Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/19/23
Area Forecast Discussion
National Weather Service La Crosse WI
648 PM CDT Tue Jul 18 2023
.DISCUSSION...(This evening through Tuesday)
Issued at 144 PM CDT Tue Jul 18 2023
Key Messages:
- Storms possible on Wednesday afternoon and evening, some of
which may be strong to severe (10-20% chance). Large hail would
be the main threat.
- Low risk of rain this weekend (20 to 30% chance).
- Increasing confidence in a warming trend to start next week.
Tonight and Wednesday Morning:
An upper level shortwave ridge builds into our region this evening
in the wake of a low that is pulling off to our east. Lows tonight
will fall into the middle to upper 50s with our typical cool spots
dipping into the upper 40s. Some river valley fog may be possible
towards sunrise when considering the light winds, clearer skies
overnight and small dewpoint depressions. The densest fog should be
restricted to the Wisconsin River and Mississippi River tributaries.
Some uncertainty presents itself early Wednesday morning with a
convective complex associated with a shortwave trough immediately
trailing the ridge axis, which might impact areas west of the
Mississippi River as shown in the 18.12 HRRR. Slight (20%) shower
probabilities have been added to our northeastern Iowa and southern
Minnesota areas to account for this scenario. Temperatures tomorrow
should be warmer (lower to mid-80s) with low-level warm advection
ahead of the evening trough.
Late Wednesday Storm Potential:
Confidence for storms is increasing for late Wednesday, but the
severe potential still is quite uncertain. Most guidance has settled
on the position of the shortwave but there is still some spread
between the models when looking at the available instability on
Wednesday evening. The 18.06 GEFS ensembles tend to want to show a
high degree of confidence (60-80%) of seeing CAPE values of 1000
J/kg across portions of northeast Iowa, southeast Minnesota and
portions of west-central Wisconsin. This is contrasted by the EC
ensembles which has much lower confidence (10-20%) in developing the
CAPE axis this significantly to see values of 1000 J/kg.
Short-term guidance appears to fall more closely in line with the
GEFS at this time with the 18.09 RAP wanting to have previously
mentioned areas seeing MLCAPE values of around 1500-2000 J/kg with
lower values east of the Mississippi River and south of I-90. This
spread is still shown in the SREF MLCAPE plumes with RST seeing
anywhere from 500 to 2500 J/kg. Much of this uncertainty in the
instability may be related to the convective complex coming through
in the morning Wednesday, which could significantly alter the
thermodynamic profiles in its wake. With the placement of the
shortwave well-resolved, the shear profiles are more consistent
between models as shown in the SREF effective shear plumes which
tend to cluster in the 45-55 knot range.
The Day 2 SPC severe outlook has put portions of our area in a
Slight Risk outlining hail and damaging winds, particularly
emphasizing the hail risk with a hatched area for the possibility of
hail 2" in diameter or greater. This is a highly conditional threat
based on how storms evolve in the morning.
Regardless of the severe threat, most of the CAMs initiate storms
tomorrow evening along and ahead of the surface cold front,
specifically north of I-90. The question seems to be how far south
will the forcing exist to develop storms along the front. Moisture
with this event is not particularly impressive with most of the
higher PWATs being well to our southwest; however, both the
deterministic 18.12 NAM and 18.06 GFS want to show around 1.5" which
could mean heavier downpours in storms. However, when considering
the minimal warm cloud depths and weaker 850mb moisture transport,
this will unlikely help the current drought situation significantly.
Through the Weekend:
Looking towards the end of the week, temperatures should remain
seasonable with highs in the 80s into the weekend. Wednesday`s
trough will push to the east and a building ridge out west, leaving
our area in a northwesterly flow pattern. Some of the long-range
guidance has occasional indications of subtle shortwaves that could
ride along the ridge and increase our shower risk over the weekend,
but the forecast only has lower chances (15-30%) at this time due to
low predictability.
Start of Next Week:
Long-range ensemble guidance next week highlight the ridge out west
attempting to build its way east towards our region. Generally
speaking, as this ridge progresses eastward it will likely have our
region in a warmer and drier setup going into next week. The GFS
ensembles have the most robust solution, already having high
confidence (50-70%) that highs mid-week will be above average into
the 90s. The degree of warming will depend on how far the amplifying
ridge out west advects into our region. Various models handle this
differently, but a larger portion of the guidance wants to trend our
area to have above average temperatures next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 637 PM CDT Tue Jul 18 2023
Fog restricting flight conditions in the Mississippi River Valley
continue to appear unlikely into Wednesday morning. Wisconsin
River Valley, given its proclivity, is much more likely to drop
into LIFR cigs and vis from fog development. Primary concern then
becomes storms on Wednesday morning and evening. Models agree on
storms waning as they advect southeast, locally reaching southeast
Minnesota near 10Z. Therefore, continued PROB30 group for KRST.
Further east, towards the Mississippi River and KLSE, increased
confidence continues for limited to no morning impacts.
Subsequent evening storms are dependent on morning storm extent
and impacts on resultant instability. Current timing for evening
storms place initial impacts shortly after 19.00Z TAF period.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Naylor
AVIATION...JAR
Area Forecast Discussion
National Weather Service Boston/Norton MA
1102 PM EDT Tue Jul 18 2023
.SYNOPSIS...
Showers and thunderstorms linger late this evening. Drier
weather is expected Wednesday into Thursday, then showers and
thunderstorms likely return Friday. A few showers may linger on
Saturday but high pressure brings sunny and less humid
conditions by Sunday and Monday.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Tweaked rainfall chances this evening based on the latest runs
of the HRRR and RAP guidance. This maintains at least a chance
of some showers into the early morning hours. The RAP was the
most aggressive at generating showers with the passage of a weak
mid level shortwave. Will be keeping an eye on this, as those
showers have not developed as of yet.
Minor tweaks to forecast temperatures to bring them back in line
with observed trends.
755 PM update...
As of 755 PM, most showers had exited northeast MA. However, a
new round of scattered thunderstorms was approaching the
Berkshires from eastern NY state. Mesoscale models do show some
of these working their way into portions of NW MA and perhaps
northern CT, before weakening by midnight. Although not very
widespread, will keep the Flood Watch going for at least a
couple of more hours. Will let the next shift assess on the 10
PM update whether to cancel it prior to its midnight expiration.
Low cloudiness was developing in the soupy air along the south
coast. That is forecast to expand across approximately the
southeastern third of southern New England overnight. Some dense
fog may again occur over Nantucket.
Previous discussion...
The localized severe weather and flash flood risk will linger into
the early evening across the interior, but convection is expected to
weaken as it approaches the coast as it moves into a less favorable
environment. However, there is still marginal instability so can`t
rule out an isolated t-storm in the coastal plain through midnight,
otherwise dry overnight.
Stratus and fog will redevelop over Cape/Islands and south coast and
advect northward. But stratus should be confined to RI and SE MA.
Lows 65-70.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Wednesday...
Another shortwave will be moving across New Eng during the
afternoon. Weak cold front which moves through overnight will likely
stall in the coastal plain during the day. Lower PWATs move into
northern northern MA where mixing may drop dewpoints in the upper
50s and lower 60s. However, higher PWATs near the coast will support
marginal instability for the possibility of a few pop-up showers and
perhaps and isolated t-storm? developing in the afternoon, mainly
across CT, RI and SE MA where higher dewpoints 65-70. Otherwise, dry
weather expected. Another very warm day with highs 85-90, but less
humid interior where drier aloft moves in, but still humid near the
coast.
Wednesday night...
Mid level shortwave moves to the east with weak subsidence
developing across SNE leading to dry weather. The weak front slides
to the south with light north winds developing. A bit less humid
with lows mid/upper 60s, with upper 50s and lower 60s NW MA.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Highlights...
* Showers & thunderstorms likely Friday
* Dry and less humid Sunday and Monday
Thursday through Saturday...
A low pressure trough moves from the eastern Great Lakes to
northern New England Thursday through Saturday and weakens.
At the surface, low pressure stretching from Lake Erie to
DelMarVa slowly progresses eastward across southern New England.
On Thursday, partly to mostly sunny skies are expected with
highs in the mid 80s. Can`t rule out a few afternoon showers,
mainly in western MA or northern CT.
Dewpoints increase Thursday night and by Friday, we are back in
soupy conditions with dewpoints within a few degrees of 70.
As low pressure approaches, showers and thunderstorms are
likely, especially in western and central portions of southern
New England. The 0-6km bulk shear values reach 40 kt, so there
is a chance of strong wind gusts with some of the stronger
storms. Also, torrential downpours will again be possible, so
isolated flooding would be a renewed concern.
The chances diminish overnight Friday night, but with surface
low pressure still in the vicinity Saturday, there could still
be scattered showers or thunderstorms around. Most of Saturday
will be dry, however. Highs both Friday and Saturday should be
in the lower to mid 80s.
Sunday and Monday...
High pressure moves into the region and air dries out throughout
the column. Finally, precipitable water values drop well below
an inch. It will be noticeably drier, with dewpoints in the
lower to mid 60s both days. Expecting mainly sunny skies and
temperatures in the mid 80s Sunday and mid to upper 80s Monday.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Forecast Confidence
Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight...Moderate confidence.
Scattered showers/thunderstorms in eastern NY will move into
western MA and northwest CT then diminish by 05Z. IFR-LIFR
stratus and patchy fog Cape/Islands and south coast, with
stratus lifting north to I-95 corridor overnight. Light SSW
winds shifting to W-NW throughout the region by daybreak.
May have some MVFR ceilings around 1500-2000 ft in CT River
Valley eastward to Worcester overnight, per latest model trends.
Wednesday...High confidence.
Mainly VFR. A few pop-up showers possible south of the Mass
Pike. W/SW winds up to 10 kt.
Wednesday night...High confidence.
Mainly VFR.
KBOS TAF...Moderate confidence.
KBOS will be right on the dividing line between VFR to the north
and IFR/LIFR ceilings to the south overnight. For now have
mentioned SCT015 with more widespread lower cigs remaining to
the south. Will need to keep a close eye on this.
VFR Wed. Have kept the sea-breeze out of the TAF for now, but
this will need to be re-evaluated.
KBDL TAF...Moderate confidence.
Mainly VFR overnight with a touch of MVFR visibility in fog
possible late. VFR Wed.
Outlook /Thursday through Sunday/...
Wednesday Night: VFR. Slight chance SHRA.
Thursday: VFR. Slight chance SHRA, isolated TSRA.
Thursday Night: VFR. Chance SHRA, isolated TSRA.
Friday: Mainly VFR, with local MVFR possible. Chance SHRA,
isolated TSRA.
Friday Night: VFR. Chance SHRA, isolated TSRA.
Saturday: VFR. Slight chance SHRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
755 PM update...
Through Wednesday night...High confidence.
Fairly tranquil conditions over the waters with mainly SW winds
up to 15 kt and seas below SCA. Areas of poor visibility in
fog tonight and Wed morning.
Outlook /Thursday through Sunday/...
Wednesday Night: Winds less than 25 kt. Seas locally
approaching 5 ft. Slight chance of rain showers, isolated
thunderstorms.
Thursday: Winds less than 25 kt. Slight chance of rain showers,
isolated thunderstorms.
Thursday Night through Friday: Winds less than 25 kt. Chance of
rain showers, isolated thunderstorms.
Friday Night through Saturday: Winds less than 25 kt. Slight
chance of rain showers, isolated thunderstorms.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Air Quality Alert until midnight EDT Wednesday night for
MAZ002>004-008>012.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...KJC/GAF
NEAR TERM...Belk/KJC/GAF
SHORT TERM...KJC
LONG TERM...GAF
AVIATION...Belk/KJC/GAF
MARINE...KJC/GAF
Area Forecast Discussion
National Weather Service Columbia SC
1032 PM EDT Tue Jul 18 2023
.SYNOPSIS...
A building ridge from the west will provide drier than normal
conditions as well as warming temperatures. Moisture will then
start to return late week as the ridge weakens, shifting the
pattern back to typical summertime temperatures and diurnal
showers and thunderstorms.
&&
.NEAR TERM /UNTIL 7 AM WEDNESDAY MORNING/...
