Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
641 am EDT Friday Sep 19 2014
high pressure will provide dry weather and comfortable conditions
through Saturday. Shower chances will increase Saturday night and
Sunday with the passage of a cold front.
Near term /until 6 PM this evening/...
no updates will be needed this morning as latest observations
match up well with the ongoing forecast. Previous discussion follows..
boundary will clear the south this morning. Broad surface high
will slowly move through New England today. Upper level heights
will gradually rise as ridge builds into the Midwest. Somewhat
interesting scenario sets up this afternoon as flow at 850 backs
toward the south and increases. At the same time...flow near the
surface remains out of the southeast. Latest NAM is showing
moisture increasing over the middle- Atlantic then driving northward
in the strengthening flow at 850. Would expect an increase in
cloud cover over at least the eastern half of the area during the
Short term /6 PM this evening through Sunday/...
models keep the moisture trapped over the area tonight and into
Saturday morning. By Saturday afternoon...the moisture mixes out
allowing for a decrease in cloud cover. Cold front will slowly
move through the Great Lakes Saturday night. Minimal upper level
support Saturday night should hinder widespread shower development
so will leave pop in the chance/slight chance range.
Front moves through Sunday afternoon getting a push from a strong
shortwave trough that will swing through the southern Great Lakes.
Models are showing a destabilizing atmosphere ahead of the front
Sunday in response to moisture pooling in the lower levels. In
addition...the 0-6km bulk shear values increase with frontal
passage. Will included the mention of thunder Sunday afternoon.
Models may be overplaying their hands a bit on Sunday...but with
current data...not out of the question that stronger convection
Long term /Sunday night through Thursday/...
cold front will exit region Sunday night.
Overall dry and cool pattern is expected for the remainder of the
long term period.
Aviation /12z Friday through Tuesday/...
VFR conditions today with minimal cloud coverage and light
Outlook...Friday night through Tuesday...
genl restrictions are likely with a Sunday cold front.