Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/24/24
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
909 PM EDT Thu May 23 2024
.SYNOPSIS...
A cold front will approach from the northwest this evening into
tonight. The boundary weakens as it pushes south into the local
area on Friday. The front lifts back north Saturday with daily
chances of afternoon and evening showers and thunderstorms
continuing through the Memorial Day weekend.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 905 PM EDT Thursday...
A weakening cold front will approach the area from the NW this
tonight. Showers and thunderstorms have struggled to initiate or
move into the region this evening. Latest radar shows some
showers in NE NC, but otherwise dry. A few CAMs hint at some
redevelopment in the SE later tonight into early tomorrow
morning, but confidence is rather low at this point. Outside of
isold/wdly scattered storms through the evening hours, expect
at partly to mostly cloudy sky overnight with lows in the 60s.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
As of 330 PM EDT Thursday...
The aforementioned weak front will stall out across the local
area on Friday. 12z NAM and HRRR are showing the potential for
scattered showers/storms during the morning before clearing and
then additional isold showers/storms developing in the
afternoon. Remainder of the guidance favors the
afternoon/evening for any showers/storms. Forecast still favors
highest PoPs on Friday after 18z (15-20% NE to 30-40% S).
Remaining summer-like and rather warm Friday with highs in the
mid to upper 80s inland, and upper 70s to lower 80s at the coast
due to a developing sea-breeze in weak flow. Mild Friday night
with lows in the 60s. 23/12z guidance has some broad
consistency in showing shortwave energy arriving Saturday in
westerly mid/upper level flow, with the boundary lifting back to
the N, but confidence in the details remains low. Given this,
PoPs for mainly afternoon/evening showers/tstms are 30-50%
across the entire area. Highs Saturday will once again be in the
mid 80s, with upper 70s to lower 80s toward the coast.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
As of 330 PM EDT Thursday...
Key Message:
- Remaining warm and humid Sunday into Memorial Day with the
potential for showers and thunderstorms Memorial Day.
Continued warm and humid Saturday night with any showers/tstms
diminishing in coverage as shortwave ridging arrives in the
westerly flow aloft. Lows will mainly be in the 60s. Highs
Sunday will once again be in the mid 80s inland with upper 70s
to lower 80s toward the coast. Less coverage of showers/tstms
are expected Sunday afternoon/evening as broad ridging prevails,
with PoPs less than 10% NE to ~30% SW. 23/12z EPS/GEFS depict
an anomalous trough digging from the Great Lakes to the
Northeast Monday through Wednesday with a cold front pushing
through the Mid-Atlantic. Confidence on timing remains on the
low-side, but given the strength of the trough more coverage of
showers/tstms are possible in the Memorial Day/Monday night
timeframe. Highs Memorial Day will once again be rather warm in
the mid 80s to around 90F (slightly lower at the coast), with
highs trending down into the upper 70s to lower 80s toward the
middle of next week with drier air also arriving into the
region.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
As of 755 PM EDT Thursday...
Storms have been slow to initiate/make their way into the local
forecast area as the weakening cold front approaches the area.
May still see a shower or storm at ECG this evening, but
confidence is lower for impact at other terminals. Brief vsby
restrictions will be possible within any precip that does
develop. Otherwise, prevailing VFR is expected.
A front stalls in the vicinity of the region Friday-Monday,
bringing daily chances for mainly afternoon/evening
showers/tstms. Chances for showers/tstms are mainly 15-20% NE to
30-40% SW Friday, 30-40% across the area Saturday, and 15% or
less NE to 20-30% SW Sunday. There is the potential for more
coverage of showers/tstms Monday as an upper trough approaches
from the NW.
&&
.MARINE...
As of 230 PM EDT Thursday...
Key Messages:
- Benign conditions expected on the waters through Sunday.
- Chances for showers and storms (especially in the afternoons
and evenings) through the Holiday weekend.
A very quiet stretch of marine weather conditions is expected
through Sunday. Expect winds of 5-15kt through Sunday with seas 2-3
ft over the ocean/waves 1-2 ft in the bay. Afternoons will likely be
dominated by sea breezes each day so winds should become onshore
during those times, otherwise expect south to southeast winds.
A cold front approaches the area on Monday associated with a
deepening low pressure center over the Great Lakes. Have continued
with winds of 10 to 20 kt on Monday, still below small craft
advisory criteria. Winds turn NW at 10 to 15 kt behind the front on
Tuesday into midweek.
Marine interests will need to keep an eye out for thunderstorms each
day through Memorial Day, mainly in the afternoon and evening.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.
&&
$$
SYNOPSIS...JDM
NEAR TERM...AM/JDM
SHORT TERM...AJZ/JDM
LONG TERM...AJZ/JDM
AVIATION...AM/JDM
MARINE...MRD
Area Forecast Discussion
National Weather Service La Crosse WI
1023 PM CDT Thu May 23 2024
.KEY MESSAGES...
- Initial Storm Chances Return Late Tonight Into Friday Morning
Primarily Providing Widespread Rainfall
- Strong to Severe Storms Possible Through Friday Afternoon As
Surface Frontal Boundary Pushes from West to East. Low
Confidence Regarding Hazard Type, None Can Be Ruled Out At
This Time
- Main Impact Will Be Heavy Rainfall, Scattered Nature Of
Afternoon Rainfall Presents Difficulty Discerning Location Of
Highest Impacts. Overall Amounts Near & Above 1" Likely. More
Precipitation Chances Return Sunday Night Into Monday,
Furthering Water Concerns.
&&
.DISCUSSION...
Issued at 257 PM CDT Thu May 23 2024
Ongoing Rain & Storms Today:
Surface low pressure early this afternoon has been meagerly
deepening across the Northern Plains. A couple of surface frontal
boundaries extend from the low with the main low level theta axis
extending from the Southern to Central and Northern Plains.
Accompanying surface observations have temperatures in the 70s with
dewpoint temperatures in 50s. An exiting surface high pressure has
provided an anticyclonic arc to the low level theta e axis,
pushing the surface warm frontal boundary near Lake Superior.
Otherwise, a pocket of drier air mass near the surface high
pressure center extends from Chicago into southeast Iowa with a
storm east-west moisture boundary farther south with dewpoint
temperatures in the 60s. A narrow appendage of the
aforementioned dry air extends northwest from Chicago, into
Trempealeau County. As a result, isentropic lift along the 290K
isentropic surface providing weak storm and precipitation
chances this afternoon. Therefore, have added slight chances in
a limited area as the moist air continues advecting northeast.
Although, this area in central Wisconsin known for very sandy
soils, potentially persisting precipitation and storm chances
later than currently expected. Will be a very near term forecast
detail.
Precipitation & Storm Chances Late Tonight - Friday Morning:
More widespread precipitation chances return tonight from the
aforementioned surface low pressure seen over the Northern Plains
this afternoon. Highest chances move from southwest to northeast
along the initial warm frontal boundary as the surface low occludes
and phases through the Northern Plains into northern Minnesota
and southern Manitoba. Separation of the PBL overnight will
limit local impacts, keeping things elevated and limiting
potential storm strength. Irregardless, have increased thunder
chances from National Blend based on instability in high
resolution model forecast skew Ts.
Precipitation & Storm Chances Through Friday:
These initial storm and rain chances shift northeast through
Friday morning before the subsequent cold front pushes from west
to east Friday afternoon. An appendage to the phasing low will
drive and strengthen the cold front, causing strong convergence
along the boundary. The occlusion of the northern low also
advects a narrow filament of instability and attendant shear.
The strengthening return flow keeps warmest air off the deck
initially, persisting an inversion before surface air can
potentially recover.
Due to the morning convection, ability for surface temperatures
to recover remains a questionable factor. The RAP remains to be
the most keen model, quickly recovering surface temperatures,
becoming surface based in a very limited window. Although, it
also persists mid level saturation through this time so hard to
confidently say the surface temperature recovery is accurate.
The highest helicity remains tied to the tight, narrow
occluding area ahead of the cold front, offset of the highest
instability and quickening cold front.
Severe Potential Through Friday:
As the cold front provides the necessary lifting, hodographs
and shear becomes quite messy as storms are undercut from a west
to east frontal boundary and a mean storm motion of southwest
to northeast. Therefore, scattered convection looks to be the
most likely with wind and hail with the highest potential
hazard types. If these ingredients line up closer, storm mode
could also be linear along the cold front with popping off
outgoing cold pools.
However, given the potential for severe, machine learning
probability forecast have 5-10% probability for tornadoes, 15-30%
for severe hail, and 5-30% for severe wind. So, will be a limited
window to keep eyes fully peeled for.
Highest Impact Concerns:
Irregardless, highest concern and impact, especially given the
recent heavy rainfall, will be potential for flooding. Given
the longer residence time of the 1" PWAT isohyet through much of
Friday, highest confidence for a widespread 1" of rainfall.
Thankfully, most rivers have begun to recover since previous
rainfall. Initial heavy rainfall Friday morning will provide a
widespread amount while the secondary wave will be more
scattered, limiting further widespread impact. Could see some
longer residence time though with those scattered storms into
Friday evening. Something to keep an eye on in coming forecasts.
Local probability matched mean (HREF) 24 hour precipitation totals
as of 12Z Saturday push 2-2.5" in our southern areas while 48
hour probability matched means only push 1". HREF storm total
precipitation maximum further spreads the 2" isohyet primarily
from northeast Iowa into central Wisconsin with highest 48 hour amounts
pushing 4" while the mean remains 1.5". Quite a spread, but a
concern.
Late Weekend Precipitation & Storm Chances:
Subsequent precipitation chances return late weekend into Monday. A
phasing bowling ball of vorticity lifts northeast before
crashing into the Upper Mississippi River Valley. Strong low
level moisture advection from a stunted Midwest atmospheric
river taps into the Gulf airmass, again providing heavy
rainfall. Highest confidence for instability grazes southern
counties from northeast Iowa into southwest Wisconsin as the
surface low is expected to wrap up and provide heaps of low
level shear. Too far to nail out details at this time.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1022 PM CDT Thu May 23 2024
A cold front will move through the area on Friday afternoon.
A pre-frontal trough will bring a round of showers and
storms. The CAMs continue to show that the highest chances of
showers and storms are from 24.12z to 24.15z for KRST and from
24.13z to 24.16z for KLSE. Additional showers and scattered
storms will possible into Friday afternoon. The confidence in
the timing of thunderstorms was so low that they were not
included in the TAFs. It looks dry in the evening, so removed
all mention of precipitation.
Winds will be southerly at 10 to 15 knots during the morning and
then shift to the west during the afternoon and increase into
the 10 to 20 knot range. Winds during the evening will gust into
the 20 to 30 mph range.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...JAR
AVIATION...Boyne
Area Forecast Discussion...Updated
National Weather Service Billings MT
943 PM MDT Thu May 23 2024
.UPDATE...
Snow has decreased over the Bighorn and Pryor mountains this
evening as the low pressure system gradually shifts east.
Additional snow accumulations in the mountains are expected to be
minor. Therefore, have gone ahead and cancelled the Winter Storm
Warning. The forecast remains on track. STP
&&
.DISCUSSION...
