Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 Kiln 191851 
afdiln

Area forecast discussion
National Weather Service Wilmington Ohio
251 PM EDT Thu Apr 19 2018

Synopsis...
a mid-level trough will move east of the region today, as
surface high pressure envelopes the Great Lakes and Ohio Valley
by tomorrow. Warming conditions are expected through the
weekend, continuing into early next week. Low pressure moving
south of the area will bring a chance of rain on Monday.

&&

Near term /through tonight/...
as a trough axis at 700mb is now well downstream of the iln
forecast area, a shift toward drier flow has occurred. There is
already a warming of temperatures occurring through the boundary
layer and even aloft, through the extent of a very dry
inversion above 700mb. This is leading to a gradual erosion of
the cloud deck, with skies ranging from essentially clear (nw
Mercer County oh) to still quite cloudy (lewis County ky).

As skies continue to clear, and the air mass becomes drier,
temperatures will cool relatively efficiently tonight. A freeze
warning remains in effect for the area currently active in the
program, with temperatures forecast in the lower 30s. It is
possible the freeze may be marginal (around 32 degrees) in some
of the southern iln counties, especially as winds will not
completely die off tonight, but per collaboration with
surrounding offices there was no strong intention to remove the
warning.

&&

Short term /Friday through Friday night/...
an expansive area of surface high pressure will be moving into
the region on Friday, with its center expected to be in southern
Wisconsin by Friday afternoon. This air mass is expected to be
very dry, with precipitable water values of around two tenths of
an inch. Despite the cool northerly flow, the dry conditions and
full sun should allow a decent warm-up from the freezing
conditions of the early morning -- with Max temps forecast to be
in the middle to upper 50s. To note, this is still below normal,
but it also represents the start of a more consistent warming
trend. With as dry as things are through the atmosphere, the
surface dewpoint forecasts could be too high, especially with
decent mixing under full sun. Thus, TD values were adjusted
downward slightly from the model blend during the afternoon.
Temperatures were similarly adjusted upward by a degree or two.
With a weak pressure gradient, however, winds should remain in
the 5-15 miles per hour range.

Winds will become even weaker heading into Friday night, where
radiational cooling conditions should be fairly ideal. Another
round of frost/freeze headlines could be necessary, but the
warmer starting point (possibly negating a freeze) and dry
conditions (possibly negating frost) make this a low confidence
suggestion as of now.

&&

Long term /Saturday through Wednesday/...
first half of the extended period will see benign weather has a
large surface high pressure system settles over the Midwest. Friday
is looking mostly sunny with temperatures rising to the the lower to
mid 50s.

High clouds will begin to increase on Saturday as upper level
moisture is forecast to still over the 500 mb ridge. Highs will push
into the mid to upper 50s.

Over the weekend, models push an upper level low out of the southern
rockies and into the southern Mississippi Valley. The upper low
begins to fill as this occurs. Due to the southern track, the
precipitation stays south of the region through the weekend. Highs
on Sunday will warm into the lower to mid 60s.

As the models eject what is left of the low to the East Coast on
Monday, some of the precipitation is pulled north into the region.
Models are showing differences in how much and exactly where the
pcpn will be, but there is enough certainty to put some low pops in
the forecast for Monday into Tuesday.

By Wednesday and 500 mb S/W drops down from the nrn Mississippi Valley.
It merges with the initial upper low to bring additional chances of
rain. Highs will generally be in the 60s for early next week.

&&

Aviation /18z Thursday through Tuesday/...
after a few remaining patchy MVFR ceilings lift over the next
hour or two, VFR conditions are expected through the rest of the
taf period. The cumulus / stratocumulus clouds will continue to
dissipate over the rest of the afternoon and evening, with clear
skies expected overnight, and straight through the day tomorrow.

Winds are slightly gusty out of the northwest at the moment, but
will diminish in intensity later this afternoon. A switch to
northerly or northeasterly winds is expected by tomorrow, but
wind speeds should remain around 10 knots or less.

Outlook...no significant weather expected.

&&

Iln watches/warnings/advisories...
Ohio...freeze warning from 2 am to 9 am EDT Friday for ohz060>065-
070>074-077>082-088.
Kentucky...freeze warning from 2 am to 9 am EDT Friday for kyz089>100.
In...freeze warning from 2 am to 9 am EDT Friday for inz050-058-059-
066-073>075-080.

&&

$$

National Weather Service Glossary of Abbreviations