Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/20/20
Area Forecast Discussion
National Weather Service Bismarck ND
945 PM CDT Fri Jun 19 2020
.UPDATE...
Issued at 944 PM CDT Fri Jun 19 2020
At 930 PM CDT, a line of showers and isolated embedded
thunderstorms was moving east toward the Highway 83 corridor. This
activity is tied to a distinct mid level shortwave that can be
seen on water vapor imagery rotating through the base of the
closed upper low spinning over Manitoba. Meanwhile, scattered
showers and isolated thunderstorms continue to regenerate over
southwest North Dakota in response to lowering mid level heights
along a quasi-stationary surface boundary. Expect these trends to
continue for at least the next couple hours. CAMs that have a
0000 UTC or later initialization time are doing a very poor job
capturing current conditions, so will only make adjustments to the
ongoing forecast based on observed trends.
UPDATE Issued at 705 PM CDT Fri Jun 19 2020
Scattered showers and a few thunderstorms have developed from
southwest to north central North Dakota early this evening. A
stronger storm cannot be ruled out in the southwest given the
presence of around 500 J/kg SBCAPE, 30 kts effective bulk shear,
relatively low freezing levels, and large surface dewpoint
depressions. But the probability for stronger storms remains low,
with model soundings suggesting storm tops will barely exceed
20,000 ft.
Other than aligning the forecast with current observations and
trends, the most notable adjustment for this update was to add
more detail to the timing of thunderstorm chances tomorrow.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 259 PM CDT Fri Jun 19 2020
Main forecast concerns are shower/thunderstorm potential this
afternoon/evening, and potential severe thunderstorms Saturday,
mainly southeast.
Currently, a broad upper level cut-off low remains over
Saskatchewan/Manitoba region with cyclonic flow in place over the
Northern Plains. Water vapor shows several embedded shortwaves
upstream of ND. Consensus remains good between the CAMS and
supported by instability generally less than 500 J/KG, while RAP is
coming in on the higher side and a bit more suspect as surface
dewpoints appear too high. Mid-level lapse rates are best in the
southwest along with right entrance support from a 60kt 500mb jet
streak that pushes off to the northeast fairly quickly this evening.
A weak surface boundary/wind shift will also support low level
convergence and shower/thunderstorm development. Therefore, will
continue to carry an area of showers and non-severe thunderstorms
spreading from southwest to east late this afternoon and evening.
Beginning to see some light radar returns on Bowman radar
approaching southwest ND. Will continue to monitor and may need to
increase pops there in the near-term.
Will also continue to carry low pops across much of our area
through the night, with cyclonic flow in place and the shortwaves
mentioned earlier. CAMS and global models support this as well,
showing another area of showers spreading into western ND around
06Z.
Later tonight and Saturday, upper low begins to pivot with shortwave
trough axis moving across the state. Return low level flow advects
dew points around 60F across the eastern part of the state,
coincident with a cold front, 30-40kts of 0-6km bulk shear and CAPE
around 500-1000 J/KG. HREF ensemble products and CIPS severe analogs
support the severe potential as well, with hail being the biggest
threat, with severe wind gust possible as well. SPC has upgraded
portions of SE ND to slight risk for severe on Saturday. We will
message potential for half-dollar size hail and 60 mph wind gusts.
.LONG TERM...(Saturday night through Friday)
Issued at 259 PM CDT Fri Jun 19 2020
The upper low remains nearly stationary before slowly moving
eastward by early next week. Occasional showers and thunderstorms
will continue through Monday, with upper level ridge axis
approaching western ND by Wednesday. This will support a brief
mid-week warming trend with highs expected in the 80s. Also begin
to see some differences in height fields in the global models
developing, so greater uncertainty with precip chances.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 705 PM CDT Fri Jun 19 2020
Chances for scattered showers and thunderstorms will continue
across much of western and central ND through the forecast period.
The best chances this evening are at KDIK, with thunderstorms
passing by to the south at the time of this writing. On Saturday,
the best chances will be at KJMS, with severe thunderstorms
possible, capable of large hail and strong wind gusts. Further
mentions of TS may need to be added in future updates, but
confidence beyond the aforementioned locations and timing is too
low. Other than potential MVFR to IFR visibility restrictions in
heavier showers or thunderstorms, VFR conditions are expected
through the forecast period, with winds mostly light and variable.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Hollan
SHORT TERM...JNS
LONG TERM...JNS
AVIATION...Hollan
Area Forecast Discussion
National Weather Service Dodge City KS
1042 PM CDT Fri Jun 19 2020
...UPDATE TO SYNOPSIS...
