Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/22/19
Area Forecast Discussion
National Weather Service La Crosse WI
1030 PM CDT Wed Aug 21 2019
.SHORT TERM...(This evening through Thursday)
Issued at 240 PM CDT Wed Aug 21 2019
Plenty of showers and storms to be seen south of the area early this
afternoon, associated with a fairly strong shortwave and surface
boundary moving through. Meanwhile, high pressure continued to move
into the forecast area and will eventually lead to clearing skies
this evening, which could set the stage for some fog, especially in
the river valleys. Model soundings indicate a sufficiently deep
light wind layer, though would like to see surface
temperature/dewpoint spread a little less in the late evening hours
for a "widespread" fog event. In addition, some clouds could slip
into northern portions of the forecast area during the early morning
hours, which could hinder fog development as well.
The trend for Thursday has been a bit cloudier and cooler than past
forecasts, with models in decent agreement of some convergence along
an inverted trough. In fact, 21.12Z NAM soundings show a little bit
of shallow instability/steep low level lapse rates across southern
Wisconsin, so could certainly see a few showers pop up. Various CAMs
tend to agree with this idea as well, so went ahead and introduced
scattered sprinkles mention for the afternoon.
.LONG TERM...(Thursday night through Wednesday)
Issued at 240 PM CDT Wed Aug 21 2019
Thursday Night to Saturday...Pretty quiet weather here with partly
cloudy skies in a not-so-clean ridge over the area. The consensus
in the latest model suite is to keep an easterly component in the
flow and this seems to spell waves of low-level moisture rotating
through. This would favor 3-6kft clouds on and off during the
period. Valley fog could certainly occur in the mornings Fri/Sat
as many parameters favor it, but due to lower confidence in the
low-cloud coverage, have left it out of the forecast for now. The
21.12Z ECMWF is very aggressive on clear skies for the period,
meaning valley fog would definitely happen. But, it seems to be
the outlier.
Saturday Night through Wednesday...Longwave pattern over North
America is evolving to a higher latitude trough during the period.
This evolution is being driven by a strong zonal jet crashing
into the West Coast and driving height falls. Thus, the
progressive longwave ridge over the great Lakes Saturday will
give way to a stronger cyclone in the northern states early next
week. It looks like the higher rain chances will hold off until
Monday when front moves in, with only a few model solutions
splashing a bit on Sunday. Then, showery with falling temperatures
into the middle of the week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1030 PM CDT Wed Aug 21 2019
Cigs/WX/vsby: latest fog/stratus satellite imagery indicating some
scattered mid cloud developing across the region - seeming to match
up with an increase in 850mb or so saturation indicated in both the
RAP13 and NAM12. The RAP would likely keep this scattered while the
nam favors going bkn - although holding VFR. Meanwhile, a mid deck
still expected to push in from the north with an upper level
shortwave Thu, likely resulting in bkn vfr cigs for Thu afternoon.
Latest meso model runs suggest a better chc for this across WI.
Expect cigs to clear south later Thu evening.
Some potential for river valley fog that could impact KLSE
overnight. Latest RAP13/NAM12 showing more a light deep wind layer
setting up earlier in the night - favorable for river valley fog.
Sfc winds staying light, but still from the north. However, threat
for bkn cigs and a T/Td spread at 03z is 10 F are not conducive for
dense river fog at KLSE. Will hold with BCFG for now and continue to
monitor.
Winds: light northerly through the period, becoming more easterly
later Thu night.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Baumgardt
LONG TERM...Baumgardt/Aufforth
AVIATION...Rieck
Area Forecast Discussion
National Weather Service Dodge City KS
640 PM CDT Wed Aug 21 2019
...Updated aviation discussion...
.SHORT TERM...(This afternoon through Thursday night)
Issued at 1145 AM CDT Wed Aug 21 2019
An active convective pattern is expected through tonight.
