Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/29/19
Area Forecast Discussion
National Weather Service Cleveland OH
955 PM EDT Tue May 28 2019
Low pressure over the region will drift northeast tonight
driving a weak cold front south into the area this evening. The
front will stall in the area tonight and Wednesday as waves of
low pressure move east along the boundary. The front will
finally drop south of the area behind low pressure Thursday.
High pressure will build in for Friday.
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
Convection has become limited to some scattered showers with
isolated thunder late this evening and all severe thunderstorm
watches and warnings have expired. Some minor flooding is still
noted in the Cleveland and Youngstown metro areas and the
appropriate flood products remain in effect for those areas. As
current rain moves east out of the area, a relative lull in
convection will occur for a few hours before activity enters the
area for daybreak Wednesday morning. With that, have low chance
to slight chance PoPs for the overnight with just a slight
chance of thunder.
Low pressure just north of Lake Erie will move east this
evening and in its wake, a cold front will move south into the
area. The front is currently in sern lwr MI into central
Indiana. There is however, convergence set up across the inland
counties from near the FDY area ene, enhanced across nern OH and
nwrn PA by the lake breeze. Thunderstorms have developed along
this convergence zone. Currently surface based CAPES are around
3500j/kg. Thermodynamics support large hail and strong downburst
winds. Shear support steady state, rotating storms especially
east half of the area. Expect strong to severe thunderstorms to
continue to spread east across the area into early evening.
Overnight convection should tend to drift sse and weaken through
the late evening. After midnight the HRRR shows convection
moving back toward the area from the west along the stalled out
boundary. The HRRR takes most of this north more across the lake
and possibly affecting some of the northwestern counties.
Towards morning another wave will be moving east through
northern Indiana toward northwestern OH. Wednesday this stalled
front will be across the area and models show another weak
impulse moving east along the front during the day. Would expect
redevelopment with the more favored area across the southern
and eastern counties. Will need to keep chance pops going
through Wednesday night. Towards morning Thursday however will
increase pops back to likely in the west as another low
approaches from the west. Highs Wednesday from north 70 north to
near 80 far south.
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Thursday will likely be another active weather day over the
forecast area. A shortwave trough over the central CONUS will
propagate east into the Great Lakes region and get absorbed into
a larger trough over the eastern CONUS. At the surface a low
will enter Ohio and move east across the forecast area. With
good forcing expected over the region along with decent
instability and moisture and some good jet dynamics, showers and
thunderstorms are likely on Thursday and some severe storms may
be possible. Have continued with the high likely PoPs, but have
not gone to categorical as there are coverage concerns at this
time. There are some timing issues still at this time, but
Thursday will be yet another day to watch in what is an active
weather week. High pressure will emerge over the eastern Great
Lakes on Friday behind Thursday`s low. Light northerly flow,
some slight cold air advection, and sinking air entering the
region will keep temperatures near to perhaps a couple degrees
.LONG TERM /SATURDAY THROUGH TUESDAY/...
Will continue with a fairly generic forecast for the weekend.
Northwest flow sets up over the region with the best energy
aloft on Saturday and again on Monday afternoon. Have the
highest PoPs during those time periods, but nothing more than
scattered showers and thunderstorms. While northwest flow will
persist over the region, not too much appears to be in place to
alter temperatures to far above or below normal.
.AVIATION /00Z Wednesday THROUGH Sunday/...
Update...At 00Z significant wx will be quickly moving east out
of the area. At this time most terminals are VFR with the
exception of TOL ERI YNG. Expect conditions to bounce between
VFR and MVFR through the balance of the evening and then likely
drop to MVFR for the overnight with a cold front stalling in
the area. Wednesday expect continued numerous
showers/thunderstorms as the front remains in place and weak
waves of low pressure move through the area along the boundary.
Expect widespread MVFR conditions Wednesday with IFR likely in
OUTLOOK...Non-VFR possible for periods of time through
A cold front will push south of the lake tonight and flow will
shift winds around to the north and then northeast. The front
then lingers over the area on Wednesday and may try to move back
north to the southern lakeshore, but flow will likely remain
light out of the northeast. The front remains over the area on
Thursday and low pressure will move northeast towards the lake
on Thursday night. Winds will flip around to the southwest and
then west with this system moving through the region. High
pressure emerges over the area on Friday and light northerly
flow and dry weather on the lake will allow for Friday to be the
best marine weather day of the period. A weak front enters the
basin for Saturday and winds may shift around to the northwest
by Saturday night. At this time, not expecting any marine
headlines on the lake.
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1056 PM CDT Tue May 28 2019
.SHORT TERM...(This Evening through Wednesday)
Issued at 332 PM CDT Tue May 28 2019
Main upper level low currently noted on WV imagery noted over
northeast CO will provide for our next chance of showers and
thunderstorms this evening and overnight. Initial round of
thunderstorms has already begun from northeast KS into central IA.
It is across this area that the main severe threat will stay with
the warm front still well south of our area near the KS/MO/IA/NE
borders. MUCAPE values over our far southern counties are only a
couple/few hundred Joules so we will likely struggle to get any
storm to approach the strong category.
