LU9DCE > ALERT 20.02.19 08:15l 206 Lines 11725 Bytes #7 (0) @ WW
BID : 18764_LU9DCE
Subj: Storm Prediction Center 20 02
Sent: 190220/0701Z 18764@LU9DCE.TOR.BA.ARG.SOAM LinBPQ6.0.18
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ESTACION DE PACKET RADIO - BUENOS AIRES (GF05OM)
BOLETINES INFORMATIVOS PROGRAMADOS (BIP)
MD 0111 CONCERNING HEAVY SNOW FOR EASTERN WV...WESTERN VA
Mesoscale Discussion 0111 NWS Storm Prediction Center Norman OK
1126 PM CST Tue Feb 19 2019
Areas affected...Eastern WV...Western VA
Valid 200526Z - 200930Z
SUMMARY...Heavy snow is expected to spread northeast along the
WV/VA border over the next several hours. Snow rates will likely
approach 1" per hour before precipitation changes to sleet.
DISCUSSION...Strong low-level warm advection appears to be the
primary contributor in a large canopy of precipitation that has
developed across the OH Valley into the central Appalachians late
this evening. LLJ is currently focused over TN but will strengthen
and translate across KY into WV by sunrise. Large-scale forcing
for ascent is expected to increase downstream across WV into
western VA over the next few hours and this is reflected well
in an expansive precip shield now spreading east of the higher
terrain. Leading edge of this activity will fall as snow with rates
likely approaching/exceeding 1" per hour. Forecast soundings for this
region suggest substantial warming will switch snow to sleet across
the southwestern half of the MCD area by 09z while the eastern WV
Panhandle and northwestern VA should remain as snow through 12z.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 36898138 37448128 38098063 38978030 39187944 38537859
37087919 36558065 36898138
MD 0110 CONCERNING WINTER MIXED PRECIPITATION FOR CENTRAL MISSOURI
Mesoscale Discussion 0110 NWS Storm Prediction Center Norman OK
0820 PM CST Tue Feb 19 2019
Areas affected...Central Missouri
Concerning...Winter mixed precipitation
Valid 200220Z - 200715Z
SUMMARY...Wintry mixed precipitation expected across the area,
beginning with freezing rain/sleet, then transitioning to mainly
rain, from south to north. Some areas may experience brief periods
of heavier freezing rain, with rates up to .05 in/hr. Farther
northwest, snow will be the main precipitation type, with brief
bursts of heavy snow possible.
DISCUSSION...A mid-level vort max embedded within a larger scale
upper-level shortwave trough is currently traversing the area, that
in tandem with strong surface-700 mb WAA, is providing deep-layer
ascent to the region. Tropospheric profiles are mainly below freezing
(per RAP forecast soundings), though the aforementioned WAA has
encouraged temperatures warming to/slightly above 0C around 850 mb,
north of the surface wet-bulb 0C line. As such, most dendrites are
expected to melt around 850 mb, before refreezing as ice pellets
in the lowest 100 mb or reaching the surface as freezing rain.
KSGF and KEAX dual-polarimetric radar data suggests that much of
the precipitation, concentrated within a northwest-to-southeast
oriented band, is falling as sleet, though multiple ASOS stations
across southern Missouri are also reporting ice accretion rates over
.05 in/hr. As such, brief bouts of heavier freezing rain are also
possible in addition to sleet. Farther northwest towards the Kansas
City Metropolitan area, vertical profiles (via RAP forest soundings)
are colder then points farther southeast, where snow will likely
remain the predominant precipitation type, even with the strong
WAA present. Brief periods of heavy snow cannot be ruled out.
As WAA will continue across the region this evening,
surface temperatures are expected to slowly warm with time,
approaching/rising above the freezing mark, where a transition
to mainly rain can be expected, beginning with the southern most
portions of the discussion area and spreading northward with time.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 37509133 37549230 37969374 38369425 39389484 39939458
40329358 40249278 39809178 39249122 38009063 37509133
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1140
PM CST Tue Feb 19 2019
Valid 201200Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION
OF SOUTHEAST MISSISSIPPI...
...SUMMARY... A few strong to severe storms might occur over the
lower Mississippi Valley later this morning toward mid day. Primary
threats appear to be a couple of locally strong to damaging wind
gusts and perhaps a tornado or two.
...Lower Mississippi Valley region...
Shortwave trough located over the central Plains by