Today through Friday night...
...Key Messages...
- Heavy precipitation for lower elevations and heavy snow for
mountains today lingering early this evening.
- Heavy rain will cause rises on area rivers and streams.
Active day of weather across the region with heavy rain in the
lower elevations and heavy snow in the mountains. There is an
upper jet passing to the south putting the region in the favorable
left exit region. RAP mesoanalysis is also depicting strong upper
divergence and frontogenesis. This strong upper forcing
combined with soundings that are saturated through a deep layer
of the atmosphere is leading to efficient rain production and
heavy rain in a short amount of time. Winds are wrapping around
the backside of the low bringing north/northwest winds through
the western areas of the CWA. Some of our northwestern counties
such as Wheatland have started to clear out. Locations in far
southeast Montana have been dry-slotted today leading to higher
temperatures and surface heating. This has allowed these areas to
remain dry so far. Precipitation will continue to spread into
these areas of southeast Montana this afternoon into evening. CAPE
will be lilted in these areas to about 500J/kg or less but 0-6km
shear will be strong with values in the 50s and 60s kts. HREF is
showing 2-5km updraft helicity tracks for locations mainly in
Powder River and Carter Counties. Due to these factors, the Storm
Prediction Center has put these areas into a marginal risk for
severe weather with the main threats being hail and wind. Most of
the region east of a line from Red Lodge to Miles City will see
additional rainfall of an inch or more. Locations to the west of
that line will begin to clear out this afternoon and receive 0.10
inches or less of additional rainfall.
Due to the heavy rainfall amounts saturating soils, there is a
risk of water ponding and localized minor flooding conditions.
This will be more pronounced in cities and towns were development
prevents water absorption or in locations with already saturated
soils. We have gotten some reports of localized street flooding on
low lying roadways in Billings. Stream and river levels are
expected to rise although there are currently no major concerns
for stream and river flooding. The Little Bighorn River near
Hardin is no longer expected to reach minor flood stage.
This afternoon and evening will continue to be windy with most
locations having a 30-60% chance of getting a wind gust over
40mph. The strongest winds will be in Sheridan County where
probabilities will be 60-90%.
Temperatures will be cool tomorrow morning with most locations
being in the low to high 30s. Some locations west of Billings
generally have a 20-50% chance of getting a freeze. Tomorrow we
will move more into a more downsloped pattern leading to warmer
temperatures in the low to mid 60s. There will be isolated showers
around tomorrow from a low pressure system to our north. Most
locations north of Billings have a 20-30% chance for
precipitation. Torgerson
Saturday through Thursday...
Next trough approaches the region on Saturday, and moves through
the area on Sunday. Low PoPs in the western mountains Sat.
morning, will increase and spread E in the afternoon. Highest PoPs
will be W of KBIL (60-80%). The high PoPs will traverse the area
from W to E Sat. night. While a few thunderstorms will occur into
Sat. night, CAPE/shear values were weak. Chances for at least 0.25
inches of precipitation will be 29% in KLVM and 21% in KBIL for
Sat. night. Temps will be near or a little below normal on
Saturday. On Sunday, PoPs will range from 30% W to 60% E. Chances
for thunderstorms will be confined E and S of KBIL. Again,
CAPE/shear looks weak. Sunday will be slightly cooler than
Saturday. Chances for at least 0.25 inches of precipitation on
Sunday were 20% in many areas.
Monday through Tuesday will be mainly dry with a warming trend due
to upper ridging. Highs on Tue. will be in the upper 70s to lower
80s. SW flow moves in on Wednesday ahead of the next trough. This
flow will bring scattered (30-40%) showers and thunderstorms into
the area in the afternoon through Wed. night. Warm weather
continues on Wednesday. Uncertainty in the pattern increases for
Thursday as ensembles have different solutions regarding the
trough. Forecast has a 20-30% chance of showers and thunderstorms,
with temps in the 70s. Arthur
&&
.AVIATION...
Moderate to heavy rain will move W to E through the forecast area
through this evening. Snow will occur in the foothills and
mountains above around 5000 ft. Expect scattered showers and
thunderstorms from Rosebud County E. Conditions will be MVFR/IFR
with areas of LIFR. Mountains will be obscured. VFR will return
to the area after 06Z, but scattered stratus and patchy fog cannot
be ruled out. Chances of showers and thunderstorms will move into
the area from the N after 18z Friday, with MVFR/IFR conditions
and areas of mountain obscuration. Arthur
&&
.PRELIMINARY POINT TEMP/POPS...
Fri Sat Sun Mon Tue Wed Thu
-----------------------------------------------------------
BIL 036/065 042/068 046/064 044/074 048/080 053/079 052/074
01/U 15/T 74/W 10/U 00/U 13/T 43/T
LVM 031/061 036/062 039/061 039/071 044/078 049/077 047/073
01/U 18/T 73/T 00/U 01/U 14/T 33/T
HDN 034/066 039/070 045/065 042/074 044/082 050/081 050/076
21/U 03/T 75/W 10/U 00/U 12/T 42/W
MLS 038/065 041/070 047/064 045/073 046/079 053/082 052/076
52/T 11/B 55/T 10/U 00/U 11/U 42/W
4BQ 039/065 042/070 047/063 045/071 046/079 053/082 054/077
+1/U 01/B 56/T 10/U 00/U 01/U 32/W
BHK 037/062 038/071 044/065 042/070 043/077 049/079 049/075
+3/T 01/B 36/T 10/U 00/U 01/U 32/W
SHR 033/064 038/067 041/061 040/071 044/078 049/080 049/076
50/U 02/T 66/T 10/U 00/U 02/T 32/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service State College PA
1105 PM EDT Thu May 23 2024
.SYNOPSIS...
Upper level riding will build into Pennsylvania Friday into
early Saturday. A shortwave passing north of the region will
push a weak cold front through the state late Saturday. Low
pressure will then track west of Pennsylvania Sunday night into
Memorial Day, with the trailing cold front coming through
Monday evening.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
The 03Z surface analysis places a stalled frontal boundary over
the southern tier of PA. A mix of cumulus and cirrus is noted
in the satellite imagery south of the front, while the arrival
of much drier air has resulted in mostly clear skies north of
the front.
The main focus for tonight will be on a potent-looking shortwave
over KY, which is progged to track eastward across VA late
tonight. Latest model guidance keeps the bulk of the convection
associated with this feature south of PA. However, increasing
large scale forcing, combined with modest instability south of
the stalled front, could support a few showers/tsra across the
southern tier of PA later tonight.
Low level moisture pooling in the vicinity of the front may
result in patchy late night valley fog across Southern PA.
Across the NW Mtns, clear skies, a calm wind and dry air should
result in efficient radiational cooling, so have shaved a couple
of degrees off of NBM guidance and added patchy fog toward dawn
in the deep river/stream valleys of the NW Mtns. Min temps
should range from the upper 40s over the NW Mtns, to the low 60s
over the Lower Susq Valley.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Any showers over the southern tier should end by mid morning
Friday, as the associated shortwave passes off of the Mid
Atlantic coast. Large scale subsidence behind this feature
should ensure fair weather for the rest of the day. Surface high
pressure nosing southeast from the Grt Lks should push the
stalled front south of PA by afternoon, with mainly sunny skies
even in the south by that time. Model soundings mix to 800mb,
where temps around 10C support highs ranging from the upper 70s
over the Alleghenies, to perhaps the mid 80s over parts of the
Susq Valley.
Surface ridging over the state should ensure fair weather Friday
night into early Saturday. By late Saturday the focus will shift
to a shortwave lifting across the Eastern Grt Lks. Diurnal
heating, combined with surging moisture ahead of a trailing
cold/occluded front, will likely result in a round of
showers/tsra in many locations late Saturday afternoon or
evening. Unimpressive pwats and the progressive nature of this
feature indicate rainfall amounts will be fairly insignificant
(<0.25 inches).
Model guidance supports fair and warm weather Sunday, as upper
level ridging builds over PA ahead of an upstream trough and a
weak surface high builds in from the Grt Lks. However, a
diurnally-driven late day shower/tsra is possible across
Southern PA, where modest capes are noted in the model guidance.
GEFS 2m temp anomalies are close to 10 degrees above normal
Sunday afternoon, translating to highs ranging from the upper
70s in the Endless Mountains to the mid 80s through the
Susquehanna Valley.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
All medium range guidance tracks a surface low west of PA
through the Grt Lks Sunday night into Monday, with the trailing
cold front likely coming through Monday night. Falling heights
and surging pwats along the attendant low level jet should
result in numerous showers/tsra beginning Sunday night and
lasting into Memorial Day. Ensemble median rainfall during this
time period is 0.75-1.00 inch for much of the area. Current
guidance indicates the best chance of severe weather will be
west of the Appalachians Mon PM, with less cape east and an
east-southeast flow to the east of the mountains.
A longwave trough will then set up over the eastern US and
persist through much of the upcoming week, with several
shortwave troughs rotating through the base of the trough.
Expect a downward turn in temperatures with 850 mb temps in the
single digits only supporting highs in the 60s to low 70s by
Wed-Thu. Given the low level instability beneath the cold pool
aloft, we have moderate confidence in scattered diurnal showers
and isolated thundershowers Tue-Wed, with the highest PoPs in NW
zones (closer to the upper low). Models diverge in timing the
departure of the trough late in the week. However, a trend
toward drier/warmer conditions looks likely.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Dry air at midlevels has translated to a dry afternoon across
central PA airspace. Expect VFR conds into the evening and
overnight. A few isolated showers may pop up across the southern
airspace, near the MD border during the evening hours, where a
cold front slows its southward advance and taps into some deeper
moisture.
Guidance continues to show the chance of low vsbys and cigs
late tonight into Friday morning, with recent GLAMP guidance
and RAP guidance suggesting JST may experience an extended
period of IFR/LIFR conditions. Given some uncertainty with
regards to extent, have kept IFR restrictions limited to JST
from 10z-14z, with MVFR conds at AOO and UNV.
Generally VFR conds will prevail on Friday.
Outlook...
Sat-Sun...Mainly VFR, but chance of showers (mainly Sat)
Sun PM - Mon PM...Restrictions possible with periods of
SHRA/TSRA
Tue...Scattered SHRA poss
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Fitzgerald
AVIATION...Gartner/Colbert
break the cap (see 06z HRRR). As of this forecast discussion, I find
myself leaning more towards Scenario #1 with latest HREF guidance
favoring a decrease in SBCIN over areas along and south of
Interstate 80.
Should scenario #1 play out, we would need to watch for storms
capable of producing damaging wind gusts and large hail thanks to
the presence of high instability (MLCAPE around 2000 J/kg), very
steep mid-level lapse rates around 7-8 C/km, favorable deep layer
shear around 30-35 kts and a more linear storm mode favored. A
tornado cannot be ruled out especially with any storm that
interacts with remnant boundaries or that can become surface based.
