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Area forecast discussion 
National Weather Service Wilmington Ohio
956 am EDT sun Aug 2 2015

high pressure over the Ohio Valley this morning will move off to
the southeast as a cold front approaches the region from the
northwest. This front will slowly move through the Ohio Valley on
Monday. The cold front is now expected to by south of the region
by Tuesday...allowing a ridge of high pressure to build back into
the area.


Near term /until 6 PM this evening/...
surface high pressure over the Ohio Valley will move southeast as
a cold front approaches are region from the northwest. A
southwest flow will develop...and with an increasing pressure
gradient...some locally breezy conditions will occur over our
northwest counties. It appears that low pressure and a lead shortwave
within a digging middle level trough will result in convection over
the western Great Lakes this afternoon and evening. The convection
is expected to remain well to our northwest through the day as the
atmosphere over our region remains slightly capped. That said...iln
area will have sunny skies with perhaps a slight increase in
clouds this afternoon. With 850 mb temperatures a little higher
than yesterday...highs will warm into the middle and upper 80s.


Short term /6 PM this evening through Tuesday night/...
models continue to have some issues in terms of convective
coverage over the region tonight out ahead of a cold front
in association with a lead short wave and strong low level jet over the
Great Lakes. Using all available high resolution models
(convection allowing) and synoptic models (convective
parameterization) appears that ongoing convection to our
northwest this evening will undergo a weakening trend as it tries
to push east/southeast toward our northern zones. Part of this
weakening trend will be due to a fairly rapid decrease in
instability as well as a shifting of low level forcing to our
northeast. A result...have brought in chance probability of precipitation for our northern and
northwestern zones. Storm Prediction Center swody1 glances our far northwest with the slight risk
for severe thunderstorms...and am in agreement with this given the
forecast scenario. Lows will drop into the middle and upper 60s.

For Monday into Monday the lead short wave moves off to
the east...a middle level trough will gradually shift south into the
Great Lakes. This will push the cold front slowly southeast through
our area Monday into Monday night. We should be able to obtain
moderate instability by Monday afternoon and early evening ahead
of the front...with strongest overall shear along and just behind
the front. Low level frontal convergence is only scattered
convection is expected. Given the moderate instability...a few
storms may become strong or even severe...but with low coverage...the
overall severe threat will be low. Highs will range from the middle
80s north to near 90 along and south of the Ohio River. With drier
air filtering in behind the front for our northern
locations...lows Monday night will drop into the upper 50s with
middle 60s expected along and south of the Ohio River near the
departing front.

Models now concur that the cold front should be south of our area
on Tuesday...which will allow surface ridging to build in from the
west as aforementioned middle level trough pushes east toward southeast
Canada. Under partly to mostly sunny skies...highs will range from
the lower 80s north to the middle 80s south.

Models continue to struggle with potential convection heading into
middle week as we return to a active northwest flow pattern. At this
time...have sided with the European model (ecmwf) which suggests that an embedded
shortwave may bring a chance of showers and thunderstorms back to our
area by late Tuesday night or Wednesday morning.


Long term /Wednesday through Saturday/...
northwesterly flow aloft will carry several disturbances through
the Ohio Valley...bringing multiple chances for showers and
thunderstorms Wednesday into Thursday. Meanwhile an upstream
upper level ridge will flatten out as it interacts with a
developing shortwave over the northern rockies. Energy associated
with this shortwave will support Lee cyclogenesis over the
Oklahoma Panhandle Wednesday into Thursday...a system which will
impact the Ohio Valley by the end of the week. The 01.12z GFS run
shifted this system and its associated quantitative precipitation forecast quite a bit further
south than the 06z run...taking it right through the iln County Warning Area on
Friday. Based on this large shift and the fact that its quantitative precipitation forecast and
upper level energy still look overdone...have used a blend more
heavily weighted towards the European model (ecmwf) /which has shown a little
better run to run consistency/ to handle this system.

With a quasi-stationary front staying to our south for several
days...a cooler and slightly less humid airmass looks to establish
itself over the region for much of the extended period. Highs will
generally range from the middle 70s to middle 80s with the warmest
temperatures staying near and south of the Ohio River. Lows will
range from around 60 to the middle 60s.


Aviation /14z Sunday through Thursday/...
VFR conditions are expected through the taf period. Relatively dry
air will remain in place in the low levels of the atmosphere
today...significantly limiting cumulus development. Clouds will
begin to increase near the end of the advance of a
weak cold front...which will be moving into the region from the
northwest. Scattered showers (and possibly a thunderstorm) will
accompany this front as it moves into the area early Monday
morning. However...this activity will be on a weakening
trend...and does not warrant anything more than a vcsh for
placement at the tail end of the taf period.

Winds today will be out of the around 10-15 knots
(with some gusts a little higher possible at the northern taf
sites). Winds will back to the south-southwest and become weaker going into
early Monday morning...before increasing and veering again early

Outlook...showers and thunderstorms will be possible on
Monday...mainly during the afternoon. Showers and thunderstorms
will be possible again on Wednesday and Thursday.


Iln watches/warnings/advisories...


near term...coniglio/Hickman
short term...Hickman
long term...kurz

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