Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/18/22
Area Forecast Discussion
National Weather Service Houston/Galveston TX
633 PM CDT Sun Apr 17 2022
.AVIATION...
VFR this evening except in/near SHRA/TSRA that are developing ahead
of a cold front. Have MVFR/IFR ceilings developing overnight behind
the front with N winds around 5 to 10 knots. Might have to deal with
possible fog development for the GLS area. Becoming VFR during the
daytime hours tomorrow with slightly stronger (maybe gusty) N to NE
winds. E winds 5 to 10 knots tomorrow evening and VFR.
42
&&
.CLIMATE...
Galveston has a low temperature so far today of 75 degrees. If this
holds through the end of the day, this will tie the record high minimum
temperature record for April 17th of 75 degrees set in 1967 and 1908.
42
&&
.PREV DISCUSSION... /ISSUED 348 PM CDT Sun Apr 17 2022/
SHORT TERM [Through Monday Night]...
Front will be making its way across the region this evening and off
the coast after midnight. Aircraft soundings out of the Houston area
still showing a pretty decent cap in place. That said, there is
still plenty of sun in place and time for additional heating, so any
localized breaks in the cap would allow for a thunderstorm or two
develop and mix in with iso-sct shras along the boundary as a few of
the CAMs are suggesting.
Looking like we might see some lingering morning low cloudiness on
Monday, but that should erode during the mid morning hours and leave
msunny skies, drier and less humid conditions. Clear & cool Monday
night. (Enjoy it...considering it might be the only night of the
week most of us see below average temps). 47
LONG TERM [Tuesday Through Sunday]...
A period of unseasonably warm weather with increasing humidity
will characterize the remainder of the upcoming week. By Tuesday,
the eastward departure of surface high pressure over the Central
Plains will allow for onshore winds to quickly redevelop, while a
developing lee cyclone in Western CO will tighten the synoptic
pressure gradient across the region. As a result, both
temperatures and dewpoints will be on an upward trend on Tuesday
with afternoon highs inching back towards the 80s. As increasing
cloud cover and WAA remain the story overnight, lows will settle
mostly into the mid/upper 60s at most locations.
While flow aloft remains mostly zonal on Wednesday, a very weak
midlevel shortwave will pass just to our north. As total PW values
climb above 1.5 in during this time, a few scattered to isolated
showers and questions are not out of the question. That being
said, coverage should be limited should storms materialize and as
such have maintained low PoP values in the forecast for the time
being. Precipitation chances otherwise remain near zero for the
remainder of the week while a relatively tight pressure gradient
will allow for the warming trend to continue into the weekend.
Most locations should see highs in the low/mid 80s by Wednesday
and the mid/upper 80s on Thursday. By Friday, locations in the
northern zones may flirt with 90 degrees. Overnight lows during
this time will also remain elevated, likely near but just below
record high minimum values with most locations in the upper 60s to
low 70s.
Heading into the weekend, an amplified upper trough looks to move
into the Northern/Central Plains while a cold front extending from
its associated surface low will move through the South Central
CONUS. Model timing of this feature remains in poor agreement,
with the latest GFS showing the front at our doorstep by early
Sunday while the ECMWF indicates a slower progression with the
boundary arriving on Monday. Showers/storms associated with this
feature will bring us our next chance of rainfall.
Cady
MARINE...
Light onshore winds remain in store this evening ahead of an
approaching surface cold frontal boundary overnight. Moderate
offshore winds will develop behind the departing front, though
winds will quickly turn to the east and later southeast by early
Tuesday. Moderate onshore winds will persist through the remainder
of the week, resulting in elevated seas. This will likely require
caution flags and/or advisories during this time. Additionally,
these conditions will be favorable for the development of strong
rip currents along Gulf-facing beaches.
Cady
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 59 80 54 81 66 / 10 0 0 0 20
Houston (IAH) 65 82 58 79 68 / 30 0 0 0 10
Galveston (GLS) 70 80 66 76 71 / 30 0 0 0 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
900 PM CDT Sun Apr 17 2022
.UPDATE...
Issued at 859 PM CDT Sun Apr 17 2022
The going forecast message continues on track, and that is snow
late this evening into overnight tapering to light snow/drizzle
during the Monday morning commute. While some light slush may
occur on some bridges along with some snow on grass in places,
this is still looking very likely to not be of notable impact.
Will have to watch some surface air temperatures dipping to
around freezing in the early morning when some drizzle, but that
too doesn`t look to be a big deal given pavement temperatures
lagging air temperatures by an appreciable amount at present.