This complex should exit the area by late morning to midday, with
potential for another line of showers and thunderstorms to move
through the area during the afternoon/evening with the surface cold
front. This threat will be heavily dictated by which scenario we see
in the morning. If we see scenario #1 play out, much of our PM
threat will be diminished with coverage more isolated to scattered
due to more atmospheric stabilization. Should scenario #2 play out,
storms during the afternoon could be stronger with more instability
to work with.
The Storm Prediction Center continues to highlight areas across
east central and eastern Iowa in a Level 1 (marginal) risk of
severe thunderstorms through 12z Friday, with a Level 2 (slight)
risk along and east of a Manchester IA to Ottumwa IA line after
12z Friday.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 207 PM CDT Thu May 23 2024
Friday Night Through Daytime Saturday...
High pressure will provide a dry start to the holiday weekend. Look
for near normal highs in the low to mid 70s, and lows Saturday
morning in the upper 40s to mid 50s.
Saturday Night on...
Active weather returns Saturday night as remnants from a complex of
showers and thunderstorms moves into the area. This complex will
dictate how things evolve for daytime Sunday, with potential for
another round of showers and thunderstorms during the afternoon and
evening. There is a chance these storms could be severe, with the
latest SPC Day 4 outlook painting a 15% chance (slight) for areas
along and south of Interstate 80. Higher chances remain to the south
of the area near a upper jet poleward exit region, where there is
enhanced upper level divergence in play. Other severe statistical
guidance including CSU and CIPs are in agreement of severe
potential, so please continue to monitor the latest forecasts if you
have plans Sunday.
Chances of showers and thunderstorms will persist into Memorial Day
as another shortwave moves into the area. Coverage looks to be more
isolated to scattered with this feature with lower levels of
moisture and forcing at play.
We quiet down by the middle of next week with high pressure moving
across the area, though this will be short-lived with zonal flow and
a renewed round of shortwaves moving into the area by late next
week. Temperatures look to average near normal for the period.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 653 PM CDT Thu May 23 2024
A complex of showers and thunderstorms is forecast to track
through eastern Iowa and northwest Illinois Friday morning,
moving in from west to east. The storms could lead to brief
IFR/LIFR ceilings and visibilities and gusty winds of 40+ kts
out of the west/northwest. TEMPO groups will likely be needed
in later updates to account for the higher potential impacts.
Additional development of scattered showers and storms are
possible Friday afternoon and evening before a cold front shifts
winds around to the west late in the period.
&&
.HYDROLOGY...
Issued at 1025 PM CDT Thu May 23 2024
The flood warning for the North Skunk River near Sigourney has
been upgraded to Major flood category. Routed water from a
sparse data area upstream where the heaviest rain fell a few
days prior has led to a rapid rise in the last 6 hours and is
now above Major flood stage. The forecast calls for a crest of
24.5 feet by Friday afternoon, but there is uncertainty in the
amount of water that remains to move through the reach and the
crest may need to be further adjusted.
The Wapsipinicon River near DeWitt was upgraded to a Flood
warning. Major flood stage is being forecast based on routed
flow, and is supported in output from the Hydrologic Ensemble
Forecast Service Model Simulation (HEFS), which places high
confidence on reaching Major Flood stage (12.5 feet). The
forecast has gone up this evening with a crest now over 13 feet
next week. This fits near the most likely range from HEFS of
12.8-13.1 feet. Some attenuation is possible as the routed
flow moves through the river system, but at the same time there
will be additional rounds of rain Friday and Sunday of which
could total over 1 to 2 inches. There will likely be changes to
the forecast in the coming days as the rain lays out and the
extent of the routed flow is better known, so stay tuned!
Routed water and additional rain through the weekend is leading
to rises on most other tributary rivers and the mainstem of
the Mississippi, especially south. Flood warnings or watches
are in effect for portions of the Cedar, Iowa, Skunk and
southern sections of the Mississippi river so please refer to
the latest Flood Statements and Flood Warnings for details.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...Speck
LONG TERM...Speck
AVIATION...Uttech
HYDROLOGY...McClure
Area Forecast Discussion
National Weather Service Goodland KS
819 PM MDT Thu May 23 2024
.KEY MESSAGES...
- Severe storms still remain possible for this afternoon and
evening.
- Cold front this evening and tonight brings strong to
potentially damaging winds; High Wind Warning is in place for
a portion of the area.
- Severe weather potential continues on Saturday along with some
fire threat for eastern Colorado.
- Warmer and potentially active pattern for next week.
&&
.UPDATE...
Issued at 815 PM MDT Thu May 23 2024
Forecast updated again to add in Rawlins county in NW Kansas to
the Severe Thunderstorm Watch.
&&
.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 212 PM MDT Thu May 23 2024
Difficult forecast for today as moisture return across eastern
counties has been a bit stronger than anticipated leading to
fairly thick stratus across the eastern counties. The dry line
is currently located from roughly Yuma to Burlington into
western portions of Greeley county Kansas; have also already
begun to see CU developing along it as of 1730Z. Forecast
continues to lean heavily on the NAMNEST as it has done the best
hinting at the cloud cover across the east and has thus far
nailed the position of the dry line. Same as yesterday, do
continue to think that the convection will occur along the dry
line as it continues to trek to the east, CI should occur around
3pm MT along a line from roughly Holyoke to Benkelman to Colby
down to Leoti. Significant differences are still seen in CAMS
with the HRRR and RRFS being dry and the NAMNEST the most
aggressive. There is some slightly warmer 700mb temperatures
around - 8-10C creating a weak cap; but do think this can be
overcome despite the overall lack of large scale forcing by not
only the dry line but also by reaching convective temperatures
which are in the low to mid 80s.
As for hazards for today: think there may be a window for some
landspouts along the dryline due to the stark difference in
temperatures along it. The warm temperatures should help to
further destabilize the surface (along with some surface
vorticity moving into the area and then as any updrafts start to
form it should help stretch them. Concern does continue for
large to very large hail as well as ample MUCAPE in the
3000-3500 j/kg range; the only caveat as to if this can be
realized is if the storms can survive long enough for hail to
remain aloft. A tornado (not landspout) threat may materialize
as well if a storm can be longer lived in the 23-01Z time frame
as the LLJ increases and streamwise vorticity increases.
Attention then turns to an incoming strong cold front during the
evening hours and overnight. There still does remain potential for
storms to develop along the front mainly to the east of Highway 83
where the better moisture still remains. Large hail, and damaging
winds will continue to be primary threats with this. Some areas for
QLCS tornado potential would also be possible along the leading
edge of the line especially with any north-south oriented
segments where the normal wind can remain perpendicular to the
line as strong streamwise vorticity remains seen in soundings
along with 0-3 and 0-1 SRH values in excess of 200 m^2/s^2.
To the west of the convection (in the more dry air) the potential
does remain for strong to perhaps damaging winds with the front.
GFS, NAM, RAP and HRRR all agree on 8-11 mb pressure rise along and
behind the front. The HRRR forecasted sfc gust has also been
consistently showing stronger and stronger wind gust potential
lying across a corridor from Graham county down into Wichita
county; to further increase confidence the HREF also is
highlighting this area as having the relative best potential for
non thunderstorm damaging winds. Have opted to issue a High
Wind Warning after coordination with NWS Dodge City.
A chilly start to the day Friday with lows starting in the upper 30s
across western portions of our Colorado counties and reaching the
mid 40s across the east. Not concerned for frost formation at this
time as winds will continue to remain breezy around 20 mph
sustained. Surface high that sets up across the area will push out
to the east as the day goes on which will lead to a fairly similar
day as what we experienced yesterday as winds will lessen throughout
the day. Similar to yesterday as well another weak wave moves off of
the Front Range and low to mid level moisture return occurs leading
to the potential for some hit and miss showers after sunset and
through the night.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 212 PM MDT Thu May 23 2024
Extended period starts off active again as well as a fast moving
trough and developing surface low moves across the area. A dry line
again will remain the main focus for storm initation, although there
remains differences in where the dry line will set up. Start time
may not be until a bit later in the afternoon/early evening due to
the timing of the wave and the better surge of moisture into the
area. Large hail and damaging winds again look to be the primary
hazards. Yet another cold front will then move through the area
Saturday night and Sunday morning which may again be the focus for a
potential second round of severe weather. Will also need to keep an
eye on fire weather potential behind the dry line and especially
across eastern Colorado where fire partners report conditions remain
favorable for fire spread.
Sunday, as the low moves off wrap around moisture looks to move into
the area again leading to a continued potential for showers and
storms. The severe threat at this time does appear to be on the
lower end of the spectrum. Currently thinking that strong winds
would be the primary threat as DCAPE values look to remain around
1000 j/kg.
Ridging then is forecast to develop across the western CONUS which
looks to lead to warmer temperatures for the region. The pattern at
this time is appearing to be fairly reminiscent potential MCS
patterns where storms form off of the Front Range and trek into
western Kansas as the Tri-State area is on the downstream side of
the ridge which makes the area more at risk to waves off of the
mountains. Moisture at this time does appear to be in place
which again would favor this. High temperatures for next week
are currently forecasted in the 80s with overnight lows in the
50s to low 60s.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 350 PM MDT Thu May 23 2024
For KGLD, VFR conditions through the forecast period. Winds,
south-southeast around 20-30kts through about 03z Friday, then
veering north-northwesterly with a cold frontal passage. Looking
for 15-30kts, w/ gusts up to 35-45kts from 03z-11z Friday. By
20z, northwest 10-15kts. LLWS 07z-11z Friday 330@55kt.
For KMCK, VFR conditions through the forecast period. Could be
some potential for VCTS through 06z, but low confidence at this
time so have left out of forecast. Winds southeast around
20-30kts through 04z Friday, then veering north-northwest
around 15-30kts. Gusts to about 45kts possible from 04z-06z. By
14z Friday around 10-20kts, then down to about 10kts by 21z.
LLWS 06z-14z Friday 320/330@50kts.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...High Wind Warning until 3 AM MDT /4 AM CDT/ Friday for
KSZ013>016-027>029-042.
CO...None.
NE...None.
&&
$$
UPDATE...JN
SHORT TERM...Trigg
LONG TERM...Trigg
AVIATION...JN
Area Forecast Discussion
National Weather Service Wilmington NC
942 PM EDT Thu May 23 2024
.SYNOPSIS...
Shower and thunderstorm chances will grow as a series of
upper level disturbances move across the region Friday through
Sunday, while a front remains stalled well north of the area.
Inland temperatures will rise into the lower 90s by Sunday,
then cool back towards normal by Wednesday behind a cold
frontal passage late Tue.
&&
.UPDATE...
Have tweaked POPs across the CWA slightly lower and pulled
slightly back the further southward extent and coastal extent
based on latest 88D trends and the latest hi-res models. Will
see debris convective mid and upper level clouds moving and
slowly partially scouring out-some as the overnight progresses
into daylight Fri. Very little tweaking needed for overnight
lows. Marine winds generally SW around 10 kt or 10-15 kt as
night time SW winds 15 to 20 kt just off the deck mix down-
some. Seas generally around 2 ft, with an underlying easterly
swell at 8 to 10 second periods dominating with wind chop above.
