Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/10/19
Area Forecast Discussion
National Weather Service Bismarck ND
1022 PM CDT Tue Jul 9 2019
.UPDATE...
Issued at 1022 PM CDT Tue Jul 9 2019
Only minor changes were made with this update relying on observed
trends and recent rapid-refresh guidance, including time-lagged
HRRR output which continues to capture precipitation trends well.
The stacked low has progressed eastward and rainfall is pivoting
southward in line with earlier expectations. Rainfall intensity is
still forecast to slowly decrease overnight, and lightning will be
at a premium owing to weak instability, especially once convection
near the vorticity maximum near McHenry County at 03 UTC weakens.
UPDATE Issued at 716 PM CDT Tue Jul 9 2019
A stacked low is centered near Minot as of 00 UTC, and while it is
slightly further west than expected at this point, it has recently
begun to shift eastward per radar and satellite imagery. Even so,
the shield of rain associated with its forcing for ascent has not
pivoted southward as quickly as earlier expected, so the primary
adjustment with this update cycle was to hourly PoPs through late
evening to account for that progression. Time-lagged HRRR guidance
captured ongoing trends well and hourly PoPs were weighted to its
output, with a ramp-up in probabilities along the Interstate 94
corridor from Dickinson to Bismarck from 03 to 05 UTC. Persistent
and strong deformation and continued moisture transport have been
and will continue to yield moderate to heavy rainfall through the
evening west of the stacked low, with a slow decrease in rainfall
intensity overnight concurrent with diminishing moisture transport
and weakening deformation. Even so, our NBM-driven QPF forecast
includes up to 0.50" inches of rain as far south as Interstate 94.
Otherwise, low-level SRH along and north of the warm frontal zone
from near Minot to Carrington has diminished and is less than 100
m2/s2 as of 00 UTC per RAP-based objective analysis and the KMBX
and KMVX VAD wind profile data. Thus, the potential for low-topped
mesocyclones has diminished considerably, and despite a residual
corridor with moderate instability characterized by MLCAPE around
1000 J/kg in the James River valley, weak effective shear combined
with midlevel lapse rates around 6 C/km suggest the probability of
any marginally-severe storms has decreased significantly. We thus
have chosen to adjust messaging to take out any mention of severe-
storm risk for the rest of the evening. We are maintaining only a
slight chance of non-severe thunderstorms in the forecast tonight
given expected weak instability and recent observed trends in both
GLM and ground-based lightning detection networks.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 230 PM CDT Tue Jul 9 2019
Concerns this period will be rain and possible rural and urban
minor flooding across the northwest and north central this
afternoon and evening. Have issued a flood advisory for northwest
and portions of north central North Dakota through 1045 pm this
evening.
With abundant low level vorticity and shallow dry adiabatic lapse
rates, will get some funnel clouds.
Otherwise expect the showers and thunderstorms to diminish
tonight and generally end on Wednesday morning. Not as cool on
Wednesday with highs in the 70s.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 230 PM CDT Tue Jul 9 2019
After the upper low exits the region Wednesday, a broad h500 ridge
replaces it, bringing warmer temperatures and generally dryer
conditions to the region. Although the ridge will be in place
across the northern plains, a shortwave trough will pass through
the ridge axis bringing a chance for thunderstorms Thursday night.
The National Blend of models did not give widespread POPs for
this, possibly because an Environmental Mixed Layer (EML) will
keep some capping in place. If the capping breaks more widespread
thunderstorms, and even severe weather may be possible.
Otherwise, widely scattered thunderstorms are possible again
Saturday night and Sunday night as the ridge axis shifts east and
backing flow aloft allows more shortwave energy to move into the
northern plains.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1022 PM CDT Tue Jul 9 2019
Rain and isolated thunderstorms with MVFR to local IFR conditions
will impact most of western and central ND overnight as an area
of low pressure slowly moves eastward. Northwest wind gusts up to
35 kt are also expected tonight west and central, and over the
James River valley Wednesday. Expect improving conditions from
west to east along with diminishing winds Wednesday, with VFR
conditions area-wide by Wednesday afternoon.
&&
.HYDROLOGY...
Issued at 1022 PM CDT Tue Jul 9 2019
Widespread heavy rainfall with observed totals of 2 to 5 inches in
northwest and north central ND through this evening will result in
rises on small creeks and streams, flooding of rural roads, and is
expected to cause the Little Muddy River near Williston to reach
minor flood stage on Wednesday. As a result, a Flood Advisory has
been extended in those areas through Wednesday evening, as runoff
will continue into the day tomorrow even after rainfall diminishes
tonight. Otherwise, a Flood Warning remains in effect for Beaver
Creek near Linton and a Flood Advisory is in effect for LaMoure
County as a response to heavy rain that occurred in those areas
Monday night.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CJS
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...CJS
HYDROLOGY...CJS
Area Forecast Discussion
National Weather Service Birmingham AL
708 PM CDT Tue Jul 9 2019
.UPDATE...
