Severe Weather - Flooding

122
ACUS01 KWNS 150558
SWODY1
SPC AC 150557

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CDT Thu Apr 15 2021

Valid 151200Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF
CENTRAL TEXAS...

...SUMMARY...
Organized severe storms are expected across west-central Texas, with
a more isolated severe threat expanding eastward along the central
Gulf Coast. Large hail will be the main hazard with today`s
activity.

...Synopsis...
A mid-level trough will continue to track across the eastern U.S. as
a second trough aloft ejects into the Plains states today. Embedded
vorticity maxima are expected to traverse the broader cyclonic flow
across the southern U.S., promoting multiple rounds of organized
convection from TX to the Gulf Coastal Plain. Severe thunderstorms
may accompany each round of storms, with the greatest threat for
severe expected across central TX later in the period.

...Much of central TX through the period...
At least isolated thunderstorms may be ongoing at the start of the
day across parts of central TX as the first in a series of mid-level
impulses drifts towards the Gulf Coastal Plain. These storms would
most likely be rooted above a stable layer (around 700 mb) north of
the cold front, fueled by a modest low-level jet beneath 7+ C/km
mid-level lapse rates, contributing to a reservoir of 1000-1500 J/kg
MUCAPE. As such, some severe hail may accompany the more intense
updrafts. Later in the afternoon, as a second mid-level impulse
ejects into the southern Plains ahead of the main upper trough,
another round of storms is expected to initiate in west-central TX
and move into the Slight risk area. While still elevated, these
storms will likely be rooted closer to the surface, with 1500-2000
J/kg MUCAPE present. Given 60+ kts of effective bulk shear and
effective SRH exceeding 150 m2/s2, multicellular clusters and
supercells are possible. With up to 8 C/km lapse rates comprising
much of the hail-growth layer, very large hail may occur with any of
the more intense, longer-lasting supercell structures. A couple
damaging gusts also cannot be ruled out. A few of the more robust
updrafts may track as far east as the TX/LA border, though
confidence in this scenario is low at this time.

Later in the evening, as the main upper trough ejects into the
Southern Plains, a 30-40 kt low-level jet is expected to transport
deep moisture northward towards OK, with deep-layer ascent and 7.5+
C/km mid-level lapse rates contributing to renewed elevated
convection. With 40-50 kts of effective bulk shear expected along
the Red River within the 06-12Z Friday time frame, a few of the
stronger updrafts may produce severe hail.

...Gulf Coastal Plain through Midday...
As the first embedded impulse drifts away from TX and moves over the
Gulf Coastal Plain, an MCS is expected to develop and propagate
southeastward towards the Gulf of Mexico through the late morning
into afternoon hours. Up to 1000 J/kg MUCAPE may reside ahead of the
MCS, promoting a risk of isolated severe hail and perhaps a couple
of damaging wind gusts through early to mid afternoon.

..Squitieri.. 04/15/2021

$$

000
ACUS02 KWNS 150526
SWODY2
SPC AC 150524

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1224 AM CDT Thu Apr 15 2021

Valid 161200Z - 171200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN TX INTO SOUTHWEST LA...

...SUMMARY...
Isolated strong to severe storms capable of hail and gusty winds are
possible across parts of eastern Texas into southwest Louisiana on
Friday.

...Eastern TX to Southwest LA Vicinity...

A weak surface low is forecast over northern TX Friday morning, with
a warm front extending southeast across east TX toward the LA coast.
Low-level warm advection will maintain 60s surface dewpoints ahead
of a south/southeastward-advancing cold front. While a strong cap is
expected around 850-700 mb, elevated convection will be ongoing
early Friday across parts of north Texas and will continue until the
cold front pushes offshore during the evening. Steep midlevel lapse
rates will result in 1000-1500 J/kg MUCAPE amid moderate shear.
While upper forcing will remain weak with generally low-amplitude
westerly deep-layer flow persisting across the region, this
combination of instability and shear should be sufficient for a few
organized cells within a broader cluster of showers and
thunderstorms. Hail will be the main hazard with this activity, as
storms should remain elevated. However, there is some low-end
potential that any storm becoming established along the warm front,
or later near the advancing cold front, could become briefly near
surface-based and produce a locally strong gust.

..Leitman.. 04/15/2021

$$

000
NWUS53 KAPX 092012
LSRAPX

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GAYLORD MI
412 PM EDT FRI APR 9 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0730 PM     TSTM WND DMG     2 NNW EAST JORDAN       45.19N 85.15W
04/08/2021                   CHARLEVOIX         MI   TRAINED SPOTTER

            DELAYED REPORT - SEVERAL TREES DOWN WITH A
            WIND SPEED OF 57MPH MEASURED BY A PERSONAL
            WEATHER STATION 13 FEET ABOVE THE GROUND.


&&

$$

407
FXUS63 KAPX 150731
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
331 AM EDT Thu Apr 15 2021

.NEAR TERM...(Today through Tonight)
Issued at 325 AM EDT Thu Apr 15 2021

...Chilly and showery today...

High impact weather potential: Low.

500mb closed low is over the ne lower MI coastline, drifting to the
sse. The upper low will pick up the pace a little bit, eventually
departing the Thumb this morning on its way to just south of BUF
this evening. Core of the cold air aloft is edging out of northern
MI, and the same is true at 850mb.

