Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 220616

Area Forecast Discussion
National Weather Service Northern Indiana
216 AM EDT Mon May 22 2017

Issued at 157 AM EDT Mon May 22 2017

Dry weather is in store for today as high pressure tracks across
the Ohio Valley. Chances of rain will increase later tonight
across southwest Lower Michigan and northwest Indiana as a weak
disturbances approaches from the west. Low chances of rain are
expected for Tuesday, with rain becoming likely by Wednesday as a
stronger disturbance slowly tracks across the central United
States. This system will be slow to exit with rain chances
persisting Wednesday night into Thursday. High temperatures today
will range from the upper 60s to lower 70s with low temperatures
tonight dropping back into the lower to mid 50s.


.SHORT TERM...(This Evening through Monday)
Issued at 401 PM EDT Sun May 21 2017

Scattered line of shallow convection along a KTOL-KVES line at this
time and to exit far eastern CWA within the hour. Expect upstream
wrap around stratocu to maintain bkn-ovc through about midnight then
gradually/partially clear thereafter as subsident ridging builds
eastward into the Lower/Mid Ohio Valley. Strong 8H thermal recovery
and good amount of insolation should result in strong diurnal rises
for Mon and have raised temps slightly, especially western CWA.


.LONG TERM...(Monday Night through Sunday)
Issued at 401 PM EDT Sun May 21 2017

Slow progress of significant northern Sask wave dive around
western Upper Great Lakes vortex to garner only limited chances
showers into northwest CWA, primarily late Monday night. Strong
surface cyclogenetic response as shortwave rotates through, but
ardent blocking nature of west coast ridge as it further builds
northeastward with time will maintain CWA in warm sector through
Tuesday, though likely marred by extensive cloud coverage. Gradual
eastward press of mid level vortex to bring increase in mid level
lapse rates and associated height falls to support increase in
convection by midday Tue with MUCAPE bumping to at least 1000
j/kg. Have added only slight chance mention at this time given
muted destabilization and weak shear profiles. Slight chance tsra
mention Wed afternoon as well over southeast CWA given slow
progression of now deeply stacked cyclone. Further delay at the
expense of coastal cyclogenesis could require greater expansion.
Gradual filling/liftout to bring west to east end of shra chances
Thu. Midweek highs running about under influence of deep system.
Thereafter, quite low confidence as suggestions of next deep
northern stream system to again be affected by blocking pattern.
However shortwaves in deep wswly flow with Southern Plains
cyclogenesis likely latching onto remnants of diffuse thermal
discontinuity TN Valley to Ozarks with chances for convection
again late Friday into the weekend.


.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 157 AM EDT Mon May 22 2017

Very little change from previous 00Z TAFS with VFR conditions
expected to hold this forecast cycle. Westerly wind gusts continue
to slowly diminish early this morning, but should stay up around
the 10 knot range into the early morning hours. Vort lobe across
southwest Wisconsin rotating through parent southwest Ontario
upper circulation will lift across the western Great Lakes region
this morning with fairly strong subsidence overspreading the
region. This should erode VFR low clouds this morning. Clouds
eventually increase late today and especially tonight across
northwest Indiana downstream of weak perturbation lifting
northeast from the Mid Ms Valley. Will keep TAFS dry at this time,
although may need to consider -shra or vcsh mention at KSBN late
tonight with the next TAF issuance. Combination of diurnal mixing
and strong deep layer subsidence should support west gusts into
the 20 to 25 knot range once again late morning/afternoon.


LM...Small Craft Advisory until 11 AM EDT this morning for LMZ043-046.



LONG TERM...Murphy

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