
afternoon as a surface trough slowly advances toward the region.
Maintained a VCTS mention for this as uncertainty remains in
amount and timing of coverage. VFR should prevail much of tonight
as instability decreases, though some patchy MVFR fog is possible
with low level moisture in place.
.OUTLOOK /SATURDAY THROUGH TUESDAY/...
Restrictions will be possible late Sunday and Monday with