Could see a solid SW 15 kt near shore Fri as seen today due to
the sea breeze.
&&
.NEAR TERM /THROUGH FRIDAY/...
A ridge axis extending northeastward from a mid and upper
level high centered over the Gulf of Mexico will move off the
Carolina coast this evening. Behind this ridge the westerly flow
near and above 700 mb will bring cooler air overhead, removing
the convective cap that has remained across the Carolinas for
the past several days. Precipitable water along the coast should
increase from around 1.2 inches this morning to 1.8 inches by
Friday morning. A series of upper level disturbances should
begin to arrive tonight, each potentially accompanied by a wave
of showers and thunderstorms.
Timing of these disturbances starts easy but gets more muddled
with time. Disturbance #1 is discernible in water vapor imagery
now across central TN into Alabama and should move across the
eastern Carolinas tonight. My forecast shows an increasing trend
in inland PoPs after 9 PM, peaking around 40 percent late in
the evening, then diminishing again after 1 AM. It`s less likely
this initial wave will reach the coast intact although clouds
should certainly increase. Forecast lows are generally in the
upper 60s inland to around 70 on the coast.
Mesoscale subsidence behind tonight`s initial impulse may keep
convection isolated Friday morning, but renewed convective
activity should develop during the afternoon hours as surface-
based instability rises to near 2000 J/kg and modest DPVA
overspreads the region in advance of another disturbance slowly
approaching from the west. High-res models suggest the seabreeze
front should be a significant trigger for convection, and my
forecast PoPs are highest (60 percent) just inland from the
coast. Forecast highs are in the upper 80s, except lower-mid 80s
at the beaches.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
Still expecting an active pattern for the weekend via the
mostly zonal mid level flow and embedded short waves. Of course
the inland Piedmont Trough and to a lesser extent the sea breeze
will play a part as well. The highest pops occur Friday night
and again Saturday pm. Guidance is trending toward formidable
NVA in the wake of Saturday`s system for Sunday and pops may
need to be reduced further there if this continues. Temperatures
look to remain above climatology throughout.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
Active pattern continues for the first part of next week as the
west to east mid level flow pushes to the south slightly with
remaining embedded shortwaves. It appears the best forcing in
several days may occur Tuesday evening when all of the elements
(surface front, mid level height falls) combine. Beyond this
still expecting dry conditions to develop along with cooler
temperatures.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
An upper level disturbance to approach from the west overnight
into Fri. Have indicated a VCTS/VCSH for the inland terminals
by 04z/05z with activity likely dissipating as it pushes closer
to the coast during the pre-dawn Fri hrs. Could see a round of
low stratus around a 2-3 hr window around sunrise. A better shot
of convection from generally 18Z Fri thru the remainder of the
fcst period. May use PROB30 groups to highlight at this time
given the upper disturbance, the sea breeze and says insolation
aiding increasing instability.
Extended Outlook...Scattered thunderstorms will be accompanied
by periodic short lived MVFR/IFR conditions through the weekend
into Monday. The best potential appears to be Friday and
Saturday afternoons when thunderstorm potential coverage and
potential increases at or above 50 percent, especially inland.
&&
.MARINE...
Through Friday...Surface high pressure will retreat east to
near Bermuda tonight as a series of weak upper level
disturbances begin to move across the Carolinas from the west.
Synoptic winds will remain south to southwest at less than 10
knots, however some higher winds will persist along the coast
through this evening due to today`s well- defined seabreeze
circulation. Additional periods of stronger winds could
accompany scattered thunderstorms on Friday, expected to be
most numerous during the afternoon hours. A few of our high-res
weather models including the HRRR explicitly indicate west to
northwest thunderstorm outflow winds developing along the South
Carolina coast late Friday afternoon.
Outside of any thunderstorms, sea heights of only 2 feet are
expected through Friday consisting of an eight second easterly
swell plus local wind chop.
Friday night through Tuesday...Overall light winds will persist
into the weekend from the south to southeast as the pressure
pattern remains weak. In time the flow will turn more from the
southwest and increase a bit in magnitude. This occurs early
next week. Significant seas will be 2-3 feet this weekend
perhaps increasing to a range of 2-4 feet early next week.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
NC...Coastal Flood Advisory until 1 AM EDT Friday for NCZ107.
SC...None.
MARINE...None.
&&
$$
SYNOPSIS...DCH
UPDATE...DCH
NEAR TERM...TRA
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...DCH
MARINE...TRA/SHK
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
832 PM CDT Thu May 23 2024
.KEY MESSAGES...
- There is a slight risk (level 2 of 5) for severe weather for all
of central and southeastern Illinois for tomorrow. These storms
could produce damaging winds and large hail.
- There is a 80-100% chance of thunderstorms on Sunday. These
storms have the potential to be severe, with a 15-30% chance for
severe weather that day.
&&
.UPDATE...
Issued at 832 PM CDT Thu May 23 2024
No significant changes needed this evening. An approaching low
pressure system will lift a warm front slowly northward through
the area overnight, increasing low level moisture and cloud
cover. Precipitation will likely hold off until late morning (West
of I-55) to afternoon (east of I-55). Lows in the lower to mid 60s
look on track, considering at least light winds, cloud cover, and
increasing dewpoints.
37
&&
.DISCUSSION...
Issued at 245 PM CDT Thu May 23 2024
There are a few rounds of low pressure systems and it associated
frontal passages over the coming days. The first of which arrives
tomorrow morning. A cold front is expected to move through central
and southeastern Illinois late morning/early afternoon tomorrow,
bringing along severe weather potential. A brief surface high
pressure will set up for Saturday before the next low pressure
system passes to the north/northwest of the CWA Sunday. This low
will bring its associated cold front through the area in the
afternoon to evening hours. This system on Sunday will have the
greatest risk for severe weather.
This forecast cycle will put a lot of focus on what is coming
tomorrow. The models are being difficult and not agreeing on timing
or how the storms will move through the CWA. They do agree on storm
type, however. It will move through as a QLCS but whether it will be
a broken line or not is up for debate. The HRRR and NAM 3km differ
in timing somewhat, with the NAM 3km being a bit slower. The line
will enter our western border between 15z and 17z. The HRRR has the
QLCS moving through as solid line that goes across the entire CWA.
Whereas the NAM 3km shows a broken line. The northern portion of the
line propagates across the CWA (north of I-72), with the southern
portion developing slightly later as the first line exits the state
around 21z. This second line stretches further south along our
entire CWA. The HRRR shows the activity exiting Illinois around 23z
but the NAM 3km shows it lingering longer to around 4z. The chances
of redevelopment behind the front is basically non existant at this
time.
Temperatures tomorrow get up into the low to mid 80s. In more
mesoscale news, the storms should be surface based. The HREF 12z run
shows a 50-60% chance of greater than 3000 J/kg of SBCAPE ahead of
the front. There is a brief cap in the morning that quickly erodes
by mid morning. DCAPE values associated with the system shows 1000-
1500 J/kg. There appears to be an inverted V signature on the 18z
HRRR soundings ahead of the front. The hazards most likely to impact
central and southeast Illinois with this round of severe weather is
primarily hail and severe wind. The wind threat is the highest risk
for tomorrow, which the inverted V soundings and high DCAPE values
support. PWAT values max out around 2 inches but the fast moving
nature and training isn`t expected will limit the flooding threat.
Localized higher amounts could occur.
Saturday a high pressure settles of the area briefly, providing us a
short break before the next round of severe weather on Sunday.
Sunday another low pressure system is progged to move just
north/northwest of the CWA, bringing the next chance for severe
weather. There is a 15-30% chance for severe weather, with the
greatest risk down in southeastern Illinois. Timing of the system is
sort of uncertain currently but it looks to move through Sunday
morning into the afternoon in a linear storm mode. This round is
looking more impressive than the system expected tomorrow afternoon.
Memorial Day, Monday, looks to be windy and pretty dry. A few pop up
showers aren`t completely ruled out but basically dry. Stay tuned as
the holiday weekend gets closer and this first system gets out of
the picture for more detailed information.
Copple
&&
.AVIATION... (For the 00z TAFs through 00z Friday Evening)
Issued at 646 PM CDT Thu May 23 2024
A line of thunderstorms or perhaps a few distinct shorter
thunderstorm lines look on track to affect the central IL
terminals Friday afternoon. However, timing and location of these
lines is still highly uncertain. At this point, have included VCTS
in all TAFs starting 17Z-20Z, but will hone in on more precise
timing of any thunderstorms at individual terminals with
subsequent TAF issuances as predictability improves. For now, have
kept all conditions VFR as MVFR or worse cigs/vsbys will likely be
fairly short-lived, but any thunderstorms could produce brief
lowered flight categories. Winds S-SE 5-10 kts overnight, becoming
S around 15 kts with gusts 20-25 kts by 15Z-18Z.
37
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Northern Indiana
638 PM EDT Thu May 23 2024
.KEY MESSAGES...
- Driest periods of the holiday weekend look to be through
Friday afternoon and again Saturday into early Sunday.
- Shower and thunderstorm chances return Friday afternoon end
evening with a strong to possible severe storms west of
Indiana 15/US 131.
- Greater chances for showers and thunderstorms Sunday
afternoon and night with both severe storms and possibly heavy
rain/hydro issues existing.
- Lingering showers may impact activities on Memorial Day and
Tuesday.
&&
.DISCUSSION...
Issued at 214 PM EDT Thu May 23 2024
An overall active pattern remains in place for the next week or so
with a few quiet periods expected in between systems. The first of
these us underway with high pressure bringing clear skies and
pleasant temperatures/humidity to the area.
The first feature to monitor will be an upper level trough that will
quickly shift east towards the region to start out the holiday
weekend. The trough and associated cold front will spark a line of
strong to severe storms across Nebraska later today which will race
east and reach western IL sometime during the first part of Friday.
From here models diverge on handling of the remnants of the complex
as well as potential new development on the cold front. The MCS will
likely weaken somewhat as it enters IL, but plenty of sunshine ahead
of it and increasing low level moisture should bring in 1K to 2K
J/KG of MUCAPE into eastern IL/western IN by late afternoon to
support re-intensification with a ramp up in the damaging wind
threat if it can organize and possibly be aided by any MCV left
over. Equally plausible is complex moves through faster with
cloud cover holding on and limiting instability over our area.
500/300 mb jet streak remains to the SW and main trough will
eject into WI, limiting overall strength of the line as well.
NAM suite and 12Z HRRR remain the most aggressive on severe
potential with a pronounced rise/fall couplet in the NAM
suggesting strong wind potential. Bit concerned that with the
lack of overall stronger wind fields in place (rather weak
shear) this could be some convective contamination, but could
also be a reflection of an MCV. For the time being, the slight
risk for the western half is warranted with a decreasing trend
likely to happen with eastern extent (unless the line becomes
well established and early enough). Some scattered showers could
occur on the cold front itself overnight. Categorical pops were
inherited and for now will be maintained for collaboration as
well as chance that convection does survive into the area with
great enough coverage to warrant it.
