IWX issues Area Forecast Discussion (AFD) at Dec 13, 3:37 AM EST143
FXUS63 KIWX 130837
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
337 AM EST Fri Dec 13 2024
.KEY MESSAGES...
- Outside of a few flurries early this morning, dry conditions
will prevail today with partly to mostly cloudy skies. Highs
will be in the 20s and 30s. Lows tonight will be in the teens
and low 20s.
- Rain will move in late Saturday afternoon into Sunday
evening, then again late Monday morning into Monday evening.
Around a half an inch of rain is expected. Highs will be in
the 40s and 50s, and lows will fall into the 30s and 40s.
- Colder temperatures return by the end of the work week, with
highs in the 30s and lows in the teens and 20s. There are
chances for snow showers.
&&
.DISCUSSION...
Issued at 335 AM EST Fri Dec 13 2024
High pressure building into the Great Lakes region beneath an upper
level ridge today will put an end to any snow chances by late
morning. Winds also shift from of the lake to more easterly, which
will end the lake enhancement to shower activity. Some of the area
will see sunshine, mainly to the north and east. Lows tonight will
drop to the teens and low 20s.
A vertically stacked low pressure system will slide into the central
plains Saturday afternoon and lift northeastward into the Great
Lakes through Sunday evening as it fills. Thankfully warm air
advection ensues and 850 mb temps rise to 1-3C, with decent moisture
transport developing on the LLJ ahead of the decaying system. The
best moisture transport/lift looks to be Saturday night into Sunday
evening, so pushed pops back from early Saturday to late Saturday
afternoon (chances) with categorical/likely pops Saturday night into
Sunday. High temperatures look to linger in the mid-upper 30s
further northeast and the low 40s elsewhere Saturday, and then into
the 40s and 50s for Sunday. Outside of a little mix where temps drop
into mid 30s, expect around a quarter to half an inch of rain.
We see a quick break Sunday night into Monday as the upper low moves
towards the east coast and an upper level ridge builds in. Lows Sun
PM will be in the upper 30s and low 40s. Meanwhile, another upper
level trough/surface low approaches from the west, moving from the
Dakotas 00z Mon to James Bay by 12z Tue. This will bring a cold
front through our CWA, with a secondary developing surface low
developing over IA). With a surface high off the eastern seaboard,
warm moist air off the gulf lifts northward ahead of the front into
our area by 12-18z Monday. 850 mb temps once again climb to around 5-
10C, so highs Monday look to remain in the 40s and 50s. We'll have
another round of rain-with categorical/likely pops Mon beginning
after 12z and continuing into the late evening. Lows Mon PM will
fall into the low to mid 30s, but likely towards Tue AM when most of
precipitation has moved out, so we have no rain/snow mix at this
point.
High pressure returns for Tuesday into Wednesday, with highs in the
upper 30s and 40s, and lows in the 20s. Cloud cover will be variable
Tuesday then increase to mostly cloudy by Wednesday. Lower
confidence on pops for Wed Afternoon (I delayed by 12 hours from the
blend pops)-the GFS suggests we'll see a weak surface low develop
and move into the CWA---but the ECMWF keeps it well south near the
gulf and limits moisture transport into the Great Lakes. Kept low
chances of 20-30 percent in for Wed night-Thu with subsequent lake
enhancement that follows in the wake of the low. Model solutions
vary quite a bit for Friday so left consensus 20-40 percent chances
in there. The ECMWF swings that developing low to the south back
northeast along the coast, which eventually merges with the deep
trough impinging from the northwest on the Great Lakes. The GFS
develops an E-W baroclinic zone and some Lake effect. It appears
we'll have some sort of precipitation but the exact details are
unclear. Temps look colder, so probably will see more snow than rain
in this period.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 100 AM EST Fri Dec 13 2024
Passage of mid level trough overnight will allow for eventual
scattering/clearing of mid level and VFR clouds. Weak west-
northwest winds to begin the period will become light and
variable during the overnight hours as a strong 1040 mb high
drifts in from the northwest. Low and mid level warm advection
will strengthen during the day Friday with some patchy WAA mid
level clouds possible. Low level ridge axis will extend from
east central WI into PA this afternoon that will lead to
southeast winds in the 5 to 10 knot range across northern
Indiana. VFR conditions should persist through this forecast
period as short wave upper ridging builds into the western Great
Lakes tonight.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...MCD
AVIATION...Marsili
Source:
IWX issues Area Forecast Discussion (AFD) at Dec 13, 3:37 AM EST---------------
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