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134
FLUS43 KAPX 170702
HWOAPX

Hazardous Weather Outlook
National Weather Service Gaylord MI
302 AM EDT Mon May 17 2021

MIZ016>018-020>036-041-042-086>088-095>099-180715-
Emmet-Cheboygan-Presque Isle-Leelanau-Antrim-Otsego-Montmorency-
Alpena-Benzie-Grand Traverse-Kalkaska-Crawford-Oscoda-Alcona-
Manistee-Wexford-Missaukee-Roscommon-Ogemaw-Iosco-Gladwin-Arenac-
Western Chippewa-Central Chippewa-Southeast Chippewa-
Western Mackinac-Eastern Mackinac-
Mackinac Island/Bois Blanc Island-
Beaver Island and surrounding islands-Charlevoix-
302 AM EDT Mon May 17 2021

This hazardous weather outlook is for Eastern Upper Michigan and
Northern Lower Michigan.

.DAY ONE...Today and tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

&&

$$

LHZ345>349-LMZ323-341-342-344>346-LSZ321-322-180715-
Straits of Mackinac within 5 nm of Mackinac Bridge including
Mackinac Island-St Ignace to False Detour Channel-
5NM East of Mackinac Bridge to Presque Isle Light MI including
Bois Blanc Island-
Presque Isle Light to Sturgeon Pt MI Including Thunder Bay
National Marine Sanctuary-Sturgeon Pt to Alabaster MI-
Grand Traverse Bay south of a line Grand Traverse Light to
Norwood MI-Seul Choix Point to 5NM West of Mackinac Bridge-
Norwood MI to 5NM West of Mackinac Bridge including Little
Traverse Bay-Sleeping Bear Point to Grand Traverse Light MI-
Point Betsie to Sleeping Bear Point MI-
Manistee to Point Betsie MI-
Whitefish Bay (U.S. Portion)/Whitefish Point to Point Iroquois MI-
St. Marys River Point Iroquois to E. Potagannissing Bay-
302 AM EDT Mon May 17 2021

This hazardous weather outlook is for the northern Michigan
nearshore waters of Lake Huron, Lake Michigan and Lake Superior.

.DAY ONE...Today and tonight.

Areas of dense fog will impact portions of Lake Michigan this
morning and again tonight.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Areas of dense fog will likely impact portions of Lakes Michigan
and Huron Tuesday morning.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

&&

$$



133
ACUS01 KWNS 170527
SWODY1
SPC AC 170525

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1225 AM CDT Mon May 17 2021

Valid 171200Z - 181200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHWEST TEXAS...

...SUMMARY...
Severe thunderstorms are forecast across portions of the southern
Plains later this afternoon and overnight. Very large hail and a few
tornadoes will be concentrated across northwest Texas.

...Southern Plains...

Well-defined upper low is currently located over the lower CO River
Valley. This feature is forecast to eject into the southern Rockies
by 18/00z as 50kt 500mb flow translates across the northern Baja
Peninsula into portions of northwestern TX by late evening. In
response, lee surface low should hold across southeastern NM which
will ensure moist southeasterly low-level flow is maintained across
the TX South Plains into far northeastern NM. Additionally, a weak
MCS has evolved over northwest TX early this morning with
considerable amount of trailing precipitation extending across the
TX Panhandle into western KS. The leading edge of this complex
should propagate slowly southeast through daybreak, likely spreading
into portions of central TX by sunrise. This rain-cooled air mass
should contribute to easterly low-level component across the TX
South Plains and a remnant convective boundary may be evident in its
wake over northwestern TX. If so, this boundary should serve as a
primary corridor for focused hail-producing supercells.

Latest thinking is intense surface heating will be noted across far
west TX into southeast NM such that convective temperatures will be
breached by 21z. Forecast sounding at MAF by 22z exhibits a 90F
surface temperature with negligible CINH. It appears thunderstorms
should develop along the dryline near the NM border, south across
west TX, then spread/develop northeast along a potential rain-cooled
boundary. Very steep lapse rates through a deep layer, extreme
MLCAPE, and ample shear for slow-moving supercells all favor very
large hail. As mid-level flow increases during the evening, there is
reasonable confidence that numerous hail-producing supercells could
emerge into an MCS that will propagate toward north-central TX.
Prior to this, some tornado threat will be noted both early in the
convective cycle, and along the aforementioned rain-cooled boundary
where shear will be maximized.

