Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/25/19
Area Forecast Discussion
National Weather Service Denver/Boulder CO
724 PM MDT Wed Apr 24 2019
.UPDATE...
Issued at 656 PM MDT Wed Apr 24 2019
Some minor adjustments for tonight. The HRRR and RAP13 both
indicate some weak showers or maybe a thunderstorm could develop
along the boundary that could push into the Denver area 04-05z.
Weak CAPE present on the 00Z KDNR and radiometric soundings this
evening. Only adjustment to broaden the slight chance of
showers/thunderstorms a little further south to included the
Denver area this evening. Also could see some light showers
activity develop late tonight following the passage of a cold
front that appears to move into Denver around 08z. Some weak post
frontal upslope coupled increasing low clouds until around 12z.
For this reason, I added slightly higher pops for the Denver area
from 09-12z tonight.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 251 PM MDT Wed Apr 24 2019
Weak high pressure ridging aloft over Colorado this afternoon
under a light to moderate northwest flow aloft. Radar showing
some light showers over the mountains and higher terrain but
showers are dissipating over the plains. Airmass is only
marginally unstable along with limited moisture. Expect showers to
remain on the light side and generally confined to mountains and
higher terrain areas near the wyoming border and the Palmer
Divide.
The main feature will be a cold front which will sweep across
northeast Colorado from the north later tonight. Current frontal
position is across Montana and will slide into the Denver Metro
area between 08-10z time frame. Could be some focus of showers and
storms along the front especially along our northern border
areas, closer to best ascent. Will have scattered coverage of
storms further north, with lesser chances further south and west.
Low clouds expected to lag behind the front a few hours and fill
in across the plains before daybreak. Temperatures on Thursday
expected to be cooler behind the front. Any showers/storms will
likely be confined to mountains and elevated terrain areas on
Thursday afternoon. The far northeast plains will be too dry and
stable for any storms.
.LONG TERM...(Thursday night through Wednesday)
Issued at 251 PM MDT Wed Apr 24 2019
Weak ridging in the west-northwest flow aloft will move across
Colorado Thursday night. Other than a few early evening showers in
the mountains, expect dry conditions overnight. This ridge will
move off to the east Friday as a quick moving trough tracks across
the Northern and Central Rockies. Lapse rates steepen and CAPE
climbs up to 500 J/kg during the afternoon. Airmass not that moist
with dew points in the 30s. Expect scattered showers over the
mountains and foothills with isolated high based storms over
plains.
Subsidence and drying will prevail Friday night behind the
exiting wave. This may bring windy conditions to the foothills and
areas near by. A dry and mild west-northwest flow aloft will be
over the area Saturday. A lee side surface trough will form over
eastern Colorado. The GFS shows thunderstorms forming along the
surface trough Saturday evening. Other models remain dry. Dew
points will struggle to climb out of the 20s, so will leave the
forecast dry for now.
On Sunday, flow aloft turns westerly. Models start to diverge on
Sunday with the ECMWF showing a cold front pushing south during
the day Sunday while the GFS is later with this feature. Airmass
moistens behind the front and should provide enough lift for
scattered showers.
For Monday through Wednesday, the weather turns cooler with
better chances for precipitation. A closed low off the California
coast weakens and lifts northeast across the region. Models still
disagree when this trough will track over Colorado. In addition to
the trough, lift from the jet stream should also produce showers
at times. Will go with cool temperatures and a good chance for
showers Monday and Tuesday. By Tuesday night, the trough will be
east of the area. A new system over the Pacific Northwest will
drift southeast towards the Central Rockies Wednesday. This system
may bring another round of showers to the area for Wednesday and
Wednesday night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 656 PM MDT Wed Apr 24 2019
Surface winds expected to remain light from the north/northeast
this evening. The high resolution models hint at some potential
showers developing along a boundary that is expected to move into
the Denver area 04-05z. Will keep vcsh in the tafs at that time
with broken mid level ceilings and VFR conditions until 09z.
Later tonight, a cold front will push through terminals between
08-10z tonight, a bit later that current forecast. Peak wind
gusts with the passage of the cold front could be in the 20-25
kt range around 08z. Expect low clouds (MVFR/IFR) to develop a
after cold frontal passage along with some brief light rain
showers, between 09-14z then improving to LIFR ceiling in the 4-5
thousand feet AGL from 14-18z then VFR Thursday afternoon.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Cooper
SHORT TERM...Entrekin
LONG TERM...Meier
AVIATION...Cooper
Area Forecast Discussion
National Weather Service Quad Cities IA IL
946 PM CDT Wed Apr 24 2019
.UPDATE...
Issued at 935 PM CDT Wed Apr 24 2019
Added fog to the forecast for late tonight into early Thursday
morning, roughly over the SW two-thirds of the forecast area where
dewpoints are in the lower 40s to lower 50 F. Winds overnight
will be light and variable under an area of high pressure thereby
promoting low-level saturation.
