Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/20/24
Area Forecast Discussion
National Weather Service Binghamton NY
1136 PM EDT Wed Jun 19 2024
.SYNOPSIS...
Hot and humid conditions with scattered afternoon and evening
thunderstorms are expected through the entire week. A break in
the heat may not come until after the weekend into early next week.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
1130 PM Update:
Strong to severe thunderstorms have popped up along an apparent
surface boundary extending from SW NY to just north of the
Finger Lakes. Surface analysis suggests this boundary may extend
further east than the current area of convection, north of
Skaneateles and Syracuse to somewhere in northern Oneida County.
The storms have fired up in an area of weaker steering flow, and
have been nearly stationary, staying just barely west of the CWA
boundary so far. SPC mesoanalysis also indicates low level
moisture pooling along the lake plain, roughly coincident with
the boundary.
CAMS not really handling things too well, though a few did
produce some convection further east than reality, and the ones
that did suggest additional storms will fire up along the
boundary near the Thruway in the next hour or two, but otherwise
not move further east. But outflow boundaries from these storms,
too far away to pick up on radar just yet, will propagate east,
and could kick up additional isolated thunderstorms across the
Finger Lakes and areas N and W of BGM overnight.
PoP grids have been increased in the far west, and along the
apparent boundary near the Thruway over the next couple hours.
PoPs tapering off to the east in time considering the
possibility of additional initiation off outflow boundaries as
previously mentioned.
Outflow boundaries from this mess will almost certainly impact
convection initiation later on Thursday.
955 PM Update:
Thunderstorms are now initiating along a convergence zone just
west of our forecast area, across NW PA and SW NY. These storms
are tapping into 2200 J/Kg of MLCAPE, with mid level lapse rates
around 6.5C/Km.DCAPE values are still around 1100 J/kg out in
this region. The CAMs are not handling this convective
initiation well at this time. Forecast grids grids were updated
to show a chance for thunderstorms redeveloping (along outflow)
further east into portions of our CWA; especially Steuben,
Yates and Seneca counties over the next several hours. Main
threat with these slow moving storms will be for isolated
strong, gusty outflow winds and heavy rainfall.
745 PM Update:
Just a few, isolated thunderstorms on the radar early this
evening. The majority of the activity has been across eastern
Delaware and Otsego counties thus far. There is abundant instability
out there, with MLCAPE over 2500 J/kg, and LIs of -8. Effective
layer shear is rather weak around 20 kts over the western
portion of the area. Looking at the latest water vapor and IR
satellite loops, there are no real triggers for added lift to
get organized convection going at this time. The CAMs,
especially the latest 22z HRRR develop some scattered
thunderstorm activity over the next few hours across Central NY.
So far the storms have been unable to push higher reflectivity
cores up above the -20C (~25k ft agl) level...however we will
continue to monitor any storms that can develop very closely
considering the high amounts of instability, and DCAPE values of
1000+ J/KG, which is highly conducive to downbursts and
localized strong winds.
Otherwise, tonight will be another muggy night with lows in the
upper 60s to 70s over the region. Just like last night, downtown
Syracuse may struggle to fall below 80 degrees. Thursday is
another hot and humid day, and heat advisories remain in effect
areawide. Scattered thunderstorms develop in the afternoon and
there is a Slight Risk for severe storms.
230 PM Update:
Isolated convection will continue at times into tonight mainly
extending from the western Finger Lakes to the Upper Mohawk
Valley where lingering boundaries exist amongst better broad
scale lift south of the prevailing westerlies. Diurnal
stabilization should end best chances, but persistent high
dewpoints will still provide fuel for any rogue meso convective
system that rides the ridge later on. Not seeing any indications
of this to be confident, but a primed atmosphere will do what
it wants.
Ridge flattens further on Thursday with stronger westerlies
expected to dip across northern NY. Once again, hot and humid
conditions will prevail, however, confidence is higher that
thunderstorms may be a little more intense and numerous than
the past several days. Strong low level lapse rates will exist
with max CAPE values likely nearing 2500 to 3000 J/kg. With the
stronger flow aloft moving in, 0-6 km bulk shear will increase
to around 20 to 25 knots, which should be enough to support a
better organization of convection than today. Locally damaging
winds will be the main threat. Also, PWATs will again be in the
99th percentile range and short Corfidi vectors of less than 10
knots suggest heavy down pours and back building thunderstorms
will be possible, with a threat for localized flash flooding.
A continuation of warm and muggy conditions at night will
continue Thursday night and with a weak stationary front in the
area, shower and thunderstorm chances will linger into the
evening.
Lows in the 70s and highs in the upper 80s to mid 90s will
persist.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
250 PM Update...
High pressure recedes to the southwest with an upper level ridge
resting over our region. Along this ridge a few disturbances move
through with a weak stalled frontal system. This leads to the
possibility for showers and thunderstorms to develop especially
during peak heating hours. Although models are trending drier
Friday morning, so pulled back on pops. Instability parameters
show CAPE values up to 1,700 J/Kg with marginal wind shear. This
suggests strong to severe storms are possible with isolated
damaging wind being the primary threat. However, any slower-
moving storms can produce heavy rainfall with PWAT values
anywhere from 1.5 to nearly 2.0 inches across the area.
Placement of the frontal system, cloud cover and shower
development will lead to a challenging temperature forecast for
Friday. Highs are expected to range in the mid 80s to lower 90s
in northeast PA and the Southern Tier of NY. Lows will follow
this same pattern with overnight temperatures ranging in the mid
60s to low 70s across the area.
Quasi-stationary front lingers over the region on Saturday before
lifting Saturday night. This allows additional showers and
thunderstorms to develop especially during peak heating hours.
Depending on the timing of when the front lifts will impact the
temperature forecast. As of now temperatures are forecasted to range
higher in the mid to upper 80s west of I-81, with highs ranging
in the low to mid 80s east.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
250 PM Update...
Upper level ridge begins to break down on Sunday as an upper level
trough starts to nudge into the region along with a surface cold
front. This brings potential for additional showers and
thunderstorms to develop ahead of the system as moisture gets
advected into our region. There is uncertainty in the timing of
the frontal passage, it appears to move through Sunday night
into Monday morning. Regardless cooler air will begin to filter
in early next week providing relief to the region. Upper trough
slowly tracks east Monday allowing another opportunity for
shower and thunderstorms to develop under this pattern. Brief
ridge along with surface high pressure builds in on Tuesday with
dry conditions anticipated at this time. Models begin to diverge
towards the end of the period, but another system could creep in
by Wednesday.
&&
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
Thunderstorms have been struggling to get going this afternoon
but given the heat ahd humidity, there is still plenty of
energy to develop thunderstorms this evening and tonight.
Anything that does form, will be isolated so left thunder out of
the TAFs for now. ELM did have dew points drop lower this
afternoon than yesterday so unless there is rain to fall before
midnight, it will be harder to get fog formation.
Tomorrow is looking a little better for thunderstorms in the
afternoon and evening but once again the storms that form will
be more scattered rather than numerous so confidence in their
locations is too low to add to the TAFs after 18Z tomorrow.
Outlook...
Thursday night through Monday...Spotty restrictions possible in
showers and thunderstorms.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Heat Advisory until 8 PM EDT Thursday for PAZ038>040-043-044-
047-048-072.
NY...Heat Advisory until 8 PM EDT Thursday for NYZ009-015>018-
022>025-036-037-044>046-055>057-062.
Air Quality Alert from 11 AM to 11 PM EDT Thursday for NYZ062.
&&
$$
SYNOPSIS...JAB
NEAR TERM...JAB/MJM/MPH
SHORT TERM...ES
LONG TERM...ES
AVIATION...AJG/JAB/MPK
Area Forecast Discussion
National Weather Service Billings MT
630 PM MDT Wed Jun 19 2024
.UPDATE...
