Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/23/19
Area Forecast Discussion
National Weather Service Lincoln IL
924 PM CST Fri Nov 22 2019
.SYNOPSIS...
Issued at 234 PM CST Fri Nov 22 2019
An upper level weather disturbance from Kansas will move into
central Illinois by late Saturday morning. This will result in
areas of light snow from northern Missouri into central Illinois
by daybreak, with mainly light rain in southern Illinois.
Accumulations of precipitation will be very light with very few,
if any impacts to travel Saturday. Dry weather and a clearing sky
will be in store for the region later Saturday and Sunday. High
temperatures will be on the cool side with readings in the 40s
through the weekend.
&&
.UPDATE...
Issued at 924 PM CST Fri Nov 22 2019
A short-wave trough pivoting around an upper low centered over
Kansas has triggered scattered light precip across central and
northern Missouri this evening. Most ob sites have shown light
rain thus far: however, the latest ob from KSTL is reporting a
rain/snow mix and KDMO is showing unknown precip. With
temperatures already below freezing across all but the far SE KILX
CWA, think the precip will begin mainly in the form of snow or
perhaps a snow/freezing rain mixture. Despite the presence of
numerous radar echoes across Missouri, a very dry mid and low-
level airmass as evidenced by the 00z KILX upper air sounding will
prevent precip from reaching the ground for several more hours.
Based on radar trends and latest HRRR forecast, have introduced
slight chance PoPs across the far SW around Winchester by 11pm.
Have then spread PoPs as far N/NE as a Galesburg...to Lincoln...to
Paris line well after midnight. Am expecting dry weather to
prevail along/northeast of I-74. Any precip that occurs late
tonight into Saturday morning will be quite light, so overall
impacts will be minimal.
however, latest ob from KSTL is
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 234 PM CST Fri Nov 22 2019
An upper level circulation in western Kansas this afternoon will
shift toward the mid-MS Valley overnight bringing an increase in
clouds and chances for precipitation. The latest low level water
vapor satellite loop confirms the lack of low level moisture
upstream in the southern Plains, with the moisture focusing on the
TN and OH valleys. This means that despite the movement of the
upper low into central IL Saturday morning, the precipitation
amounts will be on the light side with liquid equivalents less
than 0.10" in central IL and possibly up to 0.25" in far southeast
IL.
A look at the forecast soundings and available energy aloft
indicates that precipitation type should start out as light snow
in central IL, with all rain south of I-70 toward daybreak. A
brief period of freezing rain is possible toward Jacksonville and
Winchester around daybreak as we lose ice crystals aloft and the
snow changes to rain and surface temperatures hang around 32
degrees. Regardless, with low QPF amounts, any ice accumulation
would be mainly to elevated surfaces, and any snow would be a
couple of tenths of an inch or less.
The trough axis of the upper low is expected to move out of IL by
early Saturday afternoon, which will end the precipitation and
result in decreasing cloudiness
.LONG TERM...(Saturday night through Friday)
ISSUED AT 234 PM CST Fri Nov 22 2019
A backing upper level flow from NW to SW by early next week will
result in a warming trend with temperatures rising into the lower
to middle 50s Monday into Tuesday. A shortwave trough lifting into
the upper Midwest Tuesday will bring the next shot at
precipitation, mainly in the form of rain Tue into Tue evening.
Once again, it appears that the best moisture axis will be south
of the region, so rain totals should be on the lower side.
High pressure on Wednesday will bring a return to cooler
temperatures in the 40s. An upper level ridge building along or
just west of the MS Valley toward Thanksgiving will keep us on the
cooler side, but also could set-up an extended period of
overrunning precipitation for later Thursday through Friday.