GOES microphysics imagery showed stratus clouds from Iowa City to
Macomb and points to the southwest. These clouds may expand
northward overnight, transitioning into areas of fog late as
temperatures cool. Hi-res models are aggressive on potential for
dense fog and it`s something we`ll have to keep an eye on tonight.
As of 930 PM, fog has yet to form in our area. The closest dense
fog observation is to the south, with the visibility down to 1/4
mile in Pittsfield, Illinois.
&&
.SYNOPSIS...
Issued at 316 PM CDT Wed Apr 24 2019
While today certainly is not particularly hazardous as far as
current weather goes, it`s certainly fraught with challenging
details, including chaotic flow, low clouds, high based narrow
swaths of measurable rain, and daytime light fog. This is resulting
in an afternoon improvement from a wet dreary day to one that may
still be quite pleasant in some locations in the west, south, and
east, while the north central, near the Mississippi River, remains
sunny, and has been in the lower to mid 60s since Noon. The weak low
level flow around this high based vort has certainly created this
chaotic flow, as it allowed the weak precipitation process to
saturate the initially dry mid levels. The shallow stratus has only
been found on the northwest flank of any rain, likely favored there
as the cool moist low levels to the southeast of it have been
advecting into that region all day. Now that rain processes have
moved to the east, that support mechanism should break down and
allow clearing.
&&
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 316 PM CDT Wed Apr 24 2019
Clearing conditions should be the trend this evening, with some
potential for stratus and mid clouds to hang on in the southwest and
south, possibly through the night, as the flow increases from the
south tonight. Lows tonight are challenging with cloud cover, and
may vary from mid 40s northeast to upper 40s central and west.
Tomorrow, the cold front should move through from west to east, from
mid morning to mid afternoon, with a wind switch initially seeing the
main impact. Saturation appears mainly post frontal, with showers in
the cooler air, most likely light. This band of showers should be
less than a tenth of an inch in most areas. There is a low chance of
reaching convective temperature prior to the front hitting in the
southeast, and for those locations, I have added an isolated thunder
risk during the afternoon. This is a low threat, but at least is
hinted at by the Namnest and extended RAP model runs. Convective
temperatures of the mid 70s are possible, but clouds may keep that a
low threat.
Otherwise, look for mid 60s to lower 70s highs from west to east.
.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 316 PM CDT Wed Apr 24 2019
Weather pattern will turn quite active over the weekend and into
next week. The potential for heavy rainfall is very real. However,
there is considerable uncertainty on where and how much rain could
fall.
Thursday night
Assessment...medium to high confidence
The cold front will exit the area and rain will end along and east
of the Mississippi during the evening hours. Strong winds
immediately behind the front are very possible during the early
evening hours. Dry conditions are then expected after midnight.
Friday and Friday evening
Assessment...high confidence
Quiet, dry but windy conditions will be seen on Friday with
temperatures at or slightly below normal. Although soil conditions
are quite moist, humidity levels will become quite low late Friday
morning and afternoon which may result in an enhanced fire risk for
any grassy areas that have not yet greened up.
Late Friday night through Saturday
Assessment...high confidence on a storm system affecting the area.
Low to medium confidence on placement of and rainfall amounts.
The first storm system with the potential for heavy rain will move
through the Midwest. The models have been somewhat consistent with
this storm system in placing the heaviest rainfall from the MN/IA
border into southern Wisconsin. However, recent GFS runs have
trended slightly further north while the FV3 has trended slightly
south. Regardless of the model solution all models have been
pointing to Saturday as when the main rainfall will occur.
The model consensus has slight chance to chance pops late Friday
night and likely to categorical pops on Saturday.
Saturday night on...
Saturday night
Assessment...medium to high confidence
The early weekend storm system will exit the area Saturday evening
followed by dry conditions late Saturday night. The model consensus
has slight chance to chance pops for Saturday evening.
Strong winds Saturday evening will usher in much colder temperatures
with a risk of freezing temperatures in the highway 20 corridor.
Sunday
Assessment...medium to high confidence
The cold front that moved through the area with the weekend storm
system will begin moving back north toward the area on Sunday. The
model consensus has mainly dry conditions Sunday due to the dry
atmosphere over the area. Temperatures will average below normal.
Sunday night through Wednesday
Assessment...high confidence that two separate storm systems will
impact the Midwest. Low confidence on storm track and potential
rainfall amounts.
The global models are highly varied on timing and tracks of two
additional storm systems. Likewise the location of and rainfall
amounts are also highly varied.
The GFS takes both systems from the IA/MO border into northern
Illinois with heavy rain over the area.
The ECMWF as a stalled front further south and takes the first
system from Missouri into central Illinois with the second system
moving from western Iowa into Minnesota Tuesday night into Wednesday.
The CMC global takes two separate systems from the IA/MO border into
central and northern Illinois with heavy rainfall.
The FV3 takes the first system from Iowa to the IL/WI border. The
second system is much further south going from Missouri into
southern Illinois.
Given all these differences in track and timing, the model consensus
has chance to likely pops Sunday night and Monday, slight chance to
chance pops Monday night, chance to likely pops Tuesday and Tuesday
night, then chance pops on Wednesday.