Satellite imagery shows broad troffing/cyclonic flow over the
northern Rockies, but heights continue to slowly rise. Weak
diurnal convection developed over our western mountains/foothills
but this activity is already waning (though a cell just popped up
recently near Red Lodge). The more interesting area is our
southeast, where showers and some embedded thunder have developed
from near Devils Tower to southern Powder River and Carter
Counties. This is a region of low level jet forcing/moisture
advection underneath RRQ of 90kt H3 jet lifting thru eastern MT.
Instability is quite modest and thunderstorms will be weak, but
places from Broadus to Baker eastward can expect scattered showers
thru the remainder of the evening. Have raised evening pops a bit
in this area. There could be a risk of fog in far southeast MT
late tonight, especially w/ a little precip, but the HRRR suggests
the better fog potential is closer to the Black Hills. With
persistent SE winds this could lead to advection of low stratus
(or fog) by late tonight...but this is of low confidence at this
time. Otherwise, the remainder of the forecast area will be dry
with low temps mostly in the 40s (milder than last night but still
cooler than normal). JKL
&&
.DISCUSSION...
Rest of Today through Thursday Night...
A longwave trough across the NW CONUS was evident on satellite
imagery today with indication of a jet streak in the southwest
flow over Wyoming. This was helping to produce some weak
convection over the SE corner of Montana which was drifting
northward. Isolated showers/thunder was also noted across central
Montana clipping the Belts and Snowies.
Most of this weak convective activity should die off after sunset,
but we could have some showers linger in the far eastern zones
thanks to a developing low level jet overnight. No significant
impacts are expected. Lows overnight will be much milder than
last night, with readings from near 40 west to upper 40s east.
For Thursday...a bit more cloudy with an increasing chance of
showers and thunderstorms in the afternoon and into the evening
(15-40%). Better instability and shear may allow for a few
stronger storms, though there is no severe risk at this time. This
activity could linger through Thursday night thanks to available
jet dynamics and WAA in mid level. High temperatures Thursday
will range in the 70s to lower 80s, but increased dewpoints will
make it feel notably more humid. BT
Friday through Wednesday...
Friday afternoon and evening have a decent probability of strong
to severe storms as an upper trough moves into the region. Trough
will push a cold front through the area late in the day into the
evening. Low-level ESE flow from the Gulf of Mexico will push
PWAT`s to 1-1.25 inches over the E half of the area. SREF showed
MLCAPEs of 500-1000 J/kg with Bulk Effective Shear of 40-50 kt.
NBM CWASPs were in the 60s. There is a 30-50% chance of showers
with isolated thunderstorms in the morning, which could hinder
strong thunderstorm chances later in the day. Will need to watch
how this period unfolds with time. There is a 40-60% chance of
showers and thunderstorms Fri. afternoon and evening. Highs on
Fri. will be in the 70s to lower 80s.
Dry weather will then move in through Sunday, as a strong ridge
builds into the region. Temps will be in the 80s on Saturday, and
in the 90s to around 100 degrees on Sunday. Probabilities were not
very high for hitting 100 degrees. Billings had the highest
chance at 11%. WSW flow will be over the region on Monday with a
20% chance of a shower or thunderstorm E of KBIL Mon. evening.
Highs will reach the low 90s on Monday. Tuesday and Wednesday had
more uncertainty in the Clusters, with solutions ranging from
upper ridging to troughing. There will be low chances of
precipitation on Wednesday. Highs were forecast in the 80s both
days. Arthur
&&
.AVIATION...
VFR conditions will prevail through tonight with light and
variable winds. Isolated showers/thunder is expected over the
eastern half of the forecast area including the
KSHR/KMLS/KBHK/K4BQ terminals. Local MVFR conditions can be
expected with the thunderstorms. Weak convection may linger
overnight south of KEKA and K4BQ. BT
&&
.PRELIMINARY POINT TEMP/POPS...
Thu Fri Sat Sun Mon Tue Wed
-----------------------------------------------------------
BIL 047/078 056/080 058/084 060/097 062/091 058/087 059/085
00/U 24/T 41/U 00/U 11/U 11/U 12/T
LVM 039/076 048/081 052/086 054/095 056/090 052/087 052/082
11/U 14/T 30/U 01/N 11/N 11/U 12/T
HDN 045/081 056/083 056/086 057/099 060/093 057/089 057/086
01/B 36/T 51/U 00/U 11/U 10/U 21/U
MLS 049/079 057/080 057/082 058/095 063/090 059/087 060/084
11/B 26/T 61/B 00/U 20/U 21/U 32/W
4BQ 048/079 057/079 058/084 059/097 064/092 060/089 061/085
31/B 36/T 51/U 00/U 10/U 20/U 21/U
BHK 048/075 053/074 055/081 052/090 061/089 055/086 057/083
21/B 25/T 62/W 00/U 10/U 21/U 32/T
SHR 044/079 051/081 053/084 056/096 061/093 056/088 056/086
11/B 46/T 41/U 00/U 10/U 10/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Cheyenne WY
241 PM MDT Wed Jun 19 2024
.KEY MESSAGES...
- Southeasterly upslope winds expected this evening that could
lead to widespread low clouds and fog in the Nebraska
Panhandle to the east slopes of the Laramie Range to include
Cheyenne.
- Warmer temperatures and more widespread shower and
thunderstorm activity with the potential for severe storms
will return on Thursday. This may continue on Friday.
- Hot and mostly dry weather will occur this weekend into early
next week with low chances (10-20%) for showers and storms and
afternoon highs likely (>85%) above 90F degrees east of the
Laramie Range.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 241 PM MDT Wed Jun 19 2024
Inverted surface trough lays across northwestern
Colorado...north into eastern Carbon County this afternoon. This
has created a fairly tight...reverse Craig to Casper 850/700mb
height gradient. 18Z Craig to Casper 850/700mb height gradients
at -18/-3 mtrs that increase to -31/-5 mtrs at 00Z this
afternoon. Pretty rare reverse gradient winds up to 55 mph have
been reported in the Laramie Valley and over the Summit. Even
Bordeaux reporting southeast wind gusts to 45 mph. Definitely
something we don`t see very often here. Southeast winds also
pulling higher dewpoints north with low 50s in northeast
COlorado and upper 50s/low 60s in east central Colorado and
western Kansas. We have had a persistent cloud deck over the
southeast WYoming plains through the day today...which has
limited temperature rises. Currently 63 here at Cheyenne...with
low 70s out across Carbon County.
With lack of surface heating today...not expecting much in the
way of thunderstorm development across the CWA. HRRR/RAP
simulated radar do show some light QPF over the Panhandle this
evening. So did continue some low chance PoPs (30-40%) chances
for the Panhandle this evening. Perhaps of more significance is
the increased low level moisture as GFS 850 humidity increases
to 90 percent across the southern Panhandle by 00Z and upper 90
percent into the southeast WYoming plains at 03Z. Looks like a
pretty widespread stratus event for tonight and possibly
widespread fog overnight. Did add areas of fog into the forecast
for this evening and overnight. Forecast soundings support
widespread stratus and fog tonight at Cheyenne and the
Panhandle...so evening shift may need to go more widespread than
what is currently in the weather grids.
Thursday is looking good for thunderstorms with the increased
low level moisture across the area. Upper shortwave moves
through Thursday afternoon. Ample 0-6km shear with southeasterly
low level winds and upper westerly winds of 50-60kts. NAM MUCAPE
of 2500 to 3000 J/KG with similar instability on GFS soundings. HRRR
simulated radar going very aggressive on thunderstorm
development Thursday afternoon. For now...SPC has a Marginal
Risk identified for southeast Wyoming and Nebraska Panhandle.
But would not be surprised if they upgrade that of near future
updates.