The main forecast challenge and concern for tonight into tomorrow
revolves around the additional rain amounts on already very soggy
soils. The surface low will eventually pull into eastern Nebraska
and western Iowa into early Wednesday. Where exactly this tracks and
what mid level boundary the precipitation forms on will have
implication the pivot point for the heavier rain amounts. The 12z
GFS/NAM/WRFs and previous model consensus generally had the highest
across our west near the James River valley. Meanwhile, the last
couple ECMWF runs along with trends in the HRRR have tried to
pull this heavier axis to the south and a bit east, likely due to
the ongoing convection to our south hanging up the various
features further south as well. This is notable as this could
potentially shift some of the higher rain totals closer to the
area that was harder hit with Sunday night/Monday`s event. Tried
to show this trend in the latest QPF which would put a stripe of 1
to 2 inches from Lake Andes further east/northeast toward the
Sioux Falls area and perhaps NW IA, with a broad area of 0.25 to
0.75 inch amounts buffering this. While these rain amounts would
normally not be much concern, trends will need to be monitored
into the evening as the moist antecedent conditions could lead to
further impacts on rivers. WPC has continued the Marginal Risk for
excessive rainfall for areas south of I-90.
Fairly healthy rain chances are still expected for the morning hours
Wednesday across portions of SE SD into SW MN eventually fading
by the afternoon and shifting south as the upper level low
meanders slowly overhead. Could even see some thunderstorm
activity over NW IA with some lingering instability and shear,
with the GFS the most aggressive with these values. Temperatures
for most locations will be stuck in the 60s.
.LONG TERM...(Wednesday Night through Tuesday)
Issued at 332 PM CDT Tue May 28 2019
By Thursday, region will sit in between the northern and southern
stream jets with only the fading forcing left from the decaying
upper level low providing for some small precip chances. Overall,
expect improving conditions from Thursday into the weekend with no
significant systems noted. This won`t necessarily mean a
completely dry forecast but the chance for widespread, impactful
weather appears low at this time. Also expect temperatures to be
on a warming trend thru the rest of the week with 70s expected by
Thursday and 70s and even lower 80s expected thru the rest of the
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1052 PM CDT Tue May 28 2019
Forecast precipitation chances and amounts have continued to
trend downward this evening; however, scattered showers and
isolated thunderstorms are still possible overnight at sites
south of south of I-90, such as KSUX. Ceilings will vary, with
mid-level clouds north of I-90 and low cloud decks south of the
interstate. Light northeast and north winds overnight will change
to northerly and northwesterly through the evening hours
Area Forecast Discussion
National Weather Service Hastings NE
635 PM CDT Tue May 28 2019
.SHORT TERM...(This evening through Wednesday)
Issued at 351 PM CDT Tue May 28 2019
Main concern is potential for severe thunderstorms this aftn into
eve as well as ongoing flooding.
Objective and subjective sfc analysis indicates a sfc low/triple
point just S of RSL at 20Z. This is further S than expected 24hrs
ago, and also further S than what earlier runs of the HRRR this
morning were showing. A stationary bndry extends to the NE to near
STJ with a cold front extending SW from the sfc low into SW KS
and into TX/OK Panhandles. These sfc features will be key to
determining greatest risk areas for severe wx later this aftn/eve.
Sfc obs in the warm sector show temps in the upper 70s and dew
points in the upper 60s to near 70. Water vapor analysis reveals a
strong closed low over E CO, with an associated strong mid-upper
level jet streak across the Central Plains as sampled by the KAMA
12Z sounding to be around 60kt at H5. Morning soundings also
sampled very steep mid-level lapse rates on the order of 7.5-8
C/km. The steep lapse rates, combined with high theta-e airmass in
the warm sector, is leading to moderate to strong instability
with MLCAPE of 2000-3000 J/kg near far S CWA per latest SPC
Mesoanalysis. An EML at the base of the steep lapse rates is
keeping this instability capped, for now. 1-min GOES vis sat
imagery has shown some persistent clearing across north central
Kansas counties. Thick, low stratus continues to the N, in an
area of moist, easterly upslope flow, and even some drizzle and
Additional insolation as well as cooling mid-level temps should
lead to continued destabilization and eventually erode the cap
22-23Z. Large scale forcing for ascent is sufficient for tstm
development, as hinted at by persistent band of cirrus (on vis
sat) and moist plume (on WV channel) over central KS, and there
are several triggers at the sfc. The main question is when and
where storms develop. This is mostly tied to location of sfc
low/boundaries and what areas see some clearing. Agree with latest
SPC outlook that the highest severe probabilities (locally)
likely extend a little further W/SW than expected 24 hrs ago.