Although there are rain chances from Sunday night through Wednesday,
it will not rain continuously. There will be periods of dry weather
the first half of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
ISSUED AT 705 PM CDT Wed Apr 24 2019
Clear skies and decoupled winds overnight may lead to areas of
fog late tonight in Thursday morning, which could become locally
dense. Mentioned fog in TAFs but held off on dense fog until
confidence increases, and will let later shifts reassess with 06Z
TAF cycle. For Thursday, expect increasing cloud cover with brief
MVFR ceilings possible, NW winds developing behind a cold front,
and periods of light rain or showers -- mainly in the
afternoon/evening.
&&
.HYDROLOGY...
Issued at 1117 AM CDT Wed Apr 24 2019
The Mississippi is currently rising from LD11 down to LD15. The
river will begin rising again on Thursday from LD16 down to LD17.
Downstream of LD17 the river will begin rising again Friday into
Saturday.
The new forecasts for the Mississippi have slightly lower crests
from LD11 down through LD17.
HOWEVER, the current 7 day Mississippi forecast does not, repeat,
does not take into account predicted rainfall from Friday through
Tuesday. The weather forecast models are suggesting the
possibility of heavy rainfall.
Depending upon where and how much rainfall occurs crest timing and
crest forecasts are subject to change. If the rain occurs on or
just ahead of the crest then crest forecasts have the potential to
go higher than forecast.
The weather models are suggesting the heaviest rainfall from the
early weekend rain would occur from the IA/MN border into
southern Wisconsin. If this location is correct it would occur
behind the crest and would slow the rate of fall on the
Mississippi.
There is much more uncertainty regarding the second round of
potential heavy rain late in the weekend and early next week. The
weather models continue to offer different tracks for the storm
system and potential rainfall amounts.
Individuals with interests along the Mississippi are strongly
urged to pay attention to future weather and river forecasts over
the next week.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...Uttech
SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...08
AVIATION...Uttech
HYDROLOGY...08
Area Forecast Discussion
National Weather Service Houston/Galveston TX
1006 PM CDT Wed Apr 24 2019
.NEAR TERM [Through Tonight]...
Water vapor imagery shows a strong upper low over central Texas.
00Z upper level analysis has a strong nearly 100kt jet core coming
into the area with the best divergence ahead of it where there
has been strong/severe convection. There is still some strong
divergence aloft that should move over SE Texas tonight but
capping has held fairly strong and instability has decreased quite
a bit with loss of heating. The boundary layer has also become
more turned over with ongoing and previous convection. There is
still some chance at some storms through the morning hours but the
threat looks fairly small at this point. There might be enough
lift along a front that pushes through afternoon midnight to
trigger some convection so forecast will have some chances for
storms continuing. HRRR trends along with WRF show this
possibility. Again any storms that do form may become strong but
should remain below severe limits. After the storms tonight,
tomorrow looks fairly pleasant with northwest winds and drier air
moving into the region.
Overpeck
&&
.PREV DISCUSSION /Issued 636 PM CDT Wed Apr 24 2019/...
.AVIATION [00Z TAF Issuance]...
Forecasting line of storms will prove difficult tonight as
strong/severe storms run into capped atmosphere over Southeast
Texas. Cap is eroding, but unsure if it will be enough for
severe storms to continue much deeper, especially as storms seem
to be moving more quickly than in models. This is a long way of
saying that amendments may be frequent tonight as this dynamic
situation evolves. Eventually, sometime in the ballpark of mid-day
tomorrow, look for VFR conditions to return with northwesterly
winds.
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 59 80 60 83 60 / 100 0 0 0 0
Houston (IAH) 63 81 62 85 62 / 70 0 0 0 0
Galveston (GLS) 67 79 68 80 68 / 70 20 0 0 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 7 AM CDT Thursday for
the following zones: Waters from Freeport to Matagorda Ship
Channel TX from 20 to 60 NM...Waters from High Island to
Freeport TX from 20 to 60 NM.
&&
$$
DISCUSSION...
NEAR TERM...Overpeck
Area Forecast Discussion
National Weather Service Lincoln IL
846 PM CDT Wed Apr 24 2019
.UPDATE...
Issued at 845 PM CDT Wed Apr 24 2019
Have made some minor tweaks to the grids to match up with
precipitation trends.
Currently between waves moving along boundary to our south with
pcpn confined to south of I-70. As the night goes on scattered
showers are once again expected to pop-up generally southeast of
I-72/Danville after midnight as the next wave approaches the
midwest.
Fog may become an issue later tonight, particularly along and
west of I-55 where 00z HRRR, RAP, and 01z LAMP all depict low
vsbys. They have backed off some in coverage in the last few runs
so may be patchy. Thats what we have running in the grids and that
stills seems reasonable.