Overnight thunderstorm complex was exiting the NE zones at
midday. The associated outflow boundary was clearing the Oklahoma
border, but was washing out rapidly, and south/southeast winds are
expected to resume this afternoon. Cold front across northern
Kansas at midday is consistently progged by 12z NAM and the latest
HRRR iterations to be passing through SW KS during the peak
heating hours this afternoon and evening. Current frontal timing
trends suggests new convection will develop roughly along a La
Crosse-Dodge City-Liberal line around 3-4 pm. Areas north of this
line may see little if any activity, or at least comparatively
less coverage. Along with WFO Goodland, reduced pops across the NW
zones later today. Marginal 5% wind/hail probability continues
from SPC, as the frontal boundary focuses convergence in an
unstable airmass. Some strong updrafts are expected, supported by
plentiful moisture and instability, but lack of better wind shear
will limit updraft organization/longevity. Marginally severe hail
to the size of quarters, and downburst winds to 60 mph, will occur
with the strongest storms. Will need to keep an eye on hydrology
issues, particularly with any training cells, but 1) the heaviest
activity is expected to be south of the saturated soils in the NE
zones and 2) frontal push should keep the anticipated line of
convection moving southward at a pretty good clip across the
southern zones.
Temperatures this afternoon will be noticeably milder, given
previous convective outflow and loss of downslope. Afternoon
temperatures will range to the mid 80s NE, to the upper 90s in the
prefrontal environment near the Oklahoma border.
Most locations will fall back into the 60s tonight in the post-
frontal environment. Mid layer clouds will persist, along with
areas of showers/embedded thunder as shown by HRRR. All short term
models agree post-frontal stratus will invade at least the NE 1/2
of SW KS through sunrise Thursday.
Thursday`s highlight will be welcome heat relief. Morning stratus
will be persistent, gradually eroding to higher ceilings, and this
process will delay the onset of late August sunshine. In addition
to the loss of insolation, models consistently show a net 850 mb
temperature change of -6 to -8C compared to Wednesday. Stayed
several degrees above the coolest 12z MAV guidance, with
temperatures holding in the 70s NE zones, highs near 80 at Dodge
City, and 80s along the Oklahoma border. Doubtful stratus will
persist into the afternoon in late August, but if it can, coolest
guidance will verify. A refreshing break from the heat with free
air conditioning, with afternoon temperatures running about 10
degrees below normal for late August.
Most organized convection Thursday PM will be focused on the
frontal boundary SE of SW KS, but can`t rule out some post-frontal
elevated development Thursday afternoon, most likely SE zones.
Warm air advection over the meandering/retreating/washing out
frontal boundary will likely ignite some elevated thunderstorm
activity Thursday night, and pops were retained for this activity.
.LONG TERM...(Friday through Wednesday)
Issued at 145 PM CDT Wed Aug 21 2019
Friday appears convectively active. 12z ECMWF tracks a strong
shortwave trough through the northern Rockies, with strong
diffluence aloft spreading over SW KS. With established SEly
boundary layer flow maintaining healthy moisture, with dewpoints
in the upper 60s/lower 70s, at least scattered category pops are
warranted Friday afternoon/night, as shown by ECMWF QPF and 12z
MEX guidance. Further increases in pops are expected. With
improved upper support and stronger flow aloft, convective
organization may also improve Friday, with strong to severe
thunderstorms probable. Upslope flow and convection will work to
keep the heat at bay Friday, with afternoon highs restricted to
the lower 80s NE, to the lower 90s SW.
Opportunities for rainfall dwindle sharply over the weekend, with
all grids dry for all zones Saturday afternoon/evening and Sunday
afternoon/evening. Models are displaying good consistency
forecasting Sunday to be hottest day of the forecast period, with
a peak in MEX guidance near 100 and thicknesses maxing out Sunday
afternoon. Many locations, especially south of Dodge City, will
reach 100+ again on Sunday.
First weak cold front offers several degrees of cooling and a NEly
wind shift on Monday. All global models agree a stronger cold front
will arrive in the Tuesday/Tuesday night time frame. Some convection
will accompany this front, and the parent upper trough swinging
through the northern plains will deliver much cooler (below normal)
temperatures Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 640 PM CDT Wed Aug 21 2019
Scattered thunderstorms in the vicinity of Liberal will continue
off and on through the evening hours before drifting east and
southeast. A cold front moving through southwest Kansas will push
through the Garden City and Dodge City terminals by around 02z.
There is some small potential for thunderstorms in the vicinity of
these locations but will keep those TAFs dry for now. MVFR to IFR
stratus is expected to develop later tonight, along with some
visibility reductions. Cigs should gradually lift through the day
on Thursday.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 66 81 65 89 / 50 30 30 30
GCK 64 80 62 90 / 50 10 20 30
EHA 63 88 63 91 / 50 30 30 20
LBL 66 88 65 92 / 60 30 30 30
HYS 64 75 64 83 / 50 30 30 20
P28 70 83 67 87 / 40 40 30 30
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Gerard
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
658 PM CDT Wed Aug 21 2019
.Discussion...