For 00Z Aviation.
&&
.SHORT TERM...
Through tonight.
The heat is on for most locations as of noon, with temperatures in
the low to mid 90s and very humid dewpoints in the low to mid 70s.
Heat indices have already risen above Heat Advisory criteria in
Tuscaloosa and Montgomery, hitting 106 and 107 degrees. At this
time, we`re not planning on extending the area of the Heat
Advisory, and will remain across roughly the western half of
Central Alabama through 7pm.
Meanwhile, convection is developing along the NW periphery of the
trough/area of low pressure centered over southern Georgia and
the Florida Panhandle. This is the same area of low pressure that
the National Hurricane Center will be monitoring as it moves into
the Gulf of Mexico. The convection is developing within a
convergence zone as was mentioned in the previous discussion this
morning. The 12Z KBMX sounding this morning indicated much warmer
conditions aloft today than yesterday due to the upper height
rises and 592 decameter upper ridge centered over much of the
southeast. Even though mid-level lapse rates are weak due to the
higher temperatures aloft, conditions at the surface are very
unstable. RAP analysis indicates SBCAPE values of 4000-4500 J/KG
across our southern tier of counties where the most showers and
storms are expected to develop. In addition, microburst composite
parameters are higher today than they have been over the past
several days mostly due to drier air aloft. Therefore, we`ll have
to keep a close watch on these storms this afternoon, as Troy
measured a wind gust of 37 knots with a storm that wasn`t able to
get very tall or organized on radar. In addition, torrential
downpours could lead to some localized flooding and ponding in
isolated locations as some storms will be training at times as
they move from northeast to southwest this afternoon. We`ll expect
at least scattered storms to persist in areas along and south of
the I-85 corridor through late this evening.
56/GDG
.LONG TERM...
/Updated at 0348 AM CDT Tue Jul 09 2019/
Wednesday through Tuesday.
By Wednesday the low pressure system is situated to our south and
has just entered the Gulf of Mexico. As the low drifts southwestward
into the western Gulf, upper level ridging will amplify over our
area. Afternoon thunderstorm activity won`t be quite as prominent as
we have seen in previous days. The best chances will be in our
southeast counties due to more of an influence from the exiting low
pressure. Temperatures will are expected to reach the mid 90`s
Wednesday afternoon. Heat indices have the potential to reach at or
above 105 degrees particularly in areas of southern and southwest
Central Alabama.
An upper level trough and associated surface low pressure system
will move into the Great Lakes region on Wednesday afternoon. A
frontal boundary associated with this upper level system will push
southeast into the northern Mississippi Valley region Wednesday
night. By Thursday, the surface front will have entered the northern
part of our CWA increasing rain chances. While temperatures are
still expected to be in the low/mid 90`s with mid 70-degree
dewpoints, cloud cover from increasing rain chances could prevent
heat advisory criteria from being met. I will continue to mention
heating impacts in the HWO as there is still some uncertainty. The
low pressure system in the Gulf is expected to become a tropical
disturbance by the end of this week. There is still plenty of
uncertainty with regards to timing and track. Guidance has struggled
with the handling of the frontal boundary approaching from the north
and the interaction with the low in the Gulf. At this point, most
guidance seems to be tracking the low more westward. Either way, an
increase in tropical moisture from this system will allow for an
increase in shower and thunderstorm activity for much of Thursday,
Friday and Saturday. The forecast for the remainder of the period
solely depends on the evolution of this low pressure system. At this
time I have capped PoPs at 30% for Sunday afternoon and gradually
trending down to the end of the period.
&&
.AVIATION...
00Z TAF Discussion.
Outflow-driven convection continues from near EET southward to
Selma. This activity will continue to shift westward over the next
couple of hours before hopefully diminishing. Storms in SW Georgia
may enter Barbour County, but do not anticipate them reaching TOI
at this time. No widespread fog expected overnight, but will
continue to mention some MVFR visibilities at TOI due to the rain
observed there earlier today. More scattered storms on tap for
Wednesday, best chances across the south.
19
&&
.FIRE WEATHER...
