Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 09/30/19
Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
623 PM CDT Sun Sep 29 2019
.AVIATION...
For the 00Z TAFs, a small cluster of showers and tstms near KDHT
should continue to impact that terminal site until around 01Z this
evening. LLWS likely to develop at KGUY late tonight due to the
presence of a low level jet, and have included in this fcst.
MVFR cigs likely to redevelop at KAMA early Monday morning and
persist through the morning hours. Lower confidence at KGUY and
KDHT precludes mention of MVFR cigs for this fcst cycle. Another
round of showers and thunderstorms is expected to develop Monday
afternoon, and have included a PROB30 group for this weather
element at KDHT and KAMA durg that tiime period.
02
&&
.PREV DISCUSSION... /Issued 235 PM CDT Sun Sep 29 2019/
SHORT TERM...
Despite quite a bit of cloud cover, temperatures have been able
to warm into the lower 80s already this afternoon. South winds
around 20 mph are definitely helping the heat, but also the
humidity. Dew Point at KAMA has been running in the mid 60s for
most of today, so the atmosphere is primed with quite a bit of low
and mid level moisture. Satellite imagery, especially the mid
level water vapor channel shows the plume of moisture surging
northward from Tropical Storm Narda into the southern great
plains. The moisture isn`t going anywhere, and will be available
for isolated to scattered thunderstorms to develop later this
afternoon and tonight across the higher elevation to the west.
Eventually, these thunderstorms will make their way to the east,
which will be discussed in the section below.
For the thunderstorm potential today, would expect to see most of
the initiation to be towards the west, where sunshine has been
more abundant today. Visible satellite imagery shows a fine line
of cumulus building in a line from eastern New Mexico to
southwestern Kansas. Mesoanalysis shows CAPE values between 2000
and 4000 J/Kg, with CIN continually decreasing this afternoon.
These computed CAPE values may be a bit high. Using AMDAR airline
soundings this afternoon as a proxy for our sounding (equipment
issues this morning), yet the dewpoints on the AMDAR soundings are
running about 5 degrees too high, likely raising the CAPE values
too much. However, still expecting some thunderstorms to develop,
and once they do, there is enough speed shear to produce some
strong storms which will contain a hail and wind hazard.
Overnight, temperatures should fall into the mid to upper 60s, as
the wind speeds will remain in the 15-25 mph range. Wind speeds
around 1-2 thousand feet will likely be in the 30-40 mph range,
which will continue to pump even more moisture our way, setting
the stage for a few days of rain.
Fox
LONG TERM...
We are starting to sound like a broken record; nevertheless,
heavy rainfall chances are still the highlight of the forecast
package next week. There are a couple limitations but the signal
is still very strong for heavy rainfall which may lead to flooding
across the forecast area. There may be a few period where strong
to perhaps severe thunderstorms develop, but this seems unlikely
given the weak lapse rates and subtle forcing aloft. That said,
cannot rule out at least a strong thunderstorm next week.
Pattern still reflects a surge of moisture between two distinct
upper level features. This stream of moisture will flow right
over the forecast area between an upper level low to the
northwest, and upper level high across the southeastern CONUS.
These two features are progged to remain stagnant through at least
the middle of next week. Abundant tropical moisture will be
available through this time period, but the biggest question
remains...how much forcing will be available? We have very subtle
vorticity maxima embedded within the southwest to northeast flow
aloft, and an H3 jet streak that may provide some vertical lift
via ageostrophic circulations of the right entrance region.
Otherwise, we have a cold front coming through on Tuesday which
could lead to additional support. All in all, confidence is still
pretty high regarding our rainfall chances, and we do expect
amounts that could lead to flood potential in some areas. Flash
flooding may not be as likely due to this shaping up to be more of
a long duration event rather than an intensive rain rate event,
but if flash flooding were to occur it would be Tuesday when are
heaviest rainfall rates could occur. Tuesday is likely our best
chance at reaching our maximum rainfall rates during the stretch
of rain, and unfortunately it may occur during the morning
commute.
A few things to be mindful of next week will be the strength of
our forcing and/or lack there of. Upper level jet may be a big
part of our heavy rainfall chances, and if this shifts we will
need to monitor and make adjustments. Additionally, models may not
be handling the subtle pieces of energy kicking out over the
Panhandles and the subsequent timing. A few things that may make
or break our chances and worth mentioning as we move forward
during our decision making process. Lastly, the strength and
timing of the front may be off. Wednesday could end up being a lot
colder than we have forecasted at the moment. Will need to monitor
that as well.
Guerrero
&&
.AMA Watches/Warnings/Advisories...
TX...None.
OK...None.
&&
$$
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
924 PM CDT Sun Sep 29 2019
.UPDATE...
924 PM CDT
Shortwave responsible for the rain and isolated t-storms continues
moving east and showers are just about out of our eastern most
counties. As the shortwave passes, mid-high and high level
cloudiness is clearing out allowing a clear view of where the
stratus currently is located. The warm front is still south across
central IL, so there is a window of opportunity for the stratus to
develop southward some tonight ahead of the warm front.
Bigger question is in regards to fog development. Should maintain
some light easterly winds overnight, but given temps are already
at or very near dewpoints and the warm front is progged to advance
north overnight, there certainly is a threat of fog development.
Could see some dense fog, particularly near the WI border and just
ahead of the warm front, but not confident enough to hoist an
advisory at this point, just something to brief oncoming shift to
watch.
Recent ACARs soundings out of MDW support model forecast
soundings depicting a shallow stratus deck over night, while ACARs
out of MKE show a much deeper stratus deck. Have added some
drizzle to the forecast far northern IL where stratus deck is
deeper and most supportive of drizzle production.