We are warm advecting with northerly flow at 850mb, and temps at
that level will be at or above freezing by this evening across all
of northern MI, except perhaps along the ne lower MI coast. We are
seeing the impacts of this already with p-type. Can`t reliably
count on the AWOS`s to differentiate rain from snow, but Soo
Canada has had all liquid precip for several hours now. This is
reflection of a somewhat warmer airmass, but also occasionally
minimized mid-level moisture and associated loss of in-cloud ice.
APN recently had a bout of precip that started liquid then went
to snow. TVC is in the upper 30s and liquid; HTL 34f and mostly
snow.

A plume of deeper moisture will rotate into eastern upper and nw
lower MI this morning. (Some of this precip is already visible off
the coast of ESC-ISQ.) However, that also represents the back edge
of widespread precip. As we get closer to midday, that will get
drawn eastward over n central lower MI, with precip diminishing in
nw lower and eastern upper. This will continue to retreat into just
ne lower MI by mid-afternoon. However, there it will stall, or at
least send the occasional bit of energy to wobble showers back into
the ne lower MI coastal counties. This area (from Rogers to Tawas)
will need pops all the way thru tonight.

The p-type forecast is interesting. For the morning hours, best
chance for snow (and snow accums) will be in the hills of nw lower
MI. Periods of higher precip rates will favor a changeover to snow,
and this area is further displaced from the gradual warming air
arriving from the north. Have accums of up to an inch today,
centered on Kalkaska/Fife Lk. Precip coverage/intensity should
decrease by this afternoon; that and warmer should allow lingering
activity to become most/all rain over ne lower MI. That leftover
precip in ne lower MI should again get mixy toward and after
midnight tonight.

Max temps today upper 30s west to mid 40s east. Min temps within a
few degrees of freezing.

&&

.SHORT TERM...(Friday through Saturday)
Issued at 325 AM EDT Thu Apr 15 2021

...Slowly Moderating Temperatures...

High impact weather: None is expected.

Primary forecast concerns/challenges: Temperatures and cloud cover.

Models are more or less in agreement that troughing aloft lingers
across the region through much if not all of the period. This should
lead to a good deal of cloud cover so have gone ahead and steered
the forecast in that direction. Would not be too surprised if we saw
a stray sprinkle or flurry at times but overall precipitation should
be sparse. In addition, more clouds and lingering chilly air aloft
should limit the expected warmup. Do expect it to be milder but have
slowed down the temperature increase. Now expect highs to top out in
the mid 40s to low 50s Friday and the upper 40s to mid 50s Saturday.
In addition, have raised lows into the low and mid 30s for Friday
night.

&&

.LONG TERM...(Saturday night through Wednesday)
Issued at 325 AM EDT Thu Apr 15 2021

...Milder then Chilly Again...

High impact weather potential: None is expected.

Clearing skies and seasonably mild temperatures are expected Sunday
due to a nearly zonal flow aloft and weak surface high pressure.
Another trough and an associated surface cold front then looks to
move into the region at some point later Monday or Monday evening.
Another shot off chilly air then follows and this is expected to
linger through midweek. There will be chances for rain showers with
the front Monday then rain or even snow showers will be possible
Monday night into Tuesday morning. No pops are in the forecast for
Wednesday yet but could see the need for some by later shifts as
extended models are dropping another upper trough into the region.
Temperatures are expected to be near seasonal levels Monday then
several degrees below through the remainder of the long term
forecast.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1130 PM EDT Wed Apr 14 2021

Expect cigs and visibilities to continue to trend toward IFR
overnight as round of deeper moisture pivots back south on west
side of slowly departing upper level low pressure. Will likely see
combination of rain/snow increase in coverage as this deeper
moisture arrives, but not expecting any significant accumulations.
Some improvement expected as we head through today into this
evening, but still looking at mostly MVFR cigs. Winds become
northwest and a bit gusty today.

&&

.MARINE...
Issued at 325 AM EDT Thu Apr 15 2021

Nw winds will get gustier today, as low pressure north of Lk
Ontario strengthens, and high pressure presses east across the
plains. Advisories are already up on the Lake MI and Superior
waters, and expect to expand into the vicinity of Presque Isle Lt
on Huron. Somewhat brisk nw winds will continue into Friday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...SMALL CRAFT ADVISORY until 2 AM EDT Friday for LMZ323-341-342-
     344>346.
LS...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LSZ321-322.
&&

$$

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

000
ACUS11 KWNS 150002
SWOMCD
SPC MCD 150001
NCZ000-VAZ000-150200-

Mesoscale Discussion 0386
NWS Storm Prediction Center Norman OK
0701 PM CDT Wed Apr 14 2021

Areas affected...northeast North Carolina into far southeast
Virginia

Concerning...Severe potential...Watch unlikely

Valid 150001Z - 150200Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated severe hail or wind is possible for another 1-2
hours east of a small cluster of storms along the Virginia/North
Carolina border. Due to small areal and temporal threat, no watch is
expected.

DISCUSSION...A cluster of cells along the eastern NC/VA border is
currently situated within the surface theta-e axis, traveling east
along a boundary and ahead of a surface low. The environment in the
immediate vicinity of these storms is favorable for severe weather,
with good overall hodograph length, and over 200 m2/s2 effective
SRH.

A cooler air mass currently resides over eastern NC and southeast
VA, or about 50 miles downstream of these storms as of 00Z. While a
few reports of damaging wind or hail are possible in the short term,
it is expected that these storms will weaken after 01Z as they
encounter the less unstable air.

..Jewell/Hart.. 04/15/2021

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

ATTN...WFO...AKQ...MHX...RAH...

LAT...LON   36807718 36647619 36407579 36197586 35897581 35747613
            35817656 36277762 36477771 36717748 36807718