Issued at 343 PM CDT WED AUG 21 2019
Message of the day: Isolated to scattered storms are expected this
afternoon and evening with storms becoming more widespread
overnight. Isolated strong winds and hail are possible
today/tonight, but heavy rain is the main concern. Up to 3 inches of
rain is expected for parts of the area with locally higher amounts
possible. Therefore, a Flash Flood Watch has been issued from 7 PM
tonight until 10 AM tomorrow along and south of the MO River.
The storm activity took a brief late this morning, but with some
clearing in the clouds, the advancing cold front, and effective
boundary leftover from this mornings convection, we are seeing new
storm development in our western counties and out in central KS.
This activity should be isolated to scattered in nature for the
afternoon and early evening. Isolated strong to severe storms are
possible anywhere across our area, with CAPE between 1500-2500
J/kg and deep layer shear generally around 35 kts with some
pockets up to 45 kts. Winds up to 60 mph and hail up to 1 inch are
the main concerns. As we head into the overnight hours, severe
weather potential will decrease, as the flash flooding threat
increases. PWATs are expected to exceed 2 inches which is well
above normal for this time of year. Additionally, the west to east
oriented frontal boundary will stall near the KS/MO/OK/AR border
as a southwest to northeast oriented LLJ strengthens. This will
enhance ongoing convection and increase coverage across the area.
The orientation of these features will promote training storms and
with fairly weak upper level flow, the system as a whole should
take its time moving south and east. As a result, excessive
rainfall is expected tonight, mainly along and south of the MO
River. Up to 3 inches of rain is expected with locally higher
amounts possible. As a result, a flash flood watch is in effect
from 7 PM tonight until 10 AM tomorrow for counties southwest of a
line from Atchison county KS to Howard county MO. For the most
part, storms are expected to diminish/exit the area in the late
morning as the LLJ weakens and high pressure starts moving in from
the north.
Storm chances will linger Thursday for those south of the MO River,
however most should be dry Thursday afternoon and evening with drier
air advecting in from the northeast. A somewhat messy upper level
pattern looks to take shape for the weekend, allowing for a few
chances for storms Friday and Saturday but that will be
counteracting the surface high pressure nosing into the area, so
right now it looks like most will by dry for the weekend.
Temperature- wise upper 70s to low 80s are forecast starting
tomorrow through the weekend. Not bad for the end of August.
&&
.Aviation...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 654 PM CDT WED AUG 21 2019
Starting to think the bulk of the heavy rain will move south of the
terminal tonight. Thunderstorm complex/line in eastern Kansas diving
SE leads me to believe the better focus for evening/overnight
thunderstorms will reside south of I-70. Certainly not implying a
dry forecast for tonight at KMCI, but successive Hi- Res
Simulated Reflectivity also support better chances for heavy rain
well south of KMCI. Have throttled back a bit on the
aggressiveness of the precipitation forecast, but kept a mention
of off-and-on showers through the next several hours. Used the
21z/22z HRRR to take a stab at cutting off precipitation
Thursday morning. Thereafter with cool and dry air moving in,
could see some low level stratus in the MVFR/IFR domain for a few
hours before gradually clearing Thursday afternoon.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...Flash Flood Watch through Thursday morning for KSZ025-057-060-
103>105.
MO...Flash Flood Watch through Thursday morning for MOZ028>031-
037>040-043>046-053-054.
&&
$$
Discussion...Atkins
Aviation...Leighton
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
327 PM MDT Wed Aug 21 2019
.SYNOPSIS...
Widespread showers and thunderstorms over the Gila Region in New
Mexico will push south and east into the lowland deserts this
evening, triggering additional thunderstorms. A few storms will
produce gusty winds and highly localized torrential downpours.
These storms will slowly weaken as they head towards the El Paso
area. Blowing dust will also be possible this evening. Moisture
will remain in the area on Thursday, with better chances for
rainfall near and east of the Rio Grande Thursday afternoon and
evening. But a drying trend will set in for Friday and Saturday,
with even the higher terrain likely staying dry Sunday through
Tuesday. Temperatures will cool off slightly Thursday and Friday,
but triple-digit temperatures will return to the lower elevations
Sunday or Monday.
&&
.DISCUSSION...
