Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Indianapolis in
1219 PM EST Friday Nov 21 2014
the aviation section has been updated below.
issued at 324 am EST Friday Nov 21 2014
High pressure will keep dry conditions across central Indiana
through today. However...it will push off to the east as a warm
front and a strong low pressure system enter from the southwest
tonight. This system will keep precipitation in the forecast through the
weekend. In its wake...colder and drier weather will return for
Near term /rest of today/...
Issued at 1000 am EST Friday Nov 21 2014
1430z update...no major changes needed for this late morning
update. Only needed to make some minor adjustments to account for
the latest temperature and dew points trends. Otherwise previous
The main focus of the near term period will be increasing cloud
Conditions will be calm for majority of the day with dry
conditions and highs topping off in the middle to upper 30s.
However...there will be increasing cloud cover from southwest
to northeast through the course of the day as a frontal system
draped across Oklahoma and Missouri moves closer to the forecast
Short term /tonight through Sunday night/...
Issued at 324 am EST Friday Nov 21 2014
The main focus of the short term period will be precipitation chances and
types with a warm front and surface low pressure system.
First wave of moisture ahead of next system is prognosticated to enter
central Indiana from the southwest this evening. Slowed down onset
time of precipitation by a few hours as models lean more toward the Sat
03-06z time frame. Precipitation will become more widespread across all
of central Indiana after Sat 06z. Thicknesses continue to indicate
freezing rain over most of the area except the southern counties
which can expect rain. Warm air advection will quickly filter into
the area by Sat 12z though...causing freezing rain to transition
to all rain. Due to the short time period and minor ice
accumulations will continue to leave headlines out.
Surface low will continue its track across Mississippi Valley on
Saturday and Saturday night...but highest chances for rain will be
on Sunday as best lift from warm front and low pressure traverses
the area. As a result...will go with definite probability of precipitation for most of
Temperatures...expect highs to climb into the 50s with decent warm
advection...and lows to be in the 40s. The only exception will be
tonight when they still dip into the 20s and 30s.
Long term /Monday through Thursday/...
Issued at 324 am EST Friday Nov 21 2014
Model ensembles indicate a cold front will sweep across our region
Monday as strong low pressure moves east across the upper Great
Lakes. It will still be mild and wet Monday morning followed by
following temperatures Monday afternoon as precipitation diminishes.
The rest of the long term will consist of colder than normal
temperatures as an upper trough moves east across the northern U.S.
Into the Great Lakes region. Quiet weather will be the rule Tuesday
into early Wednesday. But will continue mention of low chance probability of precipitation
or flurries over northern sections Tuesday.
A weather disturbance may bring better chances of light snow late
Wednesday into Thursday with some mixed precipitation across
In regards to temperatures a MOS blend seemed reasonable most
Aviation /discussion for 211800z taf issuance/...
Issued at 1218 PM EST Friday Nov 21 2014
VFR conditions for the rest of the afternoon with clear skies and
southeasterly winds around 6-10kts. Tonight sky cover will increase
with ceilings developing around 3500 feet around 1-3z. Warm air will
advect in above the ground and bring a few hours of very light
freezing rain to the sites starting around 6z at kbmg and khuf and
8z at kind and klaf. Expect it to last for 3-4 hours before surface
temperatures warm above freezing. The low level jet will increase
during this time so also added low level wind shear at 12z as winds
increase to around 50 kts out of the southwest with surface winds
near southerly. Forecast soundings show this continuing through the
day with an inversion staying in place and off and on rain showers
and MVFR ceilings.
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