We continue to monitor the MCS and associated MCV moving into
eastern TN and northern GA. Regional radars do show a weakening
trend, especially over northern GA, but some thunderstorm
activity still remains over eastern TN. As this system moves
into the central Appalachians and eventually east of the
mountains late tonight, we still can not rule some shower
activity make into the Piedmont. Any rainfall should be light if
it makes it into the western cwa. However at this time we
continue to keep the forecast overnight dry with the expectation
that the activity dissipates before making into the forecast
area. Surface moisture will remain fairly high and will prevent
much cooling, with similar lows falling into the low and mid
70s.
&&
.SHORT TERM /7 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
General consensus among model guidance over the last couple
runs is the ridge that will build over the area will not be
quite as strong with heights still above average. This weaker
ridge will mean that temperatures will not be quite as hot,
close to seasonal average with highs in the low to mid 90s with
increased clouds but also will make our area more susceptible to
shortwaves along the weaknesses in the ridge as well as any
mesoscale convective systems that develop upstream. PWATs are
expected to increase across the area, with the HREF indicating
PWATs nearing 2 inches in the southeast portion of the forecast
area. With this deeper moisture and lift provided by the
shortwave, scattered showers and thunderstorms are possible
during the afternoon, especially across the northeast portion of
the forecast, although instability will likely be a bit more
limited with warming aloft. Increasing deep layer shear may be
able to provide a bit more organization to any storms that
develop but still with weak lapse rates, severe threat remains
low. Low temperatures will be in the mid 70s.
A similar pattern is expected Thursday with upper ridging still
centered to the west of the forecast area and NW flow
continuing. Temperatures will be similar to Wednesday with highs
in the mid 90s, although dew points will be a bit higher. Will
once again have to watch the development of any mesoscale
convective systems upstream as they move towards the area.
Instability will likely be more favorable as mid level lapse
rates steepen a bit and with deep layer shear around 30 knots,
multi-cell storms are possible with a few storms potentially
becoming strong to severe, producing damaging wind gusts. SPC
has placed the area in a slight risk, although there is some
uncertainty as to the timing of storm initiation, with the
earlier morning development, the lower the severe threat.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Ensemble trends have kept the ridge relatively strong into
Friday as NAEFS indicate that 850mb heights remain above the
90th percentile. As a result, blended guidance has trended a bit
warmer with ensemble means indicating zonal flow developing. Forcing
will likely be weaker, leading to shower and storm chances more
diurnally driven, allowing for temperatures to rise into the
mid afternoon before storms develop. Beyond Friday, ensemble
members are consistent in flipping the pattern with general
troughing over the eastern US as the NAEFS indicate heights fall
to below the 10th percentile. Temperatures will drop to below
average in response. GEFS has the highest probability of PWATs
greater than 2 inches in the southeast forecast area which will
support at least diurnally driven convection each afternoon
with forcing along the sea breeze and shortwaves pivoting
through the axis of the upper trough.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Surface VSBYs in smoke/haze have improved this evening to VFR as
winds turned more southerly. At 02z, MVFR VSBY restrictions continue
across central GA, just west of AGS/DNL. As low level flow
becomes more SW later tonight, this area of smoke could advect
into DNL/AGS, per latest HRRR smoke model. The HRRR/RAP smoke
model also indicates the area of smoke to drift east into the
remainder of the forecast area Wednesday morning, then shift
south of the TAF sites by afternoon. In addition, with westerly
surface winds increasing by Wednesday afternoon, associated
turbulent mixing could also act to keep VSBYs VFR. So,
indicated high end MVFR VSBYs in HZ at DNL/AGS late tonight, and
at all sites Wednesday morning, returning to VFR by 18z.
Otherwise, fair tonight. Area of convection well to our NW is
expected to continue dissipating as it moves SE into a drier and
more stable atmosphere. Fog/Stratus threat tonight minimal due to SW
surface and boundary layer wind staying up some ahead of an
approaching trough, along with increasing mid/high level cloud
cover from the dissipating convection to our NW.
A slight moistening of the atmosphere Wednesday, along with an
approaching upper disturbance, may provide some thunderstorm
potential by late Wednesday afternoon and evening. At this
time, confidence of such affecting the TAF sites too limited to
include a TS mention in the 00Z TAFs.
EXTENDED AVIATION OUTLOOK...Increasing probabilities of diurnal
thunderstorms and late night/early morning fog/stratus through
Sunday. Smoke/Haze from distant wildfires may continue to reduce
flight VSBYS and possibly affect surface VSBYs at times.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Cheyenne WY
258 PM MDT Tue Jul 18 2023
.SHORT TERM...(This afternoon through Thursday)
Issued at 245 PM MDT Tue Jul 18 2023
Not many changes to the previous forecast through late this
evening. Current KCYS radar loop shows mostly light rain showers
across the area (probably not reaching the ground) with a band of
heavier showers and thunderstorms extending along a line from near
Casper southeast to Torrington. Thankfully, instability is not as
great as the previous days with MLCAPE between 200 to 500 j/kg
west of the Wyoming/Nebraska border. Further east, MLCAPE is much
higher (closer to 1500 to 2000 j/kg) but significant amount of CIN
persists across the western Nebraska panhandle, which may take
some time to erode. Currently watching a decent thunderstorm cell
just east of the Black Hills and pushing south towards Chadron.
Extended POP further north towards the South Dakota border. Even
though CAPE further west is on the low side, there is a decent
potential for strong gusty winds with any of these thunderstorms
as they slide off the mountains. Kept severe thunderstorm wording
in the forecast along and mainly east of the Interstate 25
corridor. Can`t rule out some large hail too, but this should be
very isolated. Further south, some drier air has penetrated
eastward towards the southern Nebraska Panhandle, with dewpoints
dropping into the 40s from Rawlins to Cheyenne. Kept lower POP in
these area for now, but expect activity to gradually increase in
coverage later this afternoon and this evening, but not expecting
coverage about widely scattered for now. With more cloud cover
expected tonight, especially near the Colorado border, increase
low temperatures a few degrees since some locations last night
struggled to get into the mid to upper 60s by sunrise this
morning.
Cooling trend starts on Wednesday with highs mainly in the low to
mid 80s. Models show a backdoor cold front pushing south across
the plains and stalling near the mountains around noon. Thermodynamic
profiles should be less unstable due to the cooler air near the
surface. However, the front is expected to stall near the Laramie
Range and expect this region to be the focus of daytime and
evening convection. Kept a solid chance of precipitation (30 to
50 percent) mainly for the I-80 corridor and more focused on
southeast Wyoming through Wednesday evening for scattered showers
and thunderstorms. At this time, thunderstorms are not expected to
be severe but a few stronger storms are possible.
For Thursday, models continue to show a potent Pacific shortwave
trough quickly moving east across the northern Great Basin region
late on Wednesday and into the northern Front Range by midday
Thursday. This upper level trough is currently near the
California coastline based on 7.3um Watervapor imagery...and is
expected to ejecting northeast over the top of the strong upper
level high to the south. Models have trended more aggressive with
precipitation amounts each day, both in intensity and amounts, so
decided to increase POP to categorical (80% to 95%) for
widespread Rain showers and scattered/embedded thunderstorms
through Thursday and into Thursday evening. In addition to this,
we will still be behind the primary cool front, forecast to push
through the area on Wednesday, with deep east to southeast flow
ahead of the trough, and northerly winds on the backside of the
system. Impressive PW`s, even for this time of the year, with
values over an inch and approaching 1.5 inches across the eastern
plains. Upslope flow and deep moisture will likely lead to
dewpoints in the 60s to possibly mid 60s further east. Depending
on the timing, some strong to severe thunderstorms are possible,
especially along the I-80 corridor near Laramie, Cheyenne and
points east with some morning sun and surface heating. 18z HRRR
shows multiple bands of heavy showers through the day, especially
south of a line from Douglas to the Pine Ridge in the northern
Nebraska Panhandle. Will have to monitor the potential for
excessive rainfall and some flash flooding, but we have some time
for high res models to lock on to the timing and general location.
This will likely be a decent rainfall producer for most locations
through Thursday evening.
.LONG TERM...(Thursday night through Tuesday)
Issued at 229 PM MDT Tue Jul 18 2023
Showers and storms move out of the region Thursday evening before
another chance for storms Friday. A warming trend is expected
through the long term forecast, with several locations seeing 90s by
early next week. Hot and dry weather is likely to start the work
week.
A stout 500mb, 594dm ridge builds over the southwestern CONUS late
in the week, with the ridge axis located from northern Idaho south
into the Great Basin on Friday. Northwest flow aloft moves over the
region behind a departing upper-level shortwave that will produce
widespread showers and thunderstorms Thursday. Several 500mb
vorticity maximums, along with modest cyclonic vorticity advection,
are progged to traverse through the eastern side of the ridge and
provide synoptic lift across the CWA. Additionally, a weak jet
maximum develops over the Great Plains, placing the CWA in a
favorable location for additional synoptic lift generated by this
jet maximum. Warm, moist, southerly flow shifts more easterly during
the day Friday and allows for upslope flow to develop east of the
Laramie Range. While lift does not appear to be much of an issue for
storm development on Friday, SBCAPE is modest only around 500 J/kg.
Long range models have been trending down in CAPE values for Friday.
Bulk shear values remain good, around 50kt in eastern Wyoming with
pockets of 45kt bulk shear is western Nebraska. PW values are
progged to sit around 0.70 to 0.80in over western Nebraska, with
similar values expected over southeast Wyoming. Friday is looking
less impressive than previous days. The shear, moisture, and lift
should be enough to get storms to initiate, but the limited CAPE
values that are likely to be capped may be a limiting factor. Model
trends will continue to be monitored to determine if CAPE improves
and allows for better chances of severe weather. As of now, the
environment looks good enough to get storms to develop, but whether
or not they will be severe remains uncertain.
Precipitation chances taper off rapidly for Saturday and the
remaining portions of the long term. The stout upper-level ridge
moves easterly towards the CWA. By Sunday, the upper-level ridge
axis is positioned over western Montana south through Idaho and far
western Wyoming. This ridge continues to move slowly easterly and
builds into the early portions of next week. By Monday, the 500mb
ridge is progged to be at 597dm. Temperatures for Monday and Tuesday
are expected to be significantly warmer as the ridge moves over and
subsidence settles over the region. Several locations will see low-
to mid-90s for highs on Monday, with portions of western Nebraska
potentially seeing highs approaching 100F by Tuesday. This is still
a ways out, but with a stronger ridge overhead than what was seen
this week these temperatures are not completely impossible. Trends
will continue to be watched to determine if temperatures should be
decrease or increased based on how well the models agree on the
maximum strength of the ridge. Overall, this weekend looks to be
warm and dry with a hot and dry start to the work week.
On a final note, the GFS, ECMWF, and GEFS all hint at the
development of the monsoon by next week. High pressure remains fixed
in place over the Four Corners region with a strong 500mb ridge
overhead with a closed contour high over the same region.
Additionally, PW are slowly increasing over Mexico and begin to push
northerly towards the CWA early next week. This could suggest the
development of the monsoon, but these trends will need to continue
to be monitored. Some of the longer range models have suggested the
development of the monsoon for a while now, but is has not come
to fruition. However, with several models recently coming into
better agreement on this, trends will need to be monitored.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1142 AM MDT Tue Jul 18 2023
The main concern with this TAF issuance is the timing of the
convection this afternoon and location.
Latest satellite/radar showing a cluster of showers developing
between Rawlins and Wamsutter. These showers will continue to push
east through the remainder of the afternoon. Would not be
surprised that these showers advance as far east as KLAR and KCYS
by mid afternoon. With such dry conditions in place, these
showers may produce some gusty winds up to 50 mph. Another area of
concern that we are watching is the convection developing over
the Black Hills. These thunderstorms may track southeast and
perhaps clip KCDR later this afternoon. Otherwise, ceilings should
mostly stay above VFR through the next 24hrs with wind speeds
&&
.FIRE WEATHER...
Issued at 143 PM MDT Tue Jul 18 2023
Minimal fire weather concerns for the rest of the week with a high
chance for widespread wetting rainfall Wednesday night through
late Thursday. Another relatively dry day today, but precipitation
chances will increase through the afternoon and this evening.
Minimum relative humidities may briefly dip down to the mid teens
this afternoon before increasing rapidly by late this evening.
