Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 231037

Area Forecast Discussion
National Weather Service Northern Indiana
637 AM EDT Fri Mar 23 2018

Issued at 510 AM EDT Fri Mar 23 2018

Despite ample sunshine today, temperatures will remain below
normal with highs in the 40s. Snow is expected to develop late
tonight, mainly south and west of a line from near Winamac to
Marion Indiana. Several inches of snow are possible south of this
line. Warmer temperatures are expected next week but this warmth
will bring rain back to the area and it could be locally heavy.


.SHORT TERM...(Today Through Saturday)
Issued at 510 AM EDT Fri Mar 23 2018

High pressure anchored near Hudson Bay will extend south over the
region today. Temperatures will moderate a few degrees but no strong
warming with low level southeasterly flow so highs will remain below
normal despite ample sunshine.

Lee side cyclogenesis still expected tonight into Saturday as
Pacific short wave exits Rockies. Aforementioned high pressure will
only be able to drift slightly east through Saturday and will act to
block approaching surface low and steer it southward. Baroclinc zone
ahead of this wave will tighten in response to very warm air being
drawn northward while anchored high keeps cold easterly flow over
the Great Lakes. Arrival of deeper moisture surge with increasing
low level jet tonight will help develop pcpn along and north of
strengthening warm frontal zone. 00z models have trimmed the
northeast extent of pcpn while also shifting pcpn axis southward in
response to impressive dry easterly low level flow of 25-35kts. This
will create a very sharp cutoff and another tight gradient to snow

NAM12 remains outlier spreading pcpn farthest east into the drier
air while also showing over an inch of QPF into our far southwest.
NAM3 more in line with model consensus of southern shift in pcpn
along with less QPF. Consensus blends keep most pcpn and higher snow
totals south and west of a line from about Winamac to Marion. See no
reason to keep far eastern counties in Watch given these model
trends. Further trimming of watch likely if 12z runs continue to
suppress system with dry air entrainment. Accumulations around 6
inches still possible but likely confined to southern White and
maybe southern Cass county. Continue to think mainly an advisory
level event for the southwest with low impacts given air
temperatures rising above freezing Saturday. Low visibilities and
slushy snow accumulations on roads with heavier snow bursts of most


.LONG TERM...(Saturday through Thursday)
Issued at 510 AM EDT Fri Mar 23 2018

Gradual warming trend with above normal temperatures still on track
for next week but also with high chances of rain and locally heavy
rain as well.

Western Conus trough will develop with closed low forming over the
southwest Conus. This will generate climatologically favored pattern
for warmer temperatures but also heavy rainfall across the mid
Mississippi to Ohio Valley and western Great Lakes region by Tue-
Wed. Mid level moisture plume will likely develop off the Pacific
while low level jet pulls combined Gulf and Atlantic moisture
northward. Medium range models showing potential for a coupled mid
level jet aiding in large scale lift over slow moving surface
boundary. The question will be where this surface front lies next
week along with timing of individual short waves along front.
These details remain difficult to nearly impossible to determine
at these longer projection times so will have to continue with
high pops for expected rain and broad mention of locally heavy
rain potential in HWO. Rainfall amounts of 1 to 2 inches possible
and somewhere near stalled boundary could see higher amounts. This
could however, be well south of our area.


.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 630 AM EDT Fri Mar 23 2018

A strong upper level system was ejecting east out of the Rockies
early this morning. This system will race east toward the Mid
Mississippi Valley later today. As this system approaches
northern Indiana, winds will veer to the east early tonight. A
very dry east flow will help conditions remain VFR through the TAF


IN...Winter Storm Watch from late tonight through Saturday afternoon
     for INZ013-020-022-023-032.



SHORT TERM...Lashley
LONG TERM...Lashley

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