Friday looks similar to Thursday as low level moisture will
still be in place. Dewpoints in the Panhandle still up in the
low to mid 60s Friday afternoon with next upper shortwave
tracking across the CWA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Issued at 241 PM MDT Wed Jun 19 2024
A very warm weekend and start of the week is expected for southeast
Wyoming and western Nebraska. Saturday looks to be the coolest day
at this time as an upper-level trough slowly traverses east out of
the region and ridging begins to build in behind it. As the ridge
builds, it will slowly move to the east, with the ridge axis over
the region by Sunday afternoon. The GFS and ECMWF have some slight
differences in the strength of the 250mb ridge, with the ECMWF
suggesting a stronger ridge than the GFS at this time. However, at
500mb, the GFS and ECMWF are nearly identical for the exact strength
of the ridge at this level. The ridge will remain firmly in place
across the region from Sunday, with another ridge building across
the southwestern CONUS as the first ridge begins to track easterly.
Therefore, a very warm week is expected for much of the region.
700mb temperatures soar into the 15 to 20C range by Monday evening,
with corresponding surface temperatures well into the 90s east of
the Laramie Range, with many 100s possible across western Nebraska.
Mid- to upper-80s are likely west of the Laramie Range during the
weekend and into the start of the work week.
Despite the stout ridge overhead, several 500mb shortwaves will
traverse through the ridge and lead to daily shower and thunderstorm
chances across the region. With these passing shortwaves, the
temperature forecast is somewhat less confident as the shortwave
could knock a few degrees off the current forecast temperatures.
Additionally, any cloud cover produced by these shortwaves will
further act to reduce the surface temperatures. Overnight lows will
be rather warm across the region under the influence of the upper-
level ridge, with overnight lows consistently in the 50s and 60s
across the region. Luckily, dewpoint values will remain near average
for this time of year, so the hot temperatures will not any more
unpleasant from a surplus of moisture. Overall, a warm and mostly
dry long term forecast is expected. Any showers and thunderstorms
that develop throughout the week will likely be isolated to
scattered in nature, leading to some locations receiving
significantly more precipitation than others.
&&
.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1115 AM MDT Wed Jun 19 2024
Concern for the 18Z TAFs will be widespread low clouds and fog
as we continue under southeast upslope flow through Thursday.
Continued trend towards lowering flight conditions for airports
east of the Laramie Range. Latest HRRR and LAMP guidance hitting
these airports pretty hard with LIFR to VLIFR conditions. WOrst
airport may be KCYS where we could see dense fog developing
tonight. Will continue to monitor and revise timing as we get
closer to the event. But right now...looking for lowering
conditions around the 03Z timeframe.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...GCC
LONG TERM...AM
AVIATION...GCC
Area Forecast Discussion
National Weather Service Grand Junction CO
534 PM MDT Wed Jun 19 2024
.KEY MESSAGES...
- Scattered to widespread showers and storms are expected
tomorrow and Friday. Significant moisture supports the
potential for heavy rain during this period.
- Conditions dry out for this weekend, but there is still a
chance for afternoon storms daily going into next week.
&&
.SHORT TERM /THROUGH THURSDAY/...
Issued at 300 PM MDT Wed Jun 19 2024
With the trough and high anchored to the West/East Coasts
respectively, eastern Utah and Western Colorado remain under a dry
southwesterly flow, but the pattern is changing as the high pressure
builds to the west into Texas overnight into Thursday shifting the
flow in the lower levels more southerly pulling tropical moisture
off the Gulf into the region. Dewpoints along the Front Range are
already in the 50`s with dewpoints in the 40`s creeping west into
the mountains. We`re seeing some of that moisture spill over the
Divide that will likely produce some of the first isolated showers
and thunderstorms along the Divide this afternoon and evening.
Overnight the deeper moisture will start moving in from the south
with scattered showers and thunderstorms developing on the southern
face of the San Juans spreading east in tho the Four Corners area
through the morning hours. Some of these storms may become more
organizes with significant CAPE and directional shear across
southeastern Utah and southwestern Colorado to produce larger hail
and strong winds, definitely something to watch.
Moisture continues to pour into the region from the south through
the day becoming numerous through the southern and central areas
with widely scattered showers and thunderstorms spreading north to
Wyoming by evening. Overnight rain becomes more stratified with
embedded showers and isolated thunderstorms across the whole region
bringing wetting rain to much of the area along and south of the I-
70 corridor. The southern face of the San Juan Mountains is an area
of concern with the strong upslope flow bringing over an inch of
precipitation through the overnight period, yet something else to
watch with flooding possible from training/prolonged showers. The
cloud cover tomorrow will limit diurnal heating through the
afternoon, but H500 heights increase as the high pressure builds in
from the east to warm us five degrees over today.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 300 PM MDT Wed Jun 19 2024
Deep Gulf moisture will already be in place by Friday morning with
forcing from embedded shortwaves allowing convection to continue
through the morning hours. Friday looks to be a very active day as
moisture rises even further by Friday afternoon with mixing ratios
climbing to between 7 and 9 g/kg. PWAT is also upwards of 200 to 300
percent of normal on average with some pockets near the Four Corners
up to almost 400 percent of normal. Dewpoints are projected to be
well into the 50s across much of the area with dews near 60 across
the Four Corners. Basically, this all means we will have significant
deep moisture advection for efficient heavy rain potential with any
showers and storms that form. CAPE values rise up to 1000 J/kg or
more, so plenty of instability exists for strong storms to form. The
real question though which would limit how much of this instability
we can tap into is the amount of cloud cover and precipitation
lasting through Friday morning. This could limit the convective
potential due to lack of surface heating from the sun to act on the
instability. Regardless, the potential is there for heavy rainfall
and this is typically the type of moisture we would see during late
July. Gusty outflow winds are also possible upwards of 50 mph or
more but how strong these are all depends on how much instability is
left and if we can get any breaks in the cloud cover and surface
heating to help aid stronger convection. If it`s any consolation,
the latest hi-res CAMs including both the NAMNest and HRRR indicate
convection rumbling through western Colorado Friday morning with
enough of a break late Friday morning before storms fire in earnest
early to late Friday afternoon with the best period ahead of and
along the cold front associated with the shortwave trough passage
heading into Friday evening. We could see some stronger storms
during this period, with the idea that we`d see enough breaks in the
cloud cover late Friday morning into early afternoon to get some
surface heating from the sun. WPC has much of eastern Utah and
western Colorado practically along and south of I-70 included in the
slight risk category for excessive rainfall, which makes perfect
sense given the environment.
Drier air pushes in from the west after the passage of this robust
shortwave trough Friday night that will drive much of this deep Gulf
moisture eastward, leading to a drier day on Saturday and more so on
Sunday. However, enough moisture looks to linger behind with a
little bit of forcing from embedded shortwaves moving across the
north to produce some isolated to scattered storms favoring the high
terrain. Dew points are still a bit elevated also, so this is
something to watch as models might be too quick to dry things out,
which would result in more storm coverage. This seems more of a
thing Saturday rather than Sunday though as dew points come down
quite a bit by Sunday into Monday. High pressure builds back in
across the south with westerly flow remaining overhead this weekend
into early next week, before the ridge axis tries to nudge slightly
eastward by middle of next week. Models are struggling with how to
handle this but the general trend for the coming week is a return to
hot and dry conditions. Temperatures Friday into Saturday though
will be much cooler though, especially Friday given the abundant
moisture and resultant clouds and showers/storms with highs about 5
degrees below normal through Saturday. Highs jump to 4 to 8 degrees
above normal Sunday into the coming week.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 526 PM MDT Wed Jun 19 2024
A few showers and storms have formed along the northern
Continental Divide with a few lightning strikes also noted.
Scattered to broken skies are common across much of CO and SE UT
but ceilings are between 12 to 15K feet so VFR conditions
remain in place. These clouds should lift somewhat overnight
though KTEX will likely keep some broken skies. Some showers may
develop over the San Juans as moisture continues to increase.
Slight chance for some showers for KTEX but not confident to
include in TAFs yet. Conditions will start to deteroriate
around 17 to 18Z tomorrow as convection starts firing across
much of the CWA.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...DB
LONG TERM...MDA
AVIATION...TGJT
Area Forecast Discussion
National Weather Service Goodland KS
724 PM MDT Wed Jun 19 2024
.KEY MESSAGES...