..Darrow/Karstens.. 05/17/2021

$$



000
ACUS02 KWNS 170558
SWODY2
SPC AC 170557

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CDT Mon May 17 2021

Valid 181200Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
CENTRAL AND NORTHEAST TEXAS...

...SUMMARY...
Thunderstorms associated with large hail and wind damage will be
possible on Tuesday across parts of central and northeast Texas.
Other marginally severe storms could occur across much of Texas
outside the slight risk area and from parts of the southern and
central Plains eastward into the Ozarks.

...Central and Northeast Texas...
An MCS is expected to be ongoing at the start of the period in parts
of the Red River Valley. A moist and unstable airmass will be
located to the south of the MCS across much of central and north
Texas, where surface dewpoints will be in the mid to upper 60s F.
The outflow boundary with the MCS is expected to move southeastward
across north and central Texas. There is some uncertainty as to how
far the outflow boundary will move southeast but model forecasts
suggest that it could be positioned from near Dallas/Fort Worth
southwestward to east of Abilene by afternoon. Moderate instability
will likely develop by mid to late afternoon to the southeast of
this boundary. Low-level convergence along the boundary should
result in thunderstorm development during the afternoon. MCS
development will be possible late Tuesday afternoon and early
Tuesday evening from parts of the Texas Hill Country into northeast
Texas.

NAM forecast soundings near Austin and Waco have MLCAPE increasing
into the 2500 to 3500 J/kg range by 21Z/Tuesday. 0-6 km shear is
only forecast to be in the 25 to 30 knot range suggesting that the
primary mode will be multicell. Low to mid-level flow parallel to
the outflow boundary may result in squall-line development with this
line moving east-northeastward across parts of the Texas Hill
Country and northeast Texas during the late afternoon and early
evening. Steep lapse rates in the boundary layer will support a
wind-damage threat. The strong instability will also be favorable
for isolated large hail. The severe threat should persist through
much of the evening as redevelopment of strong convection occurs in
south-central and east-central Texas, being supported by a
strengthening low-level jet.

...Eastern Kansas/Eastern Oklahoma/Missouri/Arkansas...
An upper-level low will move northeastward across the central
Rockies on Tuesday with south-southwesterly mid-level flow in place
across northern parts of the southern Plains into the central
Plains. By afternoon, an axis of maximized low-level moisture is
forecast to be located from far eastern Oklahoma northward into far
eastern Kansas. Surface dewpoints along this axis will likely be in
the mid 60s F, contributing to a narrow corridor of moderate
instability by afternoon. Thunderstorm development appears likely to
take place along parts of the instability corridor Tuesday
afternoon. MLCAPE in the 1000 to 2000 J/kg range along with 30 to 40
kt of mid-level flow should support an isolated severe threat.
Marginally severe hail and strong wind gusts should be the primary
threats during the late afternoon and early evening.

..Broyles.. 05/17/2021

$$


000
FXUS63 KAPX 170634
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
234 AM EDT Mon May 17 2021

.NEAR TERM...(Today through Tonight)
Issued at 232 AM EDT Mon May 17 2021

Impactful weather: Minimal/None. Some patchy fog.

Pattern synopsis and forecast:

A split flow regime is setting up early this morning, with the nrn
jet stream running through Canada, and the srn stream running
through the central and southern states. This leaves the Great Lakes
region in a zone of basically no features or forcing aloft. At the
sfc, high pressure continued to dominate the eastern states, with a
ridge axis continuing to extend back through the Great Lakes. This
has resulted in quiet weather, with mostly clear skies and patchy
fog in a light wind regime. There was some significant marine
stratus and fog over Lake Michigan, which southerly winds pushed
into areas of eastern upper Michigan.

More quiet weather is expected today and tonight. The action in the
nrn stream gets pushed further north into Canada, as upper ridging
strengthens in srn Canada/Great Lakes region. Some weak shortwave
energy in the srn stream does start to lift north through the mid
Mississippi valley through tonight, but this is not going to impact
nrn Michigan. Rather, we will just see some passing cirrus at times,
with some afternoon scattered cumulus. The marine stratus and fog
will be common through tonight, with some of that expected over Lake
Huron as well tonight. S/SW winds will be able to push the stratus
and fog into portions of eastern upper, and perhaps some coastal
areas of nrn lower.

High temperatures today will largely be in the mid and upper 70s,
cooler near the lakeshores. Lows tonight will mostly range from the
middle 40s to around 50F.