Expect lower chances for showers and storms across the north and
west through Wednesday. However, scattered to numerous showers
and storms can be expected in the south and east during mainly the
afternoon hours. Relative humidity values should bottom out in
the 40 to 50 percent range during the afternoon hours before the
overnight recovery. Showers and storms will remain in the forecast
for good portion of the forecast period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 73 92 73 91 72 / 30 30 20 60 50
Anniston 74 91 74 90 73 / 30 30 20 60 40
Birmingham 76 94 75 93 74 / 30 30 20 60 40
Tuscaloosa 77 96 76 94 74 / 20 30 20 60 40
Calera 74 93 74 92 73 / 30 40 20 60 40
Auburn 75 90 74 88 73 / 30 50 30 70 40
Montgomery 76 94 76 92 74 / 20 50 30 70 30
Troy 75 92 74 90 73 / 20 60 30 70 30
&&
.BMX WATCHES/WARNINGS/ADVISORIES/...
Heat Advisory until 7 PM CDT this evening for the following
counties: Autauga...Bibb...Blount...Chilton...Coosa...Dallas...
Elmore...Fayette...Greene...Hale...Jefferson...Lamar...Lowndes...
Marengo...Marion...Montgomery...Perry...Pickens...Shelby...St.
Clair...Sumter...Talladega...Tuscaloosa...Walker...Winston.
Heat Advisory from noon to 7 PM CDT Wednesday for the following
counties: Autauga...Bibb...Blount...Chilton...Coosa...Dallas...
Elmore...Fayette...Greene...Hale...Jefferson...Lamar...Lowndes...
Marengo...Marion...Montgomery...Perry...Pickens...Shelby...St.
Clair...Sumter...Talladega...Tuscaloosa...Walker...Winston.
&&
$$
Area Forecast Discussion
National Weather Service Cheyenne WY
223 PM MDT Tue Jul 9 2019
.SHORT TERM...(This evening through Wednesday)
Issued at 225 PM MDT Tue Jul 9 2019
Forecast concerns deal primarily with severe thunderstorm chances
this afternoon and early evening.
Currently...Cold front moving through the area this afternoon.
Upper shortwave moving through northeast Wyoming into western
South Dakota this afternoon. Seeing a pretty strong jet max of
roughly 100kts rounding the base of that shortwave into
Converse/Niobrara and the northern Nebraska Panhandle this
afternoon. 500mb temperatures down to -13 to -15C this
afternoon...aiding in steeper lapse rates across our northern
counties. SPCs Mesoanalysis page showing surface based CAPES
around 2000 to 2500 J/KG this afternoon for that area. Radar
showing some convection over northern Converse and Niobrara
Counties this afternoon. Strongest storms up over northeastern
Wyoming in Rapid City`s area so far.
Latest HRRR showing a few thunderstorms becoming strong after 22Z
this afternoon across our northern counties with all convection
coming to an end after 01Z/02Z. Current Watch runs to 02Z...so
that looks pretty good.
For Wednesday...Much drier and more stable conditions for
Wednesday as upper ridge begins to build across our western CWA.
Have PoPs pretty much zeroed out for Wednesday afternoon.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 225 PM MDT Tue Jul 9 2019
Dry and warm weather continues through Thursday as 700mb
temperatures climb to +15 to +16C. Pretty warm surface
temperatures with mid 90s in the Panhandle to the I-25 Corridor
and upper 80s out west.
Backdoor cold front still on track for Friday afternoon. Showers
and thunderstorms expected to develop along this front Friday
afternoon/evening. This front looks to stay with us through the
weekend into next week.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1135 AM MDT Tue Jul 9 2019
VFR conditions expected through the forecast period with gusty
winds posing the main threat through 02Z this evening. Strongest
winds will be seen near KLAR and KRWL with westerly winds gusting
near 30 kts at times this afternoon. Will need to monitor the TAF
near KCDR for timing and location of thunderstorms late Tuesday
afternoon which may result in brief periods of reduced visibility
in heavy rainfall and stronger winds. Additionally, a cold front
will push through the area turning wind directions northerly for
NE Panhandle terminals after 00Z.
&&
.FIRE WEATHER...
Issued at 225 PM MDT Tue Jul 9 2019
Cold front moving through the northern Nebraska Panhandle as well
as Converse and Niobrara Counties could produce a few severe
thunderstorms this afternoon. These storms expected to end
early...before sunset today as the front moves east. Drier weather
for Wednesday and Thursday with afternoon humidity falling to
critical levels...especially along and west of the Laramie Range.
Fortunately...fuels are still being reported green and winds are
not expected to be too strong over the upcoming days. So fire
weather concerns are minor. Next chance for wetting rains and
thunderstorms return Friday afternoon as a cold front moves in
from the north. Areas along and east of the Laramie Range stand
the best chances for seeing these wetting rains.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...GCC
LONG TERM...GCC
AVIATION...MB
FIRE WEATHER...GCC
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
636 PM CDT Tue Jul 9 2019
.Discussion...