Saturday and Saturday night will be the nicest of the days for this
weekend with a stronger system in the offing for Sunday with some
lingering effects into Monday and Tuesday. Strong trough will move
towards IL Sunday afternoon, deepening further and closing off an
upper low over N WI by 6Z Mon. Low pressure will develop with
original model trends track the low across the NW part of our area
Sunday night. A few of the 12Z solutions track the sfc low a bit
further northwest. Regardless, abundant moisture will be drawn north
into the area with increasing instability and shear to bring a risk
for not only severe weather (possibly all modes), but also hydro
issues. We will continue to monitor trends as models struggling (as
expected) with evolution of convection along the warm front and
eventual cold front.
Clouds may linger on Memorial Day and beyond with the potential for
some showers around as the overall trough remains across the
region.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 637 PM EDT Thu May 23 2024
VFR/dry conditions will persist into tonight and tomorrow
morning north of a warm front. This warm front and associated
instability axis lifts into northern Indiana by late Friday
afternoon/evening with renewed thunderstorm chances and the
potential for brief gusty winds and vis restrictions. However,
confidence on timing and whether any upstream convective line
segment survives into the area before 00z Sat remains low.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Fisher
AVIATION...Steinwedel
Area Forecast Discussion
National Weather Service Jackson MS
1042 PM CDT Thu May 23 2024
...New MESOSCALE UPDATE...
.MESOSCALE UPDATE...
Issued at 1042 PM CDT Thu May 23 2024
Rest of tonight...
A mostly quiet evening should remain mostly intact through the
next few hours, but some reinvigoration of convection into the
overnight in a deeply sheared & unstable aloft could support some
severe potential. Shortwave ridge axis continues to build
eastward across the Gulf Coast region, with broad southwesterly
ascent ahead of additional shortwave energy propagating eastward
from TX / Red River Valley across the ArkLaTex into MS River
Valley into the overnight. Guidance has been a little too bullish
on the aftn convection with evening regional radars indicating
little in the way of confidence of development the next several
hours. Earlier runs of convective allowing models (CAMs),
including the HRRR & FV3, indicated some potential redevelopment
along the northwest ArkLaMiss Delta. In this zone, isentropic
ascent, some 30-40kt flow in the 310K Theta E layer, should work
on deeply unstable environment for some convergence/potential
shower & isolated storm redevelopment after 1-2AM. There has been
some run-to-run variability concerns but enough signals to at
least continue to advertise some severe potential but into the
overnight. Recent runs of the Warn on Forecast (WoFs) domains have
been a touch too far west, but on the eastern fringes there is
some development indicate in south-central AR to north-central LA
that could move into our area after 2AM. Main concerns with any
storms would be damaging wind & large hail of quarter to golf
ball size, but tornado threat looks lower so removed that from the
graphic. Flash flooding concerns remains low but westerly flow
could lead to some training potential. Left flood HWO graphic as
is. PoPs are a challenge & lowered them across the board southeast
of the Natchez Trace to more isolated to more scattered to the
northwest. Fcst & HWO severe graphic updates are out. /DC/
&&
.DISCUSSION...
Issued at 251 PM CDT Thu May 23 2024
Today through Saturday Night:
As of mid afternoon today, our forecast area is under the temporary
influence of a shortwave ridge in the wake of this morning`s
shortwave trough passage. For the time being, this has resulted in
weaker deep-layer wind shear and likely some subsidence aloft.
Farther to the west however, another shortwave trough associated
with convection over East Texas is edging eastward. It`s expected
that at least isolated to scattered storms should redevelop in the
unstable air mass to our west with SBCAPE over 4000 J/kg and
increasing shear with that next wave. A Slight Risk for severe
thunderstorms remains in place into this evening for areas in far
northeast LA, far southeast AR, and MS near Greenville and
Cleveland. A broader Marginal Risk for severe storms extends farther
south and east to encompass more of the Natchez Trace corridor and
areas northwest from there. There is also a chance that heavy rain
could cause isolated flash flooding problems if storms train over
the same areas, or a quick downpour of 2-3 inches is observed like
happened in northeast Louisiana this morning. Will carry a Limited
threat area for flash flooding in the ArkLaMiss Delta regions
through tomorrow morning.
Confidence in exact timing is low, but it appears that we should
have a relative lull in severe weather and flooding threats through
most of the daytime tomorrow. Then during the evening and overnight
hours Friday night, a shortwave interacting with a frontal boundary
over KS/MO/AR areas should trigger additional rounds of
thunderstorms that have the potential to spread southeast toward our
forecast area through early Saturday morning. A Slight Risk for
severe thunderstorms has been extended into southeast Arkansas and
northern Mississippi to cover this potential round of severe
weather. Some continued threat for strong to severe storms will
exist across those same areas on Saturday, so a Marginal Risk for
severe storms is advertised on Saturday. Given the holiday weekend
and some uncertainty in forecasted impacts and timing, please
continue to stay aware of any updates to the forecast over the
next few days. /NF/
Sunday through Thursday:
The overall active pattern will continue into early week before
seeing a reprieve for the mid week period. Starting with Sunday,
the main weather focus will be north of our area and things should
be warm/hot but basically quiet. PoPs on Sunday are 10% or less,
but chances do increase some (20-30%) for later Sunday night.
There remains quite a bit of variability for Sunday night into
Monday night as there are timing differences with the surface
front location and southward progression and being aligned with
the upper support. Due to this, confidence is not overly high
with PoPs from Sunday night into Monday night. Additionally, same
reasoning is lowering confidence in severe storm potential. While
confidence is on the low side for these time periods, there`s a
bit more of the guidance that is on the side of slower with the
front and thus the area holds more in the favorable parameter side
for getting severe storms. So while some probability exists for
severe storms at some point Monday, will allow a few more runs to
come in and build confidence in either way.
For Tuesday into Thursday...good agreement from the global guidance
of deep layer dry air filtering into the region with PWs <1.2 or sub
1.0 inch. This will help take the edge off the warmth and humidity,
but look for modification and the boundary trying to return by later
Thursday into Friday. This is typical and having a lower level
boundary to focus moisture and convergence fits the late May type of
front supports increasing storm potential by late Thursday and by
Friday. /CME/
&&
.AVIATION...
(00Z TAFS)
Issued at 740 PM CDT Thu May 23 2024
SHRA & TSRA are slow to materialize this evening, with scattered
SHRA west of the MS River corridor. Expect this to push eastward &
some late evening to overnight development at GLH, GWO & psbl, at
GTR. Confidence is too low at other TAF sites to introduce this
TAF cycle. Some low MVFR stratus is psbl overnight between
24/08-15Z Friday, with some potential IFR stratus at southeast TAF
sites. Expect mixing & lifting to VFR flight categories after
24/15Z Friday. Any low probs of aftn convection is psbl again at
GTR. Light southerly winds, generally around 10mph & gusts up to
20mph, are psbl through Friday aftn. /DC/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 72 91 72 92 / 20 10 10 10
Meridian 71 91 71 93 / 20 10 10 10
Vicksburg 72 92 72 92 / 20 10 10 10
Hattiesburg 72 92 73 94 / 10 10 0 0
Natchez 73 91 72 93 / 20 10 0 10
Greenville 72 90 72 90 / 50 10 40 30
Greenwood 71 90 71 90 / 40 20 40 30
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
DC/CME/DC
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
846 PM CDT Thu May 23 2024
.KEY MESSAGES...
- Scattered showers and storms likely Friday with some severe
weather threat during the afternoon and early evening
- Another round of showers and storms expected Sunday with some
severe threat
&&
.UPDATE...
Issued at 846 PM CDT Thu May 23 2024
No significant changes to the going forecast this evening.
Quiet weather is expected overnight, as surface high pressure
centered over Lake Michigan and the western Great Lakes drifts
slowly off to the east. Humidity will start to increase from the
south later tonight as a warm front begins to lift north from
downstate IL/IN, though skies should remain mostly clear with
temperatures settling into the upper 50s/low 60s in most spots.
Attention continues to be focused on thunderstorm trends across
the area on Friday, which will depend largely on the evolution
of convection across the Plains to our west overnight. CAM
guidance is in good agreement in upscale growth of current
storms over SD/NE into a linear MCS, which would be approaching
the Mississippi River after sunrise Friday morning. Latest high-
res trends (including new 00Z HRRR) appear to be trending toward
weakening convection moving into northern IL with a more
limited cold pool footprint, which would then allow for some
redevelopment/renewed initiation farther west along an
approaching cold front which would affect the forecast area
during the afternoon and evening hours.
As previous discussions have indicated, these later storms will
likely present a severe weather threat, thanks to steepening
mid-level lapse rates and increasing deep-layer shear associated
with the southern periphery of an upper level trough lifting
across the upper Midwest later in the day, along with more
favorable diurnal timing for destabilization. Wind looks to be
the primary threats, though the potential for an outflow
boundary/effective warm front lingering from morning activity
would potentially provide more low-level directional shear and
may support other hazards (including tornadoes) especially if
shear were stronger (perhaps from an remnant MCV?). As noted
above, much of this will be dependent upon details still yet to
evolve to our west later tonight. Going forecast has decent pops
especially across our IL counties Friday morning, with another
period of likely pops later in the afternoon/evening, which fits
current thinking fairly well. Thus no significant changes
needed at this time.
Ratzer
&&
.DISCUSSION...
Issued at 320 PM CDT Thu May 23 2024
Through tonight:
Light winds this afternoon have allowed a lake breeze to push
inland with temperatures dropping into the upper 60s to lower
70s as it moves through. Meanwhile inland temperatures have
warmed into the upper 70s to lower 80s! Overall a nice late
spring day across the area! Quiet weather is in store through
tonight as surface high pressure gradually shifts east of the
area. Expect temperatures to drop into the upper 50s to around
60 overnight.
Petr
Friday through Sunday night:
Friday-Early Friday Evening:
A vigorous upper low over the northern High Plains will result
in strong to severe t-storm development over the central Plains
into this evening. This activity will likely congeal into an
MCS, tracking east across the Cornbelt tonight, and will likely
play a significant role in our weather on Friday.
The current more likely scenario is for the MCS timing to be
slow enough for either weakening convection or remnant MCV
arriving into our western counties later in the morning/mid day.
This would allow for more heating and destabilization across
our CWA and result in either a reinvigoration of ongoing weaker
convection or renewed convective development during the
afternoon. While we certainly can`t take CAM simulated
reflectivity as gospel at this range, note that the most recent
extended HRRR runs generally favor the maintenance and/or
reinvigoration of ongoing convection.
This evolution is more concerning from a severe weather
perspective centered on tomorrow (Friday) afternoon, as the
steep mid-level lapse rate regime with dew points in the 60s
will be conducive for strong destabilization contingent upon
more solar insolation through the morning and early afternoon
allowing temps away from the IL north shore to reach the 80-85F
range. The aforementioned vigorous, negatively tilted upper
trough/closed low is expected to remain far enough northwest to
only bring our area a glancing blow of stronger mid-upper level
flow and resultant shear. However, given moderate instability
(1500-2000 J/kg of MLCAPE, modest shear (up to 30 kt) would
likely still support multicell storms with an attendant threat
of damaging winds. In support of damaging winds as the primary
threat from a multi-cellular/quasi-linear mode will be steep,
near 9C/km low-level lapse rates and 1000-1500 J/kg of DCAPE
resulting in pronounced cold pool development.