Precipitation type could be challenging, particularly Thursday
night into Friday morning. In addition, there is quite a bit of
uncertainty as to where the upper ridge axis will set up, which
will impact the placement of the overrunning/warm advection
precipitation - which could stay just west of Illinois. For now
will need to just go with a chance PoP mention of rain or snow
and evaluate this more as we get closer to the event.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 546 PM CST Fri Nov 22 2019
An upper-level disturbance currently over Kansas is spreading
clouds and light showers across Missouri late this afternoon. As
this system tracks slowly eastward, clouds will be on the increase
across central Illinois this evening: however, it appears any
light precip will hold off until closer to dawn. Forecast
soundings continue to indicate a dry boundary layer, so am
expecting ceilings to remain in the VFR category through the
entire 00z TAF period. HRRR suggests a band of MVFR ceilings may
develop across Missouri later tonight, then spill into far west-
central Illinois Saturday morning...but these lower clouds are
expected to remain west of the terminals. Have included VCSH at
KSPI/KDEC/KCMI as the scattered light precip tracks through the
area. Winds will remain light through the entire period.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Barnes
SYNOPSIS...Miller
SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Barnes
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
922 PM CST Fri Nov 22 2019
.UPDATE...
Issued at 919 PM CST Fri Nov 22 2019
Regional radars are showing band of precipitation continuing to
move into central and northeast Missouri. Surface reports indicate
that a mix of sleet and rain is occurring with this band which is
supported by evening upper air analysis which shows that
precipitation is moving into a dry atmosphere so wet-bulbing is
occurring. Have not received any reports of accumulation given
the relatively warm surface temperatures ranging from the middle
30s in Knox County to the middle 40s here at LSX. Will keep likely
PoPs going through the night as the latest RAP is showing the
upper low currently over Kansas moving east into Missouri which
will increase ascent over the region through the night. Forecast
soundings do support the mix of rain/sleeting changing to snow
over northeast Missouri into west central Illinois with mainly
rain with some snow closer to I-70 into tomorrow morning.
Snowfall accumulations still look less than 1/2 inch north of
I-70. As mentioned in the previous discussion, it is still
possible that some dry air will wrap around the upper low later
tonight so some light freezing rain/drizzle will be possible over
northeast Missouri later tonight with little if any accumulation.
Otherwise, lowered temperatures slightly over northeast Missouri
and west central Illinois based on current temperatures.
Britt
&&
.SHORT TERM... (Through Late Saturday Afternoon)
Issued at 312 PM CST Fri Nov 22 2019
The mid-Mississippi Valley is currently situated beneath a weak
upper ridge with surface high pressure building in from the
northwest. This has resulted in quiet conditions today, though
this is likely to change as a broad upper low currently moving out
of the Four Corners pushes into the region overnight. The
approaching upper low will slowly deepen a surface trough to our
southwest, which in turn will help draw the upper portions of
yestreday`s cold front back into the region this evening.
Isentropic analysis of forecast guidance reveals weak moist
upglide along this baroclinic zone overnight, which coupled with
weak DCVA associated with the slowly filling upper low, should be
enough to generate precip across much of the region.
While precip is quite likely tonight and tomorrow morning in
southern MO and IL, I`m not certain how far north the precip will
extend. The preponderance of ensemble members shows measurable
precip extending at least to I-70, with most deterministic
forecasts and ensemble means pushing light QPF all the way into NE
MO and west central IL. Therefore have continued to increase PoPs
across much of the area, with QPF ranging from around 0.1" in our
south to 0.01" in our north. Questions also remain with regards
to p-type, as sub-freezing surface temps will be creeping into
the region through the morning. Thermal profiles should be
supportive of snow into tomorrow morning, primarily for areas
north of I-70. However, it does appear that we may lose cloud ice
toward NE MO as dry air wraps into the upper low, which may result
in a brief period of freezing rain. It`s also possible the dry
air simply cuts off the precip entirely, so confidence in any fzra
is rather low. Therefore have largely stuck with just a rain/snow
forecast, with a brief mention of fzra in NE MO. No ice
accumulations are expected, and any snow accums are likely to be
limited to the north of I-70. Where snow does occur, I would be
surprised to see much more than half an inch of snow on grassy and
elevated surfaces.
BSH
.LONG TERM... (Saturday Night through Next Friday)
Issued at 312 PM CST Fri Nov 22 2019
Northwest upper level flow will take hold behind the departing
low, with a handful of embedded shortwaves forecast to push
through the region into early next week. Despite this mid level
forcing, no precip is anticipated through Monday thanks to a
steady supply dry WNW flow in the mid/low levels surface and high
pressure building into the region. As the surface high shifts to
our east on Sunday afternoon, surface winds will begin to swing
around to the south, drawing warmer air back into the region. With
that, temps should build into the 50s on Sunday and I expected
several locations to top 60 on Monday.