Northward advancing warm front should help scour out the stratus
and fog Monday morning, despite the lowering sun angle, so going
forecast for temps tomorrow still look spot on and made no
changes to temps.
- Izzi
&&
.SHORT TERM...
238 PM CDT
Through Tonight...
An extensive area of low stratus continues to encompass much of
the region this afternoon, as we remain just to the north of a
warm frontal boundary. This frontal boundary is oriented west to
east right across my far south, roughly from KPNT eastward just
south of KRZL as of this writing. Areas across far northern IL,
roughly along and north of I-80 are likely to remain under the
influence of this low stratus through the night, as the surface
warm front gradually shifts northward. We will also have to watch
out for the possibility of some low visibilities in fog north of
this boundary tonight, especially over north central IL. Surface
temperatures in this area remain in the low to mid 60s, while
surface dew points just to the south increase to around 70. As
this moisture streams northward with the front tonight, we may
see the visibilities really drop this evening, with the
possibility for a period of dense fog, especially over north
central IL. This possibility will need to be watched.
Otherwise, some remnant showers from earlier thunderstorms to our
west are likely to move across the area late this afternoon
through early this evening. While heavy rainfall is not a concern
for much of northern IL with this activity, there does remain a
threat for heavy rainfall through early this evening over my
southern areas near the frontal boundary. In fact, some of the
current storms moving across Ford county have been producing
isolated amounts up to an inch in under an hour. With additional
storms likely to move across this area yet late this afternoon,
there will be a small threat for isolated areas of excessive
rainfall over Livingston, Ford, and Iroquois counties. We also
cant rule out the possibility of a stronger storm capable of
producing strong gusty winds. These showers and storms should wane
across the area early this evening.
Temperatures tonight are likely to remain fairly steady in the
mid to upper 60s, and may even rise a couple of degrees overnight
as the warm frontal boundary lifts northward.
KJB
&&
.LONG TERM...
315 PM CDT
Monday through Sunday...
Expect areas of morning fog to give way to some sunshine for a good
part of the day Monday as a warm front lifts well to our north. A
warm and humid southerly push of air in the boundary layer will help
send max temps well into the 80s... some 15 to 20 degree above the
average for the last day of September.
Surface dew points surging into the upper 60s to lower 70s area wide
along with a modest southwest gradient will help hold min temps
Monday night in the upper 60s to around 70 degrees most locations...
a whopping 20 to 25 degrees above the average. The record high
minimum temp for Oct 1 at RFD is 63 and at ORD 71 degrees... RFD
seems well within reach, and ORD will be close.
The upper level ridge begins to break down Monday night however as
shortwave energy rides the upper flow... with energy to our north
beginning to sag south and impact the state line area of northern IL
by late night. Rain and storm changes gradually increase from north
to south from early morning through the day Tuesday getting into
areas as far south as I-80 during the afternoon. Ahead of the
scattered rain/storms however expect another very warm and humid
day as max temps Tuesday climb into the mid to upper 80s for most
areas south of I-88 including much of the Chicago metro.
Ingredients coming together for possibly another heavy rain threat
for the period Tuesday evening through Wednesday night with copious
moisture and strong forcing both along the frontal boundary as well
as ahead of a vigorous upper level trough. Current model guidance
suggests greater rainfall may stay north and west of the area with
the best upper level forcing shearing out by the time the frontal
boundary sags far enough south into northern Illinois. Even should
this scenario pan out could still see rainfall sufficient enough to
result in some localized flooding and renewed rises and flooding
along area rivers and streams Wednesday into Wednesday night. Either
way this period will be monitored closely and interests along area
rivers should monitor updated forecasts.
Significant upper level pattern shift then takes hold late week as
sprawling high pressure builds southeast from the Upper Mississippi
Valley Friday. Upper ridging follows quickly on the heels of the
upper trof via a progressive west flow. Models diverge in solutions
for the weekend period with the GFS maintaining upper ridging a
little longer while the ECMWF and Canadian maintain a more
progressive flow with another upper trough moving quickly east
into the western Great Lakes later Saturday into Sunday. For now
will introduce chance POPs and look for better model consistency
to develop with time.
Ed F
&&
.AVIATION...
For the 00Z TAFs...
632 PM...Forecast concerns include...
Lifr cigs/vis tonight.
Showers this evening.
Gusty south/southwest winds Monday.
Scattered showers will continue through mid evening and these have
helped improve cigs across parts of the Chicago area with the
terminals now vfr. This will probably continue for another 1-2
hours but as the showers end...low mvfr/ifr cigs are likely to
fill back in and then lower into lifr. There is likely going to be
a sharp cutoff to these lower clouds which may be near mdw/gyy.
Further north at ord/dpa confidence is higher for prevailing lifr
cigs overnight into Monday morning. But there is some guidance
showing improvement from south to north in the early morning hours
as a warm front lifts north. Until these trends become apparent...
confidence is low for timing. Further northwest at rfd...not
expecting any improvement this evening and vis under 1sm is
possible especially overnight. Areas of drizzle are also possible
later this evening and overnight. Cigs will eventually lift and
scatter Monday morning across northern IL with vfr then expected
for the remainder of the period.
Easterly winds generally under 10kts will turn southeast tonight
and then shift south/southwest behind the cold front Monday
morning. Speeds will increase into the 10-15kt range with gusts
into the lower 20kt range expected by early afternoon. Some gusts
may persist after sunset Monday evening. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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