Cooling trend expected to begin on Wednesday as a Canadian cool
front pushes southward across the high plains. This will set the
stage for a rainy and cool Thursday with cooler than average
conditions likely extending into Friday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...TJT
LONG TERM...AM
AVIATION...REC
FIRE WEATHER...TJT
Area Forecast Discussion
National Weather Service Grand Forks ND
930 PM CDT Tue Jul 18 2023
.UPDATE...
Issued at 930 PM CDT Tue Jul 18 2023
Other than lingering (widely scattered) showers in our east
thunderstorm activity has struggled to initiate or track into our
CWA, with isolated stronger storms remaining rooted along
instability axis to our west ahead of the approaching frontal
zone. With sunset we are going to see a trend away from the
highest impacts. The elevated instability axis does "eventually"
progress over our CWA (1000-1800 J/KG overnight according to the
RAP), and deep layer shear will remain high (though 0-3km shear is
now weaker). The lack of 850MB jet to organize activity amd the
isolated nature of the current activity (no clustering up to
develop outflow/cold pools) lowers confidence in overnight
coverage of even showers/thunderstorms regardless of severe threat.
There is still a subtle shortwave that is moving our our area but
this may only be enough to continue to support scattered shower
development overnight and isolated thunderstorms.
We aren`t out of the woods completely on severe potential in our
west this evening, but impacts and coverage potential may be
decreasing (becoming more isolated and marginal). In that case
60mph winds and 1 inch hail may be the more likely threats for
stronger storms over the next 3hr in our area if they develop or
move this far east.
UPDATE Issued at 657 PM CDT Tue Jul 18 2023
We continue to monitor upstream of our CWA and along our western
counties for possible initiation/severe thunderstorm development
over the next 1-3hr.
Steep mid level lapse rates (7.0-7.5 C/km) are confined to the
southern RRV and locations southwest, while a narrow axis of
1500-2500 J/KG MLCAPE is just west of our CWA behind the mid level
clouds and ahead of a frontal zone/well defined wind shift. This
axis is where destabilization was maximized during peak heating
due to better clearing and BL Tds pooling (60-68). Strong CAP
delayed initiation, though there had been some indications of the
CAP weakening within the previous hour to our southwest within
more agitated CU field. Due to the narrow axis of higher ML CAPE
and limited window there is still uncertainty on severe coverage
but due to the very high effective shear (40kt+) orthogonal to the
frontal zone along this axis where better mid level lapse rates
are, elevated supercell development and very large hail are still
threats if storms can initiate. HRRR continues to be a drier
model, while earlier CAMs may have been too robust with
initiation.
We are in the window though and rapid intensification
could take place if storms were to initiation along that axis to
our west. Enough cells merging within that high shear (0-3km shear
30kt+) environment/developing cold pools could carry a localized
wind risk as well, but with the window for non elevated parcels
shrinking the tornado threat may be less. If initiation is
delayed until sunset (or after),elevated marginal pulse type
convection becoming favored.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 230 PM CDT Tue Jul 18 2023
Situation in the short term remains with a window for severe
thunderstorm potential with the passage of a surface
trough/frontal boundary across the forecast area tonight. Main
upper low is currently crossing Saskatchewan and is expected to
travel southeastward across the RRV Wednesday. Have some areas of
showers across the far northeast in the WAA nose of this system,
stretching back into southern Manitoba/far north central ND. Back
to the west a weakly developing sfc low across western ND and
associated cool front/surface trough stretching southward through
west central/southwestern ND. This trough/boundary is expected to
push eastward and into central ND, just west of the forecast area
by late afternoon.
CAPE has been increasing across central/western ND with
some CIN still in place, with low level moisture increasing across
the area shown by dewpoints into the low/mid 60s along/ahead of
the boundary. Convective initiation expected to be reached toward
late afternoon as the stronger axis of instability moves east and
sfc inhibition erodes. This axis of instability will continue to
push east nosing into eastern ND by early evening, with the
gradient of CAPE expected to be oriented from near Devils Lake
southeastward into Ransom/Sargent/Richland Counties southward.
Therefore expect a window of severe threat from around late
afternoon/early evening through the evening hours as activity is
expected to develop by late afternoon just to the west of the
forecast area and track east/southeast. Instability will quickly
wane into the central/eastern portion of the forecast area, so
could still see some thunder continue overnight the overall severe
threat will diminish. Deep layer shear in the 45-50kt range with
the storms, so organized sustained storms expected with general
movement to the south and east based of the mean wind. Directional
shear showing decent turning, so any storm that can stay near the
boundary will have a greater tornadic potential, but will likely
shift more toward the hail/wind threat away from the boundary and
with any cluster development. With the more easterly boundary
movement, and southeasterly storm motion could see storms merge
into a cluster, and then expected to travel more southeastward
into northeast SD along the instability gradient by late evening.
Expect to see an area of showers/isolated storms push east into MN
overnight, with additional thunderstorm threat with the passage of
the upper low across the area Wednesday afternoon. Greater
instability and position of the cold front should confine the threat
to the eastern/southeastern portions of the forecast area.
.LONG TERM...(Thursday through Tuesday)
Issued at 230 PM CDT Tue Jul 18 2023
Will have continued northwest flow pattern across the area for the
end of the week as upper ridging builds across the west. A few upper
waves will keep some clouds around Thursday into Friday with a few
showers still possible along the Canadian border Friday. Upper
ridging to build eastward into the central US by early next week,
with potential for additional precipitation chances over the
weekend. Warmer air to move into the area by early next week with
the upper ridging, and expect a return to hot temperatures by the
middle of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 657 PM CDT Tue Jul 18 2023
Smoke is still linger near the surface at KGFK resulting
reductions in vis 4-6sm, however as the winds shift within the
first part of the TAF period this should finally clear. Aviation
impacts over the next 24hr will then mainly be determined by
coverage and track of showers/thunderstorms, and there should be
better coverage for a 2-3hr period late this evening/early
overnight (west to east across eastern ND and northwest MN)
followed by a lull, then additional shower/embedded thunderstorm
redevelopment along/north of Highway 2 corridor Wednesday (midday-
afternoon). I fine tuned timing as a best guess as current
activity and expected development so far has not been well handled
by guidance this afternoon/evening.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...DJR
SHORT TERM...MJB
LONG TERM...MJB
AVIATION...DJR
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
1037 PM CDT Tue Jul 18 2023
.UPDATE...
Issued at 1030 PM CDT Tue Jul 18 2023
Updated the forecast to address two areas of concern:
- Decreased areal coverage of PoPs overnight as convection to the
west is weakening with time and as it tries to shift east.
Strong storms appear unlikely, so removed mention in the HWO.
- Increased the areal coverage of fog late tonight and into
Wednesday morning, and also added some "dense" wording.
Details:
Latest sat/rad trends, along with trends from HRRR and other
guidance, leads me to believe convection shouldn`t be much of a
concern overnight. Activity in W Neb. has steadily weakened with
time and eastward extent, and see no reason this trend shouldn`t
continue. Another area of convection along the SD/NE border has
maintained some vigor beyond 03Z, but this activity is moving into
incr warm mid level temps (12-14C at H7) and CINH, and there isn`t
much of a low level jet to help sustain ascent. Thus, seems
unlikely activity will be able to survive to or much past the Hwy
91 corridor.
As for fog potential, observational and model trends suggest dense
fog may be incr concern for at least portions of the forecast area
late tonight until mid AM Wed. Latest obs show T-Td spreads are
already less than 4-5 deg for most locations amidst partly cloudy
skies. Sat trends show off and on clouds should push through the
area overnight, but seems unlikely mid to high cld cover will be
solid. Also, LXN and HDE have already dropped to the 4-5sm range.
Basic fog forecasting techniques and synoptic setup also favor
dense fog tonight. What little wind we do have is largely Erly,
which is a broad, gentle upslope component for us. Also, crossover
temps from yest aftn are only 68-72F, which air temps are already
at, or in the case of HDE, below as of 03Z. Another 2-4+ deg of
cooling shouldn`t be an issue as latest NBM guidance drops lows
into mid to upper 60s by dawn. Finally, HRRR and LAMP guidance
have trended more pessimistic with visibilities, as well. Overall,
confidence is incr that at least W third to half of CWA will need
a Dense Fog Advy, so incr the coverage and dense wording in the
grids and HWO as a start, and will pass along concerns to
incoming mid-shift.
&&
.DISCUSSION...(This evening through Tuesday)
Issued at 508 PM CDT Tue Jul 18 2023
-- KEY MESSAGES FOR THE ENTIRE 7-DAY FORECAST (generally
chronological):
* Thunderstorm potential tonight: Although at least for now most
of our coverage area (CWA) is still in an SPC Marginal Risk
(level 1 of 5) for severe storms this evening-overnight, feeling
here locally is that the main threat for severe activity should
remain at least slightly to our west-northwest. Certainly
cannot rule out a few stronger storms and MAYBE a rogue severe
storm, but have generally downplayed a severe threat in our
Hazardous Weather Outlook (HWOGID).
* Thunderstorms (some probably severe) more likely Wednesday:
Although it is difficult to completely rule out at least
spotty/weak storms at almost any point Wednesday into at least the
first part of Wednesday night, by far our main concern at this
point is the 3-11 PM time frame, as a weak cold front sags
southward into a moderately unstable and strongly-sheared
environment. SPC has "upgraded" our entire CWA to a Slight Risk
(level 2) of severe, which seems fairly reasonable. The main
questions at this point are storm coverage/mode, but current
thinking is for a few to perhaps several supercells developing
north or near I-80 and perhaps growing upscale into more of a
convective complex as they track south-southeastward toward/into
our KS zones. Large hail (to at least golf ball size) the
overall-biggest concern at this point.
* Thursday afternoon-evening storm potential: Although still
plenty of uncertainty at this 48-60 hour time frame, SPC
officially has parts of our KS zones in a Marginal Risk of
severe. Models are still a bit of a "split story" though, and if
especially the latest NAM is onto anything then the MAIN severe
risk could focus almost entirely southwest of our CWA
altogether.
* Friday-Tuesday overview: Although some still-highly-uncertain
thunderstorm chances linger Fri-Fri night, at least for now, our
official forecast remains void of any mentionable (15+ percent)
rain/thunderstorm chances Sat-Tues as upper ridging expands
east-northeastward over the Central Plains. While raw model data
suggests this current dry forecast may eventually be "ruined" at
times by some slight chances, the overall trend toward drier and
warmer weather remains intact. That being said, just HOW WARM it
gets early next week remains somewhat in question, as our high
temperature forecast for Sun-Mon has trended down very slightly
from before.
-- MORE DETAILS/FURTHER INFO BUILDING UPON THE KEY MESSAGES ABOVE
(including all further discussion of Thursday daytime-Tuesday):
- General overview of the large scale upper air/surface pattern:
Not a lot of time to dive into this section today, but generally
breaking the 7-day into two chunks:
1) Tonight-Friday:
The overall pattern we are currently in remains overall-similar,
meaning continued off-and-on thunderstorm chances and cooler-
than-average July temperatures. Aloft, we remain under
seasonably- strong west-northwest flow aloft, between expansive
upper ridging centered over the Desert Southwest/TX and a
persistent large scale trough centered from around the Great Lakes
northward into Canada. High temperatures Wed-Fri mainly only low-
mid 80s (except warmer south Wed), and once a weak cold front
passes through Wed night dewpoints will fall back down to no more
than upper 50s-mid 60s for a few days, making for less humid/more
comfortable conditions.
2) Saturday-Tuesday:
The latest ECMWF/GFS continue to agree that the biggest change
from the current pattern is that large-scale ridging will build
northward across the western CONUS, turning our flow aloft more
north-northwesterly than west-northwesterly. Mid level heights
will also rise over our region, but we will still remain east-
northeast of the heart of the ridge generally setting up over the
Four Corners area. As already mentioned above, do not necessarily
think our currently dry forecast for Sat-Tues will hold as some of
those days/nights get closer in time (there will still be some
weak/subtle disturbances working through the flow aloft), but
overall it should be a drier pattern, and confidence is higher
that it will be a warmer one. The main question is HOW much
warmer? For what it`s worth, our latest forecast has trended
similarly to latest ECMWF ensemble guidance and tempered highs
SLIGHTLY for the Sun-Tues time frame, but we are still looking at
highs more solidly into the low-mid 90s during this time.