On Tuesday, ensemble means continue to show strong agreement on
anomalously low upper level heights over the central portion of
the country, increasing confidence that a potentially strong
cyclone may move through the Midwest. The 12z runs of the
operational GFS, Euro, and Canadian show remarkable consensus on
low track, timing, and intensity, further bolstering confidence
that the mid-Mississippi Valley will be impacted by this storm a
few days prior to Thanksgiving. Despite the increasing confidence,
we`re still nearly 100 hours away from this event and it would be
foolhardy to try and nail down forecast specifics at this time.
Small deviations in low characteristics could on one hand result
in frozen precip, while on the other hand result in strong storms
in our region. The most responsible forecast at this time is to
say at cyclone will move through the Midwest on Tuesday, likely
bringing precipitation to the mid-Mississippi Valley. As we
approach this event and confidence increases, forecast specifics
will become more clear.
Beyond Tuesday, high pressure is expected to build into the
Midwest while yet another low pushes across the southern CONUS.
The surface high and upper level height rises should generally
keep a lid on precip chances in our region. However, some guidance
does push the northern fringes of the precip from the southern
CONUS system into our area on Thursday. Given large differences in
forecast guidance, confidence in this period is low.
BSH
&&
.AVIATION... (For the 00z TAFs through 00z Saturday Evening)
Issued at 556 PM CST Fri Nov 22 2019
Precipitation will spread northeast across the area this evening
and continue overnight. The best time for precipitation will be
late this evening into the early morning hours. The rain will mix
with or change over to snow at KCOU and KUIN with some minimal
accumulations on grassy accumulations. The precipitation is
expected to move out of the area on Saturday morning. Ceilings
will drop to MVFR after 06Z and remain that way through tomorrow
afternoon before improving to VFR on Saturday afternoon.
SPECIFICS FOR KSTL:
Rain will move into the terminal around 06Z and continue into mid
morning Saturday. The rain may mix with snow at times between
10-15Z, but no accumulation is expected at this time. Ceilings
will drop to MVFR after 06Z and remain that way through tomorrow
afternoon before improving to VFR on Saturday afternoon.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Pueblo CO
304 PM MST Fri Nov 22 2019
.SHORT TERM...(This evening through Saturday)
Issued at 244 PM MST Fri Nov 22 2019
Currently...Upper low was centered over the KS and CO state line
this aftn and was slowly edging to the east. Snow has diminished
over much of the forecast area as of 230 pm, but a band of snow
persisted stretching from southern Pueblo County down into eastern
Las Animas County which was well forecast by the HRRR. Temps have
remained in the 20s to around 30F across the plains today under
thick cloud cover, while the San Luis Valley and Upper Arkansas
River Valley warmed into the mid 30s to lower 40s.
Tonight...The upper low will continue to slowly move to the east and
out of Colorado tonight, with clearing skies later tonight allowing
for efficient radiational cooling. The latest HRRR indicates that
there will be a band of light snow continuing from southern Pueblo
County into eastern Las Animas County, as well as some spotty snow
over the mts, until around 7 pm, then things really start to shut
down. Therefore, adjusted forecast POP grids to show this with
activity essentially ending by midnight. Overnight lows under
clearing skies are expected to drop into the teens to single digits
for the high valleys, and into the lower 20s for the plains. The
rapid cooling tonight may produce some spotty areas of fog across
the San Luis Valley as well as the plains, but do not feel these
areas will last long enough to warrant a mention in the forecast.
Tomorrow...Cool and dry north to northwest flow aloft settles in
across the region, producing a pleasant day across the state. Plan
on highs in the 40s for the high valleys, and 50s across the plains.