Areas from near Arapahoe to Hastings, to York and points SE have
the greatest risk for severe storms given overlap of 0-6km bulk
shear 55-65kt and MUCAPE 2500-3500 J/kg. Both of these parameters
are more than sufficient for supercell structures. Large hail up
to at least golf ball size and damaging wind gusts up to 70mph are
the main threats. A couple tornadoes can`t be ruled out
immediately near and E/NE of the sfc low, near the boundary, which
will likely extend from near Stockton to Hebron. Storms in these
areas have best potential to be sfc based, whereas storms a county
or two to the north will be elevated above the near-sfc stable
As far as timing goes, I suspect to see some CI between 21-23Z
over our far S, and last several runs of the HRRR show activity
arriving from the W along and S of the state line in the 00Z-02Z
Later tonight, some CAMs suggest some decent cores over the N
CWA, generally N of I-80. Forecast soundings show MUCAPE of
1000-2000 J/kg and mid-level lapse rates around 7.5 C/km. However,
effective shear is rather weak around 20-25kt. Think these areas
could see a few strong to perhaps marginally severe storms, but
the weak effective shear should keep this threat limited. The SPC
marginal-slight risk areas cover this potential well. Perhaps of
greater concern would be the rain that is produced in northern
areas as they will be closest to the wrap-around moisture. Models
have been fairly inconsistent in QPF amounts in these areas, but
latest trends of EC and HRRR are a bit concerning. Current
forecast calls for around 0.5" N of the Tri-Cities, but as always,
locally higher amounts are possible.
Wednesday: Lowered highs by 2-3 deg as models show persistent
cold air advection on NW winds along with broken stratocu. This is
typically not a good setup for much warming, thus went with some
cooler CONSRAW data. Areas along and N of I-80 continue to have
best potential for rain shwrs, but amounts should be light, and
not expecting anything too convective.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 351 PM CDT Tue May 28 2019
Will continue to see some lingering influences from the departing
upper wave on Thu. The biggest impact will be continued cld cover
and cool temps, but some lt pcpn also possible so have maintained
Model variability is quite high with location and amplitude of
several mid level perturbations Friday into the weekend, so
confidence on timing and location of pcpn chances is very low.
Latest global deterministic models and ensembles for early next
week show a deep trough over the NE CONUS and a weaker, somewhat
cut-off, trough over/near SW CA. This leaves us in quasi-zonal
flow and relatively low day-to-day pcpn predictability. Overall,
though, the pattern supports near-normal temps and more dry time
than not. This is welcome news for those that need some time to
Temperatures: Expect low 70s on Thu then warmer temps near 80 for
the weekend. Mid 80s are possible early next week.
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 627 PM CDT Tue May 28 2019
IFR ceilings expected through most of the Fcst period. Dropped
mention of VCTS for now, will monitor and amend if TSRA look to
impact TAF sites. The winds will start off NE and will become NW
as the SFC low tracks to the east later tonight.
Issued at 351 PM CDT Tue May 28 2019
Will once again be monitoring the hydro situation very closely
through tonight as much of the area remains very saturated. Two
areas of most concern with be from near Phillipsburg to York
(generally S/E of Tri-Cities) as well as areas N of Hwy 92
(generally N of the Tri-Cities). Convection this eve should be
rather iso-scat and quick moving, which should keep rain amounts
from becoming too excessive. However, some heavy downpours are a
concern. The northern area of concern will be driven mainly by
wrap-around shwrs and weaker tstms. Rain rates here should be
less, but the rain duration could be longer. Model QPF varies from
less than 0.25" to as much as 1.25" in isolated spots on some of
the hi-res data. Will be watching these areas closely over next
Area Forecast Discussion
National Weather Service Grand Rapids MI
944 PM EDT Tue May 28 2019
Issued at 214 PM EDT Tue May 28 2019
- Showers and thunderstorms arriving tonight, mainly south of I-96
- Additional showers and storms possible Wednesday night/Thursday
mainly south of I-96
- Thunderstorms possible over the weekend
Issued at 945 PM EDT Tue May 28 2019
Really there is little change in our thinking as to how the
upstream convection will impact our CWA. Seems to me the best
convection will stay south of our CWA overnight. Even so, we will
get an area of showers with a few thunderstorms crossing our CWA
between 11 pm and about 5 am. The thunderstorms should for the
most part stay near and south of I-94 with the strong storms
closer to I-80.
The latest RAP model(8pm) shows a west to east low level jet from
RDF to AZO. Over time this feature moves east so by midnight the
cores of this jet is near TOL. That puts southwest Michigan in the
speed divergence area of this low level jet. That is a major
negative to strong thunderstorms. Also the nose of the best
1000/850 moisture transport does not get north of I-80. There is
some elevated instability to work with through. the area with MU
cape greater than 500 j/kg stays south of I-94 through the night.
The bottom line is we will see showers overnight near and south of
I-96, a few thunderstorms near and south of I-94 but the storms do
not look they would have any significant severe potential due to
the fairly strong frontal inversion over our CWA (RAP soundiSo we
may ng at midnight shows nearly a 10 degree rise in the air
temperature 1400 ft above the ground and 2000 ft above the
.DISCUSSION...(This evening through next Tuesday)
Issued at 214 PM EDT Tue May 28 2019
Challenging forecast for the next couple of days given the
potential for organized thunderstorms to form upstream of the
Tonight...southern parts of the CWA should see showers and
thunderstorms rolling in around midnight. These storms are
currently organizing into a complex around Kansas City. The warm
air advection wing of this developing complex is suggested to
impact mainly southern parts of the CWA. The convection should be
fairly elevated limiting the overall severe risk. They main
hazards look to be locally heavy rain and frequent lightning. If
the deeper instability ends up further north...we could end up
with some severe weather. We will need to monitor trends closely
through the evening.