Fortunately, it currently appears that dewpoints/humidity levels
should not get overly-high, which should keep heat index readings
mainly at least slightly under 100 degrees.
-- SHORTER TERM DETAILS FOCUSED SOLELY ON THESE NEXT 36 HOURS
(through late Wed night/Thurs AM):
- CURRENT/RECENT WEATHER SCENE AS OF 430 PM:
The daytime hours started with a few strong to marginally-severe
storms in our northern zones (quarter size hail confirmed in Ord),
but as was expected this elevated activity pushed off to the east
by mid- morning and it`s been dry ever since. The main forecast
"headache" today has been temperature trends, largely due to
variable cloud cover. While a more expansive deck of lower clouds
(and even some fog) that existed in our southwestern CWA earlier
today has largely dissipated/lifted, plentiful mainly mid- high
level clouds have continue streaming overhead from west-to- east.
If anything, dewpoints have also crept up a bit higher than
forecast, with most sights solidly into that "quite humid" upper
60s-low 70s range. Despite the clouds, most of the CWA should end
up reaching official highs somewhere between 79-86 degrees. Winds
this afternoon are generally 5-10 MPH out of the east-southeast
most areas.
- THIS EVENING-OVERNIGHT:
Although a severe storm is ongoing at this time in far northwest
Nebraska, have maintained a dry/thunderstorm-free forecast CWA-
wide through 10 PM/03Z. Mid level temps are quite warm over our
CWA (13-17C at 700 millibar level), which should effectively keep
us capped to any near-surface based development through early
evening. Although any more intense storms to our northwest
obviously bear close watching to make sure they don`t maintain
intensity if they survive into our western counties, agree with
general HRRR trends that activity should largely weaken as it
approaches our western edges closer to sunset. As for the
post-10PM time frame, did maintain some basic slight chances (20
percent) for storms to eventually include all but the far eastern
CWA overnight, as higher-res models hint at generally weak "junky"
showers/non-severe storms drifting from west to east. Due to lower
level capping, feel that most of this activity should be very high
based closer to 700 millibars/10K ft.), and thus only able to tap
into a few hundred J/kg of elevated instability. So while cannot
completely rule out a strong to marginally severe storm mainly
pre-midnight (IF anything to our northwest maintains intensity
into our area), expect MOST overnight storms to be weakish. In
other departments, introduced some generic "patchy fog" to mainly
west-northwest zones very late tonight/early Wed AM. Am not
overly-concerned with dense fog given passing mid-upper level
clouds, will probably have to watch especially the Dawson County
area for possible fog issues given the light breezes/high
dewpoints/humidity. Overnight low temps were changed very little
aimed mid 60s most Neb zones, upper 60s KS.
- WEDNESDAY DAYTIME-EVENING:
Certainly our main concern is what appears to be a decent setup
for at least a few (if not several) severe storms especially in
the 3-11 PM time frame. For the first several hours of the day,
did expand slight PoPs to the entire CWA, as especially higher-
res models continue to hint that weak "junky" high-based
convection could continue right on from the overnight period. But
then, at some point mid-late afternoon as the low-level airmass
destabilizes and a weak cold front arrives into our northern
zones, at least a few to perhaps several strong to severe, likely
supercellular storms could erupt, in an environment characterized
by generally 2000-3000 J/kg mixed-layer CAPE and continued
seasonably-strong deep layer wind shear of 40-50+ KT. The latest
HRRR suggest supercells could congeal into more of a complex as
they track south-southeast toward and into our KS zones, and this
seems reasonable. If anything, our PoPs are probably not high
enough in some areas, but hopefully next few shifts can refine.
Large hail to at least golf ball size seems like a good bet with
the most intense storms (note SPC has introduced a "hatched area"
for hail on Day 2 outlook), but damaging winds certainly in play
too. Not overly concerned about a tornado threat, but it`s non-
zero. Current thinking is main severe threat likely exiting our
CWA to the south by around 11 PM. In other areas, made little
change to high temps, with most places topping out 83-89 but a few
90s possible mainly KS and Furnas County area.
- LATER WED NIGHT-EARLY THURS AM:
Although later forecasts can probably trim some of the area back,
at least for now maintained slight PoPs as far north as I-80 for
anything lingering north of the main zone of activity earlier in
the evening. However, latest model trends suggest at least the
vast majority of the CWA is probably dry post-midnight. Although
not in the current forecast, will probably need to watch for more
late-night fog potential, although light winds trending north-
northwesterly should mitigate as drier air slowly works southward
behind the boundary. Did nudge up low temps very slightly, ranging
from low 60s north to mid-upper 60s south.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday)
Issued at 650 PM CDT Tue Jul 18 2023
Significant weather: MVFR CIGs/VSBYs possible early Wed AM. Scat
tstms possible late in the period.
Tonight: Quiet to start with only some mid to high clds and fairly
light E-ESE wind. Late tonight, lgt and vrbl winds, plentiful low
level moisture, and weak return flow could lead to some low
stratus and/or lgt fog. Currently looks like best chc for sub-VFR
CIGs and/or VSBYs is off to the W of the terminals, but there`s at
least some model guidance to support a chc at GRI and esp. EAR.
Kept 6sm and SCT stratus deck for now, but wouldn`t be shocked if
a few hrs of MVFR VSBYs and perhaps even IFR CIGs sneak in between
11Z and 14Z. Confidence: CIG/VSBY - low, Wind - high.
Wednesday: Once any threat for stratus/fog burns off by 14-15Z,
expect quiet/VFR conditions and Srly sfc winds around 7-10kt
through early aftn. A cold front will bring the potential for scat
tstms beginning around 21Z at both terminals, some of which could
be strong to severe. Based on latest timing, the greatest tstm
threat should end by 03Z Thu - just beyond this valid TAF period.
Confidence: Medium.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...Thies
DISCUSSION...Pfannkuch
AVIATION...Thies
Area Forecast Discussion
National Weather Service Louisville KY
811 PM EDT Tue Jul 18 2023
.Mesoscale Update...
Issued at 809 PM EDT Tue Jul 18 2023
Storms have pushed east of the watch area so Severe Thunderstorm
Watch 511 has been cancelled early. Lingering showers and storms
will continue for the next several hours before we see a lull in
activity. More activity is expected to pick up overnight mainly
across the southwestern CWA which is currently being handled with a
flood watch.
Issued at 600 PM EDT Tue Jul 18 2023
Leading line of convection is weakening over south-central Kentucky,
but could still support a wind and marginal hail threat as the
environment ahead of the line remains very moist and unstable.
Mainly making adjustments to WW 511 over its final couple of hrs.
Some concern about flash flooding, as the comma head of the MCV
seems to be situated just east of Owensboro, and the potential is
setting up for training cells on a WNW-ESE axis from there. That
zone lies just north and east of our existing Flood Watch, so we`ll
monitor the need to do an expansion of that headline during the
early evening.
&&
.Short Term...(This evening through Wednesday)
Issued at 255 PM EDT Tue Jul 18 2023
Key Messages:
- Severe storms with a significant wind threat through early evening
- Heavy rain and flash flooding possible overnight in south-central
Kentucky
MCV is fueling a mature MCS that has crossed the Mississippi River
into western Kentucky, and should continue to plow eastward into a
ridiculously moist and unstable environment. With mixed-layer CAPE
over 3000 J/kg, DCAPE up to 1200-1300 J/kg, and 40 kt of line-normal
deep-layer shear, a significant wind threat is on the table with
localized hurricane-force gusts possible. The above mentioned shear
is also supporting a few supercells ahead of the line, so large hail
is also in play and a tornado can`t be ruled out either. This line
should push through rather quickly, clearing the I-65 corridor
around 7 PM EDT and the I-75 corridor closer to 8-9 PM EDT.
Once this system clears, we`ll have a break in the action during the
latter part of the evening, with storms re-developing along a
boundary paralleling I-24 after midnight. This action will lift far
enough NE to get into south-central Kentucky, including Bowling
Green, in the pre-dawn hours of Wednesday. Training cells are a risk
with the effective boundary nearly parallel to the NW flow aloft,
and rain production will be quite efficient. Widespread 1-2 inch
rain totals will be prevalent, with localized amounts of 3 to 5+
inches possible. WPC`s Moderate risk of excessive rainfall appears
well placed, nosing into south-central Kentucky. A Flood Watch
has been issued for this area until 15Z Wednesday, and while the
heavy rain will most likely be suppressed into Tennessee by 12Z,
flood impacts could linger for a few hrs.
Low-confidence forecast for Wednesday as so much depends on the
evolution of the second system tonight, which has yet to develop.
Lingering clouds will create some temperature bust potential and
could also fuel isolated to scattered storms. Think the better
chances are Wednesday night, but really any thunderstorm in a juicy
summer environment carries the standard pulse threats of locally
gusty winds and heavy rain. One thing we are certain about is that
it will remain warm and muggy.
.Long Term...(Wednesday night through Tuesday)
Issued at 330 PM EDT Tue Jul 18 2023
---------------------------------------------------------------------
Key Messages:
- Unstable pattern continues Wednesday night into Thursday with
additional waves of showers and storms expected. Strong to severe
storms are possible with heavy rainfall possibly producing localized
flooding.
- Transition to drier weather begins on Friday with lingering rain
and a few storms possible.
- Seasonable temperatures and mostly dry conditions expected for
much of the weekend.
---------------------------------------------------------------------
The first 36 hours of the extended forecast period will feature the
most active weather as shortwave troughs continue to intermittently
slide southeastward along the southern edge of large-scale troughing
over the eastern half of North America. As these mid- and upper-
level disturbances slide through the Midwest and Ohio Valley, waves
of showers and thunderstorms will continue Wednesday night into
Thursday across central KY and southern IN. With fast flow aloft for
mid-summer, dynamic support should be sufficient for organized
convection as these waves pass through. Thermodynamic support will
bounce up and down as waves of convection temporarily stabilize the
atmosphere, although things should quickly recover given the amount
of moisture available and any insolation. Estimated timing on any
one wave of storms is difficult to predict, and hi-res guidance will
likely continue to struggle until antecedent waves of storms begin
to fire.
From an ingredients perspective, Thursday has considerable potential
for strong to severe storms as short-to-medium range progs depict
several thousand joules of CAPE with 35-45 kt of effective shear.
Drier air in the mid-levels would increase the potential for gusty
winds in any stronger storms with RAP soundings showing over 1200
J/kg DCAPE. In addition to the severe potential, locations which
experience multiple rounds of heavy rainfall could see flash
flooding issues, although storms should generally be fairly
progressive with stronger flow aloft.
As we head into the day on Friday, latest model guidance has slowed
the progression of drier air into the region, and a final mid-level
shortwave will attempt to swing across the Ohio and Tennessee
valleys Friday morning. Have increased PoPs farther north on Friday,
though the best chance for any lingering showers and storms will
still be across south central KY where the better moisture will
reside. A final sfc frontal boundary will move through the area on
Friday, with drier air and lower PWATs helping to bring rain chances
to an end as we head into the upcoming weekend.
Much of the upcoming weekend looks dry with slightly below normal
temperatures expected Saturday and Sunday. As the large scale trough
deamplifies over the eastern CONUS early next week, temperatures
should be on the upswing once again as height increases promote a
return to a more typical summertime pattern. At this time, more
typical daytime shower and thunderstorm chances should return for
the first half of next week, with temperatures expected to be around
climatological norms for late July.
&&
.Aviation...(00Z TAF Issuance)
Issued at 712 PM EDT Tue Jul 18 2023
Showers and storms are slowly pushing off to the east of the region
this evening and should give way to a lull in precipitation activity
for at least the first part of the overnight hours. Another round of
heavy rain and storms is expected to develop after midnight, mainly
across western KY into southern KY and middle TN. Latest trends have
taken this line of showers/storms a bit farther south than afternoon
forecasts, so have trended things a little better for the TAFs but
will continue to watch closely.
Otherwise, IFR to MVFR stratus is expected to develop toward dawn
tomorrow and persist through a good part of the morning hours. This
should lift to VFR levels by the afternoon.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Flood Watch through Wednesday morning for KYZ026-027-061-062-
070>073.
IN...None.
