Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
644 am EST Friday Nov 27 2015
a cold front will sag slowly southeast into the Ohio Valley this
afternoon and tonight...bringing an increasing chance of rain to
the region. The front will stall out across the Ohio Valley...resulting
in a continued chance of rain through the weekend. Cooler air will
filter in behind the front with more seasonable temperatures
expected Saturday and Sunday.
Near term /until 6 PM this evening/...
a cold front currently stretching from upper lower Michigan...across
northern Illinois and into central Missouri will sag slowly
southeast toward our area through this afternoon. Along and ahead
of this...better low level convergence/1000-850 mb frontogenetic
forcing will work into northwest portions of our forecast area through this
afternoon. While the low levels will initially be fairly
dry...expect rain to develop across our far northwest late this
morning and then sag very slowly southeast through the afternoon
hours. Given the slow movement...much of our southern/southeast forecast area
will remain relatively dry through the daytime period. Given the
southerly flow right now ahead of the front...expect some non
diurnal temperatures today...especially across the northwest
where some cooler air will begin to filter in later this afternoon
highs today will range from the upper 50s northwest to the middle
and upper 60s in the southeast.
Short term /6 PM this evening through Sunday/...
rain will continue to sag slowly southeast across the remainder of
our area through tonight as the front pushes slowly southeast.
Despite relatively high precipitable waters for this time of year...low level
forcing will weaken through tonight which should help limit quantitative precipitation forecast
amounts somewhat. None the less...will allow for categorical probability of precipitation
to push down across all but our far southeast through tonight.
There are some model differences then for Saturday into Sunday as
to just how far south the front will push. It looks like the front
should stall out somewhere just south of the Ohio River as another
or a series of waves ride east along the front. This will keep the
chance of precipitation persisting through much of the weekend...with the
highest probability of precipitation closest to the boundary...across southern portions of
our forecast area.
As the cooler air pushes in behind the front...expect more
seasonable temperature readings. Highs on Saturday will range
from the lower 40s northwest to the middle 50s southeast with highs
on Sunday in the middle 40s to lower 50s.
Long term /Sunday night through Thursday/...
model solutions on the eastward progression of the upper low have
come into strong agreement on timing and placement through Tuesday
morning...before speed differences become more pronounced as the
low passes through the Great Lakes. As the low begins to approach
the area...the surface front will move north as a warm
front...placing the Ohio Valley into a regime of warm advection
(and providing another round of precipitation). At some point...an
associated surface low will move through the Great Lakes...with a
cold front passing east across the Ohio Valley (likely in the
Tuesday afternoon through Tuesday night time frame). A final
chance of precipitation may happen on Wednesday...as the upper low
moves across the Great Lakes. While most of the activity is likely
to remain north of the forecast area...there will be a chance for
a mix of rain and snow showers wherever it does occur.
Seasonable temperatures are expected for Monday...before a brief
warm-up occurs on Tuesday ahead of the next cold front. Behind
this front...temperatures are likely to drop below normal for at
least a couple days.
Aviation /12z Friday through Tuesday/...
some light returns already on the radar this morning near Dayton
with main band of precipitation off to our west. This band of
precipitation is in association with a surface cold front that is
forecasted to move into the area tonight. The band of precipitation will
slowly approach kday this afternoon and then gradually push to the
south and east. High res models have struggled a bit this morning
with timing of the line but for now have leaned towards wrfdart as
it appears to have the best handle on things. As rain moves into
the terminals ceilings will slowly fall. Expect VFR ceilings slowly
falling to MVFR and then eventually IFR. High res models are
showing the band of precipitation weakening tonight only to restrengthen
a bit Saturday morning. IFR and MVFR ceilings/visibilities will then continue
through the taf issuance.
Outlook...MVFR/IFR ceilings and visibilities possible through Saturday
night...then again Monday into Tuesday.