AWUS01 KWNH 132050
FFGMPD
TXZ000-OKZ000-KSZ000-COZ000-140245-

Mesoscale Precipitation Discussion 0040
NWS Weather Prediction Center College Park MD
349 PM EST Sat Mar 13 2021

Areas affected...Southern High Plains

Concerning...Heavy rainfall...Flash flooding possible

Valid 132045Z - 140245Z

SUMMARY...Blossoming convection will contain heavy rainfall rates
and may result in areas of flash flooding. Areas most at risk for
flash flooding are portions of the Texas Panhandle and western
Oklahoma where wetter antecedent soil conditions are present.

DISCUSSION...Satellite imagery depicts a textbook set up for
severe weather in the southern High Plains this afternoon. A deep
upper low over the Great Basin is slowly moving east while the
left exit region of a ~130 knot jet streak at 300mb. A large scale
area of vertical ascent is ongoing across the atop the southern
and central High Plains. At lower levels, moist southeasterly flow
is located east of the dry line setting up across western Texas
with a cold front racing in from the west. Instability within the
warm sector is gradually increasing as daytime heating persists
and a steady feed of rich low level moisture continues.

RAP mesoanalysis showed roughly 50-65 knots of effective bulk
shear present, favoring organized convection from the onset.
Available MUCAPE ranges between 1000-2000 J/Kg with values
increasing as the boundary layer destabilizes further this
afternoon. Also, precipitable water levels are remarkably high
with values roughly 3-5 STDs above normal over the TX/OK
Panhandles and southwest Kansas. As the low level jet strengthens
this evening, expect an even deeper fetch of low-level moisture to
manifest itself over the Southern Plains. Look for storms to
become more congealed and linear later this evening while still
containing excessive rainfall rates.

Latest guidance indicates rainfall rates of 1-2" per hour are
likely within areas of intense convection. The lowest
concentration of FFG is focused east of Amarillo on south towards
Lubbock and areas northeast of the city. These locations dealt
with severe storms yesterday and as a result, CREST maximum soil
saturation shows a slightly higher area of saturation in those
locations. These areas are most at risk for flash flooding as
storms approach late afternoon and into the early evening hours.

Mullinax

ATTN...WFO...AMA...DDC...LUB...OUN...PUB...

ATTN...RFC...ABRFC...WGRFC...NWC...

LAT...LON 38290066 38029998 37199954 35419944 34109986
33130160 34830208 36870220 38100204

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AWUS01 KWNH 142035
FFGMPD
MOZ000-ARZ000-150230-

Mesoscale Precipitation Discussion 0043
NWS Weather Prediction Center College Park MD
434 PM EDT Sun Mar 14 2021

Areas affected...Southwest Missouri...Northern Arkansas

Concerning...Heavy rainfall...Flash flooding possible

Valid 142030Z - 150230Z

SUMMARY...Band of showers and thunderstorms approaching from the
west may contain heavy downpours and lead to areas of flash
flooding, especially where soil saturation is highest.

DISCUSSION...Surface analysis at 20Z indicated a surface low
attached to an occluded front that stretched across Kansas while a
cold front was approaching from eastern Oklahoma. The warm front
has inched its way north throughout the day and is now positioned
over northern Arkansas. Satellite imagery depicted an extensive
stream of water vapor over the Lower Mississippi Valley and a
low-level southerly fetch supplying plenty of moisture aloft to
the region. Doppler Radar showed the swath of showers and
thunderstorms reaching southwest MO and extending south into
western Arkansas.

As the afternoon progresses, the 925-850mb wind field will
strengthen and MUCAPE on the order of ~250-500 J/Kg will be
positioned over central Arkansas. The increase in low level winds
may also act to orographically enhance vertical motion aloft at
low to mid levels. These factors do support rainfall rates picking
up in intensity into the early evening hours, especially within
areas of elevated convection. That said, limited MUCAPE present
should limit rainfall rates from becoming more than 1" hour on
average.

The highlighted region's soil moisture is elevated with the
highest observed soil saturation content in southwest Missouri.
Most 1-hour rainfall totals via the 18Z HRRR lie in the 0.3-0.6"
per hour range. That said, if some areas are seeing rates of at
least 0.5" over the span of three hours (where 3-hr FFG is as low
as 1.5" in spots), then there is the potential for some heavier
cells to produce localized flash flooding. The other concern with
this round of showers and storms is the hydrologic response. Some
rivers and streams are either near flood stage or experiencing
minor flooding, so even just a few hours of moderate-to-heavy
rainfall could lead to additional flooding this evening.

Mullinax

ATTN...WFO...EAX...LZK...SGF...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NWC...

LAT...LON 38519338 37969264 37109227 36579194 36019199
35719266 35919377 36649439 37659450 38429432

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AWUS01 KWNH 161518
FFGMPD
ALZ000-MSZ000-162015-

Mesoscale Precipitation Discussion 0047
NWS Weather Prediction Center College Park MD
1117 AM EDT Tue Mar 16 2021

Areas affected...East-Central MS...Southwest to Central AL

Concerning...Heavy rainfall...Flash flooding likely

Valid 161515Z - 162015Z

SUMMARY...Some flash flooding will be likely going through the
early to mid-afternoon hours from locally training bands of
showers and thunderstorms.

DISCUSSION...The latest satellite and radar imagery shows a couple
of broken lines of showers and thunderstorms impacting areas of
east-central MS and already portions of southwest to central AL
which have recently been exhibiting some training characteristics.