&&
$$
Mesoscale...DM
Short Term...RAS
Long Term...CSG
Aviation...DM
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
846 PM CDT Tue Jul 18 2023
.UPDATE...
Issued at 846 PM CDT Tue Jul 18 2023
Going forecast is in good shape this evening, and only minor
adjustment made was to lower overnight min temps slightly in a
couple of our typically cooler spots west of the Chicago area.
Evening surface analysis places weak high pressure over northwest
IL. Dry and quiet conditions are expected overnight as the surface
high drifts slowly to the east-southeast. Mainly clear skies are
expected into the overnight hours (other than a little high-level
wildfire smoke above about 700 mb per HRRR cross sections), though
some increase in high cirrus is possible into Wednesday morning off
of convection well upstream across MN. Overnight lows will dip into
the low-mid 50s in some inland cool spots, and the upper 50/low 60s
into the metro. Dry and warmer weather persists Wednesday, though
with perhaps a little more high cloud at times as warm advection
develops into the Mississippi Valley.
Ratzer
&&
.SHORT TERM...
Issued at 222 PM CDT Tue Jul 18 2023
Through Wednesday...
Very little to speak on here in the short term. A couple of very
light, isolated showers have managed to clip our far southern CWA
early this afternoon, namely the southern portions of Livingston,
Ford, Iroquois, and Benton counties. These showers developed on the
northern flank of a rather robust storm system that`s bringing
severe weather to far southern IL. As the system continues its trek
southeastward, it will pull these showers out of the CWA likely
before the evening rolls around. The diurnally-driven fair weather
cumulus that we see overhead this afternoon will fizzle away through
the evening leaving us with mostly clear skies tonight. Low
temperatures early tomorrow morning should once again drop into the
mid-upper 50s and lower 60s in and near the city.
Tomorrow morning, the remnants of a storm system currently brewing
up in Minnesota is expected to move over the CWA. The HRRR is
consistently resolving a few morning showers north of I-80. However,
it`s the only model that brings any precip through the area. The
reason being the HRRR is notably more aggressive with the mid level
moisture advection tomorrow morning than any other model. However,
even if we were to saturate the mid levels like it`s suggesting we
will, this plume of moisture will be moving into a region of higher
pressure with little to no forcing at play. Plus, forecast
soundings, including on the HRRR, have the low levels being so dry
tomorrow morning that any precip that does manage to get stirred up
aloft likely won`t make it to the surface. Rather, most soundings
look more conducive of a bit of an uptick in mid level clouds during
the morning. More fair weather cumulus can be expected to build into
the afternoon tomorrow with highs forecast to reach the middle to
possibly upper 80s.
Doom
&&
.LONG TERM...
Issued at 312 PM CDT Tue Jul 18 2023
Wednesday night through Tuesday...
The main focus through the next few days revolves around
thunderstorm chances with a cold front late Wednesday night into
Thursday afternoon, with some storms possibly becoming strong to
severe. A strengthening mid-level wave within general WNW flow
will rotate across the CWA during this time in association with a
upper jet streak entering Iowa into western Illinois. While a
severe thunderstorm risk exists late Thursday morning into mid-
afternoon, potential will be conditional on timing, alignment of
forcing, and sufficient low-level moisture. The juxtaposition of
better forcing (far northern Illinois into Wisconsin) and minimal
MLCIN (toward central IL and northwest IN), may allow for robust
thunderstorm development along the cold front as far west as the
I-55 corridor late in the morning. Surface dew points will be
quite sensitive to initiation, with the difference between upper
60s or low 70s favoring little convection to scattered severe
convection, respectively. Generally straight hodographs with
decent deep layer shear would support strong winds and damaging
hail with multicell clusters and/or splitting supercell behavior.
Forecast refinements will be needed over the next couple days
given these subtle differences in moisture and timing.
A continued train of weaker shortwave troughs within a a deeper
low over Hudson Bay will bring additional shower and storm chances
through the weekend. The first wave will remain generally
moisture- starved and pass during an unfavorably diurnal period
late Friday night into Saturday, so will maintain just slight
chance PoPs. Better moisture prospects will return Sunday into
Monday and additional chances of showers and storms, especially
Sunday afternoon and evening.
Kluber
&&
.AVIATION...
For the 00Z TAFs...
A lake breeze boundary continues to move inland from Lake
Michigan and is now passing DPA. The northeast winds in its wake
will diminish and turn more southeasterly toward or soon after
sunset. Winds from mid evening through the overnight will
generally be light and variable then increase modestly later
Wednesday morning. Expect to see a more southeasterly direction
Wednesday with the exception of GYY where a lake breeze will
likely turn winds northeasterly.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Saint Louis MO
741 PM CDT Tue Jul 18 2023
.SHORT TERM... (Through Late Wednesday Afternoon)
Issued at 738 PM CDT Tue Jul 18 2023
Have issued a Flash Flood watch from 10 pm tonight to 7 am Wednesday
morning for the southern CWA. Parts of Crawford, Reynolds, Iron,
and Madison counties saw 1-2+ inches of rainfall earlier today which
have partially lowered FFG in those areas. Latest runs of the RAP
continued to show that a broad 30 knot low level jet will cause
low level moisture convergence beneath the entrance region of a
subtle upper jet streak late tonight. The CAMS including the HRRR
have been consistently been developing training cells across
southeast Missouri late this evening and overnight. The RAP forecast
sounding at FAM after midnight is showing PWATS over 2" with deep
warm cloud depths which will be conducive to very heavy rainfall
rates. The 12 HREF LPMM and 18Z NAM Nest are showing isolated
rainfall amounts of 3-5+ inches increasing the need for a watch.
Britt
.LONG TERM... (Thursday through Next Tuesday)
Issued at 323 PM CDT Tue Jul 18 2023
Once again by Thursday afternoon, morning convection is expected to
be east of the area, and the remainder of the day is likely to
remain humid but largely free of convection thanks to continued
convective inhibition. By the evening and overnight, a cold front is
expected to slowly sink into the area, while another shortwave
arrives from the west. Once again this shortwave may be accompanied
by ongoing convection, which may impact the region during the
overnight and early morning hours. Again, very little confidence
exists regarding exactly which areas will be impacted and how
significant it will be, but much like the previous night there will
be a preference for areas along and south of I-70 and very near the
advancing cold front.
By Friday morning this cold front is likely to be south of the
region, but there is enough uncertainty in its position that we have
maintained some chances of showers and thunderstorms into the
afternoon Friday along and south of I-70. More likely, though, is
that this front will clear the area by the afternoon, bringing
milder and drier conditions that will likely continue into Saturday.
While the pattern is expected to remain largely static into the
early next week, additional opportunities for showers will exist,
albeit with a more limited potential for significant rain
considering the overall reduction in quality moisture.
BRC
&&
.AVIATION... (For the 00z TAFs through 00z Wednesday Evening)
Issued at 629 PM CDT Tue Jul 18 2023
Expect showers and thunderstorms to develop and affect COU, JEF,
STL, CPS, and SUS late this evening and overnight. Any of these
storms will be capable of reducing ceilings and visibilities to
MVFR or possible IRF conditions in heavy rain at times. Also
expect MVFR ceiling to move into these same airports after 06Z and
remain through mid morning on Wednesday. Winds are expected to be
mainly out of the east under 10 knot outside of thunderstorms.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch until 7 AM CDT Wednesday for Crawford MO-Iron MO-
Madison MO-Reynolds MO-Saint Francois MO-Sainte Genevieve
MO-Washington MO.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Memphis TN
833 PM CDT Tue Jul 18 2023
...New UPDATE...
.UPDATE...
Issued at 820 PM CDT Tue Jul 18 2023
A couple rounds of severe storms impacted the Mid-South earlier
this afternoon into the evening resulting in wind damage across
the region and widespread power outages in the Memphis metro.
Storms have just about exited the region and the next few hours
should be relatively quiet. The Mid-South continues to sit between
a hot/humid airmass associated with the upper ridge to the SW of
the region and the upper trough over the Great Lakes/NE US
regions. As a result we will see bouts of heat along with chances
for storms over the next couple of days.
The latest CAMs do show convection developing once again across
the western OH Valley later tonight. This activity will stay
mostly north of the area through sunrise, perhaps affecting Henry
County, before sagging into West TN near the TN River during the
morning hours.
Heat Advisories and Excessive Heat Warnings have been issued for
Wednesday for the entire Mid-South. Recent rains will only serve
to increase the humidity tomorrow. Avoid outdoor activities if
possible tomorrow.
.SYNOPSIS...
Issued at 250 PM CDT Tue Jul 18 2023
A complex of showers and thunderstorms will affect portions of the
Mid-South mostly across portions of west Tennessee near the
Tennessee River into this evening with a few strong to severe
thunderstorms possible through early evening. Additional showers
and thunderstorms are possible Wednesday and Thursday mainly north
of I-40, then gradually spreading across the remainder of the
Mid-South for Friday into Saturday as a weak cold front moves into
the Lower Mississippi Valley. Very hot and humid conditions will
persist ahead of the approaching cold front with heat index values
ranging between 105 to 115 degrees on Wednesday.
&&
.DISCUSSION...
(This evening through next Monday)
Issued at 250 PM CDT Tue Jul 18 2023
GOES-16 Satellite trends depict a mature Mesoscale Convective
System (MCS) over portions of southeast Missouri and western
Kentucky. KNQA/KPAH WSR-88D radar trends show the leading edge of
convection over portions of the Missouri Bootheel and Northwest
Tennessee gradually propagating east-southeast with time.
Otherwise, a hot and humid airmass is in place across the Mid-
South with surface temperatures mainly in the lower 90s with
surface dewpoints in the 70s to lower 80s as low-level moisture
pools ahead of a quasi-stationary boundary located along the I-70
corridor. Strong to severe thunderstorm and heat concerns remain
the primary focus in this afternoon`s forecast issuance.
The aforementioned MCS will continue to propagate east-southeast
into the Tennessee Valley through this evening. Additional showers
and thunderstorms are possible along the southern periphery of
this system for areas mainly north and east of a line from
Blytheville, AR to Jackson and Savannah, TN. Surface-based CAPE
values around 5000 J/kg, moderately-steep 700-500 mb layer mid-
level lapse rates around 6.5 C/km, 0-6 km Bulk Shear values around
40 kts may support a strong to severe thunderstorm threat for the
remainder of the afternoon into perhaps early evening. Damaging
winds will be the primary threat for any thunderstorms that become
severe. QPF values across portions of northwest Tennessee near the
Tennessee River may receive 1 to 2 inches of rain through late
tonight. Confidence is low that these areas will exceed Flash
Flood guidance and subsequently held off on any flood watches for
the time being.
Elsewhere, the Heat Advisory and Excessive Heat Warning for areas
around and southwest of Memphis along the Mississippi River will
continue through early this evening. Lows tonight will remain
quite warm this evening. A very hot and humid airmass is expected
to build across the Mid-South on Wednesday as temperatures rise
into the middle to upper 90s. These very hot temperatures combined
with surface dewpoints pooling across the region will result in
heat index values rising to between 105 to 115 degrees with the
warmest readings occurring mostly along and west of the
Mississippi River. An Excessive Heat Warning was issued for areas
along and west of the Mississippi River and a Heat Advisory for
the remainder of the forecast area from noon through 8 PM
Wednesday. Additional showers and thunderstorms will be possible
Wednesday and Thursday with the
Latest mid to long range model solutions indicate the surface
boundary will begin to move south into the Lower Mississippi
Valley Friday into Saturday as mid-level heights weaken and a
series of shortwaves move through the northwest flow aloft. This
will bring a better chance for showers and thunderstorms for most
of the forecast area. Cooler and slightly drier air will build in
for late weekend into early next week.
CJC
&&
.AVIATION...
(00Z TAFS)
Issued at 632 PM CDT Tue Jul 18 2023
Ongoing convection may cause intermittent gusty winds and
temporarily reduce visibilities/ceilings for the next few hours
at all sites except JBR where it has already passed. Otherwise,
mostly VFR conditions are expected to prevail through the period.
Throughout the overnight period, southerly winds should stay
elevated enough around 10 kts to preclude any fog development.