&&
.SHORT TERM...(This evening through Thursday)
ISSUED AT 245 PM CDT Wed Apr 24 2019
IR satellite imagery shows 3 waves (northern IL, southern KS, and
southwest TX). Movement of these waves will be enough to keep
plenty of pcpn over the southern 1/2 of IL through Thursday. IL
wave to continue to move off to east as pcpn develops in
overrunning pattern over the semi-stationary front in the OH river
valley. Showers and storms over Mo to move northeast, mainly over
southeast IL overnight, all ahead of the KS wave.
Models strengthen the TX wave, developing a significant low center
that tracks into AR, increasing pcpn ahead of it and with showers
reaching into southeast IL through the day Thursday. Cold front to
sweep into IA by Thursday morning and move into IL late will bring
a chance for some additional scattered showers Thursday afternoon
and evening.
.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 245 PM CDT Wed Apr 24 2019
Dry conditions on Friday. This will not last long as another low
center to move from the rockies and move over northern IL on
Saturday. Then overrunning showers develop on Monday ahead of
another low Monday, with the rain continuing into Wednesday til
the cold front passes. As a result, temperatures will remain on
the cool side for late April into next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 650 PM CDT Wed Apr 24 2019
Waves continue to advect along the boundary to our south bringing
oscillating vsbys and lowered cigs to central Illinois terminals,
particularly KSPI and KDEC. Conditions have been significantly
worse in K3LF and KPPQ over the past few hours then KSPI, but
trends have gone downward with KSPI currently on the edge of IFR
Cigs and vsby starting to drop. RAP, LAMP, and HRRR all suggest
vsbys and cigs will be an issue through midmorning from I-55
west. For now will bottom out at 1SM and stay out of LIFR category
but this will need to watched closely.
At most sites, will use VCSH to indicate the enhanced precip
chances in the area with the final wave during the day Thursday.
With KDEC closest to boundary will go with a period of predominant
precip there.
Front will move in late Thursday and bring a wind shift and a
gradually clearing trend. Will go VFR by the end of the TAF valid
period at KPIA as drier air starts moving in.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Barker
SHORT TERM...Goetsch
LONG TERM...Goetsch
AVIATION...Barker
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1051 PM EDT Wed Apr 24 2019
.UPDATE...
Issued at 1051 PM EDT WED APR 24 2019
Evening radar trends and model data support lowering the POP for
tonight and into Thursday morning. The only values in the likely
category for tonight are now at the northern tip of the forecast
area, mainly in Fleming County. Lightning is diminishing and may
be gone by the time the only currently active cell makes it to
our area. Have maintained a slight chance of thunder only in
Fleming county.
UPDATE Issued at 633 PM EDT WED APR 24 2019
Based on observed trends, the precip potential is slower to arrive
this evening than was forecast. The GFS was the most aggressive
with bringing it into our area, and it appears the less aggressive NAM
and HRRR have a better handle on things at this point. If this
continues to be the case, the precip potential will be a bit
further north this evening. The forecast has been updated trending
that way.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 329 PM EDT WED APR 24 2019
An area of surface low pressure and its associated fronts will be
the epicenter for our weather over the short term portion of the
forecast. Currently this area of low pressure is located over
southern Illinois. From this stretches a frontal boundary
eastward, which has remained draped over NE Kentucky through much
of the morning and early afternoon. This area of low pressure is
expected to finally begin shifting northeastward this
evening/overnight, allowing the frontal boundary to lift northward
as a warm front. Meanwhile, a cold front extends southwest of the
low and is expected to begin traversing far western Kentucky
during the overnight. Another stronger area of low pressure will
then begin making its way towards the Mid-Mississippi Valley
overnight as well, reaching far western KY by 21Z Thursday. The
cold front will continue to traverse eastern Kentucky Thursday
night as the area of low pressure continues to shift northeastward
across the state, exiting into Ohio by Thursday night.
As for sensible weather, expect SW winds to be on the increase
especially after the frontal passage lifts northward as a warm
front this evening/overnight. Moisture associated with the
approaching low will lead to increased clouds as well as rain
chances, mainly across the northern CWA. Clouds will provide
insolation overnight, so lows will only fall to the upper 50s to
around 60. Then for Thursday, the area of low pressure will pass
by north of the CWA while the cold front approaches from the west.
This will overspread the rain chances across the CWA throughout
the day, especially across the northern and western CWA. Afternoon
heating may lead to some instability and thunderstorm chances, but
not expecting anything strong. Highs will generally be in the mid
and upper 70s, though northern Ky could see lower 70s. Showers and
thunderstorms will then increase overnight Thursday night as the
front passes across the CWA and the next area of low pressure
moves across the state. QPF will be quite a bit higher during this
period, especially along the Bluegrass region. For the 24 hour
period ending at 18Z Friday, between 0.66 and 1.25 inches of
rainfall are forecast across eastern KY.
.LONG TERM...(Friday through Wednesday)
Issued at 320 PM EDT WED APR 24 2019
The extended looks to feature alternating periods of wet and dry
weather, as a couple of low pressure systems and a ridge of high
pressure affect area weather. The strongest of the storm systems
will be moving through the area Friday and Friday evening, and will
bring a good soaking rain to eastern Kentucky. Saturday and Sunday
look mostly dry, with a few rain showers possible across the
northwestern portion of the area Saturday afternoon and evening.