Areas that received significant snowfall on Fri will be slow to warm
however, and max temps at those locations may fall short a few
degrees. Moore
.LONG TERM...(Saturday night through Friday)
Issued at 244 PM MST Fri Nov 22 2019
Models in general agreement through the extended period, with an
upper level low developing to the west and high pressure to the
east. There are differences in how the models want to handle the
upper low to the west, especially when it comes to ejecting the
system into the Desert Southwest. The GFS is quicker, while the
ECMWF really hangs the upper low back west, indicating the
potential for heavy snowfall over the San Juan Range. Ensembles
are actually in good agreement, slightly favoring the ECMWF at
this time.
Saturday night and Sunday...broad northwesterly flow will prevail
across Colorado during this period. Expect dry conditions to be in
place across all of southern Colorado. Temperatures on Sunday will
be warm, with upper 50s to lower 60s expected across the lower
elevations.
Monday into Tuesday...a quick moving upper disturbance in the
northwest flow will move across Colorado from Monday afternoon
through Tuesday afternoon. Expect snow showers to move into the
Central Mountains by Monday afternoon, spreading south and east
into the Palmer Divide during the evening hours, and finally south
across the Plains Tuesday morning. A cold front will arrive
Tuesday morning with low pressure developing over the Plains.
There could be a period of moderate to heavier snowfall from the
Palmer Divide, to near Pueblo Tuesday morning with the front. Snow
will come to an end from west to east Tuesday afternoon as the
upper system moves into the Central Plains. Highs on Monday will
top out in the 50s, while highs will struggle to reach the 40s on
Tuesday behind the front.
Wednesday into Friday...an upper level low is forecast to develop
over the Pacific Northwest and drop south along the California
Coast. This will spread moist southwest flow out of the Desert
Southwest and into the Continental Divide beginning late Tuesday
night, and persisting into the weekend. This pattern will heavily
favor the San Juan Range and southwest facing slopes. From Tuesday
night into Friday, 2 to 4 feet of snow will be possible, with
hazardous travel conditions expected for Thanksgiving over
mountain passes including Wolf Creek. Winds will also be gusty
causing areas of blowing snow causing poor visibilities. The rest
of the Continental Divide will also see snow, but is less
favorable in southwest flow. A foot or two is possible north of
Monarch Pass over the Central Mountains. Lesser amounts are
expected over the Sangre de Cristo and Wet Mountain Ranges
Wednesday and beyond. As for the Plains, dry conditions will
likely prevail. There may be the possibility of light showers over
the far Eastern Plains on Wednesday, but dry conditions are
expected to prevail Thursday into Friday. Wind will likely be the
main concern. Models are developing 65 kt winds at 700 mb for a
prolonged period, Thursday into Friday, which may be able to mix
to the surface. Winds will have to be watched.
As far as model differences, the GFS ejects the low across the
Desert Southwest by the weekend. The ECMWF is much slower and the
heavy snow would likely persist through the weekend with moist
southwest flow continuing. Mozley
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 244 PM MST Fri Nov 22 2019
Upper low is continuing to edge eastward late this aftn, and will
push east of CO overnight. Intermittent light snow continued in a
few areas, and one persistent band of snow is stretching from
southern Pueblo County into eastern Las Animas County. These pockets
of light snow will continue until around 02z-03z tonight, then
activity will shut off by midnight.
Expect VFR conditions across much of the forecast area over the next
24 hrs, including the three main TAF sites of KCOS, KPUB and KALS.
there may be some spotty areas of fog tonight as skies clear,
producing temporary MVFR conditions, but with the expected NW sfc
flow do not think these areas of fog will last long enough to
warrant mention. Moore
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MOORE
LONG TERM...MOZLEY
AVIATION...MOORE
Area Forecast Discussion...UPDATED
National Weather Service Shreveport LA
942 PM CST Fri Nov 22 2019
.UPDATE...
Cold front has finally exited to the southeast of the forecast
area, but scattered elevated convection persists along the 850 mb
front over Northern Louisiana. The HRRR has a pretty good handle
on the ongoing precip and indicates all of the rain will exit the
area by 08z or 09z Saturday morning. Therefore, PoPs grids were
updated to reflect latest radar trends and based heavily on the
HRRR. Overall, this resulted in trimming PoPs from west to east
and removing PoPs completely at 09z.
Otherwise, only minor changes were made to temperatures and
dewpoints based on latest observations. Updated text products will
be sent shortly.
