Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/19/22
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
620 PM MDT Wed May 18 2022
00Z TAF CYCLE
Winds will weaken with sunset this evening, then west and southwest
winds will strengthen Thursday. The strongest wind gusts should
reach 30-40 KT over northern and east central areas Thursday
afternoon, except for 45 KT over the high peaks of the Sangre de
Cristo Mountains. Strengthening flow aloft should cause gusty
conditions to linger through the evening Thursday evening in many
areas. HRRR Smoke Model depicts well developed smoke plumes traveling
to the east and southeast of fires through this evening, then more
consistently to the southeast late tonight as fire activity slows
down for the night: https://go.usa.gov/xuJbd.
.PREV DISCUSSION...229 PM MDT Wed May 18 2022...
A few storms will impact far northeast New Mexico late this afternoon
into the early evening hours and may become strong to severe,
producing gusty and erratic winds. Warm westerly winds will increase
Thursday, with well above normal high temperatures that will
challenge daily record values at a number of locales. Look for more
of the same Friday, followed by a cold front late day and overnight
that will bring much cooler temperatures to eastern New Mexico for
Saturday. Gulf moisture will infiltrate the eastern half on Monday
and set the stage for a round of showers and storms late day through
Tuesday, potentially bringing much needed rain to areas along and
east of the central mountain chain. Meanwhile, western New Mexico
will remain warm and dry early next week.
SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)...
Showers and thunderstorms are developing in northeast NM this
afternoon in response to an increase in low level moisture last
night. The storms will continue through this evening. A few could
turn severe with large hail and damaging winds before exiting into
TX. Elsewhere will be dry and comfortably cool with light winds.
The winds aloft will turn zonal and strengthen Thursday. Moisture in
the east will get shoved into TX, leaving the entire area dry and
very warm with increasing winds. Isolated wind advisories may be
needed in the north central and northeast areas. Critical fire
weather conditions will persist for most areas. Winds will be slow
to diminish Thursday night, and may increase on higher elevations of
the western and central mountains. Otherwise it will be dry and
comfortable Thursday night.
LONG TERM...(FRIDAY THROUGH WEDNESDAY)...
An upper level trough will progress east from the Great Basin toward
the southern Rockies Friday, steering stronger winds aloft over NM
resulting in windy conditions ahead of a cold front forecast to move
south across the area late Friday into Saturday. The combination of
the trough and backdoor segment of the cold front may bring a few
showers or storms far northern NM near the CO border from the Sangre
De Cristos eastward late Friday through Saturday. Cold air advection
will be most pronounced behind the backdoor segment of the cold front
across eastern NM on Saturday, where highs are forecast to be 5-20
degrees below normal. Another upper level trough will approach from
over the Great Basin on Sunday and move across the southern Rockies
and northern NM on Monday, drawing Gulf moisture northwest into
eastern NM and setting the stage for a round of storms late Monday,
with decent agreement among the 12Z medium range model solutions. A
bonus round is possible Tuesday across eastern NM, but lower forecast
confidence for Tue/Wed given some significant differences among the
medium range model solutions beyond Monday. Specifically, the 12Z
ECMWF expands a large upper high across the region from mid to late
week up to near 592dam at 500mb, while the 12Z GFS continues our
pattern of increased westerlies with a succession of troughs.
...CRITICAL FIRE WEATHER CONDITIONS WILL RETURN THURSDAY AND FRIDAY
ACROSS MUCH OF NEW MEXICO...