After dry weather Sunday and Sunday night, another weather system is
forecast to bring more rain to eastern Kentucky Monday and Monday
night. We may even see a few thunderstorms Monday night. Tuesday and
Tuesday night look to be mostly dry, with a few rain showers
possible along the Virginia border and along and north of I-64. The
Bermuda high will occasionally advance northward, giving us dry
weather Sunday and Sunday night, and then southward, allowing for
wet weather on Saturday and to start the new work week.
Temperatures will exhibit a bit of range in the extended, with max
values in the mid to upper 60s expected on Friday, and the upper 60s
to lower 70s on Saturday and Sunday. We can expect a good warm up to
begin the new work, as southerly winds allow for max temperatures
ranging from the mid 70s to lower 80s. Nightly lows will generally
be in the 40s and 50s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 815 PM EDT WED APR 24 2019
Mainly VFR conditions are expected through the period, with a
couple of possible exceptions. Showers could bring sub-VFR
conditions near/north of a KIOB-KSYM line overnight tonight, and
showers and thunderstorms may result in sub-VFR conditions
near/west of a KSME-KSYM line near the end of the period late
Thursday. However, the probability at TAF sites is too low to
warrant anything other than VCSH or VCTS at KSYM and KSME.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...HAL
SHORT TERM...JMW
LONG TERM...AR
AVIATION...HAL
Area Forecast Discussion
National Weather Service Lake Charles LA
936 PM CDT Wed Apr 24 2019
.UPDATE...
If you have been following along this evening the situation has
been settling down some, as organized line of earlier severe
storms over Texas has been on a weakening trend. with just some
disorganized showers and isolated thunderstorms entering the
forecast area of southeast Texas. The 25/00z upper air sounding
from KLCH was not very impressive as far as severe weather or
heavy rainfall parameters.
Looking ahead, some of the guidance like the RAP13 is still
bullish on the dynamics after 25/06Z with good shear, CAPE, and
PWAT values. However, there is still some inhibition noted with
small cap around 85H, and mid level dry air intrusion, which is
possible looking at latest water vapor imagery. Therefore, these
factors could keep strength of the activity in check.
SPC has lowered the severe risk for the remainder of the night
to the Marginal level (5 percent wind damage, 2 percent tornado.)
Also, WPC has lowered the excessive rainfall risk to the Marginal
level (5-10 percent.) 25/00Z 50 percentile probabilistic QPF
values (most likely) and WPC operational QPF values are down to
1/2 to 1 1/2 inches on average with only the 90th percentile
(reasonable worse case scenario) showing 2 to 3 inches on average
with some local higher amounts.
With that being said, the latest HRRR from 25/01Z still insists on
a regeneration of an organized line of healthy storms around
25/12Z along the Sabine River, with individual cells still showing
rainfall rate potential on the order of 1-2 inches per hour. That
and the still impressive RAP13 forecast soundings, don`t want to
totally down play everything, but the risk for the severe weather
and heavy rainfall is lower for tonight than it was looking like
at this time yesterday or earlier today.
Will modify the grids some based on the latest hi-res guidance and
radar trends.
Rua
&&
.PREV DISCUSSION... /issued 658 PM CDT Wed Apr 24 2019/
DISCUSSION...
00Z TAFS
AVIATION...
Ceilings range from VFR to MVFR across the region at this hour
with MVFR CIGs expected to become more dominant after sunset. A
developing squall line will approach from the west overnight along
the leading edge of a cold front. Some of these storms will have
the potential to be strong to severe with strong and gusty winds
along the leading edge of the line. Visibility reducing heavy rain
will also be possible within some of this activity.
Winds behind the front will turn westerly and remain gusty.
Ceilings will lift to VFR Thursday afternoon, but scattered
overrunning showers will continue across the area through the
evening in the wake of the frontal passage.
Jones
PREV DISCUSSION... /issued 346 PM CDT Wed Apr 24 2019/
DISCUSSION...
Mid-afternoon sfc analysis shows a cold front stretching from low
pressure near the Ozarks through the ArkLaTex to the cntl TX Hill
Country. Water vapor imagery indicates a strong shortwave crossing
the srn Plains/TX Big Bend with an initial vort ahead of it
crossing cntl TX at this time. Regional 88Ds are showing plentiful
showers/storms associated with these features out to our west...a
few strong to severe storms have been noted and a Severe
Thunderstorm Watch continues across cntl TX. Closer to home, sfc
obs indicate mostly cloudy skies with seasonal temps ongoing, but
no rainfall has been reported with the light returns making their
way across the forecast area so far this afternoon.
