Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 03/03/20
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
558 PM CST Mon Mar 2 2020
.SHORT TERM...(This evening through Tuesday)
Issued at 109 PM CST Mon Mar 2 2020
Aloft: RAP tropopause analyses...WV imagery and aircraft obs
indicated an elongated trof extending from low pres over James Bay
acrs NEB to low pres over AZ. A separate shrtwv trof was in the
NW flow over SA/MT. The initial trof will move S and E of the CWA
before sunset. The upstream shrtwv trof will then move thru
tonight... introducing NW flow for tomorrow...within which there
will be a weaker shrtwv trof...but it is fcst to remain N of the
CWA.
Surface: 1015 mb high pres was over KS. 991 mb low pres was over
cntrl Canada with a sfc trof extending S to the NEB panhandle. The
high will fill as it departs to the E tonight. Meanwhile...the
low will move E acrs Srn Canada. The associated sfc trof will
cross the CWA. Wk high pres will emerge into KS tomorrow...with a
wk low moving SE from AB to SD.
Rest of this afternoon: Variable clds...ranging from cldy to sunny
as there is a large patch of clds 6-7K ft moving E. Sun will
become more prevalent as these clds exit to the E. Clds are
holding temps down...but should see highs in the 40s...with a cpl
50-51F readings from Cambridge-Phillipsburg-Beloit.
Tonight: IR satellite shows an arc of multi-layered mid-high clds
preceding the aprchg shrtwv trof and currently moving into the
Panhandle. This band of clds will move thru tonight with clearing
from NW-SE behind it. Lows around 30F give or take a cpl degs.
Tue: Sunny and becoming brzy...espcly in the afternoon. Without
the wind...it would be warm. Highs 60-65F. Pls see fire wx section
below.
.LONG TERM...(Tuesday night through Monday)
Issued at 109 PM CST Mon Mar 2 2020
Pattern: More of what we`ve seen since mid-Nov. Low-moderately
amplified W-E flow.
Aloft: NW flow from Tue will cont thru Fri. The flow will back a
little bit Wed into Wed night as a strengthening shrtwv trof
crosses the Nrn Plns. Heights will rise over the Plns Fri though
as an amplifying ridge approaches. Once the ridge passes Fri
night...SW flow will prevail Sun-Mon. A wk shrtwv trof is fcst to
move thru Sun night into Mon AM.
Surface: Wk high pres will depart NEB/KS Wed as a Clipper dives
to ND. The cool front associated with this low will move thru Wed
night. Strengthening high pres will gradually build in and crest
over the rgn Thu night. This high will gradually drift to the E
coast thru the wknd...with NEB/KS in the windy warm sector until
the next cool front moves thru Sun night. Incrsg dwpts will help
minimize the fire danger...but it won`t eliminate it.
Temps: Continued mild. Lots of 50s and 60s until Mon...when the
warmth is suppressed and 40s appear N of Hwy 6. Sat and Sun will
be the warmest days. Would not be surprised to see some 70s Sat
and Sun. The blend of mdl 2m temps suggests widespread 70s is
possible Sun.
Precip: Dry until Sun night. The 06Z/12Z GFS both suggest a few
shwrs Sun afternoon. The 00Z and 12Z EC suggests it will remain
dry until after the passage of the cool front. If something should
develop along the cool front...some rumbles of thunder could occur
in weak instability. The EC will probably be right as 2 days of SW
flow will advect an EML over the rgn.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 554 PM CST Mon Mar 2 2020
After a brief MVFR ceiling in KGRI during the first hour, we
should have VFR conditions for the rest of the forecast. Gusty
wind should decrease quickly as the sun sets, and will probably be
on the gusty side once again for Wednesday late morning into
afternoon.
&&
.FIRE WEATHER...