- Chances for showers/thunderstorms continues overnight, mainly
across the northwest 1/2 of the area.
- Patchy dense fog is also possible across the area overnight.
- Dry and warmer Thursday.
- Hot with highs in the 90s Friday through Sunday then 90s to
low 100s Monday through Wednesday.
- Dangerous heat index values of 100 to 106 degrees east of
Highway 25 Monday and Tuesday.
&&
.UPDATE...
Issued at 710 PM MDT Wed Jun 19 2024
Moisture advection is ongoing as SE winds will continue to
stream moist air into the area. Guidance over the past several
runs shows fog development mainly along and south of I-70
starting mid evening and continuing through at least mid
morning. HRRR is the most aggressive with the fog showing a
fairly large area seeing dense fog; I`m however a little
skeptical on this as winds will remain around 10-15 mph through
the night so think this will help keep fog from becoming to
thick. For this reason, I am foregoing any fog highlights at
this time. There continues to be 20-50% chance of showers and
perhaps isolated storms moving across the area with isentropic
lift being the main factor. The best chance for seeing any
rainfall will be along and north of I-70, where a tenth or two
of measurable precipitation looks to occur.
As winds become more more southerly throughout the day tomorrow
some smoke from a large wildfire west of Roswell, New Mexico
may look to move across western portions of Yuma, Kit Carson and
Cheyenne counties in Colorado. Have not introduced haze into
the forecast at this time as would like to see some run to run
consistency but have increased sky coverage a bit to account for
this. At this time any smoke looks to remain elevated just
creating a haze in the sky.
&&
.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 130 PM MDT Wed Jun 19 2024
Tonight...latest model guidance in general agreement that the
combination of 850-500mb relative humidity and higher pops should
remain focused along and west of Highway 27 through midnight before
continuing to the northwest while weakening. Given the very poor
performance of much of the guidance the past 24 hours, I`m rather
pessimistic in the precipitation forecast. Low temperatures are
forecast to be in the middle 50s to middle 60s. Cant rule out some
fog in spots and next shift may need to update the forecast based on
latest data.
Thursday-Thursday night...drier air in the 850-500mb layer quickly
overtakes the area by mid to late morning, ending any precipitation
chances. Southerly winds strengthen during the day with gusts of 30
to 40 mph, highest west of Highway 25. Breezy winds continue
overnight, mainly west of Highway 27. High temperatures warm back up
into the 85 to 90 degree range with low temperatures in the
60s.
Friday-Friday night...a monsoonal type pattern sets up with an upper
trough to our west and ridge centered over the southeast states.
Unfortunately, moisture from Mexico is skirted to the south of the
area. There is a bit of moisture in the 700-500mb layer that moves
off the Colorado front range and into the northwest 1/4 of the
forecast area during the afternoon and evening, supporting 20%-30%
chances for showers and thunderstorms. High temperatures are
forecast to be in the upper 80s to middle 90s with low temperatures
in the lower 60s to middle 70s. It will continue to be windy with
southerly winds gusting to 40 mph during the day, slowly decreasing
overnight.
Saturday-Saturday night...500mb flow shifts from southwest flow
aloft to zonal with troughing to our north and an elongated ridge to
our south. Presently, dry weather is forecast. There could be a
few thunderstorms flirting with the northwest and western
corner of the forecast area in the afternoon/evening. High
temperatures are forecast to be in the middle 80s to middle 90s
with low temperatures in the 60s.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 1237 PM MDT Wed Jun 19 2024
The area will be under west-northwesterly flow aloft as a ridge axis
crosses the Rockies at the close of the weekend with high pressure
centered over the southern CONUS. Low pressure moving across
Alberta/Saskatchewan/Manitoba will work to (briefly) flatten the
ridge, promoting more of a zonal flow, and shortwaves moving through
will keep slight chance afternoon-evening PoPs, generally around 15-
20%. Towards the latter part of the long term period, ridging again
amplifies upstream as an upper low meanders along the coast of
British Columbia and the Pacific Northwest.
For temperatures, the warming trend continues with low-mid 90s
Sunday followed by return of near-triple digit to triple digit heat
by the start of the work week. Low temperatures are forecast to be
in the 60s to low 70s.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 502 PM MDT Wed Jun 19 2024
MVFR ceilings are currently ongoing at KGLD along with near
MVFR ceilings at KMCK. Soundings and nearly all guidance
strongly suggest that ceilings will continue to decrease
through the period with IFR to LIFR stratus becoming the main
aviation concern through mid morning. Guidance also does show
some patchy dense fog south of the Interstate; it is possible
that it may impact the KGLD terminal but should be transient in
nature and short lived so have included VCFG for the period
where this is currently favored. More hit and miss showers may
occur overnight so will continue the VCSH. VFR conditions look
to return mid morning as drier air moves into the area again;
however wind gusts of 30-35 knots look likely during the day
Thursday.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
UPDATE...Trigg
SHORT TERM...99
LONG TERM...CC
AVIATION...Trigg
Area Forecast Discussion
National Weather Service Grand Rapids MI
1024 PM EDT Wed Jun 19 2024
.KEY MESSAGES...
- Temps not as Hot Thursday north
- Risk for Strong/Svr Storms this evening
- Very warm and windy Saturday
- Thunderstorms Friday through Sunday, especially Saturday night
- Dry and somewhat more comfortable Sunday through Tuesday
&&
.UPDATE...
Issued at 1013 PM EDT Wed Jun 19 2024
Scattered convection continues overnight. Isolated storms have
moved northward towards the I 94 corridor. While the hot and
humid air mass over SW Michigan provided enough instability for
storms earlier this evening, they were stifled due to the
divergent pattern and weak shear. There is a boundary that extends
from Big Rapids to the southwest that has a persistent line of
showers. There were some storms along this boundary over mid Lake
Michigan. However, not expecting for these showers to intensify,
especially since there is weak shear, it is nighttime and the -10C
is at 20K feet.
&&
.DISCUSSION...
Issued at 303 PM EDT Wed Jun 19 2024
- Temps not as Hot starting Thursday north
Heat index values are well into the 90s at this time so we made
no changes to the headline through the remainder of today.
However, looking at Thursday, there has been a trend for a
southward shift of the axis of hottest air then. This supports
dropping the Heat Advisory for Thursday for the region north of a
line from Ottawa County to Ingham County. We already issued the
NPW reflecting this change. If this southward trend continues,
further changes may be needed the headline area.
- Risk for Strong/Svr Storms this evening
DCAPE around the area is favorable for gusty winds with any
stronger storms. ML CAPE values are over 1000 J/kg so decent
instability is in place. Effective bulk shear values have dropped
off and are under 25 knots. So far the low level convergence has
been very weak, but there are some indications that it may
increase somewhat near and southeast of a Kalamazoo to Lansing
line. If convection can develop in that region, we will be
monitoring it for possible strong wind gusts and locally heavy
rain. It`s worth noting that the main PWAT axis is shifting east
of the CWA so that dry air advection may limit the overall
convective coverage. The latest HRRR only has a few isolated cells
over the next few hours, but it does suggest some outflows from
any cells that do develop.
- Very warm and windy Saturday
Highs Saturday could vary substantially from northwest to southeast,
ranging from around 80 near Ludington to mid/upper 90s near Jackson.
Winds from the southwest Saturday afternoon will be quite strong;
although the official forecasts indicate gusts in the 20-30 MPH
range, expect model trends to bump this closer to the 30-40 MPH
range based on some of the more recent guidance. Mixing should be
substantial. A broadening spread of dewpoint forecasts among the
ensemble members hints at the mixing process and also suggests
uncertainty about how much drying will occur. The effects of heat
additionally may be curtailed by the development of thunderstorms in
the afternoon/event (see following section).