Issued at 254 PM CDT TUE JUL 9 2019
For the rest of this afternoon, the chances for new convection look
fairly low. The best chances look to be across the northeastern
quadrant of the forecast area, where there`s taller/cooler CU noted
on visible/IR combo imagery. There may also be weak low level
convergence in this area that trails southwestward to the eastern
portions of the KC metro. Have maintained low PoPs, 15-20% in this
area to capture this potential. While CAPE is ample, shear is weak
and as such, no severe weather is expected.
For tonight through tomorrow, a cold front will move through the
area tomorrow morning. This may bring a chance for storms tomorrow
morning from northeastern Kansas through west central Missouri. The
12Z HRRR shows this potential, while most other models hold off
until later in the day, when the front is further south. Since
confidence is fairly low at this point, have kept PoPs below
mentioning any weather. But during the afternoon, when heating is
near its peak in the southern third of the forecast area, chances
will increase. Have added chance PoPs to the forecast to capture
this. Again, the threat of severe weather looks low due to weak
shear. But there is ample instability so a few strong storms are
possible.
Much cooler dewpoints will fill into the area behind the front
leading to a much more comfortable feel to temperatures. Highs on
Thursday should be in the middle 80s with lower 60s dewpoints.
Temperatures may warm a few degrees Friday, but with dewpoints still
in the mid 60s, it`s still just typical summer warmth. Even over
the weekend, as temperatures climb into the low to middle 90s
dewpoints look to be in the middle to upper 60s, perhaps touching
70 degrees. So our next round of heat, shouldn`t feel as hot as a
few weekends ago with a bit cooler dewpoints in the region.
Next week, the progress of whatever is leftover from a possible
tropical system will need to be monitored. The remnants of that
system may begin to impact the area late Tuesday. The impacts will
be from heavy rain but, with the exception of northern Missouri,
which may not see much from this system anyway, much of the area
doesn`t need to have tropical enhanced rainfall.
&&
.Aviation...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 636 PM CDT TUE JUL 9 2019
VFR conditions largely expected through the fcst period, although
predawn fog cannot totally be ruled out at STJ after the 09z time
frame. In any event, will continue to monitor model trends before
possibly inserting a mention with the 06z package. The other
concern will be for possible morning convection after 13z as a
cold front moves through the region. For now, feel the prospects
are handled accordingly with a VCTS mention, however models
continue to indicate very widely scattered coverage. If this trend
continues, we may have to consider removing mention with the next
fcst issuance. SW winds this evening and overnight will veer to
the northwest after 13z before increasing to 10-15 kts during the
late morning and afternoon hours.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...CDB
Aviation...32
Area Forecast Discussion
National Weather Service Wilmington NC
1145 PM EDT Tue Jul 9 2019
.SYNOPSIS...
A cold front will be stalled nearby through Wednesday keeping
the weather unsettled. This front will lift north by Thursday
bringing an even more humid airmass still very prone to
thunderstorms. Late week storm coverage will increase as a cold
front approaches from the northwest.
&&
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
As of 1145 PM Tuesday...Convection late this evening has
organized along an east-west line just off the Brunswick County
coast. Environmental winds below 400 mb are generally
southeasterly, and many models show this convective line pushing
inland from Myrtle Beach and Southport north into Wilmington
overnight. The 02z HRRR did not initialize well with this line,
but its wind profiles agree with a slow northward drift of
anything offshore. New PoP/Wx/QPF grids show a half inch of
rain possible for Oak Island, Southport, and Bald Head Island,
with lesser amounts spreading inland. Discussion from 300 PM
follows...
Essentially more of the same for the next 24-36 hours. The
front that continues to bisect the area will continue to wobble
around and eventually dissipate. There isn`t much thermal
definition to the front (if any) but you can still see northeast
storm motions north and more sea breeze east to west across
southern zones. The convection should be more confined to
coastal areas this afternoon although all areas are somewhat
fair game. We should see a minimum tonight and do it all over
Wednesday. Lows tonight and Thursday morning will be in the
steamy 70s, yes the windows are quite fogged up in the mornings
with daytime highs, modulated by convection and possibly low
clouds again in the middle to upper 80s.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
As of 330 PM Tuesday...The frontal boundary staying off to the
north and SSW low-level flow will lead to warm and humid
conditions across the fa...highs in the upr 80s to lwr 90s with
heat indices peaking around 100. The high humidity will also lead
to low LCLs and thus thunderstorms will form readily on any and
all mesoscale boundaries while weak mid-level shortwaves lead
to larger scale lift. The end result will be a higher than
normal distribution of storms that will wane but not to zero
coverage Thursday night. PoPs 40-60% daytime Thursday, 30-40%
Thursday night.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 330 PM Tuesday...A weakening cold front drops into the
area late Friday, as a thermal trough of low pressure persists
over the weekend into early next week.