The primary upper level short wave trough for tonight`s snow is
draped from central/eastern Iowa into eastern Missouri, with a
couple of embedded waves comprising this. One of these was fairly
evident on regional radar imagery in far western Illinois moving
east-northeast. An enhanced area of lift and associated
precipitation has been persistent ahead of this and is into the
far western CWA as of 845 PM. The leading edge of this has slowed
some due to the presence of dry air below 750 mb as noted on the
00Z DVN and ILX soundings and area aircraft soundings. There is
limited moisture transport and isentropic ascent ahead of this
wave, due to its quick progression and a lot of convection
upstream in the LLJ flow. This embedded wave is also outrunning
the coldest thermal profiles, and what was earlier several
observation sites below 1SM in southern Iowa and northern Missouri
is now a site or two very briefly doing that in western Illinois.
The precipitation is actually onsetting as rain on its leading
edge with boundary layer temperatures in the western CWA still in
the low 40s.
Overall this means the west-to-east width of the snow area has
diminished from earlier on the Iowa/Missouri border. So while
heavier rates are still anticipated to occur in parts of the CWA,
it should be quite temporary. The locations that seem a smidge
favored to have a possible longer duration of snow based on radar
trends and high-resolution model solutions are LaSalle, Lee,
Ogle, and DeKalb Counties. In the Chicago metro, snow still looks
to onset around midnight with most of the snow ending by 4-5 A.M.
Some CAMs try to hint at maybe some lake enhancement with the
low- level flow off the lake, but that seems like a markedly low
contribution if it were to occur. With the aforementioned short
wave trough`s passage across the CWA late tonight into the pre-
dawn hours, the loss of ice nuclei still favors a transition to
light snow/drizzle ("snizzle").
Pavements temperatures at some sites in the coldest part of the
CWA (far northern/northwestern Chicago suburbs) are in the mid
40s as of 845 PM. While these will drop as rain moves in and
changes to snow, it shows it is a ways from freezing. So unless
under a temporary mesoscale enhanced area of snow, the ability to
get accumulation on the roads remains quite limited. Also, while
some air temperatures are touching 32 along the Illinois/Wisconsin
border due in part to thin clouds early this evening, the lagging
pavement should help to prevent much for slick spots on main
roads (apart from maybe some overpasses) during the early morning
as drizzle/mist may be favored.
MTF
&&
.SHORT TERM...
Issued at 252 PM CDT Sun Apr 17 2022
Through Monday night...
Sharp trough will move across the area tonight and bring yet
another bout of April snow to much of the area, though not
expecting much accumulation and what does accumulate should be
mostly confined to grassy and elevated surfaces. Extensive north-
south band of precipitation already evident on regional radar
mosaic extending from MN south to the Ozarks. It is this band that
will continue east in association with the trough, though the
precipitation will encounter very dry low levels initially that
will need to be saturated via top down saturation. The dry low
levels will also result in evaporative cooling which should result
in much of the area seeing primarily snow tonight, though some
rain could mix in south of the IL and Kankakee Rivers.
Once the column saturates and snow begins, it appears as though
there could be a few hours of snow, which could fall at a pretty
respectable rate at times. Surface temps are expected to be near
or just above freezing and when combined with initially above
freezing ground and pavement temps, shouldn`t favor accumulation.
However, forecast soundings do show very steep lapse rates aloft
and strong ascent in the left exit region of approaching upper
level jet, there is concern that snow could fall rather heavily at
times with some embedded convective elements. Any heavier bursts
of snow will probably knock sfc temps down to around freezing and
lead to some accumulations, perhaps locally an inch of slushy
accumulation. Can`t totally rule out some slushy accums on bridges
and overpasses, but with such marginal temps this appears pretty
unlikely.
As the trough axis passes east of the area late tonight,
substantial drying will take place in mid and upper levels.
Forecast soundings show a deep low level saturated layer remaining
with absence of mid-level moisture leaving the stratus deck void
of ice nuclei necessary for snow. Weak ascent within this
stratus deck will likely result in drizzle or snizzle (drizzle
snow grain mix) for a few hours tomorrow morning. Sfc cold front
will move across the area later Monday morning, resulting in wind
shift to westerly, which should lead to thinning/breaking up of
stratus and end of drizzle threat.
Cold air advection Monday afternoon, particularly aloft, will
result in steepening low level lapse rates and deepening boundary
layer. With vort max associated with the heart of the upper trough
pivoting toward the area during the afternoon, will probably see
some scattered snow/graupel showers develop. Coverage looks to be
greatest eastern CWA into northwest Indiana with surface temps too
warm for accumulation, but still unseasonably cold for April. The
steepening lapse rates and cold advection will also allow for
strong and gusty west-northwest winds Monday afternoon and
evening. Gusts over 30 mph are likely with gusts as high as 40
mph possible, particular in any snow showers late in the
afternoon/early in the evening.
- Izzi
&&
.LONG TERM...