- Thunderstorms Friday through Sunday, especially Saturday night
As noted in the previous discussion, we will have a surface boundary
providing a source of weak low level convergence. Very flat ridging
aloft will offer episodic opportunities for minor PV maxima to zip
across the region and allow storms to fire and then cluster into
MCSs. Timing details are uncertain but activity will generally be
guided by the diurnal convective instability cycle.
Timing for the main round of thunderstorms looks increasingly locked
into Saturday night. A deeply mixed boundary layer ahead of this
activity will elevate the chances for damaging winds as this
activity moves through. Additionally, the upper shortwave trough
looks sharper and farther south than before. Hence, QC forcing could
be more substantial than previously thought. These ingredients point
to growing severe potential for this timeframe.
- Dry and somewhat more comfortable Sunday through Tuesday
As noted before, confidence is good for a dry Monday given sharp
shortwave ridging aloft behind the aforementioned trough. PoPs
return Tuesday night into Wednesday along with unseasonably warm
temperatures. Predictability for temperatures should be fairly good,
but advertised PoPs probably can be better attributed to climatology
rather than forecast certainty.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 717 PM EDT Wed Jun 19 2024
Scattered/isolated thunderstorms were over parts of Southwest
Lower MI to start the period. They will approach several TAF sites
early this evening with KJXN and KBTL appearing to have the
highest probability to seeing a storm. It will remain unstable
through the evening so close monitoring will be needed given the
random development. A cold front will be dropping down from the
north bringing a wind shift. Moisture will be abundant along this
frontal zone. This front will dissipate over the area tomorrow and
could serve as a source for new storm development, especially
after 18z. Low clouds and some fog may impact the TAF sites later
tonight into Thursday morning but I was not confident enough to go
widespread IFR as some models suggest may happen. For now most
sites will feature a period of MVFR conditions.
&&
.MARINE...
Issued at 303 PM EDT Wed Jun 19 2024
Based on the lowering winds and waves, we cancelled the beach
hazards and small craft advisory a little early. Saturday it
looking like the next big wind/wave event.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Air Quality Alert until midnight EDT tonight for MIZ050-056-057-
064-071.
Heat Advisory until 8 PM EDT Friday for MIZ056-057-064>067-
071>074.
MARINE...None.
&&
$$
UPDATE...Ceru
DISCUSSION...MJS/TJT
AVIATION...MJS
MARINE...MJS
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
803 PM EDT Wed Jun 19 2024
.SYNOPSIS...
High pressure will remain east of New England through much of
this week, continuing our period of hot and humid conditions
through Thursday. Record high temperatures and potentially
dangerous heat index values are likely. A cold front will
slowly cross through the region on Thursday and Friday with an
increasing chance for scattered strong thunderstorms and cooler
temperatures starting on Friday.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Update 8 PM...Update this evening to trim back on pops as
thunderstorm activity from the extreme heat today has come to an
end. Also expired the heat headlines for today, before they come
in effect again tomorrow as we will have one more hot day.
Overall guidance continues to hint at early heat, before
convection develops once again towards mid-afternoon. Expecting
severe weather threat once again with damaging winds being the
biggest threat.
Showers and thunderstorms, a few severe, will continue into the
early evening hours per latest radar trends and latest NamNest
solution. HRRR continues to have an issue deriving the
convection today. This precipitation will diminish by around
sunset as the atmosphere gradually stabilizes.
Excessive heat today will lead towards another very warm night
tonight. Last night, lows were in the lower to mid 70s in many
interior areas and this will likely occur again. This sustained
heat leading into tomorrow will allow for increased heat stress
in buildings and areas without proper air conditioning.
Patchy fog can be expected tonight, especially in areas that
received heavy rainfall today. The latest HREF hints at possible
maritime fog along the Midcoast region tonight by late tonight.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
The latest 12Z operational runs and ensemble solutions continue
to suggest a more westerly component to the flow on Thursday.
This may delay the sea breeze along the immediate shoreline
allow for hazy, hot and humid conditions all the way to the
coastline for a longer period than today. In any case, this
large scale upper level ridge that has been leading to the heat will
still be intact. Expect apparent temperatures to reach or
exceed 105 degrees in many areas once again on Thursday.
Surrounding this warning, have issued Heat Advisories for the
period 15Z-23Z.
A front does cross through the region during the afternoon
hours, a little faster than guidance has suggested. However,
temperatures will soar very quickly during the morning hours to
allow for high CAPE values to develop and improved dynamics
along and near the passing cold front. Most of the area remains
in a Marginal Risk and have included strong, gusty winds and
locally very heavy rainfall in the forecast. There will be high
PWATs near 2 inches in a steep low level level lapse rates
leading to the severe weather potential.
Patchy fog once again can be expected Thursday night. Showers
will take a few more hours to diminish than today with a chance
for precipitation throughout the night.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
With ongoing heat headlines and severe weather, the long term
forecast was populated with the NBM, with only minor adjustments
made.
The heat breaks by Friday as a cold front presses southward
Thursday night. Highs are mostly expected to range from the
upper 70s to mid 80s. Showers and storms are likely across as
least southern areas as convection rides along the front.
Periods of showers and storms are likely at times through the
weekend and into early next week as we find ourselves on the
northern side of the ridge. Cooler conditions are expected on
Saturday, but a warming trend resumes on Sunday with temps
warming into the 80s and continuing into early next week. Drier
conditions likely return by midweek next week as highs warm
back into the low 90s.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Short Term...Mainly VFR conditions after the convection
diminishes this evening. However, there will be the potential
for valley fog. Maritime fog is possible along the Midcoast.
More showers and thunderstorms, some with strong gusty winds
and possible hail will return on Thursday afternoon leading to
localized IFR conditions. Scattered showers and thunderstorms
may linger into Thursday night.
Long Term...Periods of showers and storms bring restrictions at
times Friday through Monday, especially in the afternoon hours.
Otherwise, mainly VFR conditions are expected. VFR conditions
likely then prevail next Tuesday and Wednesday.
&&
.MARINE...
Short Term...South to southwesterly winds will continue tonight
into Thursday, just below SCA criteria. Winds back to the west
Thursday night as slightly drier air enters the region.
Long Term...A cold front presses southward through the waters
early Friday, with high pressure gradually building in for the
weekend. SCA conditions are then possible next week as southerly
flow increases as the high moves offshore.
&&
.CLIMATE...
RECORD HIGHS FOR JUNE 20: Concord-98, 1993 Augusta-95, 1953
Portland-93, 2020
RECORD WARM LOWS FOR June 20: Concord-73 in 1931; Augusta-67 in
1974; Portland-69 in 2020
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Heat Advisory from 11 AM to 7 PM EDT Thursday for MEZ012>014.
Excessive Heat Warning from 11 AM to 7 PM EDT Thursday for
MEZ018>028-033.
NH...Heat Advisory from 11 AM to 7 PM EDT Thursday for NHZ002>005-
007-011.
Excessive Heat Warning from 11 AM to 7 PM EDT Thursday for
NHZ006-008>010-012>015.
MARINE...None.
&&
$$
SYNOPSIS...
NEAR TERM...Cannon/Dumont
SHORT TERM...Cannon
LONG TERM...Clair
AVIATION...
MARINE...
CLIMATE...
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
800 PM CDT Wed Jun 19 2024
.KEY MESSAGES...
- Hot and humid conditions will continue across central and
southeast IL for many days. The hottest conditions of the
upcoming 7 days look to be Friday and Saturday when air
temperatures climb into the mid 90s, and heat index values peak
near or just above 100 degrees.
- Isolated thunderstorms will be possible mainly northwest of the
IL river this evening and again Thursday, with a better chance
for thunderstorms arriving Saturday night into Sunday as a cold
front moves through Illinois.
&&
.UPDATE...