Precip Chances: Highest Friday (50-60%) as the front drops into
the area. Still 40-50% Saturday, then down to just 20% at most
Sunday and Monday as deep layer moisture profiles decrease.
Temps: Near to slightly above normal through the period...highs
in the upr 80s to mid 90s with lows ranging through the 70s.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 00Z...Stationary front hanging on along the coast has
created widespread thunder and shower activity that has pushed
into the inland counties. Expect precip to end from east to west
over the next 3-6 hours. With not much changing in the patter,
have gone with a persistence forecast of fog and stratus inland
with mainly stratus along the coast. A few showers possible
along the front near sunrise tomorrow with increasing chances of
storms as the day progresses. Best chance of a shower will be
along the coast.
Extended Outlook...Early morning fog and stratus possible, with
scattered convection in the afternoon and evening throughout
the period.
&&
.MARINE...
As of 1145 PM Tuesday...Buoy reports in the Cape Fear area show
synoptic winds near 15 knots from the east even well outside of
the convection off the Brunswick County coast. This is
5-10 kt stronger than our previous forecast, and a new Coastal
Waters Forecast has been issued. Seas reported from CORMP and
NDBC buoys show 3 foot seas inside 20 miles from shore. The
CORMP Lejeune offshore buoy has 4 foot seas currently, but I am
hopeful these higher seas remain outside of the coastal waters
through the night. Widespread showers and thunderstorms just off
the Brunswick County coast are slowly drifting northward, but
may redevelop and expand overnight given the presence of the
front and a very warm and unstable airmass. Discussion from 300
PM follows...
Modest east to northeast winds continue across the waters but
should continue or begin to turn more southeast through the
evening and overnight hours. The directions could be quite
erratic for the next few hours due to convection however. The
synoptic southeast flow will continue Wednesday and turn more
southwest into Thursday morning. Speeds should be 10-15 knots
leaning heavily toward the lower end of the range. Significant
seas should hang around 2-3 feet.
For Friday through the weekend...winds continue out of the S/SW
at 10-15 kt on average, occasionally at 15-20 kt during the
evening hours. Significant seas of 3-4 ft will fall to 2-3 ft by
Sunday. This will consist of a persistent SSWly 5-6 second wave
and a weak SEly 8-10 second swell.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...MAS
NEAR TERM...TRA/SHK
SHORT TERM...MAS
LONG TERM...MAS
AVIATION...21
Area Forecast Discussion
National Weather Service Indianapolis IN
1129 PM EDT Tue Jul 9 2019
.UPDATE...
The AVIATION Section has been updated below.
&&
.SYNOPSIS...
Issued at 400 PM EDT Tue Jul 9 2019
Expect largely dry weather tonight into early Wednesday under the
influence of a gradually weakening ridge aloft. An upper level low
pressure system will push into the upper Midwest overnight into
Wednesday, which will likely spark some organized convection to
our northwest. This activity appears likely to move into central
Indiana late tomorrow into tomorrow evening, and may produce some
severe weather. In the wake of this system, another fairly dry
period is expected, with a largely dry forecast much of the rest
of the period, as the ridge reasserts control and temperatures
begin to climb again late in the weekend into early next week.
&&
.NEAR TERM /Overnight/...
Issued at 1007 PM EDT Tue Jul 9 2019
A warm July evening in progress with mainly clear skies across
central Indiana. 02Z temperatures ranged from the mid 70s to the
lower 80s.
Surface high pressure off to the east of the region and ridging
aloft will keep dry conditions across much of the area through the
overnight. The only big change to the overnight forecast was to
add in a very low threat for a stray shower or storm in the
predawn hours focused over the northern Wabash Valley. While
confidence is low...cannot entirely rule out that ongoing
convection over northwest Illinois may be able to sneak into far
northwest portions of the forecast area late tonight prior to
completely dissipating. HRRR continues to advertise this
possibility as well. Overall airmass will remain capped with
little to no instability and any impacts from convection will be
isolated and brief.
Zone and grid updates out.
&&
.SHORT TERM /Wednesday through Friday/...
Issued at 400 PM EDT Tue Jul 9 2019
Will maximize pops late Wednesday afternoon into the evening, as
it appears likely that convection will fire to our northwest
during the day Wednesday and push east/southeastward as the cold
front moves into the area. For collaboration`s sake will keep a
slight chance earlier in the day, but impact should be quite
limited.
Pops will taper off late Wednesday night into early Thursday
morning with passage of the cold front, and the remainder of the
short term will be dry.