.SYNOPSIS...
Issued at 1040 PM CDT Fri Jun 19 2020
WV imagery indicates a weak upper level shortwave trough of low
pressure moving eastward across the Western High Plains. Near the
surface, high pressure is drifting eastward out of the Northern
Plains into the Upper Midwest.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 200 PM CDT Fri Jun 19 2020
Our much needed rainfall this morning is now well east of the FA. Some
amounts were over 2", such as here at KDDC. The rest of the afternoon
will remain precipitation-free. Attention then turns to late this evening.
Terrain/upslope flow induced convection is expected to develop across
Colorado. This activity is expected to merge into an MCS and move across
the Kansas prairie late tonight through the early morning hours. Much
of the models agree in such as storm evolution. As such, have aligned
pops in a general consensus of the meso models through the next 24
hours. The main threat with the storms will be heavy rainfall. Would
not be surprised for a few locations to see another inch of rain. Right
now, the western to central zones (along and west of Highway 283) stand
to see the highest chances for storms and heavy rainfall. A secondary
threat could be some wind, however, by the time the activity reaches
this FA, this may be mitigated somewhat by the decoupling of the boundary
layer. Still, near the Colorado border, a strong to perhaps marginally
severe outflow may be possible late this evening as the convection begins
to cross the state line. For Saturday, the atmosphere will have been
worked over. Mesoscale subsidence the wake of the departing MCS will
result in a dry forecast for much of the day. Highs in the mid 80s
are expected.
.LONG TERM...(Saturday night through Friday)
Issued at 200 PM CDT Fri Jun 19 2020
Attention then turns to Sunday. An upper level trof will push out across
the Northern Plains and over the central United States. A stationary
boundary is expected across Kansas. Will have to watch out for the
potential a higher severe thunderstorm threat Sunday afternoon and
evening. CAPE will be plentiful (which is obvious because it`s Summer).
More importantly, bulk shear will increase enough for supercells. Forecast
soundings do show an environment that is supportive of large to giant
hail. In addition, there is enough directional shear that is a little
more concern for a non-zero tornado threat. Two negatives exist Sunday
for Sunday... Speed shear is weak and storm evolution is not clear
at this point in time. None of the parameters matter if you don`t have
supercells in the first place. Convection may congeal into a MCS,
in which the threat for hail and tornadoes would be very low. Heavy
rainfall and some strong/severe outflows would be the main threats.
Regardless, the weather on Sunday is something to monitor in terms
of the potential for a high magnitude severe threat and additional
heavy rainfall.
Beyond Sunday, the EC continues to suggest that the MCS pattern will
prevail across southwest Kansas. Nightly thunderstorm complexes may
continue Monday and Tuesday. Good news that will we proudly take given
the ongoing drought that we are in.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 649 PM CDT Fri Jun 19 2020
Weak upslope surface flow is conducive to thunderstorms
persisting into the area this evening, moving in from isolated
ongoing activity in eastern Colorado. HRRR model might suggest
the best opportunity for storms between 3 and 6 Z between Garden
and Liberal and a little later in time around DDC. Hays is a bit
more uncertain whether it could be impacted by CB or not.
Ceilings should drop into MVFR cat at least for several hours
with lower vsbys in locally brief moderate/heavy rain. Any
residual lower status will likely rapidly improve beyond 12 UTC in
the western areas. The stratus will linger on much longer through
late Saturday morning at HYS, but clear up by the early
afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 60 85 61 92 / 70 20 0 20
GCK 57 85 59 91 / 80 10 0 20
EHA 57 87 60 94 / 80 10 0 10
LBL 58 87 60 93 / 100 10 0 10
HYS 61 84 60 91 / 70 20 0 40
P28 65 87 63 93 / 60 40 10 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JJohnson
SHORT TERM...Sugden
LONG TERM...Sugden
AVIATION...Russell
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
638 PM CDT Fri Jun 19 2020
.Discussion...
