Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

FXUS61 KILN 230009

Area Forecast Discussion
National Weather Service Wilmington OH
809 PM EDT Thu Jun 22 2017

Moisture from Cindy will overspread the region today. A cold
front will drop southeast across the area Friday afternoon and
evening, with heavy rainfall possible ahead of this front.
Temperatures will drop below normal through the weekend and into
early next week.


A band of mostly showers has continued to push north today with
the northern extent now approaching the CWA border. This is in
response to a shortwave that is slowly pushing north and moving
up and around a mid-level ridge. As the shortwave approaches the
area, it will begin to pull east around the ridge pulling the 
rain east as well. This shield of rain also delineates a very 
moist tropical air mass in response to Cindy. PWATs with this 
air mass are at or above 2.00". A PWAT of 2.00" is close to 
record values for this time of year. 

After this band of precipitation clears the CWA there will
likely be a brief break. Early Friday morning an upper level low
over Southern Manitoba will begin to swing southeast. Another
upper level low will dive south across eastern Saskatchewan. As
this happens the upper level longwave trough axis will amplify.
Upper level diffluence will rapidly increase starting around 3
AM thanks to ILN being in between the subtropical ridge and
upper level trough axis to the north. As this occurs a band of 
showers and thunderstorms will start to fill in. There has been 
some disagreement on where exactly this band will likely form, 
but the latest ECMWF has no also pulled the band north following
suite with the NAM and CMC. This placement would put the band 
from a Wayne county (IN) to a Union county (OH) line. The GFS 
has a line that closely follows I- 71. PWATs on both the NAM and
GFS are around 2.10" at this time (near max values). Given the 
strong vertical lift and near max moisture values have kept PoPs


Friday morning looks wet as the upper level trough axis
continues to amplify with a strengthening RRQ approaching from
the west. Overall this event has the symptoms of a PRE. As the
tropical cyclone approaches a band of precipitation will form
Friday morning and be driven frontogenetically (as seen on GFS
fgen vectors). The event also is not directly from Cindy but
indirectly. The ILN forecast area is in a RRQ and the fgen band
looks to help to strengthen the upper level jet. The ILN 
forecast area is also north and left of the forecast track for 
Cindy (and north and west of a low level theta-e ridge axis). 
Run accumulated precipitation on the GFS, ECMWF, NAM and CMC 
show widespread totals of one to three inches with isolated 
totals of three to four inches. Give the strong upper level 
divergence/ diffluence, near max PWAT values, and vorticity 
advection have gone ahead and issued a Flash Flood Watch for the
entire CWA except Auglaize, Hardin, and Mercer counties. WPC 
also has the area in a day 2 moderate risk for excessive 

Friday afternoon the band of heavier precipitation will slowly
sag southeastwards as the upper level trough approaches from 
the northwest. The remnants of Cindy will also push east across 
Kentucky at this time. This means heavy rain will likely 
continue through the day Friday. Late Friday evening the 
remnants of Cindy will skirt just south of our southern zones 
with rain slowly coming to an end early Saturday morning.


Mid level trof to develop over the Great Lakes with westerly flow 
over the Ohio Valley. Surface high pressure to begin nosing into the 
Ohio Valley Saturday. Expect pcpn to stay north of the area with 
cool highs in the mid/upper 70s Saturday. 

Shortwave pivoting through the mean trof over the Great Lakes may 
lead to few showers but expect this pcpn to stay north of ILN/s FA.
Cool temperatures to continue with Sundays highs in the mid/upper 

With another s/w and the mean mid level trof across the Great Lakes 
can not rule out an afternoon shower mainly across the north Monday. 
Will limit these pops to slight chance. Temperatures look to be 
about 10 degrees below normal with highs on Monday in the lower and 
middle 70s.

Models solns sharpen up mid level trof over the eastern Great Lakes 
which may lead to a few showers or thunderstorms over the 
northeastern counties. Rather cool readings to continue Tuesday
with highs generally in the mid 70s.

Surface high pressure slide east with southerly low level developing 
on its back side at midweek. Expect dry conditions with a warming 
trend. Temperatures will be closer to normal with highs on Wednesday 
in the lower 80s.

Warm front to develop over the Great Lakes with southerly flow 
increasing. Temperatures will continue to moderate with highs 
Thursday in the lower and middle 80s. 

The ECMWF and Canadian solns bringing a progressive system through 
the Great Lakes Thursday, while the GFS holds off pcpn.  With an 
increase in moisture have allowed for a slight chance of a 
thunderstorm but confidence is not high in this chance.


A shield of -RA will continue to move north/east through the 
area this evening, affecting southern/eastern terminals with 
MVFR CIGs through 03z. With this pcpn, MVFR CIGs will 
overspread all terminals through the first several hours of the 
TAF period. As the air column slowly becomes saturated with 
increased moisture filtering into the area, some brief IFR CIGs 
may be possible between 06z-12z for all terminals. 

Towards 12z, additional clusters of SHRA with embedded TS will 
develop and begin to move southeast through the area for the 
remainder of the period. Do think that there will be periodic 
+SHRA embedded within the activity, which may lead to brief 
IFR/LIFR restrictions at times. Held off on inclusion of TS at 
TAF sites for now given uncertainty in spatial and temporal 
coverage of the thunder.

Southwesterly winds of 10 to 12 kts are expected during the day
tomorrow ahead of pcpn. As the front begins to move through
towards the end of the period, winds will shift more westerly
and eventually northwesterly. 

MVFR/IFR CIGs will likely linger for several hours behind 
shield of pcpn at end of TAF period.

OUTLOOK...Intermittent MVFR ceilings possible Saturday through 


OH...Flash Flood Watch from 2 AM EDT Friday through late Friday 
     night for OHZ042>046-051>056-060>065-070>074-077>082-088.
KY...Flash Flood Watch from 2 AM EDT Friday through late Friday 
     night for KYZ089>100.
IN...Flash Flood Watch from 2 AM EDT Friday through late Friday 
     night for INZ050-058-059-066-073>075-080.



National Weather Service Glossary of Abbreviations