Scientific Forecaster Discussion
Area forecast discussion
National Weather Service northern Indiana
131 PM EDT Wednesday Mar 12 2014
issued at 502 am EDT Wednesday Mar 12 2014
Deepening low pressure will bring heavy snow...along with windy
conditions and falling temperatures to much of the region today.
Another burst of cold air will arrive behind the low sending
temperatures to near or below zero in many areas tonight with
highs in the 20s on Thursday.
Short term...(today and tonight)
issued at 456 am EDT Wednesday Mar 12 2014
Slightly slower transition of ptype given extreme northward advection of
warm tw aloft with rap13/local WRF at or above 0c through entire County Warning Area through
07 UTC with southeastward collapse below 0c not realized until about 13 UTC in
far southeastern tip County Warning Area. Suspect though this could be a bit sooner given
extreme coalesced dynamics of upstream system hastening thermal
collapse. Dumbelled upstream height fall centroids 120-140m/12hr to
cohesively meld to around 200m/12 hour this afternoon across cntl Ohio.
Suspect continuation of upstream convective elements to persist over
next several hours across southeastern half of County Warning Area within marginally unstable middle
levels per rap13 600-400mb layer with cohesive north-S slantwise tap into
200-250 j/kg MUCAPE near Ohio River. Given continued strengthening of
leading warm conveyor belt necessitates chance/slght chance mention southeastern
half until 14 UTC with focus thereafter sliding eastward.
Effective/extreme moisture feed overlaid dynamics suggest snowfall
rates 2-4 inches per hour possible especially within convective elements and
also kvpz-kekm-koeb-kdtw line where best overlay of deep/strong uvm
in response to fgen/ageo circ reaching through dgz. Slight
adjustments northward with hiest amounts...suspect 10 inches possible in northern
Maumee basin/northestern quarter County Warning Area where northern deformation band persists
for longest duration. Sig impact to am commute expected given timing
of extreme rates. With surface low track finally affirmed by 00 UTC NAM
have confidence of south of i70 track and followed
NAM/wrfarw/rap13/prior forecast for blended tweaks. Also notably better
clustering of sref ensemble snow accums and multi model Cobb output
fostering incrsd confidence vs 24 hours ago. 12mb/3hr fall/rise
couplet with surface low over southern increases to 15mb/3 hours by midday as surface
low reaches southwestern PA...funneling deep/nearly gradient wind for
blsn/drifting snow issues into afternoon. Rapid transition to anticyclonic low
level flow by late this evening to greatly relax flow...strong
radiational cooling with peak of 925mb thermal trough across County Warning Area for
near record lows Thursday am.
Long term...(thursday through tuesday)
issued at 456 am EDT Wednesday Mar 12 2014
Bitterly cold morning to start off Thursday. Surface ridge axis begins
to shift east but warm up will not arrive right away despite this.
Well below normal temperatures will still be in place with highs only in
the 20s...15 to almost 20 degrees below normal. It will be dry but
winds will slowly increase Thursday afternoon and continue a slow
upward trend into Friday ahead of the next trough and associated surface
front to sweep through. Upper level heights and ll thermal profiles
will increase and allow temperatures to head back closer to normal levels
(above in some spots) for Friday. Not impressed with precipitation chances
at all with no real moisture to work with. NAM still holds onto some
light precipitation being possible in far southeast areas Friday night as the
front moves through. Will leave probability of precipitation alone but would not be
surprised to have a completely dry forecast.
Highs Saturday will occur early with falling temperatures through the day.
The falloff may be slowed as a fast moving wave moves from the
plains into the Ohio Valley. Main energy will translate due south
and cut off into Mexico leaving little left for this feature to work
with. Neighbor consensus was to lower probability of precipitation and confine any chance to
far south...and couldn't disagree. Air behind this system will be
colder...but not as cold as the last push with temperatures in the upper 20s
to lower 30s sun and Monday and lows in the teens and single digits.
Yet another wave will drop out of the plains and make a run at the
region for Tuesday and Tuesday night. Temperatures will climb somewhat
again Tuesday and possibly Wednesday (if slower/deeper European model (ecmwf) occurs). Models
seem to be trending towards little chance of precipitation...but hesitant
to drop probability of precipitation entirely this far out so minor adjustments made.
Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 130 PM EDT Wednesday Mar 12 2014
Steady improvement expected at kfwa over the next few hours as
deformation band exits to the east. Still a chance for some MVFR
ceilings this evening but dry air and subsidence are building quickly
and would not be surprised to see VFR conditions by roughly 21z.
Clear skies and light winds expected overnight as high pressure
slides over the region.
in...Winter Storm Warning until 5 PM EDT this afternoon for
Michigan...Winter Storm Warning until 5 PM EDT this afternoon for
Ohio...Winter Storm Warning until 5 PM EDT this afternoon for ohz001-
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