Issued at 231 PM CDT FRI JUN 19 2020
As with most June forecasts for our area what happens overnight
drives what happens during the day. This is one of those scenarios
where convection over central KS overnight will likely be the main
factor in what actually happens over our area today. Two MCVs have
developed over central and along the KS/MO border currently. CAMs
seem to handle this features somewhat well and with little forcing
in the low levels this will be the main forcing mechanism to fire up
some convection this afternoon. Cloud coverage and cooler air from
all the morning convection will limit the amount of instability over
eastern KS and western MO. The best place for possible clearing and
building instability will be just SE of the KC Metro and into
central Missouri and possibly up into north central Missouri. The
RAP has ~1500 J/kg building up in that region and the differential
heating could help create a discontinuity boundary and extra
forcing. A few strong to severe storms have formed up on the eastern
edge of the MCV. The main threat would likely be damaging wind and
heavy rain, but small hail to isolated 1" hail is possible. This
threat would be short lived and off to the east by 5-6PM with the
more stable air moving in behind it. Scattered showers and maybe an
isolated thunderstorm have started to form up behind this feature
over eastern KS and western MO with the second MCV moving over the
area, although the impacts will be mostly just isolated heavy
rainfall with these storms.
A major shortwave trough will exit Colorado this afternoon, likely
developing a line of storms over western Kansas this afternoon. This
feature and the developing LLJ overnight will be the main driving
mechanism for our area overnight. How far north the low level warm
air can recover from the cold pool this morning will determine where
the focus will be after sunset. Most guidance has this occurring
south of HWY 50, and maybe even towards Clinton, with a SW to NE
oriented line that may merge with the incoming MCS moving east over
Kansas. The SW to NE oriented line could cause flooding concerns as
training thunderstorms look favorable with the LLJ and MBE vectors
less than 10kts. With PWAT values near 1.75" these storms will be
efficient and 2-4" could drop rather quickly if this set up occurs.
How the MCS and stalled boundary to our south play out Saturday
morning will have major implications for what happens Saturday
afternoon. A shortwave trough and associated cold front will push
through the area Saturday afternoon, so forcing will not be an
issue. The question will be how quick we can recover and how much
instability will be available by the afternoon. The most likely area
to have time to recover would be east of I-35 and north of the
Missouri River. Guidance does seem to hint that this occurring as
does the Day 2 SPC convective outlook. With all the uncertainty on
how Saturday morning plays out there is low to medium confidence on
things playing as our forecast and guidance suggests. The shear
profiles are much more favorable for severe weather with bulk shear
0-6km 30-40kts, so if instability can develop then severe weather
will be in play with damaging wind and large hail the main threats.
The cold front Saturday will bring in some cooler air, but it will
be short-lived as strong southerly flow and WAA build quickly into
the front range Sunday morning and continues east into the
afternoon. This develops a dryline from western KS up into Nebraska
with a warm front over eastern Nebraska. This boundary will be the
primary forcing mechanism with 3000 J/kg to work with. A digging
shortwave trough and associated strong LLJ will set up the
possibility of a substantial MCS moving through our region Sunday
evening into the overnight hours. Damaging winds will be the main
factor with forward propagation vectors showing 70-80kts. Steep
lapse rates may also allow some large hail, but it would be more
isolated than the wind threat would be.
Monday another shortwave will enter the Northern Plains helping to
enhance boundary from OK up into IA. This boundary will move into
our area as a cold front Monday afternoon and if we can recover from
the morning MCS, may cause another round of scattered storms Monday
afternoon over central Missouri. Tuesday and Wednesday look mostly
dry with cooler high temperatures in the lower 80s. A developing
boundary Thursday evening may bring back some showers to the area as
the warmer air starts to return with southerly flow. This boundary
will move slightly to the north and be another possible focus
mechanism for showers and storms over northern Missouri Friday.
&&
.Aviation...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 636 PM CDT FRI JUN 19 2020
Light showers will persist for the next few hours, but coverage
will be minimal and impacts will be largely negligible. Overnight
tonight there will be some pockets of low clouds, but at this time
coverage doesn`t look like it will be widespread enought to
warrant prevailing flight category changes. Likewise, while the
showery activity will pick up again on Saturday, aerial coverage
appears to be rather small at this time, and hi-res models
indicate a better chance for showers east of the terminals. Will
update that thinking with upcoming forecasts.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...Barham
Aviation...Leighton
Area Forecast Discussion
National Weather Service Louisville KY
941 PM EDT Fri Jun 19 2020
.Forecast Update...