CN
&&
.PREV DISCUSSION... /issued 611 PM CST Fri Nov 22 2019/
AVIATION...
For the 23/00z TAFs, scattered convection will continue to affect
portions of the area mainly southeast of a line form KJSO to KELD
for the first few hours of the period. KLFK, KSHV, and KMLU will
be the TAF sites most likely to be affected. Most of the showers
and isolated thunderstorms should move south and east of all
terminals shortly after 23/06z, but patchy drizzle and low
clouds will persist into the mid morning hours. Ceilings and
visibilities will be somewhat variable, but in general, IFR/LIFR
conditions should prevail until around 23/15z. Beyond then,
northwesterly surface winds will usher dry air into the region and
skies should gradually clear from west to east after 23/18z.
CN
PREV DISCUSSION... /issued 310 PM CST Fri Nov 22 2019/
SHORT TERM.../Tonight through Sunday/
Temperatures continue to fall into upper 40s and lower 50s with
northwest winds in wake of a cold front, currently located east
of a line from Many Louisiana to Coushatta Louisiana to El Dorado
Arkansas. This boundary will continue to slowly move eastward and
out of the region by early evening. Showers and isolated
thunderstorms continue to develop along and ahead of the frontal
boundary, but it appears that the region will miss any severe
weather. Light rain and or patchy drizzle will continue post-
frontal as additional activity will develop along the eastward
moving 850mb front, which is currently located along a line from
Tyler Texas to Hope Arkansas. Another weak disturbance behind both
boundaries may also result in lingering patchy drizzle through
early Saturday morning before the weather and clouds move out by
late Saturday morning/early Saturday afternoon.
Much cooler and drier conditions to move into the region as
Saturday morning temps will range from the mid 30s north of
Interstate 30 to the mid 40s across Northeast and Central
Louisiana. Highs on Saturday will generally be in the 50s to near
60 degrees which is slightly below normal for this time of the
year. Dry conditions to continue on Sunday as High Pressure moves
over the region. Sunday morning lows will fall into the 30s
areawide with afternoon highs in the low to mid 60s. /20/
LONG TERM.../Sunday Night through Friday Night/
Sunday into Sunday Night will be a transition period across the
Southern Plains/Lower Miss Valley as WNW flow aloft becomes
southwesterly as our next weather maker in the form of an upper
trough takes up residence across the Intermountain West. In the
lower levels, expect to see a strong warm air advection regime
commence across our region with high temperatures in the 70s both on
Monday and Tuesday areawide. Did not introduce pops until late
Monday Night into Tuesday but pops will be on the low end chance
variety ahead of our next cold front which is poised to move into
our region from the northwest Tuesday Night.
Pretty good model consensus on the timing of this frontal boundary
pushing through our region but that is where the consensus ends as
the GFS is quick to reintroduce overrunning rainfall with
southwesterly flow aloft continuing despite the cooler, postfrontal
conditions in place beyond Tue Night. The precipitation forecast for
the middle and later half of next week will become strongly
dependent on the strength of Gulf of Mexico ridging aloft and the
degree of amplitude with the next trough digging into the southwest
CONUS next week. If our region remains more under the influence of
the upper ridge across the Gulf (ECMWF) then the timing of the
rainfall may await returning low level moisture by late next week
compared to the upper ridge axis shifted east of our region (GFS)
and our region more under the influence of southwest flow aloft and
greater rain chances as early as Wed of next week. These parameters
are impossible to determine so far out in the forecast future so for
now, have split the difference between the much wetter GFS and the
much drier ECMWF in the Wed thru Fri timeframe next week.
Thanks for the coordination efforts today FWD, TSA, LZK...prelims
to follow...13.
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 43 58 39 64 / 10 0 0 0
MLU 46 61 39 64 / 70 0 0 0
DEQ 37 54 34 62 / 10 0 0 0
TXK 39 55 36 63 / 10 0 0 0
ELD 41 56 36 63 / 20 0 0 0
TYR 39 57 38 66 / 0 0 0 0
GGG 41 58 37 65 / 10 0 0 0
LFK 43 62 40 66 / 10 0 0 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
09/15