• Storm Prediction Center 19 07

    From LU9DCE@21:5/101 to ALERT on Fri Jul 19 04:10:13 2019
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    ESTACION DE PACKET RADIO - BUENOS AIRES (GF05OM)
    BOLETINES INFORMATIVOS PROGRAMADOS (BIP)
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    MD 1521 CONCERNING 01Z OUTLOOK UPGRADE FOR PORTIONS OF FAR
    SOUTHEASTERN MT...FAR NORTHEASTERN WY...FAR SOUTHWESTERN ND...AND
    NORTHWESTERN SD
    Mesoscale Discussion 1521 NWS Storm Prediction Center Norman OK
    0126 AM CDT Fri Jul 19 2019
    Areas affected...Portions of far southeastern MT...far northeastern
    WY...far southwestern ND...and northwestern SD
    Concerning...01Z Outlook upgrade
    Valid 190626Z - 190900Z
    SUMMARY...Isolated severe risk should continue overnight. Large
    hail appears to be the main threat. Overall threat will probably
    remain too isolated for a watch.
    DISCUSSION...Storms have recently strengthened across far
    southeastern MT into far southwestern ND along and just ahead of
    a cold front. Ascent overspreading this region associated with a
    subtle shortwave trough embedded within enhanced mid/upper-level
    westerly flow may also be aiding storm development. This convection
    will likely remain elevated above a shallow near-surface stable
    layer. But, steep mid-level lapse rates are contributing to
    1500-2500+ MUCAPE, which increases with eastward extent across
    western SD. Strong mid/upper-level winds will support elevated
    supercells early this morning with mainly a large hail threat given
    the 50-60 kt of effective bulk shear. This threat for isolated large
    hail will probably persist for the next couple of hours into parts
    of far southwestern ND and northwestern SD. At least a marginal risk
    of severe storms is apparent, but the overall threat will probably
    remain too isolated to justify watch issuance.
    ..Gleason/Grams.. 07/19/2019
    ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...BIS...UNR...BYZ...
    LAT...LON 45130531 45660492 46260364 46370291 46330179 45930090
    45010089 44470157 44170262 44180404 44510499 45130531
    SPC 1200Z Day 1 Outlook
    Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254
    AM CDT Fri Jul 19 2019
    Valid 191200Z - 201200Z
    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL MN...CENTRAL/NORTHERN MI...AND WESTERN UPPER MI...
    ...SUMMARY... Thunderstorms capable of all severe threats, including
    large hail, strong wind gusts, and tornadoes, are possible across
    portions of the Upper Midwest and Upper Great Lakes today.
    ...Upper Midwest...Upper Great Lakes... Showers and isolated
    thunderstorms will likely be ongoing at the beginning of the period
    over portions of the Upper Great Lakes, supported by a modest
    low-level jet. These showers and thunderstorms are expected to
    dissipate by the early morning as the low-level jet weakens.
    A very moist air mass is currently in place over the Upper
    Midwest/Upper Great Lakes, with even better moisture upstream across
    the Middle MS Valley. This air mass will remain over the region
    today with some modest moist advection possible. As a result,
    dewpoints are expected to be mid to upper 70s across a large
    portion of the Upper Midwest and Upper Great Lakes. Dewpoints
    around 80 may be realized across southern MN near a weak surface
    low. Surface temperatures are also expected to climb into the 90s
    as the boundary layer mixes. These very warm and moist conditions
    will exist beneath relatively cool mid-level temperatures, resulting
    in very steep (i.e. 8-8.5 deg C per km) mid-level lapse rates. As a
    result, an extremely buoyant thermodynamic environment (i.e. 4000+
    J/kg of MLCAPE) will be in place. Highest buoyancy will likely
    occur across northern IA, southern MN, and west-central WI. In
    these areas MLCAPE could exceed 6000 J/kg this afternoon and evening.
    In addition to this extreme buoyancy, seasonally strong westerly
    flow aloft will extend from the northern High Plains through Upper
    MI. Generally southerly low-level flow beneath these westerlies
    results in effective bulk shear values of 45-55 kt across much of
    MN and northern WI today afternoon and evening.
    Overall, the resulting environment is very favorable for severe
    thunderstorms. Large-scale forcing for ascent will be negligible
    but convergence near a weak surface low expected to centered
    be near the southern SD/MN border this afternoon, and a warm
    front extending east from the low, will provide the impetus for
    convective initiation. Once initiation occurs, strong updrafts
    are expected to develop rapidly, with an attendant threat for all
    severe hazards including very large hail and tornadoes. Generation
    of strong cold pools are expected to result in quick upscale growth
    into a convective line. Strength of the vertical shear suggests the
    potential for a well-organized and intense convective line capable
    of significant wind gusts exists. Higher wind probabilities may
    be needed in subsequent forecasts if confidence in the development
    and location of a well-organized convective line increases.
    ...Lower Great Lakes...Northeast... Weak convectively induced
    shortwave trough is expected to progress over the Lower Great
    Lakes this afternoon, providing enough lift for thunderstorm
    development. Air mass over the region will be moderately unstable
    but weakly sheared. Expectation is for predominantly multicellular, outflow-dominant storms capable of isolated damaging wind gusts.
    ...SD... A strong low-level jet will develop across the Plains
    tonight with the resulting warm-air advection supporting thunderstorm development across SD. These initially elevated storms could produce