Our anticipated potential severe weather event still looks on
track for tonight. Convection currently ongoing out to our west
should continue to track ewd/enewd with the disturbance aloft
ahead of the primary shortwave. High res models have been
consistent in indicating a line of thunderstorms mainly in
association with a pre-frontal/outflow boundary moving into our
wrn zones late this evening, then traversing across the forecast
area through the overnight hours, departing lower Acadiana by mid-
morning Thursday. Synoptic-scale models show more of a slower
moving, more widespread convection solution...and POPs through
tomorrow are kind of a blend of the two. Forecast soundings
continue to advertise the threat for severe weather with improving
moisture through the column/good CAPE, shear and lapse rates.
Primary threats remain damaging wind gusts and possibly large
hail. Tornado threat doesn`t look as good, but a tornado or two
certainly cannot ruled out, primarily along the line as it moves
through overnight. Guidance QPFs continue to inch downward with
time with mean values topping out under 3 inches...certainly
localized higher amounts will be possible, but for now have
elected to hang onto any flood-type watches.
Once the showers/storms depart the region tomorrow afternoon/early
evening, dry weather in wake of the sfc front/shortwave aloft
looks to take hold through the weekend and into early next week.
Another weaker disturbance is progged to cross the nrn tier of the
country over the weekend, dragging a sfc boundary swd toward the
region...however all solutions are in agreement this afternoon
that the front will hang up north of the forecast area with any
precip not expected much farther south than the I-20 corridor.
Next rain chances don`t enter the picture until the very end of
the forecast period...and then only for the far wrn zones...as the
next srn stream system crosses the swrn CONUS, helping spin up a
sfc low over the Plains, then drag a cold front toward the
forecast area.
MARINE...
Caution headlines have been inserted for the outer waters west of
Intracoastal City as winds strengthen to 15-20 knots by late
afternoon, then linger through the overnight hours. Thereafter, no
flags are expected on the coastal waters through the remainder of
the forecast period.
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 66 78 59 80 / 80 60 20 0
LCH 69 79 63 82 / 80 70 10 0
LFT 69 79 62 82 / 70 80 20 0
BPT 68 80 62 84 / 80 40 10 0
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...Small Craft Exercise Caution until 7 AM CDT Thursday for GMZ470-
472.
&&
$$
PUBLIC...07
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
555 PM CDT Wed Apr 24 2019
.SHORT TERM...
247 PM CDT
Through Thursday Night...
Through the next 36 hours, there are a couple periods of
precipitation, with one being spotty light showers the rest of
this afternoon and tonight, then two being a period of
showers...with an outside chance for thunderstorms...late Thursday
afternoon and evening.
Satellite imagery this afternoon depicts a sheared and weak wave,
but still well-defined and persistent (more so pesky), across
northern Illinois. This has provided enough isentropic lift and
moisture return above 800 mb for scattered light showers and
sprinkles across mainly north central Illinois so far. Some of
this current activity will spread/re-develop eastward through
this evening as the forcing does, with northwest Indiana possibly
seeing spotty light showers all the way into early Thursday
morning. Clouds will also be very slow to depart and confidence on
low temperatures is somewhat low, but expecting little movement
this evening. Clouds should linger into the morning across
southern and eastern parts of the CWA.
The upper low across Texas this afternoon will translate northeast
into the Lower Ohio River Valley on Thursday. Meanwhile a northern
stream impulse and associated cold front will approach the area
and enter north central Illinois during the mid to late afternoon.
Both areas of forcing in the southeast and northwest will
potentially support showers, with a "squeeze" in the middle of the
CWA that will likely be precipitation free through the afternoon.
The northern stream cold front will accelerate into the area
during the evening as mid-level phasing occurs between the
systems. Deeper ascent and mid-level frontogenesis immediately
behind the front look to support a decently wide axis of showers
developing across northern Illinois into the evening. Convection
allowing and other higher resolution guidance support this in
their QPF solutions and have trended upward through today. It is
not impossible to have isolated thunder too given a region of
conditional symmetric instability hinted at by end of current RAP
run and seen on the NAM run. With at least a few CAMs showing 40+
dBZ echoes, there could be some brief heavier showers in the
evening. Activity should end from west to east late in the evening
into the overnight.
Temperatures on Thursday have potential to be into the lower to
mid 70s ahead of the front, but clouds could and likely will be
somewhat of a factor for at least part of the day. Also, a lake
breeze is likely to develop in the otherwise light boundary layer
flow ahead of the front to keep lakeside areas cooler during the
afternoon. Behind the front, winds will turn sharply north with a
several hour period of 20+ mph gusts favored.
MTF
&&
.LONG TERM...
Friday through Wednesday...
235 PM...Primary forecast concern is with a system to affect the
area Saturday/Saturday night...with an unsettled pattern early/
mid next week.
A weak ridge of high pressure will move across the area on Friday
with a strong low pressure moving from the central Plains across
the area Saturday evening. The models are in overall fair
agreement with the track of this low right across the cwa with
some minor timing differences. Rain looks to spread across the
area around/shortly after daybreak Saturday. Temperatures will be
tricky...especially across the north with east flow briefly going
southerly and then shifting northerly with the passage of the low.