There may even be some LLWS from the southwest at JBR and MKL
around 40 kts overnight. By mid morning tomorrow, another MCS is
expected to eject over west TN. MKL is the only site with any
confidence of impacts at the terminal. The HRRR is the farthest
west CAM solution and just barely clips MKL, but trends over the
last few days have proven guidance to be fairly unreliable with
the locations of these MCSs so opted to include a PROB30 for TSRA
at MKL tomorrow. MEM may experience some light precip on the
outskirts of the MCS, thus warranting the VCSH tomorrow afternoon.
Winds are expected to increase to 12-14 kts tomorrow afternoon
with intermittent gusts up to 22 kts and shift more to the
southwest.
CAD
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Excessive Heat Warning from noon to 8 PM CDT Wednesday for
ARZ009-018-026>028-035-036-048-049-058.
MO...Excessive Heat Warning from noon to 8 PM CDT Wednesday for
MOZ113-115.
MS...Excessive Heat Warning from noon to 8 PM CDT Wednesday for
MSZ001-007-008-010>012-020.
Heat Advisory from noon to 8 PM CDT Wednesday for MSZ002>006-009-
013>017-021>024.
TN...Excessive Heat Warning from noon to 8 PM CDT Wednesday for
TNZ001-019-048-049-088.
Heat Advisory from noon to 8 PM CDT Wednesday for TNZ002>004-
020>022-050>055-089>092.
&&
$$
PUBLIC FORECAST...SJM
AVIATION...CAD
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
849 PM EDT Tue Jul 18 2023
.SYNOPSIS...
Troughing will strengthen to the west this week with high pressure
offshore. Scattered thunderstorms are expected Wednesday
afternoon into Wednesday evening, some of which have the
potential to become severe. A cold front will then move into
the area this weekend, but may stall over, or just offshore
through early next week.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 8 PM Tuesday...Hazy skies continue to be reported at many
sites across ENC early this evening but HRRR smoke guidance
shows improving conditions through the evening. Otherwise, a
quiet night is in store with light SW winds persisting, which
should limit fog development.
Previous discussion...Have removed any mention of showers or
storms for the rest of the evening and overnight period. The
haze that has been hanging around all day will continue to clear
out from W to E this evening. Benign conditions are expected
with warm and muggy lows in the 70s region-wide. Light Variable
winds this afternoon and evening will become predominantly
SWerly overnight, although light, but should keep the lower
levels mixed enough to get rid of any fog threat. Of course,
sheltered areas may be shallow, patchy ditch fog.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
As of 1630 Tuesday...Mid and upper level troughing early Wed
with the base of the upper level trough flattening out relative
to how amplified it has been once the main shortwave travels
just N of the FA early, turning flow aloft more zonal. In the
afternoon, a midlevel shortwave traverses the FA. At the SFC,
pressure gradient tightens between troughing inland and the high
offshore leading to a strengthening SWerly breeze through the
day. Two separate rounds of convection will be possible,
starting in the early afternoon over the coast where showers and
perhaps a few tstorms will develop along the seabreeze. Mid to
late afternoon, in conjunction with the passage of the midlevel
shortwave, storms are expected to blossom over the Coastal Plain
propagating from W to E into and through the FA. With typical
July instability and some midlevel support, some of these later
storms have the potential to become severe with damaging winds
being the greatest threat. With that said, should the skies
remain clear through the morning and early afternoon, greater
instability will develop which would increase the threat for
hail development in the cells with the strongest updrafts. This
will be dependent on how long debris clouds from a decaying MCV
working toward the East Coast from lower Ohio River Valley
overnight tonight will last into the morning. Highs will be
highly dependent on the aforementioned cloud coverage, or lack
thereof, and timing/coverage of rain. For now, have opted for
the clearer solution early which will allow highs to reach into
the mid 90s, highest HWY17 corridor, upper 80s-90 beaches where
the seabreeze will provide some relief. With Tds in the mid 70s,
heat indices will be in the 100-105 range. Highest heat indices
will be coastal areas just ahead of the seabreeze where 105 is
expected, but expecting these values to be relatively short
lived so have opted to not go with heat advisory here.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
As of 400 PM Tuesday...
BOTTOM LINE UP FRONT: Medium range guidance continues to suggest the
return of unsettled conditions across the coastal Carolinas from mid-
week into the weekend. It still appears likely that a front will
move into/through the area this weekend, but this may not
necessarily signal the end to the unsettled weather. Temperatures
will be near to above normal through Friday, then trend back down
closer to, or even below, normal over the upcoming weekend.
FORECAST DETAILS
The Midweek to Friday period continues to look like a good
candidate for an above-climo coverage of convection, but there
are notable caveats. The primary driver of the increased
convective potential will be shortwaves/MCVs, embedded within a
WNW flow pattern aloft, interacting with a moist and unstable
airmass across the Carolinas. The CAPE/shear combination during
this period is notable, but not strikingly concerning. That
said, the potential is there for an increased risk of
thunderstorm organization each day, with the coverage of
convection highly dependent on the track of each MCV, and
possibly augmented by any previous day/early morning convection.
Those caveats lead to lower confidence regarding the severe
weather threat. The key message during this period is that an
increased risk of convection is anticipated during this
timeframe, with at least some potential for strong to marginally
severe thunderstorms. Temperatures during this period will also
be highly dependent on storm coverage, but warm thicknesses and
more of a SW or W surface flow should support above normal
temps and heat indices of 100-105. The highest heat indices may
actually be focused along our coastal areas where dewpoints will
be highest. Due to uncertainties with convective coverage and
how high the dewpoints will be, we`ll plan to hold off on any
heat headlines for now.
Over the weekend, medium range guidance continue to insist on a
front moving into the area, but potentially stalling over, or just
offshore. Meanwhile, a broad and anomalous trough is forecast to
develop over the Eastern US, putting the coastal Southeast in a SW
flow pattern aloft. This potentially sets the stage for continued
unsettled weather as low-level waves ride along the stalled frontal
boundary. If the front stalls offshore, the focus for precip would
tend to be along the coast. If the front stalls closer to the coast
or just inland, the risk of precip would extend further inland as
well. For now, the key message over the weekend and into early next
week is that "cooler" temps are expected, but not necessarily drier
conditions.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
SHORT TERM /through Wednesday/...
As of 8 PM Tuesday...Hazy skies with MVFR vsbys continue to be
reported at many sites across ENC early this evening but HRRR
smoke guidance shows improving conditions through the evening.
Otherwise VFR conditions will prevail through much of the TAF
period. Light mixing is expected to continue overnight which
will limit fog development. Some guidance is suggesting the
possibility of light fog but believe it is contaminated by the
reduced vsbys that prevailed much of the day today. Scattered
showers and storms expected to develop Wednesday afternoon which
could bring periods of sub-VFR conditions. SW wind gusts around
15-20 kt are also expected Wednesday afternoon.
LONG TERM /Wednesday Night through Saturday/... As of
400 PM Tuesday...There will be an increased risk of TSRA mid to
late week, along with an increased risk of sub-VFR conditions,
across Eastern NC. This potential may extend into the upcoming
weekend, but the forecast becomes less certain during that time.
Outside of the TSRA potential, there will be periods of gusty
winds Wednesday-Friday.
&&
.MARINE...
SHORT TERM /through Wednesday/...
As of 830 PM Tuesday...High pressure offshore and diurnally
strengthening thermal trough across the piedmont is bringing a
typical summertime pattern of stronger winds during the late
afternoon and evening hours with some late night and morning
relaxing of the pressure gradients. As such, SW winds have
increased to around 10-20 kt late this afternoon which are
expected to persist until after midnight. Winds are then
expected to diminish to around 10-15 kt through Wednesday
morning before re-strengthening to 15-20 kt in the afternoon.
Some gusts up to 25 kt are possible, but are not expected to be
frequent or widespread enough to warrant SCAs. Seas currently
around 2-3 ft are expected to build to 3-4 ft overnight and
Wednesday. There is an underlying long period 1-2 ft 15sec swell
impacting the waters with a 2-3 ft wind chop
LONG TERM /Wednesday Night through Saturday/...
As of 400 PM Tuesday...There may be some continued long period
swell impacts from distant Tropical Storm "Don" this week,
otherwise seas of 2-4 ft will be common through late week, with
breezy southwesterly winds of 15-25kt. There`s some potential
for near-SCA level winds mid-week, especially for portions of
the central and southern coastal waters. Lastly, there will also
be an increased risk of thunderstorms through at least Friday,
and potentially lasting into the weekend as a weak cold front
moves into the region.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...MHX
NEAR TERM...SK/TL/CEB
SHORT TERM...RM/CEB
LONG TERM...RM/JME
AVIATION...RM/SK/CEB
MARINE...RM/CEB/SK
Area Forecast Discussion
National Weather Service Paducah KY
905 PM CDT Tue Jul 18 2023
.UPDATE...
Issued at 905 PM CDT Tue Jul 18 2023
01z Sfc analysis shows a convectively enhanced front running from
about Mountain Home, Arkansas to Memphis. Persistent northwest
flow is deepening lee surface troughing to our west as a jet max
emerges off the northern Rockies. This system is expected to lead
to a lower level response that will increase 850mb to surface flow
over Arkansas over the southwest over the next few hours,
leading to low level convergence and frontogenetic forcing that
is expected to initiate thunderstorms as it moves northeast. 00z
SGF and satellite derived sounding parameters show mid-level lapse
rates around 7.2 C/km and MUCAPE for elevated parcels in SEMO
remains about 3000 J/kg. As lower level moisture moves northeastward
more of the region should become unstable, at least to elevated
parcels and a flash flood threat is expected to emerge due to
training convection. Still think the HRRR is perhaps a bit too far
northeast with the placement of peak activity.
I think the potential remains that convective overturning was
sufficient to mitigate the intensity of storms somewhat, but the
satellite derived soundings don`t seem to show any mid level
subsidence or warming behind today`s earlier convection. Also
watching the northern edge of the rainfall area today as a thermal
boundary sits there, but it won`t have the same FGen forcing as
flow increases from the southwest.
Essentially looks like about 60-70% probability of flash flood
warning level events overnight in the area, 20-30% probability of
considerable level events somewhere. I`d give a 20-30% chance that
we are just a little too worked over even for elevated parcels to
fully realize available instability and moisture resulting in a
lower-impact event. I`d also be watching for the event to start a
little delayed given the current frontal positions, perhaps after
midnight or later.
UPDATE Issued at 527 PM CDT Tue Jul 18 2023
Expanded the flood watch to the rest of SEMO based on the
currently analyzed position of a convectively induced boundary
expected to act as a focusing mechanism for shower and
thunderstorms tonight. Where those storms and that boundary set up
will determine where any flood risk will set up as it will
probably be a pretty narrow corridor but its simply impossible to
pin down where with any skill at this range.
&&
.SHORT TERM...(Tonight through Thursday night)
Issued at 310 PM CDT Tue Jul 18 2023
Primary concern in the short term is with heavy rain/flash flooding
potential overnight along with some severe threat.
An intense bowing MCS plowed across the southern half of the region
early this afternoon. Any severe threat with it will exit our
southeast counties by 21z. Lingering stratiform rain and elevated
convection will continue to stream southeast from Missouri across
portions of the region. Thereafter, a lull is expected during the
early evening.
As a boundary sets up across the region this evening and overnight,
storms are expected to fire up by mid-late evening. Initiation looks
to be somewhere in the 03-05z period with orientation in a NW-SE
band. The overall flow looks to allow training convection that may
slowly pivot eastward with time, before possibly shifting back west.
As the low level jet ramps up, pwats increase into the 2 to 2.3"
range. Soundings indicate a deep warm cloud layer with very
efficient rainfall production expected. 12z CAMs continue to
struggle with exact placement of the heaviest rainfall amounts, but
generally expect them to be focused somewhere across west KY at the
very least. The Flash Flood Watch was given a wide areal extent to
account for the uncertainty. The probability matched mean from the
12z HREF shows 3-5" totals, with the possibility of localized 5-7"
amounts.
Given what occurred today, the chances of surface based storms
seems rather low overnight. But some large hail potential exists
due to steep mid level lapse rates and a sizable amount of MUCAPE
present. If something can manage to organize, a few stronger wind
gusts can`t be ruled out. Flooding and hail potential appear to be
the main two threats though.