Contingent upon embedded or lead supercellular mode, there may
be just enough deep layer shear given the progged steep mid-
level lapse rates for an isolated severe hail threat. Finally,
while brief tornadoes certainly can`t be rule out, it appears
that low-level shear will be lacking, amidst a more deeply mixed
(high LCLs) regime to keep the threat lower end. This being
said, if the anticipated MCS tonight develops into a more
organized MCS, spawning a stronger MCV, then that feature could
result in locally stronger shear and a localized more
concentrated meaningful severe weather threat, including
tornadoes, given a corridor of backed south-southeasterly and
breezy boundary layer flow.
The likelihood of robust pre cold-frontal convection Friday
afternoon-early evening does cast doubt on recovery and
redevelopment of deep convection toward and beyond sunset Friday
evening ahead of the true cold front. While there should be
enough forcing around for showers and scattered embedded
thunderstorms, coverage may end up even lower than implied by
the official forecast PoPs, which were already nudged lower from
the previous forecast. The front will sweep across the area late
Friday evening and early overnight, quickly drying things out.
Saturday:
For "unofficial start of summer" activities over the Memorial
Day Weekend, Saturday continues to look like the best weather
day with sunny skies, seasonable high temps in the 70s, and low
humidity (dew points in the 40s). Weak high pressure overhead
and initial light northwest winds under it will quickly "flop"
over to northeasterly synoptically and due to lake influence in
the late morning and early afternoon, keeping highs along the
lakeshore in the upper 60s to around 70F. Saturday evening will
be pleasant, dry, and seasonably cool. Timing of lead showers
and embedded thunderstorms has slowed enough that arrival in the
southwest 1/3 or so of the CWA appears to be toward dawn Sunday,
so for all intents and purposes, Saturday night will be a dry
night for most if not the entire area.
Sunday-Sunday night:
Another strong short-wave trough is progged to move across the
Plains Saturday and into the mid Mississippi Valley and western
Great Lakes Sunday. There remains some spread in timing and
track of the attendant surface low, which will dictate how far
north the warm front (and stronger instability) will get
following morning and mid day convection (which may be fairly
extensive). Concerningly, the EPS (ECMWF ensemble) has shown a
northward jog in the track of the deepening surface low (low-mid
990s mb at peak, quite strong for late May), with a majority of
members tracking the surface low across northern Illinois and
southern Wisconsin Sunday afternoon or evening. Only a few EPS
members showed a farther south track on the 12z run. This is in
line with the overall run to run trend of the operational
ECMWF, which has indicated a track across southern Wisconsin the
past few cycles. The GEFS has also shown a run to run northward
nudge, albeit with more north to south spread. Ultimately, it
is still too soon to say with much certainty exactly how far
north the low and warm front will get, there is always potential
for prior convection to keep effective boundary farther south.
Synoptically, the global guidance suggests there will be a
coupled upper jet structure with strong synoptic ascent. The nose
of the mid-level jet has also trended farther north, and
regardless of its exact positioning, there should be sufficient
deep layer shear to support a meaningful severe weather threat
Sunday afternoon and evening in the warm sector of the cyclone
(however far north it gets). It does appear that instability will
be a limiting factor with northward extent, with higher instability
I-80 and south or thereabouts. Whether close to the surface low
and warm front or farther south in the warm sector, wind
profiles and low-level hodograph curvature are concerning from a
tornado threat perspective on Sunday.
The main issue is that if instability is indeed minimized farther
north, there may be primarily a brief tornado threat and not much
else farther north (with right-moving low-topped supercells).
Meanwhile, farther south, there may be enough instability for an
all-hazards type of threat, some of which could be significant.
While the outer range of the NAM model is typically less reliable
and prone to large run to run swings, its 12z solution can be seen
as a realistic, though less likely, outcome ceiling wise, if the
potentially available ingredients are maximized.
Our main message for Sunday is to pay close attention to
subsequent forecast updates regarding the potential for
thunderstorms and severe weather. SPC has 15% probs in its day 4
outlook up to roughly I-88, which appears reasonable. Based on
current thinking, this may be our first more favorably (or
unfavorably) timed strong synoptic system of this exceptionally
active severe weather spring across the greater region. While the
entire day probably won`t be a washout, most of the CWA should see
at least one or two rounds of showers and thunderstorms Sunday
through Sunday afternoon and evening. Regardless of the magnitude
of the severe weather threat, outdoor events will likely be
affected by lightning nearby. It does appear that the cold front
passage will be early enough Sunday evening to wind down the
thunderstorm coverage and attendant severe threat fairly quickly,
however. It will be breezy and cooler with diminishing shower
coverage behind the cold front.
Castro/Izzi
Monday through Thursday:
GEFS and EPS both suggest the upper trough responsible for
Sunday stormy weather will deepen and hang around the
northeastern U.S. early next week. There are growing indications
that this could result in our first several day period of
solidly below average temperatures in quite some time. Can`t
rule out a subtle northwest flow low amplitude shortwave
rippling down the backside of this trough and maybe bringing a
brief period or two of a few showers to the area, but overall
Monday-Wednesday looks to be fairly dry. The day to day chance
pops early next week are just slightly above climo pops and
reflect that small chance of a few brief showers at some point
early next week.
- Izzi
&&
.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 624 PM CDT Thu May 23 2024
Forecast concerns include...
Scattered thunderstorms Friday late morning/afternoon.
Gusty southeast winds Friday.
The main concern this period is thunderstorm chances and timing
Friday. There remains two possibilities. The first is the
current convection across NE continues moving east tonight and
reaches northwest IL and RFD in the late morning and continues
across the Chicago terminals in the early/mid afternoon. The
second possibility is this activity weakens and dissipates and
new thunderstorms develop across northwest IL in the mid/late
afternoon and move across the terminals through early Friday
evening. There remains too much uncertainty to determine which
is more likely or if both may possibly occur. Trends will need
to be monitored later tonight with changes with the 06z tafs
likely. For now, have maintained prob mention and added an hour
in the late afternoon for the Chicago terminals to account for
the second possibility/later thunder timing.
A lake breeze is moving west of ORD/MDW and will dissipate with
sunset with light southeast winds areawide tonight. These will
increase mid morning Friday with gusts into the 20kt range
expected Friday afternoon. Wind directions are somewhat
dependent on when thunderstorms occur and its possible that
winds may turn more southerly by late afternoon. Eventually,
winds should turn more southwest Friday evening and then shift
northwest early Saturday morning with a cold front. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1044 PM CDT Thu May 23 2024
.KEY MESSAGES...
- Thunderstorms are expected to move across the area on Friday
ahead of a cold front. A few of these thunderstorms could
become severe with damaging winds and large hail being the
primary threats.
- After a dry Saturday, two potential rounds of showers and
thunderstorms are possible Saturday night and Sunday. Both
rounds could bring strong to severe thunderstorms will locally
heavy rainfall.
&&
.SHORT TERM... (Through Late Friday Night)
Issued at 245 PM CDT Thu May 23 2024
Scattered showers and thunderstorms have been locally strong earlier
today over southeast Missouri. This activity will diminish as
another shortwave ridge will build over Missouri and Illinois late
this afternoon into this evening. This ridge will keep most of the
area dry tonight before we see rain return to the area tomorrow.
There better chances for showers and thunderstorms during the day on
Friday as the latest GFS/NAM is showing a cold front moving
southeast across CWA during the afternoon. The majority of the CAMS
including the HRRR show thunderstorms moving into the CWA by late
morning and progressing southeast during the afternoon into the
early evening hours. MLCAPES ahead of the line tomorrow afternoon
will be in the 2000-3000 J/kg range with 0-6km shear only around 30-
40 knots which favors some organized multicell and a few
supercells. The primary threats will be a few storms capable of
producing large hail and damaging winds and perhaps a brief
tornado. The chance for showers and thunderstorms will end from
west to east by late tomorrow evening as the front moves east of
the area.
Highs tomorrow will climb into the mid 80s ahead of the front. Lows
tomorrow night will begin to cool down a bit behind the front.
Britt
&&
.LONG TERM... (Saturday through Next Thursday)
Issued at 245 PM CDT Thu May 23 2024
Saturday still looks like the most quiet day of the holiday weekend
as a large surface anticyclone moves across Missouri and Illinois.
The focus then turns toward Saturday night into Sunday when the
deterministic model suite is showing a trough moving out of the
Rockies into the Midwest. There is fairly good agreement that the
lead shortwave will move across the area on Saturday night which
will bring a warm front north through the area. Given the strength
of the forcing, will keep likely/categorical PoPs late Saturday
night into Sunday morning. Consensus of available model guidance is
showing MLCAPES over 1500 J/kg with deep layer shear >40 knots
suggesting the potential for strong to severe storms on Saturday
night and Sunday morning. The bigger question is whether there will
be a second round in the afternoon and evening. This will be
dependent on how quickly the morning convection will clear out of
the area allowing recovery of instability. There is also some
uncertainty between the models with the timing of the secondary
shortwave that will move across the area during evening that will
determine how quickly the cold front moves through the area during
the afternoon. Models are showing varying timing on the front
moving across the area during the afternoon with weak convergence
along it. Will maintain likely PoPs for showers and thunderstorms
with the potential for the an additional round for strong to severe
thunderstorms. There could also be some areas with locally heavy
rainfall as the LREF is showing PWATS near 1.5".
The LREF continues to shows a pattern shift into early-mid next week
with a trough deepening over the eastern CONUS and a ridge building
over the Rockies which will lead to northwest flow aloft. There
will still be a few shortwaves moving southeast through the area
which will bring a chance of showers and thunderstorms on Memorial
Day, but we look dry as we head into Wednesday as the upper ridge
moves east into the Midwest.
There will be quite a variety in temperatures over the weekend with
highs in the 70s and 80s on Saturday and then some question on just
how warm will it be on Sunday depending on how quickly the morning
convection and clouds moves out and how quickly the cold front moves
through the area. Highs could climb well into the 80s over the
southern half of the CWA in the warm sector on Sunday ahead of the
cold front if we clear out. Then temperatures looks to be closer to
late May normals behind the cold front next week.
Britt
&&
.AVIATION... (For the 06z TAFs through 06z Friday Night)
Issued at 1038 PM CDT Thu May 23 2024
Dry and VFR conditions exist at the terminals tonight, and other
than a few low clouds that may not be widespread enough for
impacts, there are few aviation concerns until convection returns
to the forecast.
The threat for thunderstorms will return to the region from west
to east Friday, but exactly when convection will impact any one
area is still mildly uncertain and depends on convection to our
north and west tonight. Two scenarios still look plausible:
- One where an undisturbed line of thunderstorms tracks through
the region during the late morning and early afternoon, ending
any threat for later.
- Another where the line deteriorates and leaves instability
untouched for later in the day.