Issued at 942 PM Fri Jun 19 2020
Convection has all but died off this evening minus a decaying storm
in NE Nelson county and one on the Russell/Clinton line. This should
give way to a quiet overnight as an upper ridge axis slowly builds
in from the west. Given mostly clear skies, relatively calm winds,
and some low level moisture expect there could be some fog around by
sunrise. Best chance is east of I-65 and especially in the river
valleys and areas that saw recent rainfall. Otherwise, expect a
quiet night. Updated products already out.
&&
.Short Term...(This evening through Saturday)
Issued at 305 PM EDT Fri Jun 19 2020
Popcorn-like showers are starting to fire up across parts of central
KY and southern Indiana again this afternoon. So far the only cells
producing lightning were in the Bluegrass region, where SPC RAP
CAPES were over 2000 j/kg, though anticipate a few of the others
will generate thunder as well. On the plus side, the convection
remains short-lived and disorganized, with no training of cells like
last evening. On the down side, motion is relatively slow - only 10-
15 mph to the SSE, so if a N-S oriented line develops along some as
of yet unseen boundary, isolated flooding can`t be completely ruled
out, though is not anticipated.
The convection and clouds should dissipate quickly this evening,
with only scattered clouds overnight. The diurnal cloud cycle will
return with 20 pops by afternoon.
Weak southwesterly surface flow will help inch dewpoints upward
tonight and tomorrow, resulting in overnight lows about in the mid
60s to low 70s - a few degrees warmer than this morning and just
above climatology. Daytime highs will be 85 to 90 for most - also
at or slightly above the seasonal norms.
.Long Term...(Saturday night through Friday)
Issued at 305 PM EDT Fri Jun 19 2020
To start the period, we will continue to be under the influence of
some slight ridging Sunday as a trough associated with an upper
level low over Manitoba Canada stretches south through the upper
Midwest and the Mississippi River Valley. This will keep us hot and
humid and bring back unsettled weather for Father`s Day and into
early next week. Highs Sunday and Monday will be in the upper 80s to
near 90 and dew points in the upper 60s and low 70s. With the trough
just off to our west, multiple shortwaves will move in the SW flow
keeping the threat of scattered showers and storms. CAPE values
Sunday and Monday will range from 1000 to 2000 J/Kg with limited
shear, so while storms are possible the severe threat looks limited.
Upper level low over Canada slowly slides ESE over the Great Lakes
by the middle of the week, dragging a surface cold front through the
region Tuesday night into Wednesday afternoon. Increasing our
chances of more widespread rain and thunderstorms Tuesday and
Wednesday. Temperatures remain warm both day in the low to mid 80s.
Through the end of the week, while there remains a chance of showers
and storms we see a slight drying trend near the end of the week
with 20-30% PoP for Thursday and Friday.
&&
.Aviation...(00Z TAF Issuance)
Issued at 7:56 PM EDT Fri Jun 19 2020
Scattered showers and thunderstorms across the CWA are not currently
impacting any TAF sites, and conditions should quiet down once
diurnal heating diminishes this evening. Crossover Temp method does
indicate some fog potential for BWG and LEX overnight. Another round
of isolated showers and storms will be possible tomorrow afternoon,
especially for the Bluegrass.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...BJS
Short Term...JBS
Long Term...BTN
Aviation...BJS/CJP
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
700 PM CDT Fri Jun 19 2020
.SHORT TERM...
238 PM CDT
Through Saturday night...
Our recent dry spell looks like it`ll be coming to an end over
the next 24-36 hours as the persistent mid-level ridging that
we`ve had overhead will finally be giving way to eastward-
advancing troughing which has been incrementally shifting closer
each day this week. In the meantime, anticipating largely
precipitation-free conditions through the rest of the afternoon.
Have noted a few blips on radar out of the bubbling cumulus field
in northwest Indiana, but the effects of both ongoing mixing
(holding dewpoints into the mid 50s) and lingering large scale
subsidence should keep any precipitation production to a minimum
and too low to warrant a mention in the gridded forecast. Farther
to the west, surface-based instability continues to struggle to
work much farther east than the river, as mostly sunny skies have
once again allowed PBL mixing to drop dewpoints into the mid and
upper 50s across our I-39 locales. Have pared back PoPs into the
evening there and have limited things to just a mention of showers
at this point with the expectation that any of the more robust
convection remain tied to the front across central and eastern
Iowa.