Some lingering convection in the morning should quickly dissipate or
move out of the region leaving behind what appears to be a primarily
dry day. West-northwest flow remains in place though, so wouldn`t be
surprised to see some additional activity fire up by evening. Most
guidance initiates more convection by Wednesday night or especially
on Thursday as another piece of energy moves through. Decent deep
layer shear remains in place along with plenty of instability. Thus,
we will need to monitor for additional severe storms during the day
on Thursday.
.LONG TERM...(Friday through Tuesday)
Issued at 310 PM CDT Tue Jul 18 2023
Models have been struggling on where the boundary will be located on
Friday, which dictates whether are region is largely dry or yet
another day of showers and storms to deal with. For now kept in the
NBM chance PoPs.
Dry high pressure moves down across the region on Saturday with
highs only reaching the low to mid 80s along with much lower
humidity levels (dewpoints upper 50s to lower 60s). The entire
weekend may not end up dry though, as 12z guidance hints at vort
energy diving down the backside of the large trough across the Great
Lakes/Ohio Valley on Sunday. Daily rain chances continue into next
week as we remain in northwest flow with troughing to our east and
the sweltering heat ridge across the southwest U.S.
&&
.AVIATION...
Issued at 623 PM CDT Tue Jul 18 2023
Reasonably good conditions expected for the next few hours but
thunderstorm redevelopment is forecast tonight. We are expecting
storms to form from northwest to southeast and train over the same
area. Exactly where that will set up is obviously impossible to
pin down exactly but if terminals are impacted there could be
several hours of thunderstorm conditions at any given site. On the
other hand sites could go through the overnight roughly rain free
with prevailing VFR. Will be amending the TAFs for trends as it
gets closer and we can get a better bead on where things will set
up.
Tomorrow looks better with moderate southwesterly winds and VFR
flight conditions through the day.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Flood Watch through Wednesday morning for ILZ084>094.
MO...Flood Watch through Wednesday morning for MOZ076-086-087-100-
107>112-114.
IN...None.
KY...Flood Watch through Wednesday morning for KYZ001>022.
&&
$$
UPDATE...JGG
SHORT TERM...SP
LONG TERM...SP
AVIATION...JGG
Area Forecast Discussion
National Weather Service Pittsburgh PA
921 PM EDT Tue Jul 18 2023
.SYNOPSIS...
The risk for isolated to scattered showers and thunderstorms
will continue through Wednesday as a frontal boundary meanders
through the region. More widespread activity is possible late
Thursday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
A deep layer of dry air aloft and minimal forcing have kept a
lid on shower/storm development through the evening, even in
the presence of a weak boundary across southwest PA. However,
coverage has started to improve over the past hour thanks to an
approaching shortwave trough. The best instability/shear will
continue to lie to the south and of course decrease with time,
but precipitation coverage should continue to increase for a
couple hours as the wave crosses. Upped PoPs just a bit,
especially across the southern counties. There remains virtually
no chance of severe weather from this activity.
The weak frontal boundary, meandering over the north, will
drift southward tonight and stall almost halfway through the
forecast area by Wednesday morning.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
Another weak shortwave will swing through the region Wednesday
afternoon and should be just strong enough to finally kick the
front just to the south and east of the forecast area. Any
activity on Wednesday looks to be in close proximity to the
boundary and should be rather isolated. Thus, will keep pops
mainly to along and south of I-70.High temperatures will be
very close to seasonal values.
Meanwhile, the shortwave moving into the region on Thursday
seems a bit more rigorous as the 500MB trough passing across the
OH Valley as a trough seems progged for around 18Z but timing in
other models calls this into question and let alone for
initiation. Nevertheless, the HRRR and other HI-RES CAMs keep
most notable instability into the region on Thursday afternoon
and into the evening with most notable 30 knots effective shear
in eastern OH. Thus, SPC has introduced a slight risk into
eastern OH. Will expected the main threat to be damaging winds.
The other concern will be a heavy rainfall threat as PWATs into
eastern OH will be roughly 1.6 to 1.8. Thus, WPC has introduced
a slight risk for ERO. Have input these 2 concerns in the HWO.
Timing on convection has a low confidence overall on Thursday
and given a bit too late may lessen the impact of convection.
Will need to stay tuned for further updates and outlooks.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
The long wave pattern remains stagnant with a broad mid level trough
over the Great Lakes region. This will continue the pattern we have
been in for the large part of the summer. GEFS and EPS are in a
strong consensus with the height fields. Ensemble tables still
illustrate +2 standard deviation in the U wind component with above
normal flow at H7 - H3 at mid levels. Forecast speeds around 40
knots most of the long range at H5.
What does this mean? Well, more of the same with weak shortwave
troughs kicking off showers and storms especially if the timing is
right during peak heating hours.
Above average confidence in max and min temperatures with H8
temps not deviating much. Highs will be just below normal values
with 70s widespread.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
Showers and thunderstorms are struggling to develop this
evening with a notable ridge in the mid-lvls and weak surface
instability. Left mention of convection out of TAFs and kept
VCSH only at terminals that are near ongoing isolated showers,
which should dissipate over the next few hours.
Remnant moisture and radiational cooling will prompt patchy fog
development overnight tonight, with MVFR cigs/vis possible
especially at climatologically-favored terminals in/near river
valleys.
VFR conditions prevail tomorrow, though a few showers and
storms could develop generally along and south of I-70 which
would result in brief periods of lower cigs/vis at impacted
terminals.
.OUTLOOK...
Persistent eastern U.S. trough will foster continued shortwave
advection through the Upper Ohio River Valley through the week,
creating periods of showers/thunderstorms and restrictions.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Shallenberger
NEAR TERM...CL
SHORT TERM...Shallenberger
LONG TERM...Shallenberger
AVIATION...Cermak
Area Forecast Discussion
National Weather Service Pueblo CO
857 PM MDT Tue Jul 18 2023
.UPDATE...
Issued at 857 PM MDT Tue Jul 18 2023
Update to allow the Heat Advisory to expire on time, as
temperatures have cooled to below dangerous levels.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 350 PM MDT Tue Jul 18 2023
1) Hot conditions and isolated shower and thunderstorm chances
continue into the evening.
2) More widespread thunderstorm chances on Wednesday, along with
the risk of severe storms across the plains.
Hot conditions with mainly dry weather ongoing across southern
Colorado at this time, as 700mb temps around 20C are in place. In
this environment, many locations along the I-25 corridor from Pueblo
south are in the low 100s. Elsewhere, most locations are in the mid
to upper 80s and 90s. Did increase high temperatures this afternoon,
but no big changes to the current Heat Advisory in place, with
conditions improving by mid evening. Still potential for at least
isolated 5showers and thunderstorms this afternoon into the
evening time frame, as some passing mid level impulses move
overhead and as a low level easterly component into the higher
terrain is in place. While that is the case, any development over
the higher terrain and into the I-25 corridor will likely struggle
given the drier air along with westerly winds and hot temps at
700mb. Did keep low chance pops over the Pikes Peak region/Palmer
Divide, where slightly greater focus could support some higher
potential for showers and thunderstorms. In this location, gusty
outflow winds will likely accompany any thunderstorm.
Further to the east across the plains, much higher dewpoints right
along the CO/KS border are helping support some rather concerning
CAPE values. In this location and at this time, SBCAPE is
approaching 5000 j/kg. RAP analysis is also showing high amounts of
CIN in place, which some guidance indicating won`t likely erode.
This seems reasonable especially with the strong capping/high 700mb
temps in place. So, while this instability and higher moisture is in
place over the far eastern plains, this capping and generally
lacking surface trigger should limit thunderstorm development here
as well into the evening hours. There is some indication of better
lee troughing over east central and northeast Colorado late today.
If so, this could potentially offset the limiting factors and help
with a few more storms this evening. Latest HRRR run is showing this
trend and think locations from northern Bent, northern Prowers, and
into Kiowa county could see an isolated severe storm or two. If any
severe storms were to tap into this energy, large hail in the 1-2
inch range and wind gusts up to 70 mph would be possible.
Slightly cooler conditions on Wednesday, though temperatures well
into the 90s still expected over much of the plains. Temps in the
upper 80s to around 90 expected over the San Luis Valley, though
don`t look to be high enough to support the need for an additional
Heat Advisory. Thunderstorm chances, coverage, and intensity all
increase on Wednesday as increases in moisture, low level focus, and
upper level support are expected. An earlier start time is expected,
with development over and near the mountains possible as soon as
midday. Development is then expected to move into the I-25 corridor
during the afternoon hours where it will encounter CAPE in the 500-
750 j/kg range and shear in the 30-40kt range. Some potential for
pockets of higher instability, that will support the risk of severe
storms in this location, and with similar conditions over most of
the plains, this risk will extend there as well. In these locations,
think one inch hail and wind gusts to 60 mph will be the main risks.
Later in the day and further to the east, along and east of a Kim to
Lamar line, much higher instability will be in place and will
support the risk of higher intense storms. Think hail two inches or
higher and wind gusts to around 70 mph will be possible with any
severe storm.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 350 PM MDT Tue Jul 18 2023
Key Messages:
1) Strong to severe storms and locally heavy rainfall across
southeast Colorado Thursday.
2) Cooler temperatures through the end of the work week with
warmer and drier weather for the weekend.
3) Signs of the "monsoon" next week?
Wednesday night-Friday night...Ongoing strong to severe storms
across the southeast plains late Wednesday afternoon and evening
looks to send a re-enforcing surge of low level moisture back across
the area Wednesday night, with the potential for stratus early
Thursday morning across the I-25 Corridor and plains. Latest models
continue to indicate dew pts remaining in the mid 50s to mid 60s
across southeastern Colorado, with SBCAPE of 1500-2500 j/kg in place
through the afternoon. This, along with a progged short wave within
the northwest flow aloft across the Rockies will lead to the
potential for strong to severe storms producing large hail and
damaging winds across much of southeast Colorado on Thursday. In
addition, with expected increasing available moisture as PWATS
approach 150 percent of normal, heavy rain and localized flash
flooding will also be possible, especially as storms merge into an
MCS across the southeast plains through the late afternoon and
evening. With that said, SPC`s Day 3 slight outlook for severe
weather and WPC`s Day 3 slight outlook for excessive rainfall across
southeast Colorado look good. Further west, with only a slight
increase in available moisture, could see a isolated to scattered
afternoon and evening showers and storms on Thursday, with
convection expected to be higher based.
Ongoing convection across the southeast plains Thursday evening
sends another surge of moisture back across the area, with stratus
possible again Friday morning. On Friday, the best moisture and
instability looks to be shunted across the southern tier of Colorado,
with cooler temperatures looking to keep the far southeast plains
too stable. With that said, will likely see showers and storms
developing over the higher terrain, especially across the southern
mountains Friday afternoon, with storms trying to push east into the
more stable atmosphere across the I-25 Corridor and plains. Friday
looks to be the coolest day of the week.
Saturday-Sunday...Upper high across the Desert SW builds into the
Four Corners region through the weekend, bringing warmer and drier
weather to the area, with isolated to scattered high based showers
and storms possible over and near the mts. Temperatures to warm to
at and abo5ve summer seasonal levels through the weekend.
Monday-Tuesday...Operational models and ensemble data continue to
indicate the possible start of the monsoon, as the upper high is
shunted southeast of the area with PWATs progged to increase to at
and slightly above seasonal levels. This will lead to s slow
increase in shower and thunderstorm activity across the higher
terrain through the period, with some concern of critical fire
weather conditions with initial dry lightning potential across
western and into south central Colorado. Temperatures look to
remain at and above seasonal levels through early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 350 PM MDT Tue Jul 18 2023
No big change in thinking at the start of the forecast period,
with an isolated shower or storm remaining possible across COS and
PUB early this evening. Still don`t think any widespread
thunderstorms are possible, but an isolated storm capable of
producing gusty winds will remain possible. Conditions across ALS
will continue to be dry, with this continuing tonight into
Wednesday morning. Additional shower and thunderstorm chances
return by midday Wednesday at all sites. While chances will be
highest across COS and PUB, ALS will have the potential to observe
a window of showers or storms Wednesday afternoon. Development
could start earlier, with potential impacts beginning as soon as
early afternoon. Additional forecasts will likely need to include
more prevailing conditions especially for COS and PUB, potentially
through the end of the forecast period.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...EHR
SHORT TERM...RODRIGUEZ
LONG TERM...MW
AVIATION...RODRIGUEZ
Area Forecast Discussion
National Weather Service Raleigh NC
924 PM EDT Tue Jul 18 2023
.SYNOPSIS...