Low level moisture moved into eastern NM last night and is hanging
on today across the eastern plains. Showers and thunderstorms will
impact the northeast areas through late evening, with a couple
possibly turning severe. The winds aloft will increase out of the
west Thursday, and mix down to the surface, sweeping the moisture in
the east into TX. The combination of dry, unstable, breezy to windy
conditions will create widespread critical fire weather conditions
Thursday, as well as Friday. A back door cold front will impact
eastern NM Friday night, with a better push south and west Saturday
night, that could squeeze into the Rio Grande Valley. Low level
moisture will return to the east along with a disturbance aloft
passing to out north, with potential showers and thunderstorms late
Friday through Saturday evening. The weekend will be much cooler,
especially in the east. Sunday will be dry, but return flow moisture
Monday and Tuesday could trigger showers and thunderstorms in the
Red Flag Warning from noon to 8 PM MDT Thursday for the following
Red Flag Warning from 11 AM to 9 PM MDT Friday for the following
Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
744 PM CDT Wed May 18 2022
Thunderstorms that moved southwest of DHT will likely be the last
of the thunderstorm chances for DHT. More thunderstorms are
expected to move southeast out of Colorado and Kansas and they are
expected to affect the GUY TAF site this evening. AMA is not
expected to be affected by storms. Some of the storms may become
severe with damaging winds the main threat. Easterly winds are
expected to turn to the southwest by early Thursday afternoon and
they are expected to increase into the 15 to 20 knot range with
.PREV DISCUSSION... /Issued 159 PM CDT Wed May 18 2022/
SHORT TERM...Tonight through Thursday night
The HRRR and FV3 are similar in their solutions on an approaching
shortwave trough tracking eastward out of Colorado and New Mexico
later today into tonight. Northwesterly flow aloft will allow
convection that develops over the higher terrain of
southern/southeastern Colorado and northeastern New Mexico by
21Z to 23Z today to move east and south into the northwestern
Panhandles by 00Z Thursday. The FV3 seems to be a little more
overdone and aggressive with the development of the convection
with the HRRR being a little more representative but could be a
Regardless, the convection expected to move into the western
Oklahoma and northwest Texas Panhandles from southeastern
Colorado and southwestern Kansas by 01Z to 03Z Thursday and then
moving across the eastern Oklahoma and northeastern Texas
Panhandles by 04Z to 06Z Thursday. Convection should exit the
forecast area by 07Z to 09Z or so Thursday. A more zonal upper
flow expected Thursday transitioning to southwesterly Thursday
Stalled frontal boundary south of the Panhandles tonight with a
moist upslope easterly surface flow will become south and
southwest Thursday into Thursday night as a surface trough
develops to the lee of the central and southern U.S. Rockies. Hot
and dry conditions expected Thursday due to compressional heating
ahead of a cold front with record or near record high
temperatures possible. A Heat Advisory may ne necessary for Palo
Duro Canyon Thursday with forecast high temps of 105 degrees or
higher. Strong cold front forecast to push south and east across
the Panhandles by 09Z to 12Z Friday.
Any critical fire weather conditions on Thursday will be highly
dependent/conditional on where the heaviest rainfall occurs this
evening and tonight. Green up prevalent on the NDVI satellite
imagery to the west of Dalhart eastward and also east of a Guymon
to Amarillo line. Expecting best rainfall this evening and tonight
to be across the Oklahoma and northern Texas Panhandles. This
places the possible critical fire weather conditions Thursday to
be across the southwest Texas Panhandle where the driest
conditions should be. Decided to hold off for now on issuing a
Fire Weather Watch or Red Flag Warning for Thursday and may only
need a Fire Danger Statement for parts of the Panhandles that are
the driest and do not receive the most or any rainfall.
LONG TERM...Friday through Tuesday...
A cold front will begin to move through the Panhandles during the
day on Friday from north to south. High temperatures will reach
their peak earlier in the day before cooling down trend begins. As
we approach Friday night under breezy northeasterly flow,
low temperatures will range from the upper 30s to lower 50s.
Cool temperatures will continue into Saturday under continued
northeasterly surface flow with highs in some areas in the
northern Panhandles not getting out of the 50s with the remainder
of the Panhandles in the 60s. As winds subside with mostly clear
skies by Saturday night, ideal conditions for radiational cooling
will take place where low temperatures may get as low as the mid
30s for the northwestern Panhandles where some Frost headlines may
be needed. Will watch trends closely. The remainder of the
Panhandles on Saturday night will have low temperatures range from
the upper 30s to mid 40s.