A weakening subtropical ridge is being split by a weak shortwave
trough over the Texas Panhandle, with the highest 500mb heights
now over northern Sonora. Mid-level winds remain light and
variable across the region. Higher aloft, a weak upper-
tropospheric trough (note wind shift at 200 mb and slightly cooler
mid-level temps) is draped across eastern Colorado and into New
Mexico, and may be helping to focus convection to some extent,
especially over central and northern NM. Thunderstorms in our area
have mainly been focused over the higher terrain. The Sacramento
Mountains are just about tapped out, while the Gila is most active
presently.
Surface dewpoints have mixed out a little lower than hoped for,
with a lot of upper-40s around the region, and a few areas of
lower 50s mainly in the Mesilla Valley and in a few spots that
received significant rainfall yesterday. Instability is rather
limited across the lowlands, as supported by the slow development
of cu in the lowlands. There are a few bands of cu extending NNW
to SSE near the Luna/Dona Ana County border, and this roughly
coincides with an area of rainfall from yesterday evening.
LAPS and RAP analysis suggest CAPE values are merely in the
200-300 J/Kg range along the Rio Grande, and even lower over
Hudspeth County. values greater than 400 are primarily found over
SW New Mexico.
Several CAMS models from this morning and last night had very
similar solutions for this afternoon/evening with regards to
evolution of convection. The common theme indicates a coherent
cold pool (essentially, outflow from thunderstorms in the Gila all
blobbing and merging together) kicking off additional
thunderstorms as it pushes into the lower terrain S and SE of the
Gila early this evening. Depending on the model, these storms
weaken as they move towards the El Paso area, but appear to still
be strong as they move into parts of SW New Mexico and Dona Ana
County.
The main concern was that these model runs are over-estimating low
level moisture and instability, and are too strong with the
resultant lowland convection. One example is the UofAZ NAM-
initialized WRF run from 12Z, which has fairly strong convection
over Luna and Dona Ana Counties before sunset. The model suggests
pre-storm CAPE values of around 400-600 J/Kg, which is in line
with observations. Still think the highest precip coverage will be
just west of the Rio Grande, and while El Paso may see rain this
evening, the heaviest amounts and best coverage will be to our
west...again. Gusty winds and dust will be possible from any
stronger storms.
Somewhat drier air aloft will push into northwestern New Mexico
for Thursday, and the focus for thunderstorms will spread eastward
as well. Low level moisture looks to be a little higher as well,
with higher instability over most of the region. Mid-level flow
will remain weak, with highly localized heavy rainfall possible
again.
Drier conditions are still expected for Friday and Saturday,
though residual moisture will be enough for some thunderstorms in
the higher terrain. Sunday through Tuesday continue to look dry
and increasingly hot, as the subtropical ridge strengthening to
our west brings drier northerly mid-level flow to the area. The
ridge itself looks to build back over New Mexico on Tuesday, with
100-degree heat likely returning to the lowlands Sunday.
&&
.AVIATION...Valid 22/00Z-23/00Z...
P6SM FEW-SCT080-100 SCT-BKN150-200 through period. Scattered to
numerous VRB25G40KT 1-3SM TSRA BKN030-040 with greatest coverage
along and west of line from KALM-KDMN. Thunderstorm coverage will
be on decrease after 04Z, but increase over the mountains, far
eastern lowlands and NM Bootheel. Winds east to southeast AOB
12KTS but variable and gusty around thunderstorms. Winds will
become more west to northwest after 12Z across the region.
&&
.FIRE WEATHER...