Upstream, we`re monitoring a nicely defined MCV (Mesoscale
Convective Vortex) pivoting northeastward into north-central
Missouri. This feature--a result of overnight and morning
convection and associated mid-level latent heat release--has
produced a core of enhanced mid-level vorticity which should
spread northeast towards Dubuque late tonight/very early Saturday
morning. This initial wave by itself may remain just far enough to
our north and west to pass by more or less sans fanfare, but it
appears there may be a secondary vort lobe trailing this first
feature which may make a close enough approach to our I-39 county
areas towards daybreak to support at least scattered showers and
some embedded thunderstorms. As is often the case with these
remnant MCVs, the mid-levels will have warmed within the mid-level
thickness bump, and forecast soundings near the Rockford area
reveal that this mid-level warming may act as a CAPE robber on
Saturday morning with MUCAPE values generally in the 250-750 J/kg
range and may mute the degree of thunder potential with this
activity. Have generally confined the morning precipitation
chances closer to these expected vort maxes, north and west of
I-55, and have nudged PoPs up a bit more than recent hires
guidance such as the HRRR and 12z 3 km NAM would indicate.
With the potential for morning convection and increased cloud
cover--especially across our northwest--did make some downward
adjustments to the high temperatures across north-central Illinois
areas. 850 mb temperatures do still look to rise into the +17 to
+19 C range, so this still may very well support high temperatures
jumping into the lower 90s south and east of I-57 where
precipitation chances appear lowest and insolation potential may
remain maximized.
The effects of the morning convection cast some uncertainty on the
storm chances later on Saturday afternoon. Brief mesoscale
subsidence behind these departing waves may make for a relatively
quiet late-morning and early-mid afternoon. However, guidance does
show instability growing diurnally as temperatures warm. The lower
70 degree dewpoints forecast by the GFS, NAM, and RAP still appear
a bit overdone through mid-afternoon Saturday, but even the
somewhat drier ECMWF does still support MLCAPE values building
into the 750-1500 J/kg range. We`ll be in the right location in
the right entrance region of a strengthening jet to support
increasing jet divergence through the afternoon as the main
shortwave of interest--currently across the Rockies--makes its
closest approach to our region. Both mid-level kinematics and
lapse rates will be somewhat lacking tomorrow afternoon, with
generally 25-30 kts of effective bulk shear available which would
point towards multicell convection and loosely-organized clusters
as the favored storm mode. This, combined with the lack of a
steeper mid-level lapse rate environment to augment mid-level
updrafts suggests the hail potential may be on the lower end of
things, with isolated strong to possibly severe downbursts the
main threats with any activity that manages to develop through the
late afternoon and evening hours. At this point, we`re favoring a
roughly 4 pm - 8 pm window for any main strong-severe weather
risk with storm intensity gradually waning thereafter.
Shower and storm chances may linger through Saturday evening as
upper divergence and broad warm advection continue. The airmass
will remain quite moist, with PWATS still likely pushing 1.75". As
a result, the threat for locally heavy rainfall will certainly
continue, some some localized corridors of 1-2.5" of rain possible
before things wind down late Saturday night. Think the threat for
widespread flooding remains low, but we`ll continue to message the
potential for some isolated bouts of flooding through Saturday
night.
Carlaw
&&
.LONG TERM...
330 PM CDT
Sunday through Friday...
For most of the area, Father`s Day appears it will be a decent
summer day. The highest coverage and concern for thunderstorms
during the long term is on Monday through Monday evening. This
may include some risk for strong to severe thunderstorms, along
with heavy downpours and localized flooding.
In the wake of Saturday night`s convection, associated weak cold
front will push into southeast 1/3 or so CWA by 12z Sunday. Best
chance for any lingering convection (widely scattered showers and
isolated TS) Sunday morning will be southeast of I-57. While the
air mass behind the front will only be marginally drier with
respect to surface dew points, models remain in good agreement in
advection of much drier air in the 700-500 mb layer. The front
will slow it`s forward progress, so in the afternoon, the area
that appears will have any chance at a couple showers/storms will
be east-central Illinois and northwest Indiana, where modest
destabilization will occur. This will be the exception to the
rule of what will be a warm and fairly plesant summer day for most
with increasing afternoon sunshine. Highs should top out well into
the 80s, aside from an afternoon lake breeze that should slip
into IL shoreline areas and keep temps slightly cooler there.