Temperatures will moderate Sunday through Tuesday with
temperatures approaching near average values for late May. As a
H500 trough begins the strengthen over the Four Corners Region by
Monday morning into the afternoon, H700 low centered over the
central Plains will aid in the LL moisture transport into the
Panhandles. With the aid of the sfc trough, showers and some
thunderstorms may develop the second half of Monday. At this time,
all of the Panhandles have a chance of seeing at least some
rainfall. Whether it will be measurable rainfall is yet to be
Area Forecast Discussion
National Weather Service La Crosse WI
1045 PM CDT Wed May 18 2022
.DISCUSSION...(This evening through Wednesday)
Issued at 237 PM CDT Wed May 18 2022
- Severe storms possible Thursday
- Cooler through the weekend
Tonight, a shortwave will pass to the north of the area, bringing
precipitation chances to central and northern Wisconsin this
evening. Should primarily be rain showers, though with some
available CAPE, thunderstorms are not out of the question. The
showers will move out of the area tonight as the shortwave leaves
Storm Chances Late Thursday through Friday...
Southwesterly warm air advection on Thursday will increase 850 mb
temperatures to 13-19 C, thus increasing surface temps to the mid
70s and low 80s across the area. 850 mb moisture advection also
increases Thursday, with about 1.4-1.7 inches PWAT available, which
is above the 90th percentile for this time of year, according to SPC
sounding climatologies. GFS is more excited about the moisture
transport than the EC and also pushes higher moisture further north.
The RAP suggests the greatest magnitude of moisture transport,
peaking Thursday night. The models generally agree on the axis of
highest moisture transport being located from northeast Iowa toward
A surface low pressure system to the northwest will bring a front
across the area late Thursday afternoon. The warm front will align
with the strongest moisture transport and warm air advection, thus
creating a favorable area for storm initiation. CAMs suggest the
precip would begin to affect the area late Thursday afternoon or
Thursday evening. Recent HRRR runs are more excited about the precip
than the RAP and also suggest a narrower band of stronger
precipitation that moves east across the area.
Model soundings continue to suggest that capping Thursday morning
and afternoon should keep strong storms from realizing until later
in the day when the cap erodes due to more daytime heating. Once the
cap erodes, however, storms could become surface-based. RAP
soundings suggest upwards of 3000 J/kg SBCAPE Thursday night. Steep
lapse rates in model soundings combined with these high SBCAPE
values favor large hail and damaging wind to occur with the storms.
There is also a strong deep-layer shear of about 50+ knots; low-
level shear will increase as a low-level jet strengthens, which
could realize tornadoes if storms are able to tap into the shear.
SPC has included our area in an Enhanced/Slight risk for tomorrow
with a 30% hatched for hail. Storm total rain amounts look to range
from 0.3 to just under 1 inch, with the highest amounts in SE
Minnesota and central Wisconsin.
After this primary round of precipitation, more storms or showers
could develop along the cold front as it passes over the area.
However, CAPE values decrease later in the night and a nighttime
inversion could be difficult to overcome to produce more strong
Cooler Conditions Over the Weekend...
In wake of the cold front heading into the weekend, cooler
conditions are anticipated with a broad upper-level trough moving in
from the west. Temperatures at 850 mb dip into the single digits
would be near 2 standard deviations below the climatological mean
for this time of year. The NAEFS and ECMWF ENS would place these
values in the lowest 1 to 2.5 percentile. Overnight low temperatures
in the mid 30s to low 40s are possible Saturday and Sunday mornings.
If sky cover remains mostly clear in the overnight hours, even lower
temperatures could be realized.
While the end of the weekend will likely be rain free, widespread
chances for rainfall returns Monday night. Will stick with the
blended model guidance as models diverge on any one solution with
multiple waves progressing through a near zonal flow with some
solutions even showing a deepening trough over the western CONUS by
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1045 PM CDT Wed May 18 2022
While VFR conditions should prevail most of the period, several
items to note in this fairly active pattern.
In near term, outflow boundary from weakening showers and storms
approaching KLSE TAF site may bring a temporary wind shift and brief
ceilings before things clear out again. Outflow air could lead to
some local fog formation overnight as well mainly north of I-90 in
As warm front advects north on Thursday, will also have to watch for
development of mid to late afternoon convection. Confidence in this
scenario is lower, especially where it might occur so opted to not
include in TAF sites at this time. Look for increasing winds through
the day Thursday as well.
Far better chance for impacts will be as cold front enters the
picture Thursday evening and overnight. This will likely trigger
line of convection that could impact nearly all areas with brief
MVFR conditions, or at the very least VFR ceilings as this threat
slides through. Wind shift will also accompany this front as it
moves through headed into Friday morning.
