National Weather Service Raw Text Product

527 
FXUS63 KIND 051927
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
327 PM EDT Fri Jul 5 2019

.UPDATE...
The SYNOPSIS...NEAR TERM and SHORT TERM Sections have been updated
below. 

&&

.SYNOPSIS...
Issued at 327 PM EDT Fri Jul 5 2019

Scattered thunderstorms will impact central Indiana into Saturday as 
an upper level low slides through the lower Ohio Valley. A few 
storms remain possible Sunday before high pressure builds south into 
the region. With the exception of a threat for scattered 
thunderstorms Wednesday and Thursday as a upper level wave passes 
through the region...much of next week should be warm and dry.

&&

.NEAR TERM /Rest of This Afternoon and Tonight/...
Issued at 327 PM EDT Fri Jul 5 2019

Areas of convection have fired within the steamy and unstable 
airmass so far this afternoon. Focus has been northeast of the Indy 
metro and then back to the west in the Wabash Valley. 19Z 
temperatures were in the upper 80s and lower 90s and the high 
humidity was pushing peak heat indices to around 100.

Focus into the evening remains on additional convective 
development...likely heavily influenced by colliding outflow 
boundaries. Potential does exist for development to focus over 
western counties during the next few hours in particular where 
better low level moisture and instability reside currently. That 
being said as has been the case the last few days...convection will 
be driven by mesoscale features in particular and with boundaries 
littered across the area...scattered convection is possible anywhere 
across central Indiana into the evening hours. 

Storms will largely be subsevere with little to no BL shear but 
presence of downdraft CAPE levels approaching 1000 j/kg does support 
potential for healthy wind gusts as cores collapse or along surging 
outflows. Have already seen wind gusts at 45-50 mph with some of the 
storms northeast of Indy. With the slow storm motions and precip 
water levels in excess of 1.75 inches...torrential rainfall and 
localized flooding will also continue as a primary impact. 

Should see convective coverage wane near or just after sunset as has 
happened the last few days with the loss of peak heating and deeper 
instability. Approach of a weakening upper low from the Missouri 
Valley however warrants maintaining a low chance pop all night as 
the feature drifts into the lower Ohio Valley by daybreak Saturday. 
Could see patchy fog develop late tonight as well in areas where 
rain falls.

Temps...another muggy night on tap with most if not all of the area 
remaining above 70 degrees all night. A model blend will work fine.

&&

.SHORT TERM /Saturday through Monday/...
Issued at 327 PM EDT Fri Jul 5 2019

Forecast challenges focus on rain and storm chances Saturday and 
potentially a lower threat Sunday before a shift to drier and less 
humid conditions by early next week.

The aforementioned upper low will drift slowly southeast into the 
Tennessee Valley through Saturday night before shifting further away 
into the Mid South by late weekend. After being under the upper 
ridge...the core of the ridge will shift back west towards the mid 
and upper Mississippi Valley which will enable heights to slip back 
a bit across the region by Monday. 

Saturday will be another day with convection developing by late 
morning into the early afternoon across central Indiana. In addition 
to the unstable airmass...the presence of slightly better forcing 
aloft as the upper low drifts into the Tennessee Valley should 
enable a higher coverage to showers and storms by Saturday afternoon 
than we have seen the last few days. Have nudged pops up into the 
likely category as a result for the afternoon and early evening. 
Similar to the last few days...storms will likely pulse in intensity 
with limited organization...with gusty outflow winds and torrential 
rainfall and flooding serving as the main threats. 

Storms will diminish and shift south Saturday night along a weak 
frontal boundary. The boundary will remain close enough to the 
region Sunday to warrant low chance pops over the region in the 
afternoon...especially south of I-70. Most will remain dry however 
with low level flow shifting to northerly as high pressure builds 
south from the Great Lakes. The high will expand further into the 
region Sunday night and Monday with model soundings showing a drier 
airmass advecting in from the north and a mid level cap developing.

Temps...another humid day with heat indices peaking in the 90s on 
Saturday before less humid air arrives Sunday and Monday. Highs will 
remain in the mid and upper 80s into Monday with low level thermals 
supportive of a model blend. Lows will fall back into the 60s.

&&

.LONG TERM /Monday Night through Friday/...
Issued at 216 PM EDT Fri Jul 5 2019

Dry weather will bookend this period with chances for some showers
and storms on Wednesday and Wednesday Night.

ECMWF shows ridging in place across Indiana on Monday and
Tuesday...along with surface high pressure...subsidence and weak
but mainly northerly flow. Thus have trended toward a dry forecast
at that time. By Wednesday a quick moving short wave is expected
to approach Indiana from the upper midwest...passing across
Indiana through Wednesday Night and Thursday. This feature will
provide ample upper support and once again pops will be warranted.

On Thursday Night through Friday...the ECMWF shows the upper short
wave departing while strong ridging and high pressure builds 
across the American southwest. This will result lee side 
subsidence and NW flow across Indiana and the upper midwest. Thus 
will trend toward dry weather at that time with highs at or below 
seasonal normals. 

&&

.AVIATION /Discussion for the 051800Z Tafs/...
Issued at 104 PM EDT Fri Jul 5 2019

Mainly VFR Conditions are expected this taf period. Brief MVFR
conditions will be possible with any TSRA that strikes a TAF site.

The warm and humid air mass in place across Central Indiana will
continue to be favorable for diurnal afternoon and evening 
showers and storms. Forecast soundings show plenty of CAPE through
the evening hours with attainable convective temperatures. Thus 
will use VFR Conditions this afternoon with a large VCTS window 
into the evening. Should a TSRA appear to approach a TAF 
site...will include prevailing expected IFR conditions within an 
update.

Any Diurnal TSRA will diminish late this evening as heating is
lost.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE. 

&&

$$

SYNOPSIS...Ryan
NEAR TERM...Ryan
SHORT TERM...Ryan
LONG TERM....Puma
AVIATION...JP