A mid level wave rounds the base of the trough/low in the
Southwest U.S. Wednesday and heads towards the CWA for later Wed
night into Thu. There is some uncertainty as to whether this
feature makes it into CWA. The latest run of the High Res Euro
keeps it south while the GFS clips the far south with heavier
rain. We will highlight the I-94 corridor with a higher potential
for rain. Once again the main instability axis is forecasted to
remain south of the CWA. This should overall limit the severe
weather risk. If the GFS is right we could see an increased
potential for flooding.
Going forward...high pressure moves in for Friday. It will not
stay long as guidance is showing a stronger front pushing down
from the northwest Friday night into Saturday. High pressure then
moves in for Sunday drying the weather out.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 737 PM EDT Tue May 28 2019
The I-96 TAF sites are on the edge of going from MVFR cigs to IFR
cigs, as of 2330z, GRR is IFR and LAN are IFR while MKG is MVFR. I
expect MKG will go IFR due the easterly prevailing low level
wind. The I-94 TAF sites are VFR but I believe they too will
become MVFR if not IFR within the next few hours.
There is a wave on the front to our south that has convection
assoicated with it. It would seem most of the thunderstorms will
miss our TAF sites to the south in the 05z to 09z time frame as
the wave passes just south of this area. If the showers get this
far north, the cigs will improve to MVFR due to better mixing
assoicated with the convection.
Once the convection is to our east I would think IFR should
become widespread at all TAF sites by sunrise. This is from both
fog and low cigs. Since there is not a strong push of dry air it
may be hard to break those low clouds up during the day. I would
think the fog should lift by midday.
Issued at 214 PM EDT Tue May 28 2019
North winds may briefly top 20 knots this evening across northern
zones but overall the pressure gradient will be relatively weak
through Saturday. Near any thunderstorms winds and waves could be
higher so mariners will need to monitor the weather closely.
Issued at 214 PM EDT Tue May 28 2019
The rivers near Vicksburg and Maple Rapids remain above bankfull,
with only low lying areas near the river under any water. With rain
and possibly a storm in southern Michigan overnight, totals of a
quarter to half inch are possible. These totals would not overwhelm
the rivers, but may halt the downward trend of the Portage River
near Vicksburg for another day or two. The Portage River is only
several inches shy of creating relatively greater flood impacts to
buildings, but at this time it is not expected to climb that high.
Area Forecast Discussion
National Weather Service Louisville KY
1002 PM EDT Tue May 28 2019
Issued at 1000 PM EDT Tue May 28 2019
Other than some very minor tweaks to forecast products in the short
term, forecast remains largely on track. CAMs continue to indicate a
potential broken line of showers and storms could arrive to portions
of southern Indiana by sunrise tomorrow, and slowly push into the
rest of the region throughout the day. The latest (00z) HRRR is
perhaps the most aggressive CAM with storms tomorrow, and would
imply strong/severe storms starting shortly after sunrise and
continuing through much of the day. The parameters will certainly be
in place to support severe storms, even during the morning hours, so
this will be something that will continue to be monitored closely.
.Short Term...(This evening through Wednesday)
Issued at 255 PM EDT Tue May 28 2019
...Severe Storms Possible over Southern Indiana/North Central
Expect gusty southwest winds to continue through this evening with a
strong cap under upper level ridging keeping the area dry this
evening and through much of the overnight hours. Wind gusts will
decline shortly after sunset.
Tonight the upper level ridge will begin to break down allowing the
sfc front to our north to drop south into the region and end up
somewhere over central or southern Indiana by sunrise tomorrow. This
will allow showers and storms to enter southern Indiana and north
central Kentucky late tonight after midnight into tomorrow morning.
Soundings at 12Z reveal a weak cap near the sfc which is quickly
broken between 12-15Z. Plenty of CAPE (1500-2000 j/kg) will be
available for morning storms along with 45-55 kts of 0-6 km bulk
shear. Those values will increase as we head into the afternoon
hours with max CAPE expected to reach the 2500-3000 j/kg range and 0-
6 km bulk shear in the 50-55 kt range. The boundary nearby and
shortwaves along it should produce discrete cells and bowing
segments with the main svr wx threats being damaging winds and large
hail. There is a small chance for a tornado but unidirectional wind
profiles and limited windows of better effective SRH may limit that
threat overall. Still strong to severe storms are expected
throughout the day tomorrow with the best location being southern
Indiana and north central Kentucky in the best moisture/instability
axis. Only isolated chances for a storm exists over southern KY
tomorrow where the ridge and capping will be stronger.
Temperatures tonight will be in the upper 60s to lower 70s for lows.
Highs tomorrow will range through the mid 80s to low 90s. Southwest
winds will be gusty again tomorrow 20-25 mph outside of any
.Long Term...(Wednesday night through Tuesday)
Issued at 315 PM EDT Tue May 28 2019
Wednesday Night - Thursday Night...