Area Forecast Discussion
National Weather Service Boston/Norton MA
1016 PM EDT Wed May 18 2022
Thursday will feature cool conditions, with rain in the morning,
then tapering off in the afternoon from west to east. A
significant warmup then begins Friday, peaking this weekend with
90 degree highs possible both Saturday and Sunday. A cold front
arrives late Sunday, with the chance of showers and
thunderstorms. More seasonable temperatures return for the start
of the new work week.
.NEAR TERM /UNTIL 5 AM THURSDAY MORNING/...
1015 PM update...
Mid/high clouds continuing to increase from west to east late
this evening. Temps will continue to fall given light winds and
dry airmass with dew pts in the 30s. However, overnight with
clouds lowering and onshore winds developing, temps will level
Leading edge of rain shield now moving into the Catskills of NY
and Poconos of PA, and will arrive in western MA/CT after
midnight, and towards morning for eastern MA and RI. It will be
a chilly morning rain with temps in the 40s and 50s.
Heavier/moderate rain will impact the morning commute across CT
into western/central MA, including the cities of Hartford and
Springfield. Farther east, steadier rains hold off until later
in the morning across RI and eastern MA. Also, rain intensity
may decrease somewhat as it moves east, as lead short wave
deamplifies with time, as trailing short wave becomes the
.SHORT TERM /5 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
A mid level shortwave moves through New England on Thursday with
a reflection at the surface. Isentropic lift behind the warm
front will bring widespread rainfall to all of southern New
England Thursday morning as warm and moist air is lifted over
the dry airmass in place. Additionally, models have started to
hint at a secondary low forming offshore off Long Island and
crossing nearby, providing better forcing for some higher
precipitation totals along the south coast. Even so, not
expecting any more than a quarter inch of rain for anyone, save
for potentially the islands. That being said, some of the high-
res guidance like the HRRR is even drier. The highest rainfall
totals will likely be along the south coast and then northwest
MA closer to the parent low, with lesser amounts over central-
northeast MA. A dry slot moves in at 500 mb late
morning/afternoon which will cause rain to diminish throughout
the afternoon and early evening. By Thursday night mid level
ridging begins to move overhead once again; expecting dry
conditions and clearing skies.
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
* Warming trend begins Friday, with 90+ degree highs possible
both days this weekend. Daily record highs may be challenged.
* Cold front arrives later Sunday with the chance for showers and
thunderstorms. More seasonable temperatures return for the start
of the new work week.
The main issue during this portion of the forecast will be the
heat Friday into this weekend. Latest guidance continued to slow
the arrival of a cold front, so it is looking more likely that
high temperatures across interior southern New England could
reach the 90s both Saturday and Sunday. Onshore winds will keep
the immediate coasts cooler. Heat-related headlines are likely
for at least a portion of southern New England sometime this
weekend. Some record high temperatures could be challenged. The
Climate section below has those details. Once a cold front passes
through sometime from late Sunday into Monday, then more
seasonable temperatures are expected through early next week.
This portion of the forecast will remain mainly dry as well. The
next best chance for showers and possible thunderstorms will be
ahead of a cold front sometime late Sunday into early Monday.
There is a low risk for some showers towards the south coast and
adjacent coastal waters Friday night. There could also be an
isolated shower or thunderstorm late Saturday. It will all
depend on how strong the subsidence inversion will be. At this
time, thinking the greater risk for showers will be farther
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
0215z update...no change from previous TAFs.
VFR and dry to start, but MVFR in SHRA approaches western CT/MA
toward 06z and 12z eastern MA and RI. Earlier discussion below.
SHRA overspreads the region from west to east, trending toward
MVFR with isolated IFR possible. Steady rain in the morning,
tapering off west to east in the afternoon. South wind
increasing 10-20 kt. Vsby may lower 1-3 miles in areas of fog
during the afternoon and evening.
Dry with diminishing cloudcover overnight. Winds light and
BOS TAF: High confidence.
KBDL TAF: High confidence.
Outlook /Friday through Monday/...
Friday: VFR. Breezy.
Friday Night: VFR. Breezy. Slight chance SHRA.
Saturday through Saturday Night: VFR.
Sunday through Sunday Night: VFR. Breezy. Chance SHRA.
Monday: VFR. Breezy. Slight chance SHRA.