Issued at 800 PM CDT Wed Jun 19 2024
Had a few showers form in McLean Co. recently along a weak
convergence zone, and also in northern Knox Co. along a weak cool
front. This will dissipate over the next 1-2 hours with the loss
of diurnal heating. The front will meander southeast near the IL
River overnight, but with no upper support will leave the forecast
dry. Subtle low level convergence will lead to muggy dewpoints
around 70F, and have raised mins a degree or two to a 70-74 range,
highest over the central CWA. Winds to be light and skies mostly
clear tonight.
25
&&
.DISCUSSION...
Issued at 335 PM CDT Wed Jun 19 2024
A frontal zone trailing from Lake Michigan southward to near the
OK/TX panhandle area is beginning to develop some thunderstorms in
the section near the Mississippi River, as well as a growing
cluster in north-central MO. This activity should creep eastward
late this afternoon and evening and promote at least isolated
storms into the Illinois River Valley. The latest HRRR model run
focuses activity just west of the Illinois River well into the
evening, while other available high resolution models keep
activity primarily west of the ILX forecast area. Have opted to
extend PoPs farther east and later into the evening than previous
forecast with this HRRR run, although kept at slight chance/20
percent. With effective bulk shear exceeding 30 kts in a corridor
around the Mississippi River, SPC has continued a Marginal Risk
for severe thunderstorms containing damaging wind gusts that
extends into parts of Knox County.
Another disturbance looks to track along the stalled front
Thursday, promoting additional thunderstorm chances.
High pressure and dry conditions look to prevail Friday into
Saturday, then an upper level wave looks to drive the frontal zone
through central IL over the weekend promoting more widespread and
perhaps stronger thunderstorm activity, although at present,
timing looks to be unfavorable for severe storms, arriving late at
night. At this point, have 30 to 70 PoPs with this feature,
highest NW of the Illinois River.
Temperatures should be quite hot through Saturday, as the warm
pre-frontal air mass dominates, and dewpoints around 70 are
forecast. Expect highs in the low to mid 90s, peaking Saturday.
Heat index should be well into the 90s, if not exceeding 100
Friday and Saturday. A bit of a respite is forecast for Sunday and
Monday with temperatures maxing out around 90, then more hot
weather is forecast again starting Tuesday.
37
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 601 PM CDT Wed Jun 19 2024
Diurnal cu and a couple isolated showers will dissipate this
evening, leaving mostly clear skies and light southeast winds
overnight. Winds to veer southwest after sunrise near/under 10 kt
through 00z. Diurnal cu will again be prevalent on Thursday, with
a few isolated showers/storms around, but coverage way to low to
mention in TAFs.
25
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service North Platte NE
655 PM CDT Wed Jun 19 2024
.KEY MESSAGES...
- Abundant moisture will invade wrn/ncntl Nebraska tonight and
remain across the region through Friday night. Weather
conditions will support heavy thunderstorms which could become
severe in some areas Thursday and Friday. SPC suggested an
isolated severe weather risk both days.
&&
.SHORT TERM /THROUGH THURSDAY/...
Issued at 330 PM CDT Wed Jun 19 2024
A few things supporting locally heavy rainfall tonight are 850-700mb
moisture and theta e transport into the Sandhills is strong. In
fact, PWAT will double in about 18 hours, between 12z this morning
and 06z tonight reaching values of 1.50 inches. BUFkit also suggests
warm precip processes will be significant operating to around
11Kft. The focus is a warm front predicted to lift into wrn Nebraska
and be located near or south of the SD border by Thursday morning.
It is worth noting, winds aloft will be fairly strong and wrn
Nebraska will be positioned in the RR quad of a southwest to
northeast oriented 300mb Jet. This should present a negative force
on the northward moving warm front. The result is the potential for
back-building storm development which would also produce cool
outflow impeding the northward motion of the warm front.
The modest low level jet tonight, around 30kts, will veer off toward
morning and the RAP model shows a 700mb dry intrusion which will
cutoff the deep convection. Still light to moderate rain could still
occur below the dry air at h700mb.
The POP forecast leans on the HREF which is a blend of models
favoring the Sandhills and ncntl Nebraska for an inch or more
rainfall tonight. The HREF probability for an inch or more rainfall
is 60 percent or higher from Grant to KOGA to KTIF to Rose by 12z
Thursday morning.
The next heavy rain chance should develop Thursday afternoon across
nwrn Nebraska where the front will be hung up. The dynamics look a
bit strong as a closed h850mb low should from circulating from sern
WY northeast to near Gordon by 12z Friday morning. The HREF probs
for 1 inch of rainfall increase to 90 percent from Ellsworth Neb. to
Martin SD. Thus, to focus appears to be strong with an inverted trof
setting up across far wrn Nebraska.
This set-up will be favorable for at least isolated strong or severe
storms late in the afternoon and in the evening. A fairly strong
"hot prod" of warm air advection will be directed due north through
ern Colo and the srn Panhandle, aimed at the stationary front to the
north according to the RAP. A narrow belt of 2500-3000 J/KG MLCAPE
should be located just south of the cold front and deep layer shear
near 50kts would support severe storms.
The CAMs are mixed in the location of the storms, all of which
suggest at least isolated HP storm development, vary considerably
with the direction of storm development. Some track the storms
northeast into SD while others more easterly through the Sandhills.
The HREF is tracking the storms more northeast, consistent with the
upper level flow. It`s worth noting some CAMs show merging storm
activity resulting in 1 hour storm totals of 2 inches or more.
Our forecast Thursday night is similar to the WPC QPF favoring
northwest Nebraska for the best rain chances.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 330 PM CDT Wed Jun 19 2024
An active weather situation should continue through Friday evening
followed by a cold front which will stabilize the atmosphere
for a few days. Warmer drier air will follow with a modest heat
wave setting up through Wednesday.
Focus, instability and 30-50k wind at h500-300mb could support
strong to severe storms late Friday. At 60hrs, the NAMnest is
hinting at this with storms firing along a stalled front draped from
Chappell to Springview. A blend of the models places this front, or
focus, farther northwest across northwest Nebraska. The model
consensus suggests severe storms will most likely form along and
north of highway 20. Warm air advection for storm development will
be moving north through ern Colo/far west KS favoring wrn Nebraska
and PWAT will remain near 1.50 inches.
The upper level ridge across the ern U.S. will retrograde west next
week and h700mb temperatures will warm to around 15C presenting a
relatively stable atmosphere. At the same time, sfc low pressure
will form across the nrn Plains and this should set up a modest heat
wave across wrn/ncntl Nebraska. POPs are low next week, isolated to
low-end chance.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 642 PM CDT Wed Jun 19 2024
Rain showers and thunderstorm chances will be possible
throughout the evening and overnight hours, with additional
thunderstorm chances Thursday afternoon into the evening.
Showers and thunderstorms will be mostly scattered this evening,
then should see more widespread rainfall tonight across much of
the forecast area, including terminals KLBF and KVTN. Cigs will
also lower overnight bringing MVFR to IFR conditions, generally
after midnight through the morning hours, with lingering lower
cigs across northern Nebraska through the end of the forecast
period. Winds will be gusty out of the southeast Thursday around
10kts with gust of 15 to 20 kts.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Gomez
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
746 PM CDT Wed Jun 19 2024
.KEY MESSAGES...
- Widely scattered thunderstorms are possible this evening
mainly along and north of a Dixon to Waukegan line which
could produce locally gusty winds.
- Hot and muggy conditions will prevail through the end of the
week, although cooler conditions are expected near Lake
Michigan on Thursday and Friday.
- Periodic chances for thunderstorms will continue, though most
hours will remain dry.
&&
.DISCUSSION...
Issued at 252 PM CDT Wed Jun 19 2024
Through Tonight:
Increasing coverage of cumulus this afternoon combined with
deep mixing has helped keep heat indices mostly in check so far
this afternoon with temperatures in the upper 80s to lower 90s.
Expect a couple more degrees of warming yet this afternoon with
peak heat indices in the 95-100 degree range.