Diurnally driven convection from Wednesday PM will likely be dying
off late Wednesday evening with the loss of heating. However,
convection is supposed to redevelop to our SW and move into the
region toward dawn on Thursday.
The Ohio River Valley will be in the broad SW flow between the
weakening upper ridge over the SE CONUS and a central CONUS
shortwave trough Wednesday night into Thursday. Ahead of the
shortwave trough, a surface low will strengthen a bit over the
Wabash River Valley and into the lower Great Lakes by early Thursday
evening. Given the weakening of the upper ridge and the steady
strengthening of mid to upper level flow ahead of the central CONUS
trough, expect to see isolated to scattered showers and storms
across our northern CWA early Thursday morning, and scattered to
numerous shower and storm coverage by later Thursday ahead of the
sagging cold front behind the surface low passing north of the
region. Still being on the periphery of the upper ridge, expect
modest buoyancy (~1000-1750 J/KG ML CAPE) to develop in the presence
of strengthening deep layer shear (~40-50 knots). A few of the
storms could become strong to severe, especially across the NW half
of the CWA. Right now, we are only in a general thunderstorm risk
from SPC, however expect we could be upgraded to Marginal or Slight
with coming updates, assuming we are able to realize the modest
The cold front passes through later Thursday evening and we will
return to mostly dry conditions. However, a few post-frontal showers
could linger around. After mild Wednesday night lows in the upper
60s and low 70s, look for Thursday highs in the low to mid 80s.
Thursday night lows drop off nicely behind the cold front with mins
finding their way back down to the low 60s by Friday morning.
Friday - Tuesday...
The remainder of the long term forecast will seem like more of a
pattern flip as the upper ridge will become established across the
western CONUS and shallow troughing takes hold of the eastern CONUS.
This will result in a persistent NW flow pattern across our CWA,
with several disturbances dropping through that flow. Overall, high
and low temps will average about 10 degrees cooler than what we had
been seeing in our upper ridge/summer-like pattern. Now we will be
much nearer climatological norms with highs mostly in the low 80s
and lows mostly in the upper 50s and low 60s.
After lingering showers and a few storms on Friday with a passing
shortwave, Friday night and most of Saturday should be dry. By
Saturday evening through Sunday, another round of showers and storms
is expected as a frontal boundary and secondary shortwave drop
through the NW flow aloft into our region. Will continue with sct to
num pops for this time. Sunday night through Tuesday then look
mostly dry as Canadian high pressure at the surface and dry NW flow
aloft hold over the area behind the cold front. Some convective
activity could come close to our western CWA fringes, but overall
think we will stay mostly dry. Temps will be quite pleasing with
highs topping out on either side of 80s and lows in the upper 50s
and low 60s.
.Aviation...(00Z TAF Issuance)
Updated at 720 PM EDT Tue May 28 2019
VFR conditions expected most of the overnight hours. Isolated to
scattered showers/storms may move in or develop over parts of the
region after 09z, with additional showers/storms arriving after
sunrise tomorrow morning. Confidence is very low in the timing and
placement of precipitation, as much of it will be influenced by how
convection evolves this evening over the Plains. Outside of brief
storms, VFR conditions are expected for the duration of the forecast
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
814 PM CDT Tue May 28 2019
814 PM CDT
A large shield of rain with embedded thunderstorms is spreading
across northern Illinois this evening, with the likelihood of
stronger to possibly severe storms in western Illinois tracking
into the southern CWA after 930 p.m. The concerns for flash
flooding are increasing as well, which brought about the expansion
of the Flash Flood Watch a couple hours ago.
Area of rain and embedded storms spreading into north central
Illinois is driven by a few features...1.) the far northern area
by a remnant MCV and 2.) much of the area by returning moist and
warm advection aloft of 35 kt as seen on the 00Z ILX sounding.
Much of the region is also under quickly increasing larger scale
forcing for ascent ahead of a stronger short wave, likely
convectively enhanced, in southwest/south central Iowa. Cloud tops
also continue to cool on satellite, with values of -70C to -77C
in eastern and southern Iowa. All of this, with the support of
convection allowing models, indicate rain and embedded convection
having upscale growth over the area through midnight. High
absolute moisture values...including 850 mb dew points of 14-15C
as noted on upstream ILX and SGF soundings and precipitable water
at or above 1.50 inches...support heavy rainfall rates. Also the
nose of the 35 kt moisture-replenishing low-level jet is
positioned into the southern and central CWA ahead of this ongoing
convection. So we are concerned with a several hour (3+) period
of heavy rain rates, and the far southern CWA could have multiple
waves of these into overnight / early Wednesday morning. So flash
flooding could easily become realized, and may need to consider
expanding the watch into a portion of northwest Indiana. While
some of the upper forcing is moving north of east, the convective
focus for the heaviest rain rates will likely hang near the
850-925 mb baroclinic zone, and this is slightly south of the
greater Chicago area. Will need to continue monitoring trends
though to ensure flooding threat is indeed west/south of the city.