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
High forecast confidence through Thursday.
This afternoon...NW winds 05-10 kt, with gusts up to 20 kt. Dry
weather and good vsby.
Tonight...light and variable winds as high pressure remains over
the waters. Then becoming south late as low pressure approaches.
Chance of sprinkles in the morning.
Thursday...poor vsby in rain and fog, improving somewhat in the
afternoon from west to east.
Thursday Night: Winds west 5-10 kt. Seas approaching 5 ft on the
Outlook /Friday through Monday/...
Friday: Winds less than 25 kt. Seas locally approaching 5 ft.
Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain showers.
Saturday through Saturday Night: Winds less than 25 kt. Areas
of seas approaching 5 ft.
Sunday: Winds less than 25 kt. Seas up to 5 ft. Slight chance
of rain showers.
Sunday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of
Monday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Chance of rain showers.
Daily record high temperatures...
Sat May 21st...
BOS 93F (1921)
PVD 93F (1996)
BDL 93F (1996)
ORH 88F (1975)
Sun May 22nd...
BOS 93F (1959)
PVD 94F (1941, 1992)
BDL 95F (1992)
ORH 90F (1911, 1992)
Area Forecast Discussion
National Weather Service Louisville KY
1012 PM EDT Wed May 18 2022
Issued at 925 PM EDT Wed May 18 2022
Earlier severe convection fueled by the forcing on the "tail" of the
MCV overlapping with return flow/instability has weakened
substantially over the last hour. More recent updrafts have tried to
go up, but in an area that has been worked over by the earlier
storms. Could continue to see isolated-scattered showers with a few
rumbles of thunder, but the SVR threat has diminished enough that we
have dropped WW 240 a bit early.
Fog formation will be our other concern through the night,
especially in the areas that saw substantial rain earlier. Locally
dense fog can`t be ruled out, but will hold off on any headlines for
the time being and just massage the extent of where we mention it.
Issued at 525 PM EDT Wed May 18 2022
Did a quick update to the grids and forecast to add in Severe
Thunderstorm Watch 240 which is in effect until 10 PM CDT. Updated
grids and products are now available.
As expected, storms have increased in intensity as they cross the I-
65 corridor. Two strong storms were being tracked at the moment.
The first was over LaRue county which will pose a large hail and
wind damage threat. The second storm of concern is over Marion
county and this will pose a large hail and damaging wind threat.
Latest mesoanalysis reveals an area of lower 80s over southern KY
with dewpoints in the mid-upper 60s. This is yielding MLCAPE values
of 1000-1500 J/kg. However, the lack of significant winds from obs
suggests that this activity is still not fully rooted near the
surface. In fact, mesoanalysis data suggests that we still have
some 50-100 J/kg of CINH across much of southeastern sections.
Higher values of CINH appear to the northeast across the Bluegrass
region which seems reasonable given the general heavy rainfall and
some embedded lightning.
Further southwest, high resolution satellite imagery shows a
developing Cu field trying to develop across the Karst region of
central KY. We can see some agitated Cu over
Logan/Butler/Warren/Hart counties where this is co-incident with
higher instability values. However, bulk shear values are weaker in
this area, and slightly higher over toward the LaRue/Marion county
storms. Latest CAMs want to weaken some weak MLCINH over this
region in the next few hours. HRRR has been hinting of convection
going up around 23Z or so, so we`ll continue to monitor closely.
So in terms of severity, the highest risk of severe weather exists
to the southeast of the current LaRue/Marion county storms. Areas
such as northern Taylor, Marion, Boyle, Casey, and Lincoln counties
should prepare for strong/severe storms over the next hour. Large
hail will be the primary threat along with intense lightning and
wind gusts of 45-50 mph.
Further north, we have some additional rounds of convection working
across the Louisville metro area. This area has largely been worked
over by previous convection. Trailing line of agitated Cu has been
trying to develop from Jasper eastward towards Scottsburg. Last few
CAM runs have been trying to further develop convection within this
area, but latest few WoFS runs have been much less eager to develop
anything. By far, the WoFS runs have been targeting previously
mentioned areas of south-central KY (Lake Cumberland region) through
about 800 PM EDT.
We`ll continue to monitor the northern activity and have the option
of expanding SVR box 240 if need be.