&&

.SHORT TERM...(Tuesday through Wednesday)
Issued at 232 AM EDT Mon May 17 2021

...Warm with Increasing Shower Chances...

High impact weather: None is expected.

Primary forecast concerns/challenges: Pops.

Folded over omega type ridge moves across the region through the day
Tuesday. The passage of this feature will allow for energy now
evident on water vapor imagery over the western Plains to move
northeast into Michigan. Increasing moisture (precipitable water 1
to 1.5 inches) along with some lift from this system will bring
increasing chances for showers Tuesday night (likely pops). Not a
lot of evidence of instability with perhaps a couple of hundred J/kg
of mixed layer cape so will leave thunder out of the forecast.
Rainfall amount generally in the tenth or two range. Perhaps a few
leftover or even pop up showers Wednesday. Highs Tuesday in the mid
70s to low 80s. More clouds Wednesday should limit highs to the 70s
but humidity will be on the rise with surface dewpoints of around
60.

&&

.LONG TERM...(Wednesday night through Sunday)
Issued at 232 AM EDT Mon May 17 2021

...Warm and Muggy into the Memorial Day Weekend...

High impact weather potential: None is expected at this time.

A strengthening upper level ridge centered across the southeastern
states retrogrades to the west. Moisture/humidity moving northward
around the ridge is expected to bring very warm and humid conditions
to northern Michigan. There will be chances for mainly diurnally
driven instability showers. Plus it looks like a little better
chance for thunder during the day Friday and Sunday with decent
moisture (pw/s of 1.5-1.75 inches). In addition, a surface cold
front will approach the region from the north Sunday bringing better
chances for showers and possibly storms. Highs will be well into the
70s to the low 80s (even a few mid 80s). Lows in the muggy 50s to
low 60s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1152 PM EDT Sun May 16 2021

VFR conditions through the period with just some passing cirrus
and a few high based cumulus. Light winds with expected lake
breeze development later this morning into the afternoon. No vis
restrictions expected.


&&

.MARINE...
Issued at 232 AM EDT Mon May 17 2021

High pressure will continue to dominate the eastern states through
Tuesday, with a ridge axis extending back through the Great Lakes.
Wind speeds will remain on the lighter side, with afternoon lake
breezes expected. No wind/wave issues anticipated, and no rain until
possibly Tuesday night. Stratus and fog will be an issue over
portions of Lakes Michigan and Huron through Tuesday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

NEAR TERM...SMD
SHORT TERM...AS
LONG TERM...AS
AVIATION...MB
MARINE...SMD


264
ACUS11 KWNS 170609
SWOMCD
SPC MCD 170609
TXZ000-OKZ000-170745-

Mesoscale Discussion 0647
NWS Storm Prediction Center Norman OK
0109 AM CDT Mon May 17 2021

Areas affected...portions of north Texas and southwest OK

Concerning...Severe Thunderstorm Watch 180...

Valid 170609Z - 170745Z

The severe weather threat for Severe Thunderstorm Watch 180
continues.

SUMMARY...A couple of strong storms may persist another 1-2 hours,
with near 1-inch hail and locally strong gusts possible. Gradual
weakening in thunderstorm intensity is expected with eastward
progression and downstream watches are not expected.

DISCUSSION...Clusters of storms are ongoing across portions of the
Texas South Plains eastward into north Texas and southwest OK. A
severe-warned forward-propagating line of storms near the Red River
has weakened considerably over the past 30 minutes as outflow has
surged ahead of the line and convection moves into a weaker midlevel
lapse rate environment. Furthermore, a southerly low level jet
further west over western TX is weaker across western/central OK and
north Texas. Overall this should result in a continued decrease in
thunderstorm intensity both with the cluster of storms near the Red
River to the Dyess AFB vicinity and a couple of weakening supercells
just northwest of Fort Worth.

A couple of stronger cells east of Lubbock will continue to pose a
threat for near 1-inch hail and perhaps a strong gust over the next
hour or so. This activity is occurring near the stronger low level
jet and in a steeper midlevel lapse rate environment. However, this
activity is also expected to gradually weaken through storm
interactions and as convection progresses eastward into a less
favorable downstream environment.

..Leitman.. 05/17/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...FWD...OUN...SJT...LUB...MAF...

LAT...LON 33350128 33730141 34030131 34000089 33899999 33919968
34289916 34779886 34969866 34839821 34419766 33889740
33239722 32829729 32549758 32439869 32430034 32740078
33350128