As for the severe thunderstorm threat...a well-defined bowing
segment approaching the Peoria area has shown better organization
and is riding the instability gradient around 925 mb eastward. The
stable layer is shallow there, and this has enough structure to
continue a wind threat eastward possibly into the southern CWA.
Rainfall rates within this are very heavy too (2+" per hour).
Mid-level lapse rates as noted on the ILX sounding as well as
analyzed by the SPC RAP mesoanalysis are steep (8C per km
800-500mb) and could support a hail threat given 50 kt of deep
layer shear, especially in any developing stronger cells ahead of
this area. In addition, any west-to-east convection in a pseudo-
warm advection wing, would further enhance the training convection
threat for possible flash flooding.
If any flash flooding were to develop -- and again the trends are
increasing that at least some flooding will likely occur in/near
the CWA -- this could continue into Wednesday morning.
245 PM CDT
Through Wednesday night...
Showers, thunderstorms and associated heavy rainfall are the main
focus once again. Complex of storms crossing the area this
afternoon will continue eastward and exit to the east in the next
few hours. Frontal boundary hung up to the south will continue to
be the focus for new and potentially severe development through
late afternoon. Attention then turns to the wave that is moving
from northeast Kansas into NE/IA/MO and generating thunderstorms.
Thinking continues to be that this will congeal into an organized
complex and track eastward into the area from mid evening into the
early overnight. Guidance has struggled with the current complex
crossing the area so there is some question on how this may impact
the next complex this evening. However, given that there is
larger scale forcing at play, have somewhat better confidence in
the trends that had things been more mesoscale driven. That said,
placement of the heaviest axis of precipitation and its eastward
extent is still somewhat uncertain. Provided the expected complex
arrives from the west, low/mid level ascent will be increasing out
ahead of it this evening and should support the development of
elevated convection on more of an east-west axis across central or
northern parts of the area. Am leaning towards central areas
being the more likely location for this to occur vs. northern
areas given the current complex crossing the area perhaps limiting
any northward push of features that earlier guidance had
anticipated to occur without the complex occurring. The heart of
the expected MCS would likely track a bit to the south as the
lower level instability gradient is likely shunted a bit south
thanks to the current afternoon convection.
Have opted to keep the previously issued flash flood watch as-is. With
uncertainty in how the next complex will shape up and any
developing impact the afternoon activity will have going forward
do not have any additional confidence over what the earlier shift
had on any expansion. So far, the current activity has generally
produced a half inch or less of precipitation. Moisture transport
should increase into the evening but the activity also looks to be
rather progressive. Certainly cannot rule out isolated flash
flooding outside of the current watch though. Will pass concern
onto evening shift.
May see lingering showers and thunderstorms in the southern or southeastern
CWA Wednesday morning but expect a break in additional activity
through most of the afternoon. Another series of troughs is
expected to eject eastward across the plains and Mississippi River
Valley Wednesday bringing more chances for showers and storms
244 AM CDT
Wednesday night through Monday...
The frontal boundary which appears poised to push its way south of
the forecast area Wednesday afternoon, and perhaps very briefly
dry things out, begins to lift back north Wednesday night into
Thursday morning at the same time models show height falls aloft
associated with the ejection of a cluster of shortwaves from the
upper trough still sitting to our west. Considerable moisture
convergence at low levels along with continued high PWAT values
through this period would support yet another chance of heavy
Precip chances appear to diminish somewhat by Thursday afternoon and
evening as low level support becomes less favorable, but the passage
of an upper level trough axis along with the southward departure of
the frontal boundary could still support some scattered showers.
By later Thursday night into Friday precip chances diminish further
as drier northerly flow develops at low levels and the upper trough
has passed to our south. Presently Friday is looking like a good
day to dry out from all the recent and upcoming rainfall.
Confidence for the weekend and beyond becomes much lower as the
upper pattern transitions at least briefly to a more subtle quasi-
zonal to weakly cyclonic flow with embedded disturbances across the
eastern CONUS, downstream from the next deep trough digging into the
Pacific coast. Models are suggesting one of those disturbances
could traverse the area sometime on Saturday, though timing is a
question. There is better agreement that Sunday and Monday will be
dry with rising heights aloft and drier air under a Great Lakes
ridge at the surface.
For the 00Z TAFs...
Main concerns are the thunderstorms marching east toward the
terminals this evening... and increased NE flow again behind the
convection overnight enabling an onshore flow and hence pockets of
IFR and possibly even LIFR through daybreak and into the mid
Extrapolated timing of ongoing leading rain edge crossing the
Mississippi River and in northwest Illinois has showers and
embedded thunder arriving at ORD and MDW from 02-03 UTC. Strong
moisture transport north into this large area of rain and thunder
suggests a period of many hours of rain (~6-10) possible at the
terminals. Embedded thunder within the larger rain area is
expected to diminish however as the night transitions into
Reinforced northeast/onshore flow becomes well established again
as the larger convective area moves off to the east and south...
hence expect cigs to lower back to IFR conditions around 09-10 UTC
with rain cooled air and cold marine layer undercutting very moist
IL...Flash Flood Watch...ILZ003-ILZ008-ILZ010-ILZ019-ILZ032 until 7
Flash Flood Watch...ILZ011-ILZ020-ILZ021-ILZ022-ILZ023-ILZ033-
ILZ039 until 7 AM Wednesday.