.Short Term...(This evening through Thursday)
Issued at 339 PM EDT Wed May 18 2022
...CONDITIONAL RISK OF STRONG/SEVERE STORMS THIS AFTERNOON/EVENING...
Near Term through 800 PM EDT
Risks: Strong/Severe Thunderstorms
Confidence: High on PoPs
Low on Severe Risk
Afternoon satellite data shows a well defined remnant MCV that just
crossed into Indiana from Illinois. Cluster of initially multi-
cellular convection that developed over southern IL has moved
northeastward and has taken on more of a linear form as it moves
eastward across southern IN. Forcing has been strong enough along
and just south of the vorticity max to drive/develop convection.
However, model proximity soundings and mesoanalysis suggest that
buoyancy has been tempered by ongoing cloudiness and limited
insolation. In addition, the convection is a bit displaced from
more deep/rich moisture which has been confined to western TN and
far southwestern KY. The current convection is moving at around 35
knots which would place it in the Louisville Metro within the hour
(reaching I-65 by around 400 PM EDT). While instability has been
tempered a bit along and west of I-65, the storms will probably
remain steady state as they come into the Louisville metro. Main
issues here will be very heavy rainfall, gusty winds of 40-45 mph,
and perhaps small to near severe hail with the strongest cores. This
activity moving through the metro at the early part of the evening
rush will be problematic due to ponding of water on roads along with
East of I-65, we`ve seen some partial clearing as high level cloud
debris has mixed out and temperatures east of the I-65 corridor have
increased into the upper 70s and will likely warm into the lower 80s
in the next hour or two. Recent CAMs, including WoFS, have been
suggestive that convection may undergo an uptick in strength east of
the I-65 corridor this afternoon. This activity could be rather
strong to severe as it moves eastward toward the Lexington area this
Further south, overall threat remains largely conditional as it will
be a race to see if the MCV outpaces the moisture return to the
south and west. Previous CAMs had remained pretty dry across
southern KY, mainly due to a small amount of CINH just below 700
hPa. However, in the last few runs, we`ve started to see the CAMs
mix out that CINH and an east-west band of convection may eventually
develop across portions of south-central KY this evening. Overall
confidence in this is admittingly low at this time. However, we`ll
continue to monitor trends closely throughout the evening.
Overnight (800 PM - 800 AM EDT)
Risks: Southern KY Thunderstorms
Patchy Fog over southern IN
As mentioned above, we could see development of an east-west band of
convection down across southern KY this evening. Convection may be
more focused in the Cumberland Parkway corridor. Given model
proximity soundings, if convection gets going, storm mode could be a
mix of supercells and multi-cellular convection with a risk of
damaging winds, large hail, and perhaps an isolated tornado. This
activity should push east of the Lake Cumberland area by late
Into the overnight hours, the latest guidance keeps us rather dry
with perhaps another round of showers/storms rolling through
southern KY late in the overnight period. Aviation guidance has
been suggestive that winds will diminish overnight and with a soupy
airmass in place and recent rains across southern IN, patchy to
locally dense fog may become an issue. This fog may develop a
little further south into portions of north-central KY where this
afternoon`s rain falls. Lows overnight will be in the low-mid 60s.
Risks: Strong/Severe Storms
We should start off the day with partly cloudy skies along with some
morning fog, especially across the north. A stalled out boundary
should be located somewhere across southern KY and this feature is
expected to move northward through the morning hours. Another in a
series of MCVs is forecast to move eastward and result in additional
thunderstorm development across the region in the afternoon and
evening. The greatest risk of severe weather will be on the south
side of this frontal boundary and ahead of the approaching MCV.
Model proximity soundings show a decently unstable airmass in place
with MLCAPE values in the 2300-2800 J/kg range with a bit of low-
level and deep layer shear. In general, damaging winds and large
hail would be the main hazardous weather threats. However, given
the rather deep layer shear and speed sheer, some isolated tornadoes
are possible, mainly from the bootheel of MO eastward into southern
KY. Current SPC slight risk looks appropriate right now and further
augmentation seems possible once the convective evolution becomes
clearer. Highs on Thursday will be in the mid-upper 80s.
