• MESO: Heavy Rain - Floodi

    From Weather Alert@618:250/1 to All on Sat Mar 13 18:55:00 2021
    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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  • From Weather Alert@618:250/1 to All on Sun Mar 14 19:15:00 2021
    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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  • From Weather Alert@618:250/1 to All on Tue Mar 16 14:27:00 2021
    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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  • From Weather Alert@618:250/1 to All on Thu Mar 18 18:13:00 2021
    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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  • From Weather Alert@618:250/1 to All on Sun Mar 28 07:40:00 2021
    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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