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Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
504 PM PDT Tue May 28 2019
updated aviation discussion
Afternoon temperatures will be notably warmer this week with only
a slight chance of afternoon and evening thunderstorms in the
mountains. Overnight and morning coastal low clouds will persist
through the week.
.SHORT TERM (TDY-FRI)...28/121 PM.
An upper level trof currently extends southward through
California. It will fill over the next few days, and then an area
of closed circulation aloft will slowly work from central
California through the CWA and then south of our area during the
A weak impulse associated with the trof will move over the area
this afternoon. Afternoon heating will help the clouds build over
mountain areas this afternoon. Already seeing some cumulus over
the San Gabriel mountains and north of the Ventura County
mountains. Watching the LIs drop by the hour, so some rain is
looking likely, with a slight chance of thunder.
Expecting 3 to 5 degrees of warming today in the coast and valley
locations with higher amounts at higher elevations. Max temps
will stay below normal today, but this should be the last cool day
for the next few days.
The HRRR and our local WRF are indicating elevated winds along the
western Santa Barbara south coast this evening from roughly 7 pm
to 11 pm with sustained winds of 30 mph. Will keep to monitor the
area for a possible low-end wind advisory.
Increasing onshore flow will help develop marine layer stratus
and bring it to the coasts and the lower valleys tonight and into
The trof fills in a bit Wednesday and the dry and slightly
cyclonic flow will persist of the area. Skies should clear by
late morning. NAM and the ensembles agree there will be a chance
of showers and slight chance of TSTMs over the higher mountains
again. The atmosphere will continue to warm under the high sun,
and afternoon high temperatures will rise another couple of
degrees. Less warming along the immediate coast where the return
of stratus will drop the starting point. The marine layer will
repeat Wednesday night and it will likely arrive a little sooner
since the onshore flow is stronger.
A weak upper low moves out of Oregon on Thursday and slides
southward down the state. By afternoon the stratus will have
pulled off the coast, but the mountain areas will begin to cloud
up as the upper low provides both lift and instability. Still
looks like Thursday will be the best day for TSTM development,
especially over the Ventura County mountains. Thursday will be
the warmest day of the week.
The upper low moves moves closer on Friday and it will be not too
different than Thursday. Heights drop a few DM, so afternoon
temperatures will cool back to Wednesday levels. Onshore flow
should keep the marine layer stratus as a morning feature. Again a
chance of afternoon showers and possibly thunder in mountainous
.LONG TERM (SAT-TUE)...28/128 PM.
Very little day-to-day change in the extended forecast as the
upper level low migrates over us and then to our south. Moderate
onshore flow will keep the night through morning low clouds going
through the period. Expecting little change in high temperatures
until next Tuesday when heights have climbed to 584 DM. While
there will be some afternoon cumulus over the mountains each day,
there will likely be insufficient moisture and instability to
create a risk of thunderstorms.
At 2330Z at KLAX...there was a weak inversion at 1600 ft deep.
The top of the inversion was near 4000 ft with a temperature of 15
Moderate confidence overall in the 00Z TAFs. Low clouds and
IFR/MVFR cigs are forecast to develop tonight and move into the
coastal and vly airfields, with the onset ranging from about 06Z
at KSMX to about 14Z at KSBA, KCMA, KBUR and KVNY. The low clouds
are then expected to clear to VFR by late Wed morning to early Wed
afternoon. The timing of the onset and dissipation of the low
clouds may be off +/- an hour or two. There is also a 30%-40%
chance the low clouds may not affect KBUR and KVNY at all during
For KPMD and KWJF, there is hi confidence in VFR conditions
through Wed afternoon. Gusty W winds are expected this evening.
KLAX...Moderate confidence overall in the 00Z TAF. Low clouds and
MVFR cigs are forecast to affect the airfield from about 12Z-19Z
Wed and again aft 03Z Wed evening. Otherwise, VFR conditions can
be expected for most of the TAF period. The timing of the onset
and dissipation of the low clouds may be off +/- an hour or two.
KBUR...Moderate to hi confidence overall in the 00Z TAF. Low
clouds and MVFR cigs are forecast to affect the airfield from
about 14Z-17Z Wed. There is a 30%-40% chance the low clouds may
not affect the airfield at all during the period. Otherwise, VFR
conditions can be expected for most of the TAF period. The timing
of the onset and dissipation of any low clouds may be off +/- an
hour or two.
For the outer waters, high confidence in forecast. NW winds will
remain at Small Craft Advisory (SCA) levels much of the time thru
Wed night. There is a 30% chance of SCA level winds Thu thru Fri.
For the inner waters north of Pt. Sal, moderate confidence in
forecast. Winds are expected to reach SCA levels this afternoon
and evening, then SCA conds are not expected thru Sat. However,
there is a 20% chance of SCA level winds during the afternoon and
evening hours Wed, and a 30-40% chance during the afternoon and
evening hours Thu.