Severe weather will be possible tomorrow, mainly northwest as the
system may be weakening with loss of heating as it moves into the
central and southeastern area. Looks like a fairly typical mid
summer setup with ample instability and minimally adequate shear.
Significant dry air aloft and climatology suggests damaging winds
will be the primary threat. There is significant instability in
the hail growth zone, but in the absence of significant rotating
updrafts it is difficult to get much beyond marginally severe hail
this time of year. Window for severe weather potential looks to be
the 4 to 10 PM time frame.
Temperatures will drop back closer to seasonal normals for a
couple of days through the end of the short term before creeping
back toward the 90 degree mark in the long term period.
&&
.LONG TERM /Saturday night through Tuesday/...
Issued at 248 PM EDT Tue Jul 9 2019
Ensembles continue to be in good agreement with the broad ridging
across the Southern Plains beginning to expand north and east
throughout the extended periods. This suggests a slow warming
trend for late weekend into early next week. Guidance presently
indicates a rather quiet stretch of weather; however, there may be
a slight chance of thunderstorms from a system skirting the region
Mon into Tue. Otherwise a rather quiet stretch coming up with
temps slowly warming into the lower 90s and overnight lows in the
mid to upper 60s.
&&
.AVIATION /Discussion for 100600Z TAF Issuance/...
Issued at 1129 PM EDT Tue Jul 9 2019
VFR conditions expected throughout the forecast period.
The Ohio Valley will remain under the influence of surface high
pressure and ridging aloft tonight. Isolated convection over
northern Illinois may slip into the northern Wabash Valley late
tonight before diminishing...but cirrus blowoff will likely drift
across the terminals during the predawn hours. Winds will be light
and variable.
On Wednesday a frontal boundary will approach the region from the
northwest by late day. Model soundings show a more favorable
scenario for cu formation during the afternoon...and a growing
threat for isolated to scattered convection during the mid and late
afternoon continuing into the evening. Confidence remains far too
low regarding expected coverage and direct impacts to terminals to
include any precip mention at this point...but a VCTS will likely be
needed with a future TAF issuance. Southwest winds generally less
than 10kts are expected Wednesday.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...Nield
NEAR TERM...Ryan
SHORT TERM...Nield
LONG TERM...Beach
AVIATION...Ryan
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
917 PM CDT Tue Jul 9 2019
.UPDATE...
Issued at 909 PM CDT Tue Jul 9 2019
Scattered showers and thunderstorms are getting ready to exit the
far southern part of the CWA. Have gone with mainly dry weather
the rest of the night as latest RAP runs are showing little in the
way of forcing for additional convective development. Going
forecast temperatures look good for tonight with lows staying in
the 70s.
Britt
&&
.SHORT TERM... (Through Late Wednesday Night)
Issued at 325 PM CDT Tue Jul 9 2019
Isolated to scattered thunderstorms this afternoon should weaken and
dissipate by late this evening. The rest of the overnight period
should be dry or mostly dry, but did keep slight chance PoPs across
northeast Missouri and west-central Illinois after midnight tonight
as a prefrontal trough approaches from southeast Iowa. This
prefrontal trough may attempt to serve as a focus for showers and
storms into early Wednesday, but weak/nebulous forcing for ascent
along it suggests any activity would be isolated in nature. The late
morning and early afternoon hours should be dry, but the expectation
is for additional showers and thunderstorms to develop along the
trailing cold front. The atmosphere will be very unstable (MLCAPE
values 2500-4000 J/kg) with sufficient shear for organized
convection (20-25 knots). Damaging winds should be the primary
threat with multicellular clusters in an environment characterized
by high DCAPE values. Large hail may also be a threat aided by steep
midlevel lapse rates, but freezing levels around 14,000 feet AGL
will likely make it difficult to get severe criteria hail down to
the surface in the absence of a rotating updraft.
The best chance of storms appears to be from late afternoon through
the early evening hours for parts of west-central and south-central
Illinois where the low-level convergence and forcing for ascent
associated with the shortwave trough will be strongest. More capping
will exist across far southwestern portions of the CWA which may
also help limit the coverage of storms. The threat for thunderstorms
should diminish behind the cold front across southeast Missouri and
southwest Illinois by midnight. Decreasing cloudiness is then likely
for the remainder of the Wednesday night period.
The other main focus continues to be on heat/humidity on Wednesday
afternoon/early evening. With the expectation of little to no
convection during the morning and early afternoon hours, confidence
has increased for temperatures to reach the low to mid 90s across
parts of the area. Warmest conditions should be across the urban
heat island of St. Louis where mid 90s are forecast. These
temperatures combined with dewpoints in the mid 70s should yield
maximum heat index values around 105F Wednesday afternoon/early
evening, and as a result have issued a heat advisory. Behind the
cold front, seasonable temperatures will begin to infiltrate the
area with lows Wednesday night/Thursday morning dropping back into
the mid 60s to near 70 degrees.