Attention then turns to what could be a pretty messy day
convection wise on Monday. Most of Sunday night will be dry and
mild. The quasi-stationary boundary that will have stalled over
far southern or southeast CWA later Sunday will lift back north as
a warm front on Monday in response to surface low pressure
tracking northeast into Wisconsin. There is fairly substantial
uncertainty on the important details on Monday, including:
coverage and magnitude of potential morning to mid day convection
and associated effects on how the rest of the day and evening
plays out; exact track and timing of surface low which will affect
northward progress of warm front.
Some of the guidance has a pretty strong convectively modified/enhanced
mid-level short-wave moving across the area from late morning
west to mid to late afternoon east, while other guidance is a bit
weaker and disjointed with the large scale forcing. Mid-level
lapse rates are progged to remain modest at generally under 6.5
C/km. Depending on the timing and evolution of the above
described details and how much destabilization can occur in the
seasonably high moisture (dew points 65-70) amidst temps well into
the 80s to possibly near 90, there may be some threat for strong
to severe thunderstorms in the area. This would especially be the
case if wind fields can be strengthened by stronger mid-level
wave/possible MCV. Otherwise, it could be another messy multi-cell
episode with isolated strong to perhaps severe downburst potential
into the evening. Cold front will sweep across the area late in
the evening and overnight, likely bringing an end to the
convection.
Thereafter, the pattern will trend cooler through Thursday with
many dry hours, though with occasional lower end chances for
diurnal instability driven showers and perhaps a few thunderstorms.
This will take place as an upper trough centered over eastern
Canada gyrates slowly eastward, with subtle short-waves traversing
the local region. Tuesday is modeled to have stout low and mid-
level dry advection behind the front by more reliable ECMWF
guidance, so appears to have a sub-mentionable chance for any
isolated thunderstorms. It`s possible if trends hold, we may be
able to remove Tuesday`s PoPs, followed by a bit better signal for
diurnal showers Wednesday PM. Signs point toward mid and upper
ridging returning by Friday, so temps should return to near or
above normal levels.
Castro
&&
.AVIATION...
For the 00Z TAFs...
The Lake Michigan lake breeze is (slowly) drifting across the ORD
airfield, but has stalled over or within a mile to the east of MDW.
With weakening SW gradient flow as daytime mixing diminishes, the
lake breeze should push through MDW in the next hour. Light and
variable winds generally in the SE quadrant are expected into mid-
morning Saturday before SSW winds in excess of 10 knots with gusts
around 20 knots become common late Saturday morning through the
evening.
A TS complex over northeast Missouri is expected to shift NNE while
slowly weakening through the early overnight hours. This activity
should remain well west of the Chicago terminals, but may briefly
clip RFD as a few -SHRA in the 03-06Z window. Another weak wave
ejecting from Kansas will again brush RFD but not the Chicago
terminals after daybreak. Finally, a more pronounced wave from
ongoing convection in Oklahoma should be an impetus for TS develop
Saturday afternoon and early evening. Confidence in occurrence has
increased enough to introduce a TEMPO TS in the 21-01Z window for
ORD/MDW/DPA, and 19-23Z at RFD. Briefly heavy rain and gusty winds
are possible with any convection. Widely isolated development may
occur prior to 21Z over the Chicago metro, but coverage should
remain rather low.
Kluber
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
Visit us at weather.gov/chicago
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/NWSChicago
www.twitter.com/NWSChicago
www.youtube.com/NWSChicago
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1047 PM CDT Fri Jun 19 2020
.UPDATE...
Issued at 934 PM CDT Fri Jun 19 2020
Showers and thunderstorms have moved out of the area temporarily.
Latest radar mosaic is showing some new activity starting to
develop over central Missouri where the RAP is showing some weak
low level moisture convergence. Water vapor imagery is showing a
weak shortwave trough moving into western Kansas that the RAP
shows weakening as it moves northeast across the area later
tonight. There will continue to be some weak moisture convergence
as the 30KT low level jet veers late tonight, so will maintain the
low chances for showers and thunderstorms into Saturday morning
over the northwest half of the CWA. Going lows still look good, so
made only minor adjustments based on the latest observations.
Britt
&&
.SHORT TERM... (Through Late Saturday Night)
Issued at 331 PM CDT Fri Jun 19 2020
Widely scattered thunderstorms have developed this afternoon across
parts of Missouri as expected, and a cluster of storms is moving
toward central Missouri from the west. The SPC mesoanalysis page is
showing 1500 to 2000 J/Kg of MLCAPE over central Missouri ahead of
the cluster which quickly falls off to less than 500 J/Kg in east
central Missouri. There`s not much in the way of shear from in
central and eastern Missouri, so the most likely organized storms
will only be clusters like the one moving into central Missouri.