    isolated large hail. As they move eastward, low-probability potential
    exists for a few downdrafts intense enough to produce strong wind
    gusts at the surface.
    ..Mosier/Bentley.. 07/19/2019
    SPC 0600Z Day 2 Outlook
    Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234
    AM CDT Fri Jul 19 2019
    Valid 201200Z - 211200Z
    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
    GREAT LAKES INTO NEBRASKA AND IN PARTS OF EASTERN COLORADO...
    ...SUMMARY... An isolated severe risk will exist from Nebraska
    eastward into the central Great Lakes and over parts of eastern
    Colorado. Damaging gusts and large hail are the primary threats.
    ...Central Great Lakes into the central High Plains... A belt of
    strong westerlies will be confined to the states bordering Canada on
    Saturday with a flattened mid-level ridge over the OH Valley. A cold
    front initially over the Upper Midwest extending west-southwestward
    into the central High Plains will move southward, with the front
    accelerating south through most of eastern CO and into western KS
    by early evening. A reservoir of rich boundary layer moisture over
    the Midwest (characterized by 70s degrees F surface dewpoints) will
    contribute to a very unstable airmass from the MO River east through
    the middle MS Valley. Model guidance varies on the placement of
    storms over the Upper Midwest early Saturday morning. Nonetheless,
    it seems some of the early day activity may continue into parts of
    the central Great Lakes with other development occurring during
    the afternoon in the vicinity of the front farther west in IA.
    Isolated damaging gusts/hail are the primary risks with the stronger
    storms. Farther west over the central High Plains, increasing
    low-level moisture will accompany a post-frontal upslope regime.
    Strong heating coupled with orographically forced ascent will
    promote storms developing near the terrain-favored locales before
    spreading east into the plains. This activity will likely weaken
    by early-mid evening.
    ...Mid-Atlantic states into much of the Southeast... A mid-level
    ridge extending across the southern tier of states will favor
    isolated to scattered diurnally driven storms. Ample heating leading
    to steepened low-level lapse rates and a weak shear environment
    will promote pulse thunderstorms. A few of the stronger cores may
    yield localized gusty winds and perhaps small hail. This activity
    will weaken by the early evening.
    ...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: 5%
    - Marginal Hail: 5% - Marginal
    ..Smith.. 07/19/2019
    SPC Day 1 Fire Weather Outlook
    Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK
    1254 AM CDT Fri Jul 19 2019
    Valid 191200Z - 201200Z
    ...Synopsis... A strong mid to upper level jet will start to exit
    the northern Rockies today. Some stronger mid-level flow will remain
    on the back edge of this jet and some of these winds may mix toward
    the surface across portions of the Great Basin and northern Rockies. ...Portions of the Great Basin into central Wyoming.... A belt of 15
    to 25 mph winds is expected to develop from far southern California northeastward into central Wyoming. In addition, portions of this
    area will have relative humidities below 10 percent. This area is
    covered by a broad elevated delineation, but conditions will likely
    vary widely throughout the area from localized critical conditions
    to very little fire weather concerns in others. This is due to
    a combination of patchy low-level moisture as monsoonal moisture
    is pulled northward in some areas, and terrain affects leading to
    localized areas of stronger low-level flow.
    ...Snake River Valley in Idaho... Winds are expected to increase
    to 15 to 20 mph in the Snake River Valley during the afternoon
    hours with gradually decreasing relative humidity. There may be
    a period in the late afternoon when relative humidity drops below
    15 percent yielding the possibility for short duration, localized
    critical conditions.
    ...Northern Rockies... Some critical meteorological conditions
    are possible in north central Montana due to downslope flow, but
    fuels across the area do not warrant a fire weather area at this
    time. However, these dry and breezy conditions will help dry fuels
    across the area which may lead to receptive fuels by late in the
    weekend or early next week.
    ..Bentley.. 07/19/2019
    ...Please see www.spc.noaa.gov/fire for graphic product...
    SPC Day 2 Fire Weather Outlook
    Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK
    1254 AM CDT Fri Jul 19 2019
    Valid 201200Z - 211200Z
    ...NO CRITICAL AREAS...
    ...Synopsis... Once the mid-level jet streak exits the northern
    Rockies Saturday morning, flow will remain mostly weak across the
    western CONUS with the only remaining flow in southern Montana
    where fuels are not yet cured and precipitation has been bountiful
    for the past few weeks. Therefore, the risk for new large fires
    on Saturday will be mostly low across the CONUS.
    Some weak to moderate surface winds may develop across northern
    Arizona and far southern Utah during the afternoon, but winds are
    expected to stay mostly below 15 mph across this region. Therefore,
    no elevated delineation is warranted.
    ..Bentley.. 07/19/2019
    ...Please see www.spc.noaa.gov/fire for graphic product...

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    The meta-Turing test counts a thing as intelligent if it seeks to devise
    and apply Turing tests to objects of its own creation.
    -- Lew Mammel, Jr.

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