Gosselin
.LONG TERM... (Thursday through Next Tuesday)
Issued at 325 PM CDT Tue Jul 9 2019
Seasonably cool temperatures are likely on Thursday behind the cold
front as 850-hPa temperatures drop into the mid teens. All in all it
should be a fairly comfortable day for mid July with highs generally
in the mid 80s, lower humidity, and plenty of sunshine.
Dry weather is likely to continue through this weekend as a
seasonably strong surface high pressure slowly moves southeastward
across the area. Temperatures will moderate a bit each day, with
highs on Saturday back above normal into the low 90s.
Seasonably hot/humid weather should return on Sunday heading into
early next week as the mid/upper level ridge builds back into the
area and 850-hPa temperatures once again near 20C. Dry weather is
favored to continue into Monday, and then focus will shift toward
the remnants of a tropical cyclone and its path. Lots of uncertainty
with its path, but based on climatology, a further west landfall
along the Gulf Coast (SE TX/SW LA) would have the potential to pose
a threat across the mid-Mississippi Valley. Speaking of
climatology, a track this early in the season through the area
would be extremely rare. In fact, dating back to 1950, only one
storm (Claudette 1979) passed within 100 nautical miles of St.
Louis within the month of July. At this very early juncture, kept
PoPs in the slight chance category.
Gosselin
&&
.AVIATION... (For the 00z TAFs through 00z Wednesday Evening)
Issued at 617 PM CDT Tue Jul 9 2019
Isolated showers and thunderstorms across eastern Missouri into
southwest Illinois are expected to diminish this evening. The
chance for showers and thunderstorms will increase on Wednesday
afternoon as a cold front moves southeast across the area. The
strongest storms will have potential to produce MVFR/possible IFR
ceilings and visibilities in heavy rain.
SPECIFICS FOR KSTL:
Isolated showers and thunderstorms will move away from the
vicinity of the terminal before 01Z. Then mainly dry and VFR
conditions are expected through Wednesday afternoon before a
cold front moves into eastern Missouri bringing a chance of
thunderstorms to the terminal late on Wednesday afternoon into
Wednesday evening. The strongest storms will have the potential
to produce MVFR/possible IFR ceilings and visibilities in heavy
rain.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Heat Advisory from 11 AM to 8 PM CDT Wednesday for Jefferson MO-
Saint Charles MO-Saint Louis City MO-Saint Louis MO.
IL...Heat Advisory from 11 AM to 8 PM CDT Wednesday for Madison IL-
Monroe IL-Saint Clair IL.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
800 PM EDT Tue Jul 9 2019
.SHORT TERM...(This evening through Wednesday night)
Issued at 358 PM EDT TUE JUL 9 2019
...STRONG TO POTENTIALLY SEVERE THUNDERSTORMS POSSIBLE WEDNESDAY
AFTERNOON AND EVENING...
Quiet weather will continue across Upper Michigan into the early
evening, with lingering smoke over the east half remaining in place
until southerlies can gradually push it out tonight. This has kept
temperatures cooler there than out west (70s vs low 80s).
Upper level clouds will begin to increase from the west through this
evening out ahead of an upper level trough out in the Dakotas and
associated sfc low. An area of warm frontal showers, with at least
some embedded thunder likely, will move in from the west late this
evening into the overnight. This round will gradually decrease in
intensity and coverage through the morning hours of Wednesday.
The trough and sfc low will skirt the MN/Canada border Wednesday
morning. Strong southwesterlies are expected to traverse the Upper
Peninsula, and there is a distinct possibility that enough of a dry
slot works it`s way into Upper Michigan to allow for brief midday
clearing in spots. Warm, moist air will continue to pour in ahead of
the sfc cold front, with dew points into the mid to possibly upper
60s in the morning and afternoon temperatures climbing into the
lower 80s. It will feel quite sticky during the day, but relief will
come by Thursday.
Most CAMS continue to indicate redevelopment beginning over the
western UP generally around 18Z (WRF-ARW is an outlier with a line
of storms running from IMT to ERY 17Z-21Z). Coverage is expected to
increase though the afternoon from west to east, exiting by about
midnight tomorrow night.
