Area Forecast Discussion
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FXUS61 KPBZ 250742
Area Forecast Discussion
National Weather Service Pittsburgh PA
342 AM EDT Tue Oct 25 2016
High pressure will bring dry and cool conditions into Wednesday.
Low pressure will bring showers back into the forecast Wednesday
night through early Friday.
.NEAR TERM /THROUGH TONIGHT/...
General northwest flow will continue through the day today with
some indications of a bit of a multi-lake fetch enhancing moisture
flow toward the northern portions of the area. Model soundings and
hi-res solutions both favor the continuation of a stratocumulus
deck generally from Pittsburgh northward and developing into the
ridges through the morning with diurnal enhancement likely toward
early afternoon on Tuesday. A shower or two will be possible in
the far northern reaches of the area due to very unstable low
level lapse rates and some indications of saturation depth through
the stratocumulus layer. Otherwise, the area remains dry through
the day today with over-lake fetch decreasing late. This should
start to allow for the dissipation of stratocumulus by that
As high pressure continues to slowly build toward the area into
the nighttime tonight, surface flow should gradually relax. This
will basically entirely remove the lake influence in the
temperature field across the area and allow for fairly optimum
conditions for radiational cooling. The only fly in the ointment
may be some incoming mid or high clouds from the west. However,
because model depictions of mid and upper level RH fields are less
than impressive, it seems more likely this possible cloud cover
will be somewhat insignificant. Thus, low temperatures were
allowed to fall toward or below freezing on a fairly widespread
basis outside of the urban core. However, since we will be two
weeks beyond the end of the normal growing season, no additional
frost or freeze headlines are planned at this time beyond the ones
already in effect this morning. Fries
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
As a deepening Great Lakes low pressure system approaches
Wednesday, a warm front will lift across the area. This will bring
an increase in clouds, but dry air near the surface should
maintain a dry forecast through much of Wednesday. Shower chances
increase Wednesday night as the surface low moves into IN/OH.
Models seem a bit slower with the approach of this system, but the
general track largely remains the same. Categorical PoPs have been
included across the north for Thursday morning with likelies
An increasing low-level jet will keep Wednesday night lows relatively
warm and return gusty winds to the region Thursday. Timing details
could change some, but the current forecast follows a GFS-modified
diurnal trend instead of a more climatological trend. The upper
low will close off over New England Thursday night, keeping cold
northwest flow across the region into Thursday night with
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
Any lingering northwest flow showers should wane Friday evening as
high pressure briefly crosses the region. Models show another
system dampening the crest of the broad upper ridge to the west
early Saturday, but significant model differences exist on track
and timing. Regardless, unsettled weather looks to continue over
the weekend, with focus of rain showers north of Pittsburgh.
Thus, have maintained the likely PoPs across the northern 1/3 of
the forecast area. A building ridge will then establish over the
southeastern CONUS early next week with drier and much warmer
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
VFR conditions seem most likely to continue at all sites through
the period. Some lake-induced showers may wander as far south as
KFKL and KDUJ for a time toward morning, making some MVFR
conditions a possibility, however they shouldn`t linger.
Stratocumulus should also start to scatter out from the southwest
by afternoon with all sites likely to see nearly clear conditions
by evening on Tuesday. Fries
.OUTLOOK /TUESDAY THROUGH FRIDAY/...
The next chance for general restrictions will late Wednesday into
Thursday as the next disturbance crosses the region.
OH...Frost Advisory until 9 AM EDT this morning FOR OHZ039-048-049-
WV...Frost Advisory until 9 AM EDT this morning FOR WVZ004-012.