Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
751 PM EDT Monday Aug 3 2015
a cold front will push southeast through the region this afternoon
into this evening. A ridge of high pressure will build back into
the area behind this front on Tuesday. This ridge should keep dry
weather over the area through at least Wednesday. On Thursday an
area of low pressure will move in from the west bringing wet
conditions back into the area.
Near term /until 2 am Tuesday morning/...
showers and thunderstorms are still expected to redevelop this
afternoon. Looked at latest amdar sounding from cvg (17z) and
there is a pretty good cap in place at 850mb. The best upper level
lift also appears to be off to the east. There remains a good
amount of instability above the cap though. GFS soundings are
forecasting cape values around 2800 j/kg. NAM is showing values
around 4000 j/kg. The GFS appears to be doing the best with the
forecast soundings as latest Storm Prediction Center mesoanalysis shows cape values
around 2500 j/kg. GFS soundings also showed some of a cap in
place. A cold front is currently stretched just north of an
Indianapolis to Wapakoneta line and will provide the source of
lift and thinking is that coverage will start to increase in the
next couple of hours as the cap is able to be modified. There is
also some stronger middle and upper level winds which will support
titled updrafts and convective organization. Given the shear and
instability Storm Prediction Center has the area in a slight risk.
Short term /2 am Tuesday morning through Wednesday night/...
Tuesday morning leftover rain will be exiting our southeastern
counties along with the cold front. Much drier air will then be
filtering in from the northwest. Precipitable waters on both the NAM and GFS are
forecasted to fall near 0.75" by Tuesday afternoon. During the day
Tuesday the upper level low will continue to rotate over the
Quebec/ Ontario border with southwest Ohio falling in the
covergent region of the trough axis. 850 mb temperatures are also
forecasted to remain around 15 degreees c which would support
highs in the lower to middle 80s.
An area of weak high pressure will remain across the area
Wednesday keeping mainly dry conditions across the region. The
front that moved through the area Monday evening will also remain
stalled just southwest of the area Wednesday. The NAM pushes the
front slowly north a little quicker than the GFS and Euro and
therefore brings in rain chances slightly sooner than the GFS and
Euro. Given the low precipitable water air have leaned towards Wednesday being
dry as per the Euro and GFS.
Probability of precipitation will then quickly increase Wednesday night as a shortwave at
500 mb approaches from the west. Precipitable waters also start to quickly
increase Thursday morning as a warm front lifts north.
Long term /Thursday through Monday/...
frontal boundary is forecast to reside just south of the Ohio River
at 12z. GFS/NAM suggest lift may already be sufficient enough to
support showers at that time...with elevated instability also
leading to a chance of thunderstorms. Wave of low pressure riding
along the front /linked to a middle-level shortwave/ may allow the
front to lift somewhat northward during the day Thursday/Thursday
night. Am not sure how far north this boundary will get...and this
will help determine if any portion of the County Warning Area /southern?/ Could
experience severe weather. For now...forecast reflects boundary
located along the Ohio River as low pressure rides along it with
showers and thunderstorms likely across the majority of the County Warning Area.
Probability of precipitation have been increased to reflect higher confidence in measurable
rainfall. In fact...there will be a concern for heavy rainfall and
flooding during the Thursday to Thursday night time frame.
As the wave departs...front will be pushed south toward the
Tennessee Valley into Friday. Will allow probability of precipitation to lower from northwest to southeast
during the day Friday. Consensus leans towards a dry forecast over
the weekend as high pressure builds in from the north...with
potential for a shortwave affecting the area on the new day 7
Aviation /00z Tuesday through Saturday/...
ongoing convection in vicinity of cvg/luk will continue for the
next hour or so...along with the isolated cell northwest of cmh. With
frontal passage tonight winds will become light and will go west to
northwest. Winds should become clear overnight as the convection
Skies should be mainly clear with VFR conditions on Tuesday under
high pressure...as some fair weather cumulus develops
Outlook...showers and thunderstorms will be possible Thursday.