After a fairly active late afternoon and evening for thunderstorms
today, storm chances will gradually be diminishing going into the
weekend. This is when high pressure builds back in from the west
and pushes moisture south of the area. After a slight cool down in
temperatures the next couple days, highs will again rise to above
100 degrees for many lowland locations at least Sunday and Monday
with relative humidities falling back into the teens. Winds will
generally be under 15 mph but could be a bit breezy Sunday as a
deep west-northwesterly flow sets up over the area. Vent rates
will mainly be fair to good for the remainder of the week.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 74 96 74 97 / 20 20 30 0
Sierra Blanca 69 92 68 92 / 10 40 50 10
Las Cruces 68 94 69 95 / 80 10 20 0
Alamogordo 68 95 69 97 / 50 20 10 20
Cloudcroft 54 72 54 74 / 70 50 10 30
Truth or Consequences 68 95 69 95 / 30 10 10 0
Silver City 62 88 64 87 / 40 20 20 10
Deming 67 95 68 95 / 80 10 20 0
Lordsburg 68 96 68 94 / 40 10 10 20
West El Paso Metro 74 95 74 96 / 20 20 30 0
Dell City 71 96 69 97 / 20 30 40 20
Fort Hancock 75 97 74 97 / 10 30 50 10
Loma Linda 69 90 69 92 / 30 30 30 10
Fabens 73 96 73 96 / 20 30 40 10
Santa Teresa 71 95 71 96 / 30 20 30 0
White Sands HQ 71 94 72 96 / 50 20 30 0
Jornada Range 67 94 67 95 / 80 10 20 0
Hatch 67 95 68 96 / 80 10 20 0
Columbus 69 95 71 95 / 80 10 30 0
Orogrande 70 95 70 96 / 30 20 20 10
Mayhill 58 81 58 83 / 60 50 10 40
Mescalero 57 82 58 84 / 60 50 10 30
Timberon 57 80 57 82 / 50 50 20 40
Winston 57 87 59 86 / 30 30 10 10
Hillsboro 64 92 65 93 / 50 30 20 0
Spaceport 66 94 66 95 / 60 10 20 0
Lake Roberts 56 87 57 87 / 30 30 10 20
Hurley 62 90 64 90 / 50 20 20 10
Cliff 61 96 62 95 / 30 10 10 20
Mule Creek 64 92 65 89 / 10 10 10 20
Faywood 63 90 65 91 / 60 30 20 0
Animas 67 96 67 93 / 30 20 20 10
Hachita 67 95 67 93 / 60 20 30 0
Antelope Wells 66 92 66 90 / 50 40 40 10
Cloverdale 65 88 64 85 / 30 40 40 20
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
25-Hardiman / 26-Grzywacz
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1116 PM EDT Wed Aug 21 2019
.UPDATE...
Issued at 1116 PM EDT WED AUG 21 2019
A few extremely isolated showers/thundershowers lingered late
this evening, and adjustments have been made for this. The rest
of the forecast looks to be on track.
UPDATE Issued at 827 PM EDT WED AUG 21 2019
Forecast was largely on track. The only substantive change was to
allow precip to mostly die out for a time tonight, before it
starts to redevelop during the predawn hours.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 343 PM EDT WED AUG 21 2019
Diurnally driven CU has started to develop over the last hour or
two, in addition to some high clouds moving over the region. An
upper level shortwave has just shifted east of the region, so expect
better convective development to be outside of our CWA. However,
can`t rule out an isolated shower or thunderstorm popping up this
afternoon, especially with CAPE values over 3,000 J/kg in most
locations. Furthermore, like yesterday, any storm that does develop
could be strong as a result, and may produce strong winds given the
DCAPES over 1,000 J/kg yet again today. So far, however, the CAMS
are holding strong that convection should not develop until later in
the evening...so we shall see if that holds true. Only included low
end isolated pops at this time.
As we head into the evening and overnight, ample instability will
remain in place. This will couple with lowering heights aloft, and a
cold front which is poised to move SE closer to the Ohio River
through the overnight. CAMS are in fairly good agreement that after
some isolated convection potential during the evening, a larger
complex of showers/storms will develop and move eastward into the
CWA for the second half of the overnight. The HRRR is the only CAM
not showing this, or at least at the timing of the others, but it is
also at the very end of its run, so taking that into consideration.
The GFS and ECMWF are also on board with precip after 6Z as well.
Pops will continue to increase throughout the day Thursday as moist
SW flow increases and the front begins to traverse southward into
the state. The introduction of overcast cloud cover and precip will
prevent temperatures from being as hot as previous days, with highs
in the mid and upper 80s. However, CAPE values of between 2,000 J/kg
and 3,000 J/kg will still lead to decent convection ahead of and
along the frontal boundary. This boundary is then expected to become
stalled across the state heading into the overnight Thursday night,
with the much of the CWA still expected to see scattered to numerous
showers and thunderstorms. SPC has us in a marginal severe risk for
the Thursday/Thursday night time period. Hopefully this system will
finally bring us a more widespread soaking rain as well, with PWATS
topping well over 2 inches in some locations after 6Z Friday. WPC
has placed us in a marginal risk of excessive rainfall for this time
period as well.
