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Area forecast discussion 
National Weather Service northern Indiana
652 am EST Wednesday Nov 25 2015

issued at 355 am EST Wednesday Nov 25 2015

High pressure centered over New England will provide dry weather
into Wednesday evening. A frontal system will then slowly emerge
from the plains and bring a period of wet weather for the latter
part of the week. Highs today will primarily be in the lower to
middle 50s. Lows Thursday morning will be in the upper 30s to
lower 40s.


Short term...(today and tonight)
issued at 344 am EST Wednesday Nov 25 2015

Little substantive change in short term period. Low level warm air advection through
the period/initially weak but with near full insolation favor
current forecast/warmer mav/ec guidance. Slight upward adjustment with
non diurnal trend for Wednesday night with eastward progression of cloud
cover. Fine tuned timing of ramping low/Middle Range chance probability of precipitation
later tonight into northwestern County Warning Area. Initial high 100-150mb 925 mb
condensation pressure deficits attest to initial dry sub cloud
layer to overcome. With time however as i295k ascent continues and
leading/eastern flank of Richer 1000-850 mb mixing ratios overspread
northwestern County Warning Area suspect a few hundreths by daybreak/northwestern third. Believe
large scale/persistent middle tropopause height rises across southern Great
Lakes as Nevada cutoff becomes rexed lends amplification of ridge
from Gomex into middle addition to antecedent dry subcloud
layer point to muted/initial response until greater northern
stream wave influence and arrival of Richer low level Theta-E ridging
into County Warning Area awaits for dys2-3.


Long term...(thursday through tuesday)
issued at 344 am EST Wednesday Nov 25 2015

Temperatures surging well into the 50s (possibly 60 southeast) remains
the main story into Thanksgiving as southwest flow deepens within
pre- frontal low level jet. However...skies will trend cloudy with a period
of rain possible into northwest in/southern Michigan as corridor of low level
isentropic upglide/Theta-E advection folds in. Bulk of rain still
on target to sink east-southeast through the local area Thursday night into
Friday as positively tilted upper trough translates through the
Great Lakes and forces frontal boundary through. Highs probability of precipitation and
moderate quantitative precipitation forecast warranted given ample moisture return and anafront
setup under the right entrance region of a 120-130 knots 300 mb jet.
Drier otherwise Post frontal into Saturday as temperatures cool closer to
seasonal norms.

Flow pattern likely remains progressive thereafter as large
leftover negative height anomaly over the western US Sunday
emerges into the north-central US by early next week. Shortwave
ridging aloft in advance should help maintain low level ridging
across at least the central Great Lakes...with primary uncertainty
Saturday night into Sunday how far north rain shield reaches with
renewed SW flow/lead shortwave. Latest guidance has trended more
suppressed with this wave through the Ohio/Tennessee valleys...but given
the run-to-run inconsistencies opted to retain low-middle chance probability of precipitation
(highest south). Medium range guidance actually more consistent
with main system/surface occlusion (and associated rain chances) to
lift through around Monday night-Tuesday.


Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 643 am EST Wednesday Nov 25 2015

Primary focus on developing low level wind shear Wednesday night as 2kft jet ramps to
50-55 kts...highest in vicinity of ksbn. Also timed arrival of
light rain and lowering cloud bases as top/down saturation begins
in earnest. Conditions may further lower into IFR range beyond the
current taf valid period at ksbn...though likely dependent upon
rain coverage/intensity.


Iwx watches/warnings/advisories...
Lm...Small Craft Advisory from 3 PM this afternoon to 11 PM EST
Thursday for lmz043.

Small Craft Advisory from 10 am this morning to 11 PM EST
Thursday for lmz046.



short term...Murphy
long term...steinwedel

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