Either way, conditions improve by 03Z when a cold front advances
through. More benign conditions prevail from then on through the
end of the TAF period.
MRB
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
756 PM EDT Thu May 23 2024
.KEY MESSAGES...
- Another shortwave and low pressure system will bring a round
of showers and a slight chance (around 20% chance) for some
thunder to Upper MI late Friday into early Saturday.
- There will be more opportunities for rain next week although
model uncertainty leads to low forecast confidence on
timing/extent.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 344 PM EDT Thu May 23 2024
Current RAP analysis shows the mid level low along the southern end
of James bay with it`s associated 995 mb low pressure center still
over James bay, but just northwest of the mid level low. With weak
sfc high pressure at around 1012 mb building over the CWA, mostly
sunny skies have been the predominant sky conditions for much of the
UP this afternoon. This has allowed for temps to warm up into the
60s for much of the UP; onshore flow has kept cooler temps along
Lake Michigan between Manistique and the Mackinac Bridge as well as
near Lake Superior. The sunny skies have also helped mixing yield a
breezy day with west to northwest gusts up to 20-30 mph, strongest
in the Keweenaw. Winds will gradually diminish into this eveing as
high pressure continues to build in. Some diurnal cumulus has
developed over the southern UP and will continue to increase this
afternoon with the support of a mid level shortwave moving east
through northern WI. Afternoon highs are expected to peak in the mid
50s to mid 60s near Lake Superior, 60s along Lake Michigan east of
Manistique, and upper 60s to mid 70s elsewhere.
Some slight chances for showers return to the forecast along the
WI/MI state line with the best chances for showers in Menominee
County late this afternoon where there is better instability (5/23
12Z HREF mean MUCAPE up to 250 j/kg in south central). Accumulations
will likely be only a few hundreths at best, but showers moving
through Menominee county could bring up to 0.1" to 0.2" of rain on
the high end if the NAM Nest solution is favored.
As daytime heating ends and high pressure continues to build in
tonight, skies will mostly clear out helping temps settle slightly
cooler than normal into the upper 30s to upper 40s. While mostly
clear skies are expected with dry weather, cloud cover increases
late into Friday ahead of the next low pressure system. This
approahcing low will also turn light winds northerly then eventually
easterly by Friday morning.
&&
.LONG TERM /FRIDAY THROUGH THURSDAY/...
Issued at 344 PM EDT Thu May 23 2024
Wet, active weather continues on and off through the extended period
before we briefly dry out for the middle of next week.
By Friday, the focus will shift to the next shortwave emerging from
the western CONUS mid-upper level trough. This shortwave lifts NE
through the Plains and Upper Great Lakes, eventually swinging into
Manitoba and Ontario phasing once more with the broader troughing
over the western CONUS/Canadian Prairies. Increasing isentropic
ascent, 850 mb theta advection and moderate q-vector convergence out
ahead of the shortwave will lead to another quick round of showers
across the area beginning late Friday afternoon in the western UP
and spreading eastward during the evening. Instability off soundings
looks pretty minimal, with just a few hundred j/kg of CAPE indicated
in HREF plots, so thunder should be fairly limited. Otherwise,
guidance continues to favor widespread rain amounts of 0.10-0.25in,
but EPS ensembles also show probabilities of 40-60% for amounts of
0.50in or more south central and southeast. Showers quickly exit
eastward during the pre-dawn hours of Saturday with clearing skies
expected as drier air works in.
Saturday should be dry with ridging/subsidence behind the exiting
shortwave. Expect partly cloudy skies and seasonable temperatures
for the rest of the day with highs mostly in the 60s with a few
cooler mid 50s readings near Lake Superior.
There remains quite a bit of uncertainty in the Sunday-Tuesday time
frame regarding the track/strength of the next western CONUS wave
and developing cyclone. This ejects NE from the lee of the southern
Rockies into the Great Lakes region late weekend into early next
week, but many of deterministic models (particularly the GFS, UKMET
and Canadian) as well as ensembles continue to flip-flop on the
exact track with some runs taking a deep system as far north as the
Straits, and others suppressed more over the southern or central
Lower Peninsula and coming in comparatively weaker. A more southerly
route would have little if any wind and rain impacts to the UP,
while the more NW route would bring a chance for more significant
rainfall as well as gusty winds. The ECMWF, on the other hand, has
been the most consistent of the models advertising generally a more
phased and deeper system for the last several runs with a more
northern/western track through the Central Great Lakes, and thus,
greater rain and wind impacts for Upper Mi in the late Sunday into
Memorial Day time frame. Given the huge spread depicted in the
tracks of the ensemble members it`s still too soon to latch onto any
one model solution with great certainty, thus leading to poor
forecast confidence during this time frame. For now, will continue
to lean on the model blend for forecast details and wait a bit
longer for models to sort out their continuity/consistency issues
and hopefully come into better agreement over the coming days.
PoPs persist into Tuesday as the system moves into Quebec, and
associated wraparound moisture curls into the area while another
shortwave ripples through. Most of the models and ensembles do seem
to be in general agreement showing a trend toward ridging and drier
conditions for Wednesday into Thursday next week. Otherwise, expect
more or less seasonable temperatures through the forecast period.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 754 PM EDT Thu May 23 2024
Dry air mass associated with sfc high pres ridge drifting across the
area tonight will allow VFR to continue at IWD/CMX/SAW. Winds will
also diminish to aob 5kt during the evening. On Fri, low pres
lifting across the Northern Plains will swing an occluded front to
the ne. That front will be approaching western Upper MI at 00z.
Although some shra well ahead of the front may push into the w half
of Upper MI mid and late aftn, the main area of shra and isold tsra
will hold off until early evening. So, for now, fcst only reflects
shra and MVFR cigs arriving at IWD around 22z. Shra/MVFR conditions
will reach CMX/SAW just beyond this fcst period. During the aftn, E
to SE winds will increase and become gusty to around 25kt at IWD/CMX
and to around 20kt at SAW. LLWS will also be possible at IWD in the
aftn.
&&
.MARINE...
Issued at 344 PM EDT Thu May 23 2024
Low pressure that impacted the area over hte past couple of days
continues to weaken over James Bay while a weak high pressure ridge
builds over the Great Lakes. Winds have been on the decrease today
in response, still gusting to 20-25 knots out of the west in the
eastern portions of the lake, but dropping below 20 knots to the
west. Winds finally fall below 20 knots to the east later this
evening. The period of light winds doesn`t last long over the
western lake, however, as northeast winds will begin to ramp up to
30 knots late tonight into Friday in advance of another low pressure
lifting from the Northern Plains towards Lake Winnipeg. Guidance
indicates around a 60-70% chance for gales Friday afternoon through
the early evening over the western quarter of Lake Superior. East to
southeast winds gradually increase over the east half of the lake on
Friday but generally stay 20 knots or less, but 25kt gusts will then
become possible for a brief period into the evening and overnight
hours. Winds over the west half becoming southwest behind the low
and the passage of its cold front late Friday night into Saturday
and generally stay in the 15 to 25 knot range. Winds decrease late
Saturday behind the exiting system, then expect light winds of 20
knots or less across Lake Superior for the rest of this weekend as a
high pressure ridge builds over the area. Looking ahead to early
next week, another system moving out of the Plains will head towards
the Great Lakes. This could present another opportunity for gusty
winds, but confidence is low given quite a bit of uncertainty on the
exact storm track.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning from 11 AM EDT /10 AM CDT/ to 8 PM EDT /7 PM CDT/
Friday for LSZ162.
Lake Michigan...
None.
&&
$$
SHORT TERM...Jablonski
LONG TERM...LC
AVIATION...Rolfson
MARINE...LC
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
1023 PM EDT Thu May 23 2024
...New UPDATE...
.UPDATE...
Issued at 1006 PM EDT Thu May 23 2024
Active evening across the region due a strong upper jet moving
across the Tennessee valley. Satelittle and radar shows a MCV
moving across east Kentucky. The upper forcing has produced
widespread thunderstorms with a good deal of organization with the
convection. Effective shear up to 35 knots and 0-1km shear near 15
knots were favorable to produce supercells especially over
southeast Tennessee and southwest North Carolina. Reports of
possible funnel clouds also reported as well as PingPong hail.
Continued upper forcing continues to produce strong convection
over southeast/central east Tennessee, generally south of
interstate 40. This activity will move east out of the area soon
after midnight.
Latest HRRR shows widely scattered to scattered showers continuing
through the early morning so will continue with low chance PoPs.
Some fog development is possible.
&&
.SHORT TERM...
(This evening through Friday)
Issued at 307 PM EDT Thu May 23 2024
Key Messages:
1. Strong to severe storms this evening with the main threats being
wind gusts and hail, mainly affecting locations along and west of I-
75.
2. Another round of showers/storms is expected Friday afternoon, but
mainly in southern sections as an upper level disturbance moves
through that area. A few strong to marginally severe storms are
possible.
Discussion:
Convection is starting to blossom in the Plateau and southern
portions of the TN Valley. Over the next few hours, this activity
will expand and intensify as clouds clear out and surface heating
builds. Mesoanalysis shows the best instability to our west, so the
storms that are developing in Middle TN will have the best chance of
becoming severe, and with a an effective shear max located over the
northern Plateau/eastern KY, that area will have the highest severe
chance as those storms track NE. Damaging wind gusts and large hail
will be the primary threats, and locations that have repeated storms
may experience localized flooding. Most of this activity should
weaken or exit the area by midnight.
Overnight, a moist low level air mass will be in place that will
favor fog and low cloud development. The models show that this
will be slow to lift in the morning, but by noon we should have
some good surface heating to aid in destabilization. In the
midlevels, a weak shortwave trough/500 mb vort max will be
crossing northern AL and GA in the late morning and early
afternoon, which may bring showers to the southern sections as
early as 10 AM. CAMS are not in good agreement with the
development of convection tomorrow, so confidence is low. But it
does appear that areas south of I-40 will have the best chance of
showers/storms, and that a few of these could be strong to
marginally severe, with wind/hail being the main threats.
&&
.LONG TERM...
(Friday night through next Thursday)
Issued at 307 PM EDT Thu May 23 2024
Key Messages:
1. An unsettled period with multiple rounds of showers and
thunderstorms for much of the period.
2. Some of the storms may be strong to severe at times, with the
higher chances for severe storms looking like Sunday and/or Monday.
Localized flooding will also be possible.
3. Drier and cooler air moving in toward the end of the period, but
a few additional showers and/or storms still cannot be ruled out.
Discussion:
Unsettled weather pattern will continue, as 500 MB flow remains
somewhat flat through the weekend, with a series of disturbances
touching off rounds of convection. By Sunday, deepening of a
trough near the Great Lakes will usher through a cold front
accompanied by organized convection around Monday morning that has
caused SPC to put us in a 15+% area in the severe weather outlook.
However, as the present Watch attests, chances of severe weather
will not be limited to Sunday night/Monday. Furthermore, repeated
rounds of rainfall will increase proneness to localized flash
flooding from today through Monday.