There is 700-900 J/Kg downdraft CAPE back toward central Missouri
which intersects with the areas of higher MLCAPE, so we`ll have to
watch for the possibility of strong gusty winds with the storms in
central Missouri. The storms should weaken and largely dissipate by
03-04Z this evening due to loss of heating/instability. Additional
thunderstorm activity may move into the forecast area from the west
overnight as a 20-30kt low level jet associated with a shortwave
moves into Missouri. Think best chance for overnight storms will
stick to central and northeast Missouri.
Another short wave will move out of the Plains and into the Midwest
on Saturday. This wave will finally give the front draped over
northwest Missouri the push it needs to get it moving southeast.
Showers and thunderstorms still look likely to develop ahead of the
front, and while there is a chance that convection could develop at
any time Saturday, the period when storms will be most likely will
be between 300 PM and 1000 PM. 2000 J/Kg MLCAPE once again, but
probably a bit more shear in the 20-30kt range will produce a
marginal severe wind/hail threat, but that threat should diminish
fairly quickly as daytime heating and instability decreases.
Carney
.LONG TERM... (Sunday through Next Friday)
Issued at 331 PM CDT Fri Jun 19 2020
Guidance has the flow aloft becoming quasi-zonal in the wake of the
short wave and the front stalls over southern Missouri. The front
will continue to be a focus for thunderstorm development on Sunday
across southern Missouri and Illinois. The pattern them becomes
highly amplified Monday into Wednesday as a strong upper level low
drifts down across the U.S./Canada border in the Great Lakes Region.
The flow aloft over the Mid Mississippi Valley turns to the
northwest and this should finally give the front the push it needs
to clear the area on Tuesday. Cooler and less humid air is expected
to filter into the mid Mississippi Valley behind the front. Medium
range guidance shows a few short waves moving through in the
northwest flow which could produce some scattered showers or
thunderstorms Wednesday or Thursday, but it doesn`t look like
anything strong at this time. Interestingly, the mean and spread of
ensemble temperature guidance for Tuesday through Thursday seems to
be much tighter than in previous runs, so confidence is increasing
in at least a short stretch of below normal temperatures next week.
Medium range guidance diverges by the end of the week though with
the GFS turning quasi-zonal aloft, and the ECMWF beginning to build
an upper level ridge. Either way, we should see temperatures back
to near or above normal and potentially another uptick in
thunderstorm activity.
Carney
&&
.AVIATION... (For the 06z TAFs through 06z Saturday Night)
Issued at 1026 PM CDT Fri Jun 19 2020
Showers have recently developed southwest of KCOU and will
possibly affect that terminal through 09Z, so have included VCTS
in the TAF. Showers and thunderstorms will move northeast and
affect KUIN between 09-12Z. Additional showers and thunderstorms
will possible during the afternoon and evening at all of the
terminals. Any thunderstorms will have the potential produce
MVFR/possible IFR visibilities and ceilings. Winds will remain
under 10KTS outside of thunderstorms.
SPECIFICS FOR KSTL:
Dry and VFR conditions are expected through at least early
afternoon on Saturday. Then thunderstorms chances will increase
during through the afternoon and evening hours and have included
VCTS during the late afternoon and early evening hours. Any
thunderstorms will have the potential produce MVFR/possible IFR
visibilities and ceilings. Winds will remain out of the southwest
through the period.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
757 PM EDT Fri Jun 19 2020
.UPDATE...
Deep and persistent westerly flow as seen in evening TBW sounding
has pushed robust afternoon convection well east of the local area
with only a few isolated storms left on old boundaries early this
evening. Dry air aloft continues to wrap from the Gulf into the area
and expect rain to end shortly with clear skies overnight. Have
updated grids and forecasts based on satellite and radar trends.
&&
.AVIATION...
Thunderstorm have waned and moved east with VFR conditions and
light winds tonight into Saturday morning.
&&
.Prev Discussion... /issued 1151 AM EDT Fri Jun 19 2020/
SHORT TERM (Rest of Today through Saturday)...