.LONG TERM...(Friday through Wednesday)
Issued at 412 PM EDT WED AUG 21 2019
The models are in decent agreement showing a northern stream
trough over the northeastern CONUS and zonal flow over Kentucky
for the start of the long term. Meanwhile, ridging will be the
story for north-central CONUS for the end of the work week. This
pattern will gradually shift east, with ridging taking hold over
the northeast for late weekend. Another northern stream trough
will then build and begin advancing towards the Great Lakes and
Ohio Valley by Tuesday. A stalled surface front will move slowly
over eastern Kentucky into early Friday morning, but eventually
will make its way southward over the Tennessee Valley Saturday
morning. High pressure will build over the Great Lakes during this
time as well. This high pressure will then progress eastward
through the weekend, with a cold front slated to approach and
stall over the upper Mississippi Valley Tuesday. High pressure
will also take hold to the east of Kentucky for midweek.
The best chance for showers will be Friday as the cold front
stalls over the state. Instability is not impressive, but a few
thunderstorms in the afternoon and early evening cannot be ruled
out. By the weekend, shower and storm chances will become more
diurnally driven. Both the GFS and ECMWF, as well as the Canadian
and NAM, show little to no QPF for most of eastern Kentucky for
Saturday. Some chances remain along the Tennessee and Virginia
borders, however. Furthermore, the ECMWF shows no QPF for Sunday
into Monday, whereas the GFS shows some activity in east-central
Kentucky during this time. Lowered PoPs given by the blended
solution for Saturday and Sunday because of this.
High temperatures will be in the lower 80s through the weekend,
but rebound back to the mid 80s by next Tuesday. Lows will
generally be in the lower to mid 60s Saturday morning, but
gradually increase to be in the upper 60s by midweek.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 827 PM EDT WED AUG 21 2019
Conditions were predominantly VFR at the start of the period.
There were some very isolated showers over southern KY, with sub-
VFR conditions. These should largely die out this evening, leaving
benign weather until very late tonight. Scattered showers and
thunderstorms are forecast to develop after about 08Z and last
into the day Thursday. An increase in coverage is expected during
the day, with most places experiencing rain and associated MVFR
or IFR conditions at some point. However, timing at any given
location is problematic, and only VCTS has been used in TAFs.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...HAL
SHORT TERM...JMW
LONG TERM...CGAL
AVIATION...HAL
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
653 PM CDT Wed Aug 21 2019
.SHORT TERM...
122 PM CDT
Through Thursday ...
Water vapor pictures a bit more amplified flow across the northern
Great Lakes courtesy of a closed upper low south of James Bay. This
will drive a cold front south into northern Illinois this evening.
Upstream to the west there are several convectively altered waves
embedded in the westerly flow, and an MCV present in the radar loop
across Iowa.
SPC Mesoanalysis depicts and axis of MLCAPE is currently capped
along and ahead of the front that according to the RAP plan view may
erode. But there is an axis of deep layer moisture convergence, and
this combined with upper level energy from Iowa is enough forcing
for elevated thunderstorms above the capping inversion. Small hail
and heavy downpours would be the more likely hazards given the
elevated nature of the storms. This wave, while not easy to pick
out on satellite, is in an area well depicted by the RAP, and this
wave is projected to continue across the northern metro area this
afternoon.
Meanwhile the Iowa convection and associated MCV should be able
maintain additional showers and thunderstorms into our western
area this afternoon as they continue to follow the 850-300mb wind
and forward propogating vectors to the northeast. We will need to
watch this axis as well as the mid level flow does increase and
mid level lapse rates are fairly impressive above the elevated
mixed layer here as well, and shear is increasing which may allow
storms to maintain some organization.
For tonight the evolution and coverage is still slightly muddled,
and there is a short gap between the current wave and continued
shortwave energy farther upstream in Iowa. This energy will shift
across central IL should maintain and axis of showers and some
thunderstorms along and south of I-80, with some activity possibly
hanging back to the northeast across the metro area. Instability
will wane quickly tonight thus thunder coverage should trend
downward.
High pressure behind the cold front and drier dewpoints suggest a
mostly dry and slightly cooler day Thursday, though will hang onto
some lower precip chances near central IL close to the front, though
some guidance tries to trigger a shower closer to the upper trough
toward northern IL.
KMD
&&
.LONG TERM...
146 PM CDT
Friday through Wednesday...
Surface high pressure is expected to dominate across the Great
Lakes region Friday through much of the upcoming weekend. Overall,
this is expected to result in pleasant (early autumn-like) weather
across the area through this period. High temperatures are
expected to be mainly in the 70s, with overnight lows in the 50s.