Post frontal precip chances on Tues and Wed will likely be
scattered in nature and not likely to be heavy. Models are
diverging that far out now anyway, with the ECMWF maintaining
something of a blocking pattern, while the GFS has backed off of
that solution and instead wants to continue with more of a
northwesterly flow across the nation that keeps us impacted by
another shortwave or two. We will cheer for the ECMWF`s quieter
solution, but will have to wait and see what pans out.
&&
.AVIATION...
(18Z TAFS)
Issued at 250 PM EDT Thu May 23 2024
Showers and thunderstorms are developing in Middle TN and the
Cumberland Plateau. They are expected to increase and spread into
the northern half of East TN through the evening, impacting TYS
and TRI. MVFR conditions with gusty winds of 30-40 kt are
possible, possibly IFR if a storm moves directly over the
terminal. Tonight, a moist air mass will result in fog and low
clouds, likely MVFR at CHA and TYS but TRI may drop to IFR.
Another round of showers and storms is expected late in this TAF
period, mainly affecting CHA and TYS.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 67 83 67 88 / 30 60 40 50
Knoxville McGhee Tyson Airport, TN 64 79 64 85 / 70 60 50 50
Oak Ridge, TN 64 79 63 85 / 70 50 50 50
Tri Cities Airport, TN 61 79 61 81 / 60 50 40 60
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...DH
LONG TERM....GC
AVIATION...DH
Area Forecast Discussion
National Weather Service Springfield MO
914 PM CDT Thu May 23 2024
.KEY MESSAGES...
- Thunderstorms move into the area Friday morning. Some may be
severe with large hail and damaging winds.
- If enough instability remains, additional strong to severe
storms may develop Friday afternoon along and south of
Interstate 44 with large hail and damaging winds.
- Additional severe weather and heavy rain chances Saturday
night into Sunday.
&&
.MESOSCALE...
Issued at 847 PM CDT Thu May 23 2024
The 00Z KSGF sounding showed a very unstable atmosphere with
2100j/kg of ML CAPE however a substantial cap remains at 800mb.
A weak 700mb ridge has remained across the area today into this
evening which has prohibited any storm development given the
cap. A very moist airmass has moved in with dew points in the
65-70 degree range across the area. A low level jet was
increasing across Kansas which was fueling a cluster of storms
across Nebraska. Additional storms were forming across Oklahoma.
Very little in the way of storm chances are expected for most of
the overnight as we likely remain capped. Latest model guidance
suggests the bulk of the Nebraska storms to move east towards
northern Missouri and Iowa. However the low level jet will begin
to veer and guidance suggests that a band of showers and
thunderstorms may begin forming across eastern Kansas after 4am,
entering western Missouri closer to 6-8am. Steep mid level
lapse rates and adequate shear may allow for a few storms to
become severe. These would likely be elevated with large hail
the main threat. This band of thunderstorms looks to work its
way through the area during the mid/late morning hours (8am-
Noon) with that severe threat continuing. It is possible that
storms attempt to become surface based if enough heating occurs.
Most likely area for this would be east of Springfield. This
area of thunderstorms would be ahead of an approaching cold
front.
Several questions remain with the afternoon and evening
thunderstorm development. How much does the morning development
work over the atmosphere? How fast does the cold front work
through the area before additional storms form? From a synoptic
standpoint, the area will be positioned in a favorable upper
level jet location therefore lift should not be an issue. Some
high res models and the RAP continue to show an impressive
amount of instability during the afternoon ahead of the front
(3000-4000j/kg of ML CAPE). IF this amount of instability were
to develop then severe storms would be likely with large hail to
the size of golf balls and damaging winds being the main
threats. Hodographs look fairly straight with low level winds
remaining southwesterly which would limit the tornado threat
however increasing the threat for some splitting supercells
with large hail. These higher severe chances are favored along
and south of I-44.
Therefore we will need to monitor how the morning development
transpires. If clouds/precip linger longer than expected than
instability/severe weather would be lower. The other factor is
the speed of the front however most guidance has it reaching
the I-44 corridor by 4-5pm. If its quicker than the severe
threat would be more southeast of the area.
Additional updates to come overnight into Friday morning.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 251 PM CDT Thu May 23 2024
Short range forecast remains generally on track though timing has
slowed with the system lifting into the Dakotas and associated
trailing cold front advecting across the Plains.
Through tonight - a warm front has progressed northward through
the forecast area with a cap limiting convection from
developing. With the shift of winds to the south, dew points
have climbed into the middle 60s to near 70...with even more
moisture streaming into the system as evident by the stratus on
satellite.
Thunderstorms are expected to develop in the highly unstable and
sheared environment across the Plains this afternoon into this
evening...though questions on cold pool development advancing the
arrival time of thunderstorms overnight vs storms moving well ahead
of the line and losing their organization.
CAM model soundings in agreement that MLCAPES above 3000 J/KG will
be in place over southeast KS this evening though some disagreement
on whether the cap will break until forcing from the approaching
outflow arrives so there may be a few scattered thunderstorms from
evening into the night before the main band of strong to severe
storms arrives over southeast Kansas into western Missouri toward
sunrise.
This band of storms will likely weaken and then strengthen once
once again increase in coverage and strengthen Friday afternoon
over the eastern half of the forecast as the front works its
way east across the forecast area. While uncapped, the
atmosphere ahead of the convection will loose some of its
instability thanks to warming mid level lapse rates.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 251 PM CDT Thu May 23 2024
Southwesterly flow will resume as the western trough digs then
advects eastward into the Plains Saturday. Progged soundings reveal
an uncapped, highly unstable atmosphere. The veering profile lacks
strong lower level winds at the present, though anticipate winds to
strengthen as the surface low deepens rapidly over Kansas. Similar
to the system tonight...the nocturnal elements may lead to severe
threats diminishing and then redeveloping farther east on Sunday.
Of concern with the Saturday night/Sunday system will be increasing
precipital water leading to the potential for very heavy rainfall
rates falling on moist soils from recent storms.
A trailing shortwave will be monitored for the potential for showers
Monday...otherwise the Holiday through midweek will be mild with
highs in the 70s to near 80 and drier dew points. Dry weather will
then prevail into midweek as a welcome surface high builds across
the central US.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 543 PM CDT Thu May 23 2024
VFR conditions are expected through tonight and into early
Friday. A line of thunderstorms will move into during the day on
Friday, especially late morning and afternoon and may need to
include prevailing groups in future updates. A period of MVFR
ceilings looks to arrive by morning as well. Winds will begin to
turn southwesterly by Friday afternoon with a switch to the
northwest at the very end of the TAF period. Low level wind
shear is likely tonight at JLN.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
KS...None.
MO...None.
&&
$$
MESOSCALE...Burchfield
SHORT TERM...Runnels
LONG TERM...Runnels
AVIATION...Burchfield
Area Forecast Discussion
National Weather Service San Diego CA
852 PM PDT Thu May 23 2024
.SYNOPSIS...
Cooling through Saturday with gusty southwest to west winds in the
mountains and deserts. The strongest gusts are more likely on
Friday afternoon into Friday night. Night and morning coastal low
clouds will extend inland across all of the valleys and onto the
lower coastal slopes of the mountains with slower daytime clearing
for coastal areas. High pressure to the south will bring warming
for Sunday through Wednesday. The marine layer will become
shallower with night and morning coastal low clouds only extending
inland into portions of the valleys by the middle of next week.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.Evening Update...
Onshore flow continues at this hour, with some mountain passes
seeing wind gusts 40-60 MPH, mainly through the San Gorgonio Pass.
Winds will briefly drop off through the morning, before ramping
back up by Friday afternoon. As the trough progresses through the
area, winds will become more widespread into the deserts. There
is a low to moderate chance in seeing wind gusts over 45 MPH in
the deserts per latest HRRR and NBM model runs this evening.
Low clouds will continue to fill in the coastal basin through the
nighttime hours. HREF gives most areas a low chance in 50%+ sky
cover Friday afternoon, though with a deepening marine layer
throughout the day, clearing may be short lived near the coast.
Otherwise, minimal forecast changes through the cooler weekend and
warmer parts of next week.
.Previous Discussion (140 PM Thursday)...
A low/trough embedded in the mean cyclonic flow over the western
U.S. will move inland to our north tonight and Friday and will
bring stronger onshore flow. The marine layer will deepen, cooling
will spread inland, and there will be periods of gusty southwest
to west winds for the mountains and deserts with the strongest
winds for Friday afternoon into Friday night. The additional
deepening of the marine layer to 4500-5000 feet Friday night
into Saturday morning could bring patchy drizzle at lower
elevations west of the mtns.
There will be gusty southwest to west winds in the mountains and
deserts, with the stronger winds on Friday and Saturday. The winds
will peak Friday afternoon into Friday night with gusts mostly 40
to 50 mph except in the northern Coachella Valley below the San
Gorgonio Pass where winds could gust to around 60 mph.
High temperatures today will cool a few degrees from those on
Wednesday. There will be further cooling on Friday. The deserts
will continue to cool slightly on Saturday while the coast and
valleys warm slightly. With the cooling, high temperatures for the
mountains and inland valleys will be as much as 10 to 15 degrees
below seasonal averages on Friday.
For Sunday through Wednesday...
Building high pressure to the south will compete for dominance
with the low/trough to our north and could bring warming through
the middle of next week. The greatest warming is expected for
Sunday and Monday with slight additional warming for Tuesday and
Wednesday. With the warming, high temperatures on Wednesday will
be around average for the coast and valleys and around 5 degrees
above average for the deserts, mostly in the 80s for the Inland
Empire and the upper 90s to 104 for the lower deserts. The marine
layer will gradually decrease in depth with night and morning
coastal low clouds only extending inland into portions of the
valleys by the middle of next week.
&&
.AVIATION...
240400Z...Coast/Valleys/Foothills...BKN/OVC low clouds will continue
to spread overnight, reaching all areas by 11Z Fri with bases 1800-
2500 ft MSL and tops 2500-4000 ft MSL. Higher terrain will be
obscured but most VIS below the cloud bases will be 6+ miles. Slow
clearing will occur Fri with valley partially clearing 17Z-21Z Fri
with the coast partially clearing 18Z-22Z Fri, though bases will
generally rise to 2700-3700 ft MSL Fri in areas that remain cloudy
Fri afternoon. Stratus will become widespread again Fri evening.
Mountains/Deserts...Clear skies with mostly unrestricted VIS will
continue through Fri evening. Areas of winds from the west with
surface gusts 25-45 knots will occur at times through Fri evening
from the mountain crests east/north through the desert slopes and
into the deserts, including near San Gorgonio Pass. Strongest winds
will be after 00Z Sat. Local blowing dust could reduce VIS to 3-5
miles after 21Z Fri.
&&
.MARINE...
West to northwest winds will gust near or slightly over 20 knots in
the outer coastal waters (30-60 NM from the coast) each afternoon
and evening Friday through Sunday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from noon Friday to 2 AM PDT Saturday for San
Gorgonio Pass Near Banning.
PZ...None.
&&
$$
PUBLIC...APR/PG
AVIATION/MARINE...Maxwell