This could mean a brief warm up through the northern cwa with most
of the day north of I-80 fairly chilly. Didn/t get to fancy with
temps yet but this will likely require further refinement as this
time period approaches.
The models continue to show a swath of accumulating snow north of
the cwa with this system. But a southern shift to this system
could bring the snow potential further south. Its still possible
that a few snow flakes mix in on the back side of the system
Saturday night. Though it appears that much of the qpf will have
ended by this time.
The gradient will tighten as the low departs with high pressure
building across the Western Great Lakes and the speed of the low
will add to a short period of potentially very strong winds
centered around 06z Sunday. Forecast soundings would support wind
gusts into the 40-45 mph range. Did not go this strong yet...but
this time period will also need to be monitored for strong winds.
A series of low pressures may affect the area early/mid next week
with several days of cooler easterly flow...periods of showers...
and potential large temp differences from north to south across
the cwa. cms
&&
.AVIATION...
For the 00Z TAFs...
Light radar returns falling across the region continue to be mainly
just virga as very dry air remains in place. Small chance some
terminals may see a trace of precipitation, so did leave VCSH in
the TAF for the next couples hours. Light easterly winds will
remain in place for the rest of the night. Pleasant conditions are
expected Thursday, but there will be a lake breeze developing in
the afternoon. Expect that to impact wind directions at MDW after
20z and ORD after 22z. Showers will commence mainly after 00z
Thursday evening across the region with flight categories staying
MVFR or better.
MM
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
657 PM CDT Wed Apr 24 2019
.SHORT TERM... (Through Late Thursday Afternoon)
Issued at 346 PM CDT Wed Apr 24 2019
An upper level trough stretching from southern Iowa down through
southwest Texas into Mexico is moving slowly eastward this
afternoon. Models are in good agreement that the trough will force
low level cyclogenesis over Texas tonight along the front which has
been nearly stationary from Texas up through Arkansas into the mid
Mississippi Valley. The resulting closed surface low is forecast to
ride up along the front overnight tonight and Thursday...moving into
the lower Ohio River Valley by 00Z Friday. Guidance continues to
show weak to moderate low level moisture convergence through the
night tonight in southwest flow at 850mb ahead of the trough. While
moist of the resulting convection will likely stay over far
southeast Missouri and Kentucky, there will probably be areas of
light rain tonight as a result of this moisture convergence...mostly
confined to areas along and southeast of I-44 in Missouri and I-70
in Illinois. The RAP is showing a bit of elevated instability
across southeast Missouri into southern Illinois as well, so a few
rumbles of thunder aren`t out of the question either. Also of note
tonight: visibility guidance gets very low over a wide swath of the
forecast area...mainly along and north of I-70. Dense fog with
visibility less than 1 mile is possible, and conditions may warrant
a dense fog advisory, though I do not have enough confidence yet to
issue one at this time.
Low level moisture convergence increases sharply on Thursday morning
as the center of the surface-850mb low moves into northeast
Arkansas. There will likely be a sharp cut off to the resulting
precipitation in Missouri and Illinois Thursday...and right now that
cut off looks to be just southeast of I-44 through southeast
Missouri into southwest and south central Illinois. There may be
some potential for heavy rain and flooding if the rain persists
through the day...though it`s not clear just yet whether the heavy
rain threat will reach as far north as our southeast Missouri
counties. For now we will just continue to monitor the heavy rain
potential.
Carney
.LONG TERM... (Thursday Night through Next Wednesday)
Issued at 346 PM CDT Wed Apr 24 2019
Period begins with the southern stream low, that is expected to lift
NE into the area tomorrow, moving east out of the area. Meanwhile,
an upper trof within the northern stream and associated surface cold
front will push south into the area. With strong CAA with this front
and good upper level support, believe showers should develop along
and just behind the front into the evening hours.
For the remainder of the forecast period, model solutions are in
fairly good agreement. However, there are differences in timing of
an upper low opening and ejecting into the Plains late in the
period. While there are some differences from one cycle to the next,
the overall trends are similar.
With zonal to slightly ridging flow, have trended near or just above
median temperatures through the end of the forecast period. PoPs
remain near the low chance range with more uncertainty on timing.
Tilly
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 636 PM CDT Wed Apr 24 2019
IFR or LIFR ceilings are expected at KUIN and the St. Louis area
terminals through Thursday morning. IFR or low MVFR ceilings are
also expected at KCOU. MVFR visibilites will drop to LIFR at KUIN
and KCOU late tonight and early on Thursday morning. Conditions
will improve to VFR or high MVFR on Thursday afternoon as winds
turn out of the northwest allowing drier air to move into the
region.