The activity is focusing near and north of a weak instability axis
with MUCAPE values of 500 to 1000 j/kg but also along the gradient
of a deep-layer moisture convergence max which is seen being
rather strong across areas of southeast MS. The 850 mb flow is
quite convergent across this region, and this is fostering an axis
of relatively strong low-level forcing for which the convection
has been tending to focus along.

Additionally, GOES-16 WV imagery shows the upper-level flow is
rather divergent over the region, and this is favoring some
organized deep-layer ascent. Satellite imagery is also confirming
the ongoing convection becoming increasingly aligned with the
deep-layer steering flow and thus fostering an environment
conducive for trainng convection.

Already there has been some locally heavy rainfall this morning of
2 to 3+ inches which has acted to moisten and locally saturate the
soil conditions across the region, and any additional rainfall is
likely to encourage runoff problems and some flash flooding.

There will likely be additional heavy rainfall from locally
training bands of showers and thunderstorms going through the
early to mid-afternoon hours across areas of east-central MS and
through areas of southwest to central AL which is strongly favored
by the recent HRRR guidance. Expect locally an additional 2 to 3+
inches of rain going through mid-afternoon with some of this
occurring over areas already hit earlier by heavy rain.

As a result, expect there to be some uptick in runoff concerns and
some areas of flash flooding as a result.

Orrison

ATTN...WFO...BMX...JAN...MOB...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON 32848669 32738609 32358620 32048671 31748769
31548859 31438929 31468997 31848992 32178929
32458847 32758759

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AWUS01 KWNH 182136
FFGMPD
VAZ000-WVZ000-OHZ000-KYZ000-190100-

Mesoscale Precipitation Discussion 0059
NWS Weather Prediction Center College Park MD
534 PM EDT Thu Mar 18 2021

Areas affected...Central/Southwest WV...Eastern KY

Concerning...Heavy rainfall...Flash flooding possible

Valid 182130Z - 190100Z

SUMMARY...Scattered pockets of heavy showers and thunderstorms may
result in an isolated flash flood threat going into the early
evening hours.

DISCUSSION...The latest GOES-16 satellite imagery in conjunction
with radar has been showing a general uptick in the coverage of
showers and thunderstorms over the last couple of hours with some
locally heavy rainfall rates that are locally approaching and
exceeding 1 inch per hour across areas of central/southwest WV and
eastern KY.

A few things are fostering this uptick in convection which include
the arrival of a mid-level low/trough from the OH Valley which is
bringing steeper mid-level lapse rates farther off to the east
toward the central Appalachians. That coupled with mid to late-day
solar insolation is allowing for the boundary layer across the
region to become at least modestly unstable with MLCAPE values of
500 to 1000 j/kg. In addition to this, the latest mesoanalysis
depicts a notable moisture convergence max extending from western
WV down into eastern KY, and near an elongated wave of low
pressure.

The FFGs across areas of central/southwest WV and eastern KY are
relatively low, and already some of the scattered convection has
been resulting in some 1-hour FFG exceedance and locally elevated
CREST max-unit streamflow values via FLASH.

Generally, the expectation is for the convection to remain
scattered in nature, but with the moisture convergence parameters,
instability and added support from orographics, the convection
should tend to hang for a few hours going through at least 00Z.
The HRRR guidance favors some occasional 1 to 1.5 inch/hr rainfall
potential with an isolated storm total perhaps to near 2 inches.

This set-up will favor at least an isolated flash flood threat
going into the early evening hours as result.

Orrison

ATTN...WFO...JKL...MRX...PBZ...RLX...

ATTN...RFC...LMRFC...OHRFC...NWC...

LAT...LON 39608044 39138037 38288082 37658175 36878284
36678345 36818385 37098381 37678291 38008260
38438235 38548236 38978182 39578091

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AWUS01 KWNH 280803
FFGMPD
VAZ000-WVZ000-TNZ000-KYZ000-281302-

Mesoscale Precipitation Discussion 0082
NWS Weather Prediction Center College Park MD
403 AM EDT Sun Mar 28 2021

Areas affected...Southern/Central Appalachians

Concerning...Heavy rainfall...Flash flooding likely

Valid 280802Z - 281302Z

Summary...Widespread moderate to embedded heavier rainfall
spreading over portions of eastern Tennessee, eastern Kentucky,
southwest Virginia, and southern West Virginia early this morning
may lead to localized flash flooding. Rainfall amounts of 1-2"
will be possible.

Discussion...An organized line of thunderstorms associated with a
large scale mid/upper trough and cold front pushing eastward will
continue to slowly inch eastward toward the southern/central
Appalachians this morning. A corridor of higher moisture,
currently analyzed between 1.2-1.4" will lift north/northeastward
ahead of the approaching front. This front will also bring some
elevated instability, upwards of 500 J/kg, through about 10Z,
particularly for portions of TN, southeast KY, and southwest VA.
The last several runs of the HRRR have depicted the scenario
fairly well and show a footprint of 1-2" possible with some
localized amounts up to 3".

Antecedent conditions are quite wet, particularly for northeast
TN, extreme southeast KY, and southwest VA where 1-hour flash
flood guidance is 1" or less, and the 14-day departures are
running up to 300 percent of normal. The expected rainfall is
likely to reach this threshold, based on the latest HREF
probabilities. Further north into WV, drier soils and below normal precipitation departures the last 14 days may preclude a flash
flood threat, but the longer duration with moderate rates could
lead to flooding issues for the more sensitive locations.

Taylor

ATTN...WFO...JKL...MRX...RLX...RNK...

ATTN...RFC...LMRFC...OHRFC...NWC...

LAT...LON 38818116 38748067 38258042 37988056 37428102
37198132 36788173 36688202 36208280 35738340
35778385 36318430 36988456 37928330 38328250
38698169

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