General model consensus is that SBCAPE will maximize over the
central UP in the 1500-2000 J/kg range, though again if more
sunshine is able to break through the potential is there for a brief
period of 2500-3000 J/kg. Deep layer shear should be in the
neighborhood of 40 kts though the lower resolution models place that
number closer to 50-55 kts. Regardless, initial development will
have the potential to become supercellular with all weather hazards
including hail up to 1.5 inches, strong winds, frequent lightning,
and heavy to perhaps torrential rainfall. Climatologically tornados
are very rare here. Nonetheless, a brief spin-up is not out of the
question with RAP soundings indicating the potential for 0-1km shear
of ~15 kts and 0-3km shear nearing 30 kts. There is some minor
discrepancy between models on whether LL flow will be unidirectional
or have a slight backed component. In all likelihood, storms should
grow upscale into a multicell, or more likely linear configuration
owing to boundary parallel flow and strong linear forcing along the
front.
A much more comfortable air mass will begin to move in Wednesday
night with dew points back down into the 50s across the region by
12Z Thursday. Models are heavily hinting at some upslope fog/
drizzle/light rain over the northern tier of counties overnight. Low
level moisture is likely still overdone in the NAM as usual, so
while I have included this in the forecast, confidence is not very
high in this solution at this time.
.LONG TERM...(Thursday through Tuesday)
Issued at 242 PM EDT TUE JUL 9 2019
The end of the week into early next week, we`re looking at
fluctuating day-time temperatures in the 70s and 80s as we remain on
the norther periphery of upper-level ridging building across the
southern Rockies and Plains. While we will see periods of drier
weather at times, we should still see periods of active weather with
shortwaves ridging the northern edge of ridging to our southwest.
Thursday will be a cool day across the area, especially near Lake
Superior as we remain under the influence of north to northwest
winds behind the system exiting to out east. It certainly is not out
of the question that we could see some marine fog/drizzle along the
shoreline and inland early-on during the day Thursday. As high
pressure starts to drop south, drier and and subsidence should help
dry things out Thursday afternoon and night.
Thursday night/Friday morning, high pressure quickly drops south as
another shortwave tracks southeast across the region, bringing a
cold front into western parts of Upper Michigan. This will bring
back chances for showers and thunderstorms out west Friday morning.
As the front continues to push east across the Upper Peninsula, the
rest of the area will a chance for showers and thunderstorms
Friday/Friday night. Based on the NAM and GFS, with around 30-40
knots of deep-layer shear and an axis of MUCAPE between 1000-2000
J/kg we could see a few strong to severe storms along the cold
front. Forecast soundings do show ample dry mid-level air in place
with a skinny CAPE profile, so coverage may end up being more
scattered in nature, especially given the subtle nature of the
shortwave. Therefore, not expecting any widespread impacts at this
time.
The upcoming weekend looks nice as another area of high pressure
drops south across the area. Will need to keep an eye on how smoke
may evolve across the area with active wildfires to our northwest in
Canada. However, temperatures should warm a couple degrees above-
normal with a gradual warming trend into early next week. By early
next week, models are in fairly good agreement with surface high
pressure sliding well southeast of the region, placing us back under
warm/humid moisture return. With this moisture return, depending on
when we see additional shortwave/fronts move across the area we
certainly look like we will be getting back into an active weather
pattern. Right now there is quite a bit of uncertainty as to when
the better chance for precipitation will arrive. Given the
uncertainly, didn`t make any changes to the PoPs that far out, but
they certainly could be overdone at times early in the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 747 PM EDT TUE JUL 9 2019
Showers with perhaps some rumbles of thunder will eventually make
their way into the KIWD and KCMX areas, but them making it to KSAW
overnight is highly questionable. However, storms tomorrow
afternoon are expected to reignite, which may very well impact all
three terminals. As that time inches closer, look for refined
details in timing in subsequent TAF issuances. VFR conditions
should otherwise predominately prevail.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 242 PM EDT TUE JUL 9 2019
Winds will remain between 10 and 20 knots, with the strongest winds
expected over the eastern half of Lake Superior this evening through
tonight. As a cold front passes over the lake tomorrow, winds will
become light from west to east throughout the day. As this front
passes through, thunderstorms are possible along with the
development of fog as humidity levels increase, and especially so if
heavier precipitation develops. Behind the front, winds will become
westerly late in the day Wednesday, and then northwesterly overnight
into Thursday. As winds become northwesterly, expect speeds to
increase to between 20 and 25 knots. Not out of the question that a
few higher platforms over the eastern half of the lake could gusts
closer to 30 knots due to the elevated wind just off the surface.
However, based on the stability of thermal profiles, confidence is
low that these winds will reach the lake`s surface. Winds will then
relax for the end of the week/weekend, with speeds expected to
remain below 20 knots.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...KCW
LONG TERM...Ritzman
AVIATION...lg
MARINE...Ritzman