For the inner waters south of Pt. Conception, moderate to high
confidence in forecast. Winds are expected to reach SCA levels
this afternoon and evening across western portions of the SBA
Channel. Otherwise, SCA conds are not expected thru Sat.
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
for zones 645-650. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 AM PDT Thursday for
zones 670-673-676. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK (FRI-TUE).
Showers and thunderstorms are possible each afternoon and evening
in the mountains through at least Friday. There is a small chance
for heavy rainfall and isolated flash flooding accordingly.
Area Forecast Discussion
National Weather Service Paducah KY
858 PM CDT Tue May 28 2019
Issued at 858 PM CDT Tue May 28 2019
Based on radar observations to our west and north, and the latest
CAM data, have updated the forecast to limit PoPs late tonight
primarily to southern Illinois and southeast Missouri after 4 AM.
Strong to severe storms do not seem very likely in this scenario,
but will keep the mention of a stray strong storm in the HWO.
Locally heavy rainfall and lightning will be the most likely
impacts late tonight.
UPDATE Issued at 700 PM CDT Tue May 28 2019
Updated aviation discussion for 00Z TAFs.
.SHORT TERM...(Tonight through Thursday night)
Issued at 330 PM CDT Tue May 28 2019
Upper ridge shifts east tonight and Wednesday, leading to more of
a general southwest flow regime aloft, with a sfc frontal
boundary draped north of the region. This boundary will make an
attempt to settle southward toward the forecast area Wednesday
night, but will likely hold off reaching us until Thursday. Latest
HREF CAMS tend to suggest some sct thunderstorms later
tonight/Wed morning, mainly over se MO and sw IL as an MCS (or
weakening MCS) tries to spill southeast from MO/IL. Climatology
would dictate a weakening trend at that time frame, but will need
to monitor its progress. Chance of severe seems low but not zero.
Becoming a bit more concerned with the severe storm risk
Wednesday, especially for the later afternoon and evening hours.
12Z CAMS now are hinting at another area of convection to get
going Wed AM out over the southern Plains. This round of
thunderstorms would try to build east toward se MO/sw IL Wed
afternoon. Instability will likely be moderate to strong (SBCAPES
AOA 3000 J/KG) in wake of any morning convection. In addition, AM
convection may actually serve to leave a sfc boundary draped e-w
across the middle of the forecast area, which could interact with
the afternoon storms. Both 12z NAM and RAP sounding now introduce
a greater amount of wind shear late in the day into the early
evening, esp over se MO/srn IL/sw IN. O-6 KM bulk shear is
significantly higher than advertised yesterday, with values closer
to 40-45 kts over those areas. In fact, SPC has now upgraded the
day 2 Outlook to a slight risk over all of that 3 state region.
In addition, locally heavy rainfall, generally over southeast MO
and southwest IL could become an issue Wed/Wed night if storms
manage to undergo training within the moist warm sector. Will hold
off on any headlines for now. Will be interesting to see if any
precursor heavy rains develop late tonight in that region. If so,
flash flood watches may be required later tonight or Wednesday AM.
Short wave energy and sfc cold front are still expected to cross
the region Thursday. However, extensive cloud debris and weakened
instability should preclude much of a strong to severe risk.
.LONG TERM...(Friday through Tuesday)
Issued at 330 PM CDT Tue May 28 2019
Medium confidence in the extended with the ECMWF having the most
stable solution. The Canadian has similar timing but very stingy
with the qpf leading up to the extended. The GFS stalls the front
over us through Friday. This is yet another flip flop in its
solution. With this in mind will weight the ECMWF heavier with the
The overall synoptic scale features remain similar with the upper
level high sinking southward into the Gulf. We expect two closed
upper level lows...one over the west coast and the other near
Hudson Bay. This will place us in a near zonal flow aloft starting
Friday then becoming northwest as we head into the weekend. Upper
level ridging will take place over plains. This northwest flow
will allow for minor perturbations in the flow rotating around the
upper low in Canada. This will allow for low chance pops as we
head through the weekend. There will also be a weak cold front
which should approach the area mainly Saturday night and move
through Sunday. This will enhance rain chances but still
relatively low pops and qpf. It may drop temperatures and dew
points a couple of degrees but thats about it. The best chance of
encountering a thunderstorm through the extended will be in the
peak heating of the day. However these spokes of energy are
difficult to time that far out and relatively weak. Temperatures
will be lower than it has been averaging between 80 and 85 for
highs through the extended.
Issued at 700 PM CDT Tue May 28 2019
VFR conditions are expected through most of the period. A decaying
line of showers and perhaps some thunderstorms is expected to move
into portions of southeast Missouri and southern Illinois late
tonight and early Wednesday morning, likely dissipating as it
pushes further east into the area. Much of the afternoon should be
dry as cumulus develops in the recovering atmosphere ahead of a
second round of showers and storms Wednesday evening. South to
southwest winds will diminish to 5 to 10 knots tonight, then
increase to around 10 knots with some gusts of 15 to 20 knots by