Issued at 250 PM CDT Sun Apr 17 2022
Tuesday through Sunday...
Tuesday starts under northwesterly flow and cold-air advection
(CAA) in the wake of Monday`s low pressure system, with a surface
ridge to our west. Low temperatures will be at or below freezing
Tuesday morning except near Lake Michigan, where the moderating
water temperature will keep temperatures in the mid 30s. Warmer
weather is in store as the ridge axis shifts overhead Tuesday
afternoon. This ridge passage will weaken overall synoptic wind
flow, which in turn will allow a lake breeze to set up in the late
morning/early afternoon, switching winds to the northeast near the
lake. 925 mb temperatures will jump above freezing as the ridge axis
passes overhead , which when combined with mostly clear to partly
cloudy skies will allow high temperatures to climb to around 50
degrees, although the lake breeze will keep near-lake temperatures
in the mid 40s.
Winds will become southerly Tuesday night as the ridge axis moves
east, in addition to the approach of our next front. Warm-air
advection (WAA) will set up in this southerly flow, leading to lows
near 40, and highs in the 50s on Wednesday. Precipitation starts
early Wednesday morning as a warm front moves through. With a
boundary nearby, WAA and ample moisture, there is a decent chance
for some isolated thunderstorms to develop Wednesday afternoon.
Additionally a 50+ kt low-level jet (LLJ) will accompany the warm
front, potentially bringing surface wind gusts of 35 to 40 mph in
the afternoon. The cold front associated with this system will be
relatively weak, and doesn`t pass through until overnight
Wednesday/early Thursday morning, with decent WAA occurring the
entire time. Temperatures will be even warmer on Thursday, as we may
quickly jump from sub-seasonal temperatures to above normal
temperatures, with lows in the mid to upper 40s, and highs in the
upper 60s to near 70!
Models are indicating that another weather systems moves in quickly
behind the Wednesday system, with a warm front moving up from the
south Thursday afternoon. Disagreement on the timing and location of
this system continues, so confidence in exactly when precipitation
occurs next weekend is low. But presently models agree that under
continued southerly flow and WAA, temperatures will be above normal
Friday and Saturday, with lows in the 50s and near 60, and highs in
the 70s, and approaching 80 on Saturday. Under this warm, moist
scenario there will be a chance for showers and possible afternoon
thunderstorms throughout next weekend.
BKL
&&
.AVIATION...
For the 00Z TAFs...
Several aviation concerns through the TAF period:
1. Band of rain (likely switching to all snow) reaching the
terminals around midnight (5Z)
2. Confidence is high in IFR vis/cigs prevailing through the
overnight hours with periods of LIFR likely, possibly as early as
snow onset (VLIFR not out of the question based on upstream
trends)
3. Snow switches over to drizzle/tiny ice needles early Monday
morning with continued IFR cigs with lingering LIFR vis/cigs
possible (10-14Z)
4. Scattered rain/snow/graupel showers are possible in the
afternoon - may mix down higher gusts to near 40 kt
Quiet conditions are expected through the evening hours ahead of our
approaching weather system with light easterly winds. A lead arc
of precipitation is currently along an axis from Moline to Peoria
to Bloomington. This will continue to lift northeast toward the
area. Have this timed out to reach the terminals around 5Z. At
this time it is falling mainly as rain, with a transition to snow
beginning on the northwest side. Further to the northwest across
east central IA, snow also continues with LIFR to occasionally
VLIFR vis occurring where snowfall rates are highest. Expect this
lead arc of rain to transition over to snow on its approach, thus
will maintain starting the TAF off as snow, although a brief
tempo of -RASN may be considered prior to that.
Did move up the PROB30 3/4SM vis to 6-9Z to account for the
expectation for quickly deteriorating conditions after
precipitation onset. It is not out of the question that we may see
vis briefly dip to VLIFR as has been seen upstream, but
confidence is too low to have a formal mention in the TAF.
Once the lead band of snow moves through a loss of cloud ice toward
daybreak should help reduce snowfall rates with drizzle/small ice
needles persisting through mid morning along with some fog
development. Gridded model guidance has been somewhat aggressive
with lowering vis during this period for the Chicago area terminals
so opted to introduce a PROB30 for LIFR vis possible from 10-14Z.
Expect improving vis and cigs through the daylight hours tomorrow
with lingering light rain/snow showers. Winds also become gusty out
of the WNW in the afternoon with gusts to near 30kt possible into
the evening. There remains a signal for scattered rain/snow/graupel
showers in the afternoon as well which could mix down even higher
gusts to near 40 kt beneath any showers that develop.
Petr
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...LMZ744-LMZ745...1 PM Monday to 3 PM
Tuesday.
Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743...1 PM Monday
to 10 AM Tuesday.
&&
$$
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