SPECIFICS FOR KSTL:
IFR or LIFR ceilings are expected to remain over the terminal
through Thursday morning. Some light showers will be possible
terminal through tonight. Conditions will improve to VFR or high
MVFR on Thursday afternoon as winds turn out of the northwest
allowing drier air to move into the region.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
751 PM EDT Wed Apr 24 2019
.SHORT TERM...(This evening through Thursday)
Issued at 423 PM EDT WED APR 24 2019
Water vapor imagery and RAP analysis show zonal flow across the
northern CONUS/southern Canada. A rather vigorous shortwave was just
n of MN over northern Ontario. Low-level jet of 35-45kt ahead of
this trof has supported a few -shra/sprinkles over ne MN. Some of
these sprinkles have moved into western Upper MI recently. Mid-level
clouds that have been spreading over western Upper MI today have
held temps down a bit from what was expected, but still most
locations over the w half of Upper MI have topped out in the 60s
this aftn.
For the next few hrs, expect a few sprinkles moving from western
Upper MI into central Upper MI. Otherwise, aformentioned shortwave
will continue to shift e across northern Ontario tonight. Associated
cold front currently moving across northern MN should be over
central Upper MI at 12z Thu. Satellite imagery currently shows some
convective looking mid-level clouds vcnty of the front, but no shra
yet. Many of the models develop isold/sct shra along the front over
ne MN during the next few hrs, and with a little weak instability
lingering aloft tonight, a few -shra may accompany the front as it
moves into the area during the night. Will be a mild night ahead of
the front. Low to mid 40s should be the rule for much of the fcst
area.
Front will slow down Thu in response to a vigorous shortwave
tracking across s central Canada. This wave will reach nw MN Thu
evening. Expect increasing post frontal lake breeze component off
Lake Superior during the day to help push the front s out over Lake
MI. Until it does so, there may be a few shra vcnty of the front.
Some of the high res guidance, NAM in particular, generate
convection over Menominee County in the aftn due to build up of
several hundred j/kg of mucape with the convergence from the front
and lake breeze development off the Bay providing the forcing. Have
some doubts on that much instability, but will be something to
monitor Thu aftn. Behind the front, another surge of drier air will
follow. Leaned fcst toward the drier GFS idea and incorporated some
of the dry air mix down potential to lower dwpts, especially over
the nw half Thu aftn. Not much cooling follows the front for Thu.
With temps rising back into the 60s, min RH may tumble to 20-25pct
over the interior nw half. With wind off Lake Superior, it will be
cooler along the lake, especially e of Marquette. Temps there may
briefly rise in the morning before the front passes, then fall back
thru the 40s.
.LONG TERM...(Thursday night through Wednesday)
Issued at 343 PM EDT WED APR 24 2019
Although regionally the pattern will remain active through the next
7 days, no widespread significant precipitation events are expected
through next Tuesday, which is good news for area rivers that will
be able to recede through the weekend. Generally near to below
normal temperatures are expected into early next week as well.
Thursday night, a shortwave will dive in from the NW, bringing some
cloudiness and perhaps a shower or two over the north and east, but
thankfully the airmass will be too dry for much in the way of rain.
Friday, mainly just some diurnal cumulus and cooler temperatures
back in the 45-53 degree range. CAA will continue into the weekend
with Sat highs struggling to rise above the lower 40s.
Medium/long range models have flip-flopped again with the system
moving in this weekend, bringing the main precip shield back south
into WI. However the 84 hr NAM remains further north, so still
cannot rule out some precip across the southern CWA, especially near
Menominee. If it does clip our area, main ptype appears to be snow
per model soundings, and a jog back to the north could mean several
inches mainly on grassy surfaces at MNM. GFS soundings are very
dry during this time along the WI border, perhaps due to
persistent northerly flow, with NAM soundings saturated through
the column. Reality will likely end up somewhere in between.
Brief, relatively weak ridging will allow for some sunshine Sunday
that will bring temperatures back near 50 inland west. Weak
shortwave activity on Monday may lead to a few light showers mainly
over the west. Flow should be more zonal on Tuesday with quiet
weather likely to continue, however a more robust shortwave will
ride up the eastern side of a persistent Western CONUS trough into
the middle of the week that is expected to bring our next chance for
appreciable rainfall. Track, timing, and intensity are still in
question at this time, with the ECMWF being the most bullish with
rainfall potential over the UP Wednesday into Thursday. Although the
deterministic GFS brings the bulk of the precipitation well to our
southeast, GEFS ensemble mean precip indicates a tendency back
towards our area. Continued chance POPs during this period, only
increased slightly from the blend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 741 PM EDT WED APR 24 2019
With low-levels remaining relatively dry, VFR conditions will
prevail at KIWD/KMCX/KSAW through the forecast period. A cold front
moving across the area tonight into early Thursday may produce some
isold light showers.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 423 PM EDT WED APR 24 2019
Ahead of an approaching cold front tonight, expect s to se winds
generally in the 10-20kt range, strongest over the e half where
gusts may reach 20-25kt for a time. Behind the front, westerly winds
should be under 20kt on Thu. In the wake of another passing cold
front Thu night, w to nw winds of 10-20kt are expected on Fri over
western Lake Superior and 20-30kt over the e half. Not out of the
question for winds gusts to reach gale force over the e. High pres
ridge building into the northern Great Lakes should support winds
falling to mostly under 20kt for the weekend.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...KCW
AVIATION...JLB
MARINE...Rolfson