A weak surface trough will hold over the North Carolina Piedmont
through mid week, as a warm and humid air mass persists over the
region.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 924 PM Tuesday...
The evening surface analysis shows a cool frontal boundary draped
across the Mid-Mississippi Valley into the lower Great Lakes.
Dewpoints behind the front ranged from the upper 50s to mid 60s.
Haze associated with smoke continues to be observed over portions of
the Sandhills and Coastal Plain. The latest HRRR smoke shows this
haze improving overnight and tomorrow morning, though some patchy
haze will likely persist into Wed. While otherwise high pressure was
present across the SE US, including NC, a series of MCVs
(thunderstorm complexes) were well evident on satellite/radar. One
MCV was present over central/eastern KY, a second and more
noticeable over eastern TN, and a third moving into northern MS/AL.
The latter MCV is the strongest at the moment, moving into a more
favorable region of instability with dewpoints in the upper 70s to
near 80. The one MCV over eastern TN is progged by the last few runs
of the HRRR to track into the NW Piedmont of central NC overnight,
then into south-central VA to the far northeast Piedmont by sunrise
Wed.
Convection was ahead of these MCVs over the NC Appalachians tied to
a lee trough but this activity has since weakened in the last few
hours. While the aforementioned MCV should continue to weaken as it
tracks eastward overnight, moving into drier air and a more stable
environment, models show persistent low-level 850-mb WAA, which
would support chances of isolated showers/storms across the western
Piedmont, including the Triad, as the MCV moves east. The 00Z GSO
sounding showed nearly 1000 J/kg of elevated instability. Models
show this instability persisting overnight, which should support
storm chances as mentioned. Isolated showers or a few storms may
extend as far east as the US-1 Corridor/Triangle shortly before
sunrise but coverage should be much less than the Triad. Overnight
lows will be in the low to mid 70s, coolest in the NW and warmest in
the SE.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
As of 220 PM Tuesday...
The main weather story for Wednesday will be the remnants of
tonight`s thunderstorm complex (as noted in the near term disc) and
to what extent thunderstorms redevelop across central and eastern NC
during the afternoon.
The HREF members to varying degrees show showers and tstms
reigniting across central and eastern NC in assoc with the MCV
drifting across the state and taking advantage of daytime heating.
One limiting factor may be the presence of cloud cover during the
morning from earlier convection and what limits those cloudy have on
instability. Currently our CWA is included in SWODY2 marginal risk
with damaging wind gusts the primary threat with any storms that
grow to become severe. The general consensus among the CAMs show a
line of showers and tstms developing around mid-day across the
eastern Piedmont and I-95 corridor, then intensifying as the storms
move east of I-95 during the mid to late afternoon. High temps will
be dependent on cloud cover and rain location and timing. For now,
we have stuck close to climo which is highs from the upper 80s
across the Triad to lower 90s across the Coastal Plain. If the rain
does move through during the afternoon across the eastern half of
our CWA, that could result in the warmest readings across our
western Piedmont zones, which is expected to mostly avoid the shower
and tstms development during the afternoon. Lows Wednesday night in
the lower 70s.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 325 PM Tuesday...
A Piedmont trough develops over the region on Thursday which will
increase chance showers Thursday and Friday afternoon/evening.
Temperatures these days will range from low 90s in NW to mid 90s SE.
With dew points forecast to be in the mid to upper 70s especially in
the afternoon this will result in heat indices of 100 in the
triangle region to 108 in the Sandhills and Coastal Plain region
both days. Thus a heat advisory may be issued for the Triangle
region south on Thursday and possible Friday. Also, Thursday SPC has
the far SW portion of the FA in a D3 slight risk for severe
thunderstorms, with the main hazard being damaging wind gusts. As
the trough moves over the region especially on Thursday afternoon
some destabilizing along the boundary could develop a few organized
multicells. Expecting more scattered coverage rather than
widespread.
Over the weekend strong surface low over the lower Great Lakes lifts
to NE with a trailing cold front over the Carolinas and into the
lower MS valley. As the front sags just to the south of the region,
slight to chance PoPs remain in the forecast for the
afternoon/evening hours with the best chance of showers and
thunderstorms in the southern half of the CWA. With the passing of
the cold front late Sunday, expect afternoon scattered thunderstorms
Monday and Tuesday especially in the Sandhills and Coastal plain
regions. Temperatures over the weekend and into early next week will
be a tad below average with highs in the mid to upper 80s and lows
in the mid to upper 60s.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 800 PM Tuesday...
VFR conditions will generally dominate central NC, with a couple of
exceptions. First, in the far E and S of the area (including
FAY/RWI), areas of smoke will persist with frequent MVFR vsbys
(generally holding at 4-6SM) through much of tonight. This smoke may
linger through Wed morning and may spread areawide, but vsbys should
generally trend back up to 6SM or greater everywhere. Scattered
storms over the NC mountains currently are generally dwindling and
not making much progress eastward, although there is a possibility
that a few remnant showers may brush INT/GSO late tonight, 08z-12z.
Otherwise, the current fair skies will yield to a mix of scattered
to broken mid and high clouds from W to E tonight through Wed.
Surface winds will be light mainly from the W or SW tonight before
increasing to 6-12 kts Wed.
Looking beyond 00z Thu, scattered storms are expected to be ongoing
over central NC Wed evening, mainly east of the Triad and perhaps
affecting RDU/FAY/RWI, although exact storm location can`t be
pinpointed at this time. Any storms should decrease gradually in
coverage overnight, although a few showers are possible overnight
Wed night, with local sub-VFR fog. Another round of scattered
showers and storms is possible starting as early as Thu morning,
remaining possible through the day Thu and into the evening. Daily
typical isolated to scattered showers and storms, mainly from mid
afternoon to mid evening, will remain a possibility Fri through Sun,
with the potential for pockets of early-morning fog as well. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Hartfield
NEAR TERM...Kren
SHORT TERM...np
LONG TERM...CA
AVIATION...Hartfield
Area Forecast Discussion
National Weather Service Tallahassee FL
929 PM EDT Tue Jul 18 2023
...New UPDATE...
.UPDATE...
Issued at 926 PM EDT Tue Jul 18 2023
Hazy conditions continue across the region this evening, and with
light winds, this shouldn`t change overnight. In fact, patchy fog
could be possible toward daybreak. Upstream MCS over Northern
Alabama is expected to weaken/dissipate before reaching our CWA
overnight, so left rain chances out of the forecast. Everything
else is on track, so no other changes planned.
&&
.NEAR TERM...
(Through Wednesday)
Issued at 313 PM EDT Tue Jul 18 2023
Hot and hazy conditions are poised to continue through the Thursday
as the service area is sandwiched between a strong ridge over the
Desert SW and narrow, yet extensive trough cascading down the
Eastern US. The latter is associated with broad cyclone north of the
Great Lakes that is helping to advect smoke from the Canadian
wildfires via N-NW "conveyer belt" flow while keeping the seabreeze
confined near the coast. The airmass has also been unseasonably dry,
characterized by widespread Precipitable Water (PW) values of 1.4-
1.5", per afternoon SPC mesoanalysis The combination of large-scale
subsidence by the ridge and corresponding surface high pressure has
mostly suppressed convection so far today. The only exception is
in the extreme SW FL Big Bend where PWs are slightly higher. For
tonight, hazy skies likely stick around, followed by possible
patchy fog development during the early AM hrs. Best potential
appears to be along/south of the I-10 corridor where the seabreeze
may sufficiently moisten up the boundary layer. Overnight lows
are in the muggy mid 70s. Any fog should scour out shortly after
sunrise. However, kept the mention of haze as suggested by the
HRRR Smoke model.
Looking at tomorrow, mostly dry weather prevails, but a decaying MCS
(currently over the MO Valley) may provide a focus for isolated to
scattered convection across our northern-tier GA counties via a
remnant outflow boundary. Better moisture recovery may also prompt
seabreeze-forced convection farther south. No organized severe
weather, nor flooding is anticipated, but gusty winds, frequent
lightning, and a brief downpour or two are possible. As for
temperatures, forecast highs are firmly in the mid 90s away from the
immediate coast. These values are a couple degrees lower than the
raw NBM, which is on the high end of the "model certainty" envelope
and right up there with MOS guidance. Peak heat indices are mostly
in the 100-104 degree range (below advisory criteria) thanks to
somewhat drier air hanging around.
&&
.SHORT TERM...
(Wednesday night through Thursday night)
Issued at 313 PM EDT Tue Jul 18 2023
Upper high pressure is expected to linger over the
area throughout the short term. Persistent NNW flow extending to the
mid levels will continue advecting dry air across the region
resulting in clear skies during the overnight hours Wednesday and
all throughout Thursday. Additionally, subsidence aloft juxtaposed
with the aforementioned midlevel dry air will continue suppressing
showers and thunderstorms across the area. Temperatures will reach
the mid to upper 90s across the area, though heat indices are
expected to remain just short of heat advisory criteria. Overnight
lows will hang around the mid 70s.
&&
.LONG TERM...
(Friday through Monday)
Issued at 313 PM EDT Tue Jul 18 2023
Multiple shortwave perturbations will round the base
of an upper trough just north of the Great Lakes gradually eroding
the ridge over our region. As a result, a persistent stormy period
is forecast to begin starting on Saturday with PoP`s generally
ranging from 50-70% areawide through Monday perhaps continuing
beyond that. Increasing surface moisture throughout the long term
with persistent cloud cover overhead will likely cool temperatures
down as well with daytime highs starting off the long term in the
mid 90s then gradually decreasing to the low 90s. Overnight lows
will continue to stay within the mid 70s.
&&
.AVIATION...
(00Z TAFS)
Issued at 713 PM EDT Tue Jul 18 2023
Haze continues to be the main weather feature in the TAFs this
cycle. Have prevailing 6SM HZ at all sites for the next 24 hours.
Another plume of thicker haze is currently over central GA, moving
south. Thus, have included tempo groups with vsby restrictions to
MVFR over the next 4 hours at ABY and VLD. Patchy fog may also
develop late tonight at all sites, so have included tempo groups
for all sites from 10-13z. Confidence is too low in TSRA coverage
to include any mention for tomorrow afternoon at this time.
&&
.MARINE...
Issued at 313 PM EDT Tue Jul 18 2023
A light to moderate breeze out of the west southwest will
remain persistent across our waters over the next few days with seas
generally 2 feet or less. There will be low chances for isolated
showers over the next few days, although chances and coverage will
begin to increase Friday into the weekend. Locally intense and
erratic wind gusts are likely near and within thunderstorms.
&&
.FIRE WEATHER...
Issued at 313 PM EDT Tue Jul 18 2023
High pressure building over the area will continue to suppress
storms across the area over the next few days. This will in turn
lower RH values as temperatures increase into the upper 90s,
generally ranging from 40% inland to 60% MinRH near the coast.
However, MinRH values could drop below 40% in our northernmost AL
and GA counties. Elevated dispersions are possible within our SE AL
and SW GA counties Wednesday with High dispersions possible on
Thursday in our northernmost SW GA counties. Chances for rain begin
to slightly increase on Friday.
&&
.HYDROLOGY...
Issued at 313 PM EDT Tue Jul 18 2023
Chances for rain will remain low for the remainder of the
work week as high pressure settles in over the area. Chances for
rain and thunderstorms will increase once again on Saturday and last
through the weekend. However, there are no flooding concerns at this
time.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 75 96 76 97 / 0 20 0 10
Panama City 78 91 77 91 / 0 10 0 10
Dothan 74 94 74 95 / 0 10 0 0
Albany 74 96 75 96 / 0 20 0 10
Valdosta 74 96 75 97 / 0 20 0 10
Cross City 76 94 76 95 / 0 20 0 30
Apalachicola 78 88 78 90 / 0 10 0 10
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Godsey
SHORT TERM...Worster
LONG TERM....Worster
AVIATION...Young
MARINE...Worster
FIRE WEATHER...Worster
HYDROLOGY...Worster