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Area forecast discussion 
National Weather Service northern Indiana
614 am EST Friday Nov 28 2014

issued at 334 am EST Friday Nov 28 2014

Cloudy skies and unseasonably cold temperatures will continue through
today with afternoon highs ranging from the upper 20s north to the
middle 30s south. Much warmer air will overspread the region this
weekend with highs tomorrow expected to top out in the middle to
upper 40s.


Short term...(today and tonight)
issued at 334 am EST Friday Nov 28 2014

Disturbance aloft embedded within potent jet streak across ND will
shear southeastward today within continued northwest follow aloft. Western periphery of polar
ridge is extremely dry as indicated in upstream kdvn/kilx 00z radiosonde observations
and no doubt borne out in top down saturation failure currently seen
from SW WI into central Illinois. Vast majority of 00z based guidance takes
strongest 295-300k pressure perturbation across central lower Michigan directed along nose
of stronger ll moisture flux aligned west/eastward weakening jet streak. However this may
yet clip far northestern zones lt this afternoon/early evening shld sub cloud pressure
deficits erode sufficiently. Regardless have generally cut probability of precipitation
throughout in what will be a non measurable event at most.

Even though ll warm air advection ramps sigly this afternoon on backside of polar ridge
one more round of well below normal temperatures expected given cold start and
incipient cloud cover. However this will conversely hold temperatures up tonight
west/near steady temperatures expected after temperatures peak this afternoon.


Long term...(saturday through thursday)
issued at 334 am EST Friday Nov 28 2014

Roller coaster temperatures are the main story for this long term period as
perturbed but largely zonal flow keeps chances for high impact
weather at a minimum. Southern Great Lakes will be well entrenched
in the warm sector of surface low pressure developing over the upper
Midwest on Saturday. 850mb temperatures surge into the middle teens by late
Saturday but stubborn low level inversion will prevent US from fully
capitalizing on this warm air aloft. Expect persistent and
relatively thick stratus deck...along with low sun angle...will
prevent any substantive planetary boundary layer mixing. Nudged saturday's highs down a
bit to be more in line with latest raw guidance but still maintained
temperatures around 50f in our southwest out of respect for very warm
conditions right above the surface. Models continue to generate
light quantitative precipitation forecast in warm air advection regime late Saturday into Sunday but still think
chances of seeing any precipitation in our area during this time are very
low. Moisture depth seen on forecast soundings is awfully thin for
the production of hydrometeors. Furthermore...entire cloud layer is
above freezing with no potential for mixed phased/bergeron processes
to occur. Synoptic forcing is virtually non-existent with just some
broad/weak moist isentropic ascent in the very low levels of the
troposphere. If anything...expect just some patchy drizzle...mainly
confined to Saturday night with a little better Theta-E surge.

Slightly better chances for precipitation late Sunday as cold front sweeps
through the area. Good low level convergence should generate a few
light rain showers...especially in our southeast where deeper
moisture will reside. Surface front will clear our County Warning Area by Sunday
night and signal the start of strong cold air advection...with 850mb temperatures
returning to almost -10c. Expect most precipitation will end by the time
temperatures turn cold enough for snow. Some concern for a secondary vorticity
maximum to swing through and light up an elevated fgen band over our
area on seen in the 00z Gem and to a lesser extent the
European model (ecmwf). Will keep an eye on it but the Gem solution appears to be
largely an outlier and will lean toward drier consensus.

Middle of the week looks relatively dry with the next trough not
arriving until late Thursday or Friday. Temperatures will moderate somewhat
by the end of next week but still holding around average for early


Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 609 am EST Friday Nov 28 2014

VFR conds expected through the period. Shearing disturbance aloft across WI
inducing vigorous middle level based radar echo from southern WI into northwest in yet
unable to overcome saturation void existing below cloud base. Expect this
will continue to be the case through the day west/continued dry entrainment as
ll southwesterly follow increases even though secondary wave seen turning out
across western ND will likely illicit a even stronger middle level fgen response lt
this afternoon but again expected to lie up across Southeast Michigan.


Iwx watches/warnings/advisories...


short term...T
long term...agd

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