.Long Term...(Thursday night through Wednesday)
Issued at 340 PM EDT Wed May 18 2022
Synopsis...The medium range portion of the forecast will be marked
by substantial amplification in the upper-level pattern as a
longwave trough digs over the West and Central US and a high
pressure seats over the northern Caribbean with ridge axis extending
all the way to the Northeast US. The above scenario will allow the
main storm track/cold front to stretch roughly from the Great Lakes
towards the Texas Coastal Plains with plenty of moisture transport
ahead and along of the main baroclinic zone given deep, warm-sector
southwesterly flow. It is important to note that while the trough
amplifies southward, a closed low over Baja California will be
sheared off and the resultant PV advection will likely serve as a
forcing mechanism for pre-frontal convection during the weekend.
First part of the forecast enjoys good confidence on the synoptic
picture; however, usual uncertainties exist with mesoscale features
that will be resolved during the next couple of days. On the other
hand, the forecast for next week is still pending on better
agreement between main global guidance. Essentially, the
deterministic ECMWF and CMC 19/12Z runs depict a more progressive
flow aloft with the Central US trough slowly lifting northeast and
high pressure centered over the Southwest/Intermountain West. The
GFS, however, is more amplified, slower, and rather blocky with the
high pressure further south over Sierra Madre, Mexico.
Thursday Night - Saturday Morning...Even though rain/storm chances
will be winding down past diurnal instability peak, there is a low
chance of lingering convection north of I-64 after sunset associated
with earlier activity that is progged to focus along a mesoscale
boundary lifting through central Kentucky. The possibility of
marginally severe weather, mainly for wind gusts and hail, will be
conditionally determined by how the environment evolves in the early
Thursday afternoon. Dry air and subsidence will provide a sunny and
dry Friday as the headlines shift to the heat and possible record
temperatures on Friday and Saturday. See Climate section below for
Saturday Afternoon - Sunday...Scattered showers and storms will be
approaching southern Indiana and central Kentucky around noon on
Saturday. Periods of heavy rain and lightning associated with pre-
frontal convection will be common during the afternoon and evening.
A few isolated and brief instances of severe weather cannot be ruled
out, but overall the best dynamic and kinematic support will stay
over the Midwest as the forcing attendant to the cold front passage
looks very weak. The best timing for severe hail or wind could be
related to pulse storms on Saturday afternoon given the lack of deep
shear for organized convection. In addition, flooding concerns will
have to be monitored, especially on Sunday, due to the quasi-
stationary character of the main baroclinic zone and the possibility
of training convection.
Next Week...Precipitation chances will ultimately depend on what
model blend is utilized. So far, there is warming trend in place as
winds turn to the east and then to the south by midweek. Although
timing and location of the rain or possible storms chances are
questionable, it is safe to expect deteriorating weather conditions
.Aviation...(00Z TAF Issuance)
Issued at 755 PM EDT Wed May 18 2022
- Storms possible this evening at KLEX and overnight at KBWG
- Low CIGs/VIS possible across southern IN and portions of northern
KY early Thursday morning
- Storm chances return across the area Thursday afternoon & evening
Current radar imagery shows scattered storms ongoing across east-
central KY this evening, with frequent lightning being observed in
storms along with brief IFR visibilities in the heavier downpours.
While KHNB and KSDF are expected to remain dry into tomorrow, KLEX
may still have some of these storms push through over the next
couple of hours. Moving into the overnight hours, may see some
additional storms develop over southern KY, possibly impacting KBWG,
so have included TEMPO group to cover this potential threat, however
confidence remains low. Model guidance is then suggesting some lower
ceilings and visibilities may build in across southern IN, north-
central KY and north-eastern KY so have included periods of MVFR to
IFR conditions at KHNB/KSDF/KLEX towards sunrise.
After a dry lull, chances of showers and storms will return by
Thursday afternoon and evening, generally towards the end of the TAF
period. Confidence is low on timing and location for tomorrow`s
activity, so have only included mention of PROB30 into the KSDF
Winds overnight will be around 5 kts generally out of the W/SW then
strengthening out of the SW during the day Thursday with speeds
between 5-10 kts.