Dry conditions prevail at this hour; however, attempts at
shower/storm development is already underway across portions of
northwest Illinois into south central Wisconsin ahead of an
approaching cold front. Expect this activity to gradually expand
in coverage as it shifts southeastward into the Rockford area
and along the Wisconsin-Illinois stateline. RAP mesoscale
analysis highlights a narrow axis of 1000-1500 J/Kg of MLCAPE
ahead of the front which intersects a region of DCAPE values to
1000 J/kg (inverted V soundings) with slow storm motions and
little shear (~15kts) suggests that any storms that develop
would be rather pulse-like and capable of strong downbursts
resulting in locally gusty winds to 50 mph for areas mainly
along and north of a Dixon to Waukegan, IL line. A very
localized gust to 60 mph can`t be fully ruled out.
Hit and miss isolated storm development still can`t be fully
ruled out south of these areas into Chicago and south of I-80
but this potential remains low with most areas expected to
remain dry. Accordingly will continue capping shower/storm
chances at 20% in these areas.
In the wake of the frontal passage over the lake, expect fog
development over the lake overnight into Thursday morning, this
could ooze inland particularly along the immediate shoreline. It
is possible that it pushes further inland, per the latest RAP,
but confidence in that scenario occurring is not especially high
and will let the evening shift get another look at that
potential.
Petr
Thursday through Wednesday:
A frontal boundary will be meandering across the cwa on Thursday
and will likely be the focus for at least isolated
thunderstorms with perhaps the best coverage along/north of I-80.
With northeast winds off of Lake Michigan, there may also be
enough convergence for isolated thunderstorms in the Metro area
as well. Overall confidence is low and current 30-40% pops
north to 20% south seem reasonable for now. Some of this
activity may linger into Thursday evening, but there should be a
gradual decrease in coverage with most of Thursday night dry.
High temps on Thursday may be back into the lower 90s for most
areas, especially south of the boundary mentioned above. Lowest
confidence for temps is generally from I-88 north and then
across then near the lake. Temps will be coolest near Lake
Michigan, perhaps only in the upper 70s/lower 80s right along
the shore. Where temps do make it to the lower 90s, heat index
values may be in the mid/upper 90s.
Most recent trends in guidance would suggest that Friday into
Friday night may end up mainly dry across the area. If any
precip did develop, probably near the IL/WI state line Friday
afternoon. Lowered pops to just slight chance (20%) on Friday
and removed pops for Friday night. High temps on Friday are
likely to be back in the lower to possibly mid 90s for most
areas, except cooler near Lake Michigan with northeasterly
winds. Heat index values would again be in the mid/upper 90s,
away from the lake.
Winds turn southwest Saturday and increase with gusts possibly
into the 30 mph range, ending any cooling near the lake. High
temps will reach the mid 90s for most locations but with
dewpoints in the mid/upper 60s, heat index values will peak in
the upper 90s to around 100.
Thunderstorm chances will be increasing Saturday afternoon into
Saturday evening as a cold front moves across the area. Best
timing may be after sunset which may limit instability and
coverage. Despite a larger scale feature, guidance still
showing a range of possibilities from the potential for heavy
rain to only scattered coverage. Blended pops are in the likely
range (70%) and this seems fine from this distance, though
duration is likely to only be a few hours at any one location.
Precip also looks to be progressive with perhaps some lingering
showers Sunday morning with most of Sunday likely ending up dry.
Dry weather is then expected through at least Tuesday morning.
By that time the models show another potential chance for
thunderstorms sometime from Tuesday afternoon into Wednesday
morning and while confidence is low, this has been a time period
the models and their ensembles have been highlighting for
potential thunderstorms.
The frontal boundary Saturday night/early Sunday morning will
bring slightly cooler and slightly drier air, but given peak
sun angle and mainly sunny skies, high temps Sunday and Monday
may still reach the upper 80s for most locations. cms
&&
.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 746 PM CDT Wed Jun 19 2024
- ISOLD SHRA in VC of Chicago terminals, with locally
variable/gusty winds, will fade by around sunset
- Wind shift to light northwest, then light northeast expected
tonight
- Northeast winds expected to continue Thursday
- SCT TSRA expected, mainly west of ORD/MDW Thursday afternoon
ISOLD SHRA in VC of the Chicago terminals should dissipate by
around sunset, but in the meantime small scale weak microbursts
will likely lead to splats and variable and gusty winds near the
showers.
Cold front will move across the terminals mid-late evening with
winds becoming light northwesterly for a time, before likely
flopping around to light northeasterly late this evening or
during the overnight. There is some uncertainty on timing of
shift to light northeasterly, it is possible that could be after
06z even.
Once winds settle in from light northeasterly direction, could
see some fog development overnight. Most likely scenario would
be some MVFR VSBY in light fog during the pre-dawn hours
Thursday. If skies clear out and winds go lighter, than some
patches of thicker fog and lower VSBY would be possible,
especially DPA/RFD/GYY.
Weak frontal boundary will be stalled out in the area Thursday
afternoon. Lake should contort the boundary around the south end
of Lake Michigan and may push the more favored area for
afternoon SCTD TSRA south and west of ORD/MDW/GYY. Can`t rule
out SCTD TSRA developing west of ORD/MDW and then being pushed
east closer to the terminals into the cool side of the weak
front. Confidence is low, so opted to keep TSRA out of ORD, MDW,
and GYY for now, but will be something to keep a close eye on.
- Izzi
&&
.CLIMATE...
Issued at 347 AM CDT Wed Jun 19 2024
With a low temperature of 78 degrees, Chicago broke its warmest
low temperature record for June 18th yesterday, while Rockford
tied its daily warmest low temperature record of 74. A few
additional temperature records (namely today`s warmest low
temperature records and Saturday`s high and warmest low
temperature records for Chicago and/or Rockford) may be
threatened over the next few days.
Here are the daily high and warmest low temperature records
for Chicago and Rockford for each day through Saturday, June
22nd:
Chicago
----------------------------------
Day: 6/19 6/20 6/21 6/22
----------------------------------
Record High: 102 104 101 97
Record Warm Low: 78 78 74 76
Rockford
----------------------------------
Day: 6/19 6/20 6/21 6/22
----------------------------------
Record High: 99 101 100 97
Record Warm Low: 76 73 71 73
Ogorek
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...Air Quality Alert until midnight CDT Thursday night for INZ001-
INZ002-INZ010-INZ011.
Air Quality Alert from 1 AM Thursday to 1 AM EDT Friday for
INZ019.
LM...None.
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Area Forecast Discussion
National Weather Service Phoenix AZ
521 PM MST Wed Jun 19 2024
.UPDATE...Updated Aviation Discussion.
&&
.SYNOPSIS...
Another day of quiet weather and near normal temperatures today
before we get our first taste of monsoonal moisture and strong high
pressure building back over the region tomorrow. An Excessive Heat
Warning will be in effect tomorrow for portions of South Central
Arizona. On Thursday afternoon, thunderstorms are expected to
develop along a line east of Phoenix extending south southeast
through central Pinal County and down to Tucson. Strong, gusty
outflow winds are anticipated with the thunderstorms that develop
tomorrow, and with this there will be the potential for blowing dust
in the eastern deserts. Daily chances for mainly mountain and some
isolated lower desert thunderstorms will exist Friday and through
the weekend.
&&
.DISCUSSION...
Troughing still dominates much of the Western US, with 500 mb
heights over the region ranging from 583-587 dam according to RAP
analysis as of late this morning. As a result, temperatures across
the lower deserts will once again hover near normal in the 100-107
degree range this afternoon. However, these quiet conditions and
near normal temperatures will be very short lived. Overnight
tonight, some large-scale flow features are expected to set up in a
way that will allow moisture to surge into southeastern AZ.