Winds will primarily be northeasterly off the lake, especially
Friday and Saturday and this may result in a few lake effect
clouds, especially on Friday. However, of more concern is the
increased threat of rip currents at Lake Michigan beaches Friday
due to building waves up around 4 foot due to the breezy
northeasterly winds over the lake. This may result in the need for
a beach hazard statement for the southern Lake Michigan beaches.
As the surface high over the Great Lakes gradually shifts towards
New England later in the weekend and early next week expect the
surface winds to shift southeasterly on Sunday, then southerly on
Monday. These southerly winds will allow a warmer and higher
dewpoint airmass to shift northward back into the area by Monday,
resulting in a return to 80 degree temperatures. Our chances for
showers and thunderstorms will also return to the forecast by
early next week with this increase in warm moist air ahead of
another storm system, which looks to move across the Midwest.
KJB
&&
.AVIATION...
For the 00Z TAFs...
653 PM...Only forecast concern is a lake boundary/wind shift to
northeast early this evening.
A lake boundary has moved into far northeast IL and is moving
south/southwest. Winds are already slowly turning more to the
north/northwest but this boundary may shift winds north/northeast.
This boundary then curls back toward the lake further north making
for a low confidence wind direction forecast during the evening
hours for ord/mdw. Winds are likely to remain northerly but may
remain north/northwest for much of the evening. Winds should turn
more northeast Thursday morning with speeds into the 10-15kt range
in the afternoon/early evening.
A few showers will be possible this evening mainly south of the
terminals. Otherwise dry weather is expected. Some light fog is
possible across northern IL but the best chance for fog is
expected to remain south of the terminals. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Nashville TN
813 PM CDT Wed Aug 21 2019
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
Other than a tiny little shower just to the west of the KOHX
radar, Middle TN remains very quiet this evening. Storms upstream
will lose their steam over the next couple of hours, but the wave
responsible for them won`t. In fact, it is likely to give us a
shot of showers and maybe even a rumble of thunder around sunrise
tomorrow morning across our northern counties. The HRRR has been
pretty persistent with this feature, as well as a couple other hi-
res models.
A late morning to early afternoon lull is possible before another
wave bring showers and thunderstorms to a large swath of the mid-
state tomorrow afternoon. A few strong storms will be possible as
they make their way across the area, especially late afternoon and
early evening in the best heating of the day. So, if you have
outdoor plans tomorrow evening, you will want to check the
forecast and make sure you`re weather aware.
&&
.AVIATION...
00Z TAF DISCUSSION.
High pressure is in place over the deep south this afternoon. This
has acted to minimize the convective development across the mid
state. Conditions will change through the taf period, however, as
a frontal boundary approaches from the north on Thursday
afternoon. Prior to that, a weak disturbance may bring some
isolated shower activity close to the taf sites toward 12z. Otw,
look for shower and tstms coverage to begin and increase after
18z-20z.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......Unger
AVIATION........21
Area Forecast Discussion
National Weather Service Riverton WY
546 PM MDT Wed Aug 21 2019
.SHORT TERM...(This evening through Thursday)
Issued at 220 PM MDT Wed Aug 21 2019
Today the west and southwest continue to be hot and dry with RH
values in the teens to even a few single digits. Highlights are
not out for today as winds will still be too light. The bigger
story today is instead the threat for strong to possibly severe
storms across central and northern WY. RH and dewpoints are both
higher on the eastern side of the Divide mainly thanks to the
boundary that previously moved into those areas yesterday. Skies
were clear this morning and there is plenty of time for heating
and instability to grow. With this set up of moister air and
growing instability the weak shortwave moving into the area fired
off a few storms even sooner than previously anticipated. Storms
have been mainly sticking to the mountains and have decreased in
strength when moving into lower elevations. Based on mesoscale
analysis, NAM was indeed a bit too aggressive with CAPEs and GFS
has done a better job with predicting 2000 J/kg. Both the NAM and
HRRR have showers and storms lingering in eastern areas the
longest with all activity ending by 06Z. The main threat from any
storm will be strong winds and some smaller hail, but even weaker
showers could produce strong gusts when they collapse and die.
Thursday morning, the upper level trough axis should be over Idaho.
