Scientific Forecaster Discussion
Area forecast discussion
National Weather Service northern Indiana
1241 am EST sun Mar 9 2014
issued at 647 PM EST Sat Mar 8 2014
A ridge of high pressure will build into the southern Great Lakes
and Ohio Valley regions tonight resulting in decreasing cloudiness
and cold conditions. High pressure will move off to the east on
Sunday which will allow south winds to develop. The south winds
will bring moderating conditions into the early parts of next week
with highs above normal by Monday. Low temperatures will range
from 5 to 10 above zero across central lower Michigan to the lower
to middle 20s across central Indiana. High temperatures on Sunday
will range from the lower 30s across central lower Michigan...to
the middle to upper 40s across central Indiana.
issued at 856 PM EST Sat Mar 8 2014
Water vapor imagery this evening depicts a positively tilted short
wave from the northern Great Lakes into the Central Plains. This
short wave will move across the region overnight allowing low
level ridging to eventually overspread the area. Until the passage
of this short wave late tonight...patchy stratus will continue to
be possible especially in consideration of strong low level
inversion noted in 00z kilx radiosonde observation. Earlier evening update sent
mainly to refresh late afternoon wording...with forecast elements
in good shape. Some potential of some patchy shallow fog exists
late tonight/early Sunday morning given lingering near surface
moisture. Low level thermal troughing anchored across the eastern
Great Lakes combined with better radiational cooling conditions
overnight should support forecasted mins from lower teens north to
upper teens south. Still feel that warm side of guidance is
reasonable for tonight given lingering trapped moisture beneath
low level inversion and relatively lower snowcover albedo.
Short term...(this evening through sunday)
issued at 300 PM EST Sat Mar 8 2014
Patchy light snow and drizzle in vicinity of a southeastward sinking elevated front
will continue to taper off from northwest to southeast late this afternoon/early evening.
No accumulation/impact anticipated on roads. Large scale
drying/subsidence overspreads tonight into Sunday morning in wake
of a positively tilted shortwave trough. Brief cold/dry advection
burst should help scatter out low stratus from northwest to southeast...although
some concern that extensive stratus deck may linger longer than
currently forecast with 925 mb ridge axis not modeled to translate
through until later tonight. Otherwise...may see some patchy fog
develop toward daybreak given lingering near surface moisture/clearing
skies/and winds becoming light as surface ridge nudges in.
Low level flow veers southwesterly tomorrow as surface high folds
south and next northern stream upper wave tracks into Ontario.
Ample sunshine with bulk of warm advection clouds bypassing north
will support a modest temperature recovery into the 30s to near 40.
Long term...(sunday night through saturday)
issued at 300 PM EST Sat Mar 8 2014
Progressive split follow to start will evolve to amplified pna state by
lt period. Potential phasing issues west/potent SW impulse dropping out of
Canada still plague middle periods and expect successive model iterations
will be slow to catch on west/system evolution. Thus see little reason to
stray from prior forecast given continued indicated high spread.
However ll thermal ridge inadv of this system will yield a mild weather
Mon-Tue...although tempered somewhat Tuesday in face of increasing clouds
and veering to nearly follow. Some semblance of low pressure advg through the
Ohio River Tuesday night-Wednesday will bring snow to the area yet details remain
uncertain. Brief cold air advection Wing tucks in behind this system for Thursday followed
by a series of SW disturbances embedded within steepening northwest follow
Aviation...(for the 06z tafs through 06z Sunday night)
issued at 1226 am EST sun Mar 9 2014
Extremely dry subsident airmass continues to advect into northern Indiana.
Concern for greater br formation at kfwa either side of sunup
given airfield on western flank of higher dewpoint tongue and
sites typical drainage bias. Thereafter...VFR met conds to prevail
with focus on wind and core of 2kft jet aloft as strong low level jet core
currently across eastern Dakotas slides southeastward into northern in.
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