A broad area of abundant low-level moisture associated with Tropical
Cyclone Alberto moves westward into central Mexico tonight, high
pressure currently centered over the East-Central US elongates
westward, and a trough digs south along the California Coast. Strong
easterly winds along the northern periphery of the tropical system
will begin to wrap around the anticyclone to the north, move over
southeastern AZ, and are also enhanced by height falls to the west
thanks to the trough along the California coast. ECMWF EFIs
associated with the moist east southeasterly flow tomorrow morning
and Thursday night exceed 0.9, indicating a significant signal.
These strong ESE gradient winds will diminish during the day, but
are expected to pick back up Thursday night. Wind gusts in
Southern Gila County during this time are expected to peak between
40-50 mph (HREF 50th percentile gusts are at or above 40 mph
through much of tomorrow morning and Thursday night.) As a result,
a Wind Advisory has been issued for the populated high terrain
areas of Southern Gila County tomorrow morning through Friday
morning.
Tomorrow afternoon, several weather hazards are expected to impact
South-Central AZ. Localized areas of Excessive heat will develop as
ensemble mean H5 heights increase to around 591 dam along our
eastern CWA. Forecast highs range from 110 to 114 across the Phoenix
Metro Area, and an Excessive Heat Warning will be in effect for much
of Maricopa and Northern Pinal Counties from 10 AM - 8 PM MST. In
addition to the excessive heat, thunderstorms will begin to initiate
during the afternoon along a line connecting Tucson, through central
Pinal County, to just east of Scottsdale. This is because a pseudo
dryline sets up here, as strong, moisture-laden southeast flow
(as discussed previously) meets dry, southwest flow at the mid
levels overhead. A strong gradient in SBCAPE is apparent early
tomorrow afternoon, with HREF mean values peaking in excess of
1000 J/kg to the east of the aforementioned line, and dropping off
to near zero as you travel west towards Buckeye. The main threats
associated with these storms will be gusty outflow winds and the
potential for blowing dust, with HREF probabilities of 35+ mph
winds between 50- 70% and probabilities for 58+ mph winds around
10-30% centered over eastern Pinal County. Steering flow will be
south southwesterly tomorrow, so storms will move away from the
Phoenix Metro Area after forming, and the associated outflows will
not be quite as strong as they would be otherwise. Rainfall
accumulations will be light, if any, over the lower deserts,
however, some very localized areas (particularly over the high
terrain to the east) will have the potential to see up to 0.5".
Thunderstorm chances continue Friday and through the weekend. The
trough positioned along the California Coast will begin to recede to
north and progress eastward on Friday, with a jet streak downstream
of the base of this trough. The upper level divergence over AZ from
this jet streak should create a favorable synoptic setup for the
development of thunderstorms, particularly over the high terrain
of South-Central AZ. Thunderstorm chances range from 40-60% over
Southern Gila County on Friday, and have increased up to 20-40%
over portions of the eastern lower deserts. With LREF mean dCAPE
values still reaching up to 2000 J/kg on Friday, strong, gusty
outflow winds will likely be a concern for Friday as well. With a
south southwesterly steering flow continuing on Friday, Phoenix
will not see much activity unless decent convection over the
higher terrain of southern Maricopa and southwest Pinal County,
and/or colliding outflows from convection from the east and
southeast.
.PREVIOUS DISCUSSION...
Moisture levels should continue to improve into Saturday as
ensemble mean PWATs increase to between 1.6-1.9" over much of
southwest and south-central Arizona. However, the upper level
ridge will also be strengthening and shifting right over the
region this weekend causing increasing subsidence. Forecast
confidence this weekend is fairly low due to placement of the
ridge. We will most likely have afternoon higher terrain
convection over the weekend, but it may struggle to survive into
the lower deserts. That doesn`t mean we can`t have a very good and
fairly widespread thunderstorm day with the set-up like we are
expecting this weekend, but it would take considerable colliding
outflows. For now, the NBM shows 10-20% PoPs this weekend over La
Paz and Yuma Counties, 20-30% PoPs over Maricopa County, and
30-45% PoPs over the eastern Arizona high terrain. Any convection
in this higher PWAT environment this weekend will have the
potential of bringing localized heavy rainfall.
Hotter temperatures will also spread westward Friday into the
weekend with highs topping 110 degrees across much of the
southeast California lower deserts to near 110 degrees across
southwest and south-central Arizona. The increased moisture will
also exacerbate the heat with temperatures feeling even hotter
given the increased humidities and keeping overnight lows well
above normal. In fact, overnight lows near 90 degrees in the
Phoenix area will be possible as early as Thursday night before
lows increase areawide by Saturday night with readings mostly
staying in the low to mid 80s or higher. The temperature forecast
for this weekend is of lower confidence compared to usual due to
the potential convection and cloud cover. By early next week,
ensemble guidance favors some strengthening of the sub-tropical
high with H5 heights likely rising to between 593-596dm. Moisture
levels will likely depend on the position of the high center with
some indications of the center shifting a bit more to the south
toward Mexico which may bring some drier air in from the
southwest. For now, the NBM favors this drying as it lowers PoPs
from west to east early next week. If guidance is correct and our
heights increase next week, we are nearly certain to fall under
another round of excessive heat. NBM forecast highs currently inch
toward the 115 degree mark by next Tuesday or Wednesday, but then
show signs of backing off later next week as the ridge is likely
to start to weaken.
&&
.AVIATION...Updated at 0020Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Winds will favor diurnal tendencies through the evening and
overnight period before S to SE winds increase Thursday morning
starting around 15-16Z with gusts to around 20 kts. Winds are
expected to then veer toward the southwest in the afternoon with
sustained speeds around 10-12 kts. Uncertainty increases going
into the late afternoon and early evening timeframe tomorrow as
thunderstorms are expected to develop to the east of the
terminals. As of now, thunderstorm chances will be greatest east
of the metro area tomorrow with the greater threat for the
terminals being gusty outflow winds moving through Phoenix. The
latest HREF indicates around a 70% chance for outflow winds in
excess of 30 kts and about a 10-20% chance in excess of 50 kts.
Timing and magnitude of outflow winds remain quite uncertain, but
the most favored direction is expected to be from the east. SKC
conditions will persist through much of the period before FEW-SCT
decks around 12 kft develop tomorrow afternoon into the evening.
Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns are expected through the next
24 hours. Winds will predominantly favor the west at KIPL with
extended periods of light and variable winds expected tomorrow
morning and afternoon. Could see a period of westerly gusts to
around 20 kts this evening at KIPL before subsiding. At KBLH,
winds will favor the S to SW with some afternoon breeziness. SKC
conditions will persist.
&&
.FIRE WEATHER...
Near normal temperatures today will warm back into an above
normal category as the first signs of monsoon flow and moisture
return affect eastern districts late this week through early next
week. Widespread dry conditions will prevail today with minimum
afternoon humidity levels 10-15% following poor to fair overnight
recovery of 15-45%. Moisture will surge into eastern districts
Thursday morning allowing minimum RH to only fall around 25% with
fair to good overnight recovery of 40-75%. The moisture surge
will be accompanied by unusually strong easterly winds Thursday
morning through early afternoon with gusts of 35-45 mph possible.
Wind speeds will gradually weaken into the weekend with east
southeasterly winds persisting through Saturday. With the moisture
increase, scattered afternoon thunderstorms will be possible over
higher terrain areas of eastern districts and potentially into
portions of the lower deserts. Lightning with fairly low wetting
rain chances combined with erratic, gusty outflow winds may be
significant concerns for eastern districts this weekend despite
the higher RHs. Western districts should see slightly better
moisture over the weekend, but CWR will remain below 5%. High
pressure is then expected to strengthen over the region by early
next week leading to even hotter temperatures along with slightly
drier conditions.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning from 10 AM to 8 PM MST Thursday for
AZZ534-537>555-559.
Wind Advisory from 9 AM Thursday to 5 AM MST Friday for AZZ560-
562.
CA...None.
&&
$$
DISCUSSION...Whittock
PREVIOUS DISCUSSION...Kuhlman
AVIATION...Smith
FIRE WEATHER...Kuhlman