This trough is bringing a cold front, increased moisture and
precipitation chances, and also will tighten the pressure
gradient. As just the tail end of the system will impact WY, the
northern third of the state has the greatest chance of showers and
thunderstorms. Southwestern WY will remain dry. Breezy winds will
develop across the state as the pressure gradient tightens
through the day with the approach of the system. Wind gusts will
be strongest across southern portions; gusts 30 mph to 35 mph are
currently expected. With the moisture from this system confined to
the north and a mostly west flow prevailing in the south, RH
values will once again be in the teens to single digits across the
south. The low RH and gusty winds will combine to create critical
fire weather during the afternoon and evening hours.
.LONG TERM...(Thursday night through Wednesday)
Issued at 202 PM MDT Wed Aug 21 2019
On Thursday night, the strong shortwave trough axis will track
across the CWA. The models are still indicating -7 lifted indices
over Johnson County by 00Z Friday along with elevated capes.
Strong thunderstorms are still possible well into the evening in
Johnson County Thursday evening. The NAM is the fastest bringing
the trough axis through Thursday night with the other models
bringing it through Friday, along with a mid and upper level low
trying to cut off over Northern Wyoming Friday, but should be
inconsequential with lack of moisture. High temperatures will be
several degrees cooler Friday east of the divide behind the trough
axis and associated weak cool front due to come through Thursday
night. Winds with this strong shortwave will likely extend the
critical fire weather conditions into Friday along with the low RH
behind the trough axis.
By Saturday, we will be in a well established zonal flow as a fast
west northwest flow establishes over the Northwest quarter of the US
including Wyoming. A fast moving shortwave within the flow could be
enough to kick of some thunderstorm activity in our northeast zones
Saturday evening and to a lesser extent late Sunday. Otherwise, the
winds will be the most prominent feature with this next shortwave as
winds surface under the right front quad of the associated jet max.
These winds will usher in drier air so Sunday is shaping up to be
another potentially critical fire weather day. Temperatures will
increase Sunday as well, with highs in the 90s east and 80s west.
Similar conditions are expected Monday with continued breezy
conditions as another ripple in the flow keeps the gradient rather
tight, but with slightly higher RH and decreased temperatures.
The models are struggling with the timing and placement of the next
shortwave feature for Tue/Wed. The GFS keeps the jet well to our
northeast and without a shortwave feature to speak of for our area.
The Euro tracks this next shortwave through us Tuesday and the
Canadian Wednesday. With the uncertainty of the models, kept very
low pops in the north and northeast for Tuesday and Tuesday night.
The steering winds will be from the north northwest behind this
trough coincident with an associated cold front, so at some point
during the middle of next week, we should see a trend of noticeably
cooler weather as 700mb temps begin to drop to 6C.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 542 PM MDT Wed Aug 21 2019
Slow-moving thunderstorms arrayed in a line from near KWRL to KCPR.
These are the two terminals most likely to be impacted, particularly
KCPR where heavy rain could produce brief MVFR. This convection is
slowly moving east and is expected to decrease in intensity and
coverage between 02Z-03Z/Thu with only a few lingering showers
through 04Z/Thu. Other terminals should be VFR through the forecast
period. Thursday morning will be quiet with light winds. However,
another round of convection will develop Thursday afternoon with
most impacts across the north. Have not included VCSH at this time,
but KCOD, KWRL, and KJAC hold the most potential. Winds will also
pick up in the afternoon and will become breezy for most
terminals with highest winds gusts at at KRKS and KCPR.
&&
.FIRE WEATHER...
Issued AT 202 PM MDT Wed Aug 21 2019
...Multiple Fire Weather Watches for Thursday afternoon across
southwest Wyoming...
Conditions today will be similar to Tuesday with isolated to
scattered thunderstorms returning mainly over the mountains during
the remainder of this afternoon. Some storms may be strong with
gusty winds being the main threat. West of the Divide will remain
hot and dry this afternoon, with poor RH recovery tonight. Winds
will be stronger today than Tuesday but not to the point of causing
fire concerns. Thursday will see a cold front push across Wyoming
east of the Divide. This will bring more afternoon showers and
thunderstorms east of the Divide, mainly in zones 281 and 285, and
increase winds in the still very dry areas west of the Divide. A
Red Flag Warning has been issued for many fire zones along and
west of the Divide for Thursday afternoon and evening. These
critical fire weather conditions will extend into Friday across
the southern zones.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 8 PM MDT Thursday for WYZ288-289-
300.
Red Flag Warning from noon Thursday to 8 PM MDT Friday for
WYZ277>279.
&&
$$
SHORT TERM...Bourque
LONG TERM...Lipson
AVIATION...Jones/Bourque
FIRE WEATHER...Lipson