The weather pattern is setting up to be an active one this
afternoon and at least early this evening across central and
eastern southern portions of the peninsula. A mid/upper level
trough continues to pivot across the deep south accompanied by
significant upper jet energy for this part of the country late
into June. The central and southern parts of the state will sit
under the RRQ of this jet this afternoon...within a favorable
upper divergence/diffluence pattern to promote lift. In Florida,
we look for reasons why it will not rain during the summer, and
anything extra in terms of atmospheric lift...generally seems to
seal the deal for widespread convection. Well north of I-4, we run
into less column moisture, and there the convective activity may
be somewhat more limited in nature. However, along and south of
the I-4 corridor, moisture is abundant, with PW values at or above
2" today.
Greatest weather concern will exist in the form of locally heavy
rain and localized flooding over roughly Highlands,
central/southern Polk, and parts of Hardee/DeSoto counties. Give
this general area a little spread in interpretation...as nothing
is weather is a sharp line. 1000-700mb layer flow is from the
SW...but generally still on the light side. This should allow the
east coast seabreeze to migrate inland with time early this
afternoon. All indications from the ensemble guidance are that we
will have a decent convergence zone setting up across the
aforementioned area to support robust convection. Given the focus
for storms in this area, once they develop, updrafts will feed on
a fairly moist column and upper support. RAP runs continue to
indicated 20-30kts of deep layer bulk shear in this region for the
afternoon/early evening, which suggests a slow-moving
multicellular convective mode. A bit concerned about an NW to SE
band organizing and not moving much off the convergence zone.
Ensemble probabilities off the HREF for >1" are 90% or higher
across this entire area. That is a fairly significant signal of
agreement among the members. Given this, localized amounts in the
2-4" range should be considered as a reasonable worst case
scenario through 02Z. Thereafter convection should fade rather
quickly.
SPC has also outlooked inland areas in a marginal risk for severe
weather. Given the robust convection expected, a few damaging wind
gusts and/or quarter sized hailstones can not be ruled out with
the strongest and/or most precipitation loaded cells.
Saturday...
A more typical summer type pattern begins to return for the
weekend as the upper level energy/troughing pivots away from the
region early in the day. Surface ridge will lie across the south-
central peninsula, generally to the south of the I-4 corridor.
The flow around this ridge axis will favor a scattering of storms
around Lee county and southward where layer winds are weak or from
the SE. Further north, a SW wind will push any convection fairly
quickly away from the coast into the interior zones. However,
there are some indications that some drier air will arrive aloft
from I-4 northward and keep the overall convective extent more
limited, especially compared to today. Outside of the summer
storms, expect partly cloudy skies, and temperatures generally
peaking in the lower 90s.
LONG TERM (Sunday through next Thursday)...
The second half of the weekend into much of next week looks like a
typical late June weather pattern. The subtropical ridge will lie
across the Florida peninsula, with some minor migration north and
south on a daily basis. The exact pattern of storms will depend on
this migration, but we see no day with a well-defined either
westerly or easterly flow to say that the favored area will be
here vs there. As we get closer, these more detail about the
ridges possible will emerge and some finer tuning can be done to
daily spatial and timing aspects of the rainfall probability
forecast, but for now, near normal temps and rain chances is
sufficient and appropriate to message.
MARINE...
Thunderstorms are increasing in coverage over the coastal waters
early this afternoon to the south of Anna Maria Island and Siesta
Key. Mariners are urged to check local forecasts and radar before
heading out on the water this afternoon. Further north, storm
coverage looks to be more isolated in nature.
High pressure will remain in place over the eastern Gulf of Mexico
through the upcoming weekend, leading to mostly benign conditions,
outside of typical scattered showers and storms. The storms will
be most common during the late night and morning hours. Mariners
can expect light east to southeast winds over the Gulf waters,
with the flow along the coast turning onshore each afternoon as
the sea breeze develops.
FIRE WEATHER...
High pressure and abundant moisture over the state expected to keep
minimum RH values comfortably above critical thresholds through the
period with no fire weather hazards expected. Greatest shower and
thunderstorm chances likely over interior and southern locations.
&&
.Preliminary Point Temps/PoPs...
TPA 75 90 76 92 / 20 30 10 30
FMY 74 91 75 91 / 20 60 30 50
GIF 72 92 74 93 / 40 50 10 50
SRQ 74 90 76 92 / 10 30 10 40
BKV 70 92 72 93 / 20 30 10 30
SPG 77 90 78 92 / 10 20 10 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE...25/Davis
UPPER AIR...99
DECISION SUPPORT...99