Scientific Forecaster Discussion
fxus61 kpbz 290534
Area forecast discussion
National Weather Service Pittsburgh PA
134 am EDT Mon may 29 2017
shower and thunderstorm chances continue overnight. Weak high
pressure will keep Memorial Day mostly dry with seasonable
Near term /through today/...
the ongoing forecast aligns well with current conditions and
trends as a cold front begins to cross into western zones.
Rain rates have been on the decrease over the past hour and
expect this to continue through the night. Northern Indiana
County....Jefferson County...and areas along and north of I-80
have received a good deal of rain today, however, additional
rain is not expected to result in any further flood issues as
rain amounts observed upstream with the approaching front which
will cross the region shortly have been relatively low.
Previous discussion follows..
Evening update made to Nix the Flash Flood Watch as the focus
for heavy rain and localized flooding has shifted northward in
the vicinity of the warm front with residual outflow boundaries
allowing for additional storms to develop. Overall, expect
strength of storms to diminish with time with the loss of
heating, but threat for heavy rain will linger until the
approach of the cold front tonight. Latest hrrr keeps this
reasoning, as the bulk of the precipitation remains situated
north and east of the Turnpike. Will outline this area in the
hazardous weather outlook for the night with the thought that
most of the water issues will remain localized.
Cold front is still progged to pass overnight, with it east of
the region by 8am. Warm advection and low level mixing should
be sufficient to keep temperatures above seasonal averages
Weak surface and mid level ridging should keep most of Monday
dry before a shortwave, pivoting through the broad upper trough
centered over the Great Lakes, brings the return of moist,
southerly flow and convergence for precipitation late.
Temperatures should be close to or just above seasonal norms.
Short term /tonight through Tuesday night/...
shortwave will skim the region to our north Monday night and
Tuesday, bringing another front across the region that should
provide some scattered showers. Held off on thunder for Tuesday
for now as models disagree on stability, however steepening
lapse rates may allow for it. Precipitation coverage will wane
behind the boundary Tuesday night. Fairly seasonable
temperatures are expected.
Long term /Wednesday through Sunday/...
the Great Lakes/northeast Continental U.S. Trough will remain through the
end of the week, with periodic shower chances from shortwaves
moving through the flow. By next weekend, the upper pattern
becomes more zonal, and a frontal boundary could stall out
somewhere near or in our region. This boundary could provide
more focused rainfall chances, but its placement remains in
question. Temperatures will remain near or just a few degrees
Aviation /05z Monday through Friday/...
occasional MVFR/local IFR conditions are expected in showers
ahead of an approaching cold front. Isolated thunderstorms are
possible until frontal passage but with limited coverage did not include
in the tafs. A brief period of MVFR ceilings are expected behind
the front, with VFR returning this morning as surface ridging
builds in. A wind shift from SW to west is also expected with
restrictions are possible Tue/Wed with an upper trough, and
again Fri with low pressure.