Updated at 350 PM EDT Wed May 18 2022
================== Near-Record High & Warm Minimum Temperatures =====
Fri Morning Fri Afternoon Sat Morning
Louisville: 72/72 (1877) 93/91 (2018) 73/72 (1877)
Bowling Green: 70/69 (1998) 91/96 (1921) 71/71 (2004)
Lexington: 67/69 (1996) 90/91 (1944) 70/69 (1893)
Frankfort: 68/73 (2004) 91/92 (1964) 70/69 (2004)
Area Forecast Discussion
National Weather Service Memphis TN
837 PM CDT Wed May 18 2022
It`s a quiet evening across the Mid-South in the wake of a subtle
shortwave trough moving east across Middle TN. Large-scale
subsidence did keep convection from developing this afternoon
despite a warm and unstable air mass over the region. A few
thunderstorms have developed over the Ozarks in the right entrance
region of an upper-level jet max right along the 700 mb thermal
gradient. The latest HRRR runs have initialized this convection
but quickly dissipate it, maintaining dry weather area wide
overnight. A few of the other CAMs are a bit more aggressive with
convection developing along the outflow boundary just north of the
MO/KY state lines.
Scattered nocturnal convection near the TN/KY border remains in
play as a southwesterly low-level jet near 30 kts results in
enhanced convergence in this area. Will it be strong enough to
produce organized convection is another question, but it`s
certainly worth maintaining slight chance PoPs overnight. The
potential for severe weather is pretty low given the increasing
stability overnight. For tomorrow, it appears most of the
convection will remain to our north, though a moist, unstable air
mass could yield scattered thunderstorms around peak heating.
Weak deep-layer shear should discourage organized severe weather,
but a few strong storms are possible given the strong instability.
.PREV DISCUSSION... /issued 332 PM CDT Wed May 18 2022/
Zonal flow aloft will continue across the Midsouth through
Thursday night. The main east-west storm track will prevail to
our north, from southern Missouri to the lower Ohio River valley.
This corridor will be positioned south of the 250mb polar jet,
extending across the upper Midwest and Great Lakes.
Not especially great agreement among the short term convective-
allowing models (CAMs) regarding rain chances from northeast
Arkansas through the Missouri bootheel through Thursday evening.
The main driver for PoPs in these areas will be scattered showers
and isolated storms along the far southern periphery of mesoscale
convective complexes (MCSs) moving east from the mid-Mississippi
River valley into the Ohio River valley. Timing of these systems
will tight to upstream convection over the central plains.
Upper level ridging will push the storm track further north on
Friday, in advance of a positively-tilted longwave trof over the
Rockies. Model consensus over the past day have trended slower
with the arrival of midlevel height falls and surface frontal
passage through the Midsouth - now depicting passage through the
Midsouth Saturday night. In the interim, the presence of an
elevated mixed layer should cap mixed-layer CAPE nearing 3000
J/kg Saturday afternoon, accompanied by midlevel lapse rates of
8 C/km. Given the presence of the EML and weak deep layer bulk
shear (< 15kts), warm sector storms will likely a difficult time
developing before late Saturday afternoon.
As rain chances increase Saturday night, effective CAPE will fade,
limiting severe weather threat. Some uptick in severe potential
may occur over north MS and the TN valley Sunday morning, until
the surface cold front passes.
For the Monday and Tuesday periods, today`s model consensus looks
similar to yesterday`s deterministic GFS depiction of a compact
shortwave ejecting from the Arklatex Tuesday afternoon. The
aforementioned front will rapidly lift north as warm front Monday
night, in advance of the upper wave.
Similar to yesterday, medium range model consensus begins to fade
by 168 hours. GFS and to a lesser extent, the Canadian depict the
southern branch wave train continuing into Wednesday night, while
the ECMWF weak northwest flow aloft following initial shortwave
passage Tuesday night. The ECMWF ensemble mean is closer to the
Canadian and GFS, suggesting unsettled weather over the Midsouth
for the middle of next week.
VFR conditions expected through the period. Potential exists for
VCTS north of JBR and MKL but confidence remains too low to
include in at these sites. Otherwise, mainly rain free conditions
expected through the period. S winds will diminish to 3-7 kts
tonight and increase on Thursday with occasional gusts especially
by Thursday afternoon. In addition, LLWS may develop at MEM late
Thursday evening in response to a 45-50 low level jet developing
over the Lower Mississippi Valley.