Issued at 109 PM CST Mon Mar 2 2020
Fire wx conds should be near-critical Tue and possibly Thu
afternoons. Tue N of I-80...and espcly N of NEB Hwy 92. Thu
confidence is low as winds will be highest where RH`s will be more
marginal (25-30%)...and that will be E of Hwy 281. We need some
time to refine the RH fcst and where the risk of near-critical
might be...if it even occurs.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...Heinlein
FIRE WEATHER...Kelley
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
857 PM CST Mon Mar 2 2020
.UPDATE...
856 PM CST
While the weather is quiet across the region this evening, there`s
actually quite a bit going on aloft. None of this is expected to
translate into much in the way of sensible impacts for us, but did
end up adding a mention of snow and rain to our northern-most
counties tomorrow morning and can`t rule out some sprinkles or
flurries this evening south of I-88.
GOES-16 Simple Water Vapor RGB loops depict an elongated PV
anomaly and attendant upper jet streak arcing across central
Missouri with convection blossoming within a region of enhanced
divergence. Farther to the north, have noted some increase in
mid-level radar echoes across parts of our area at the far reaches
of this aformentioned jet streak. The evening RAOB out of central
Illinois (ILK) sampled a still parched 700-1000 mb layer, although
recent VAPOR AMDAR soundings have shown a propensity for things to
get a bit more saturated down to around 800 mb or so. This is
corroborated by neighboring radars which are pinging returns down
to around 6,000 feet or so. As a result, can`t rule out some
flurries or spits of light rain as this activity moves overhead
through the rest of the evening. Based on the current trajectory
of the blossoming convection to our south, it appears that the
northwest edge of this activity should remain just south and east
of our area tonight, but showers might get close to clipping parts
of Benton county late.
Farther upstream, the first in a series of fast-moving clipper-
like systems is pinwheeling across the northern Great Plains and
looks to be moving overhead through the morning hours on Tuesday.
Large-scale forcing for ascent actually looks pretty good with
this feature, with 120/12hr 500 mb height falls and jet divergence
spreading into the area with the arrival of the parent trough
axis. Evening model guidance is showing a narrow window for deeper
lower-tropospheric saturation during the 6-11 am timeframe, and
this does now appear sufficient to eke out some light QPF mainly
near the WI/IL state line. Thermal profiles may be a little
marginal, but respectable dynamic cooling is advertised such that
a snow/rain mix appears possible as a narrow band of precipitation
quickly spreads eastward. Have added some mentionable rain/snow
chances north of I-88 as a result, with flurries (or sprinkles) to
the south. No impacts are expected given the overall marginal
nature of things, but a brief burst of more moderate rain/snow or
all snow appears to be within the envelop of possibilities near
the state line in the morning.
Nudged wind gusts up a smidge in the afternoon as guidance
continues to support fairly deep mixing well into upper 30 kt
flow, supportive of sporadic 35 to 40 mph gusts. Beefed up
afternoon sky cover a bit as it looks like we`ll mix readily into
a Cu field, and wouldn`t be shocked to see a shower or two try to
develop with afternoon heating given the depth of mixing and
sliver of surface-based instability on area BUFKIT soundings.
Updated products have been transmitted.
Carlaw
&&
.SHORT TERM...
233 PM CST
Through Tuesday night...
Main focus in the short term is on a pair of clipper-type systems
which will move through the forecast area. The first one, late
tonight, will be rather moisture-starved with the greatest
potential for precipitation largely north of the forecast area.
The second one, late Tuesday night into early Wednesday, appears
to have more potential to produce a little light snow across parts
of the area. Windy conditions are expected between these systems
Tuesday, with west gusts 30-35 mph likely during the afternoon.
In the near term, the cold front which moved through the area
last night was now well to the east and southeast of the cwa this
afternoon. Northwest winds have slowly diminished as the gradient
has weakened, ahead of weak high pressure spreading east from IA.
This weakening of the gradient has allowed a weak lake breeze to
develop with more of a northerly push into northwest IN, while the
slightly westerly component to flow above the boundary layer was
holding the IL portion closer to the shore. This should continue
to be the trend through the remainder of the afternoon, especially
with the thickening of a mid-level cloud deck associated with a
passing minor-amplitude short wave aloft.
