Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 221744

Area Forecast Discussion
National Weather Service Northern Indiana
1244 PM EST Wed Feb 22 2017

Issued at 1233 PM EST Wed Feb 22 2017

Clouds continue to slowly break up across the area today as dry
air works in allowing a chance for temps to rise into the mid to
upper 60s before the day ends. Clouds will slowly work back into
overnight tonight keeping lows in the upper 40s to mid 50s. Then
Thursday will have increasing chances for rain late as a low
pressure system approaches from the Plains. Severe weather is
possible on Friday as a front moves through the area. High temperatures
Thursday and Friday will be in the 60s before falling to more
seasonable temperatures for the weekend. As the cold air begins to
move into the region on Saturday, a chance for snow showers is


.SHORT TERM...(Today and Tonight)
Issued at 356 AM EST Wed Feb 22 2017

Expansion of dense fog advisory in time /additional hour/ and
areal extent to include St. Joseph Co. MI with most dense fog
confined to northern periphery of high level cloud shield
associated with shortwave/vortex over deep south. While point
visibilities will likely to continue to oscillate, overall do not
anticipate much improvement over next few hours as southern stream
system pulls southeastward into Gulf of Mexico with idyllic
longwave losses in fog area/nwrn to nrn cwa holding firm. As
middling eastern Dakotas frontal wave pushes into western/Upper
Great Lakes anticipate relatively quick mix out of dense fog,
perhaps into temporary 2kft agl stratocu layer before scattering
out this afternoon coincident with approach of precedent low level
thermal ridge. Suspect an aggressive/overperformance of surface
temps over mos, but reigned in slightly given initial cloud
cover/overly optimistic prior forecast and cooler
temperatures/lows observed this morning. Nonetheless still
affording record/near record afternoon highs. Sufficient mixing in
advance and with dry fropa overnight should preclude any
substantive br formation.


.LONG TERM...(Thursday through Tuesday)
Issued at 356 AM EST Wed Feb 22 2017

Primary focus remains on convective potential later this week with a
highly conditional severe risk. Ejection of complex intermountain
vortex into northern/central plains Friday and into Upper Great
Lakes by Saturday morning. Associated strong/deep frontal zone
progressing eastward through this time with mid/upper 50s dewpoints
surging northward into CWA Friday afternoon. 06 UTC NAM now showing
a bit better congealing of low level jet focus midday into Fri
afternoon/50-60 kts deep layer shear/1400-1800 j/kg MUCAPE...whereas
00 UTC rendered more faster eastward translation of low level jet.
Extensive cloud cover/remnant decay of earlier convection could
render instability much less. Regardless must continue to mention
first severe event potential Friday in HWO.

Thereafter little change from latest blend with broad CONUS trough
and wrap around moisture for rain to snow Sat. Thereafter gradual
warming trend/heights rise until a more deep/GOMEX moisture laden
system approaches late dy6-7.


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1233 PM EST Wed Feb 22 2017

Morning LL cloud cover and VISBY reductions were dissipating as
drier air worked into the region. Expecting cloud decks within MVFR
criteria, but some breaks to VFR are possible especially at SBN.
Then as we move into the overnight hours, low level moisture moves
back in, but a low level jet between 30 and 40kts passes overhead
allowing sfc winds to be too strong for widespread fog, however
there appears to be a better chance for low level stratus/br. Shear
appears marginal as the jet passes overhead so have left it out of
this issuance.




LONG TERM...Murphy

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