Farther to the northwest, GOES water vapor imagery depicts an
upper level trough propagating southeast across the northern
Plains and Canadian prairies. This trough is progged to amplify as
it continues to move east-southeast across the upper Midwest
through Tuesday. The approach of this wave will induce a period of
warm advection isentropic ascent late tonight into Tuesday
morning, which will work to saturate mid-levels across the region.
The strongest forcing for deep ascent, and more complete
saturation looks to be mainly north of the forecast area across
WI, while drier air in low levels and the relatively brief
duration of forcing farther south into the LOT cwa produces
perhaps only a few flurries mainly north of the I-80 corridor.
Surface low pressure with this system will pass well north of the
area, while a trailing cold front passes Tuesday morning. Winds
will shift west behind the front, and will become gusty by the
midday/afternoon hours. Forecast soundings indicate fairly deep
mixing by early afternoon with gusts of 30-35 mph likely. Deep
mixing will help temps top out in the 45-50 degree range. Winds
will gradually diminish after sunset Tuesday evening.
Another clipper will follow quickly behind the first, and is
progged to dig a little farther south. Guidance differs slightly
with the track of the surface reflection with this system, but
generally brings the low across central/northern IL Wednesday
morning. This track favors a bit better potential for some light
precipitation across the area late Tuesday night, primarily in the
form of some light snow. Some minor accumulations are possible,
generally from a dusting to a few tenths of an inch, though
relatively warm ground may tend to limit this somewhat.
Ratzer
&&
.LONG TERM...
233 PM CST
Wednesday through Monday...
The clipper system will quickly shift through the area Wednesday
morning. Most guidance does keep the surface low track near the area
in a favorable position to support a window of snow, given favorable
lapse rates in the moist layer that extends through the dendritic
growth region. Guidance has latched onto this a bit better, but
location of the band of snow may need refinement, thus we have
carried somewhat lower precipitation chances (30-50%). This will be
a quick hitter and will exit eastward quickly mid morning.
The northwest flow wave parade will have its conclusion Thursday
morning, and this will drive a bit more cold potent Thursday
afternoon/evening. Model guidance does paint some light QPF with
this stronger front, though moisture is still limited and this
front may yet still some through dry as low pressure meanders
along the Gulf hogging moisture. A pocket of colder air will be
found behind the front this time around, Friday will end up the
coolest day this week with highs in the 40s, still near or maybe a
tad above normal, though it will be breezy again to make it feel
cooler, especially lakeside. Lakeshore flooding is the main
concern with the push of stronger winds aided by cold advection
over the lake.
As is fairly common in spring, these cold spells become short lived,
and this one is no exception. The weekend will begin dry and mild
as large upper ridging will build over the central CONUS coupled
with deep south-southwest flow returns (some cooling IL lakeside due
to some SE component possible). Area wide temperatures rebound back
to near 60 on Sunday with no lake breeze expected.
Precipitation chances safely hold off through the weekend, though
rain chances will return at some point Monday.
&&
.AVIATION...
For the 00Z TAFs...
Other than some periods of BKN MVFR ceilings at RFD this evening,
VFR conditions are expected for all sites through the period. Light
W winds are expected into the overnight hours, though may actually
be VRB from NW to SW. SW winds will begin to increase late tonight,
then continue to quickly increase while becoming W by late Tuesday
morning. W gusts to 30 knots are expected through the afternoon
hours, with some gusts as high as 35 knots not out of the question.
While conditions should remain dry through the period, a quick
moving trough may allow for some sprinkles/flurries around daybreak
Tuesday. Additionally, diurnal cumulus during the afternoon may
become deep enough to produce widely isolated light showers in the
afternoon.
Kluber
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...9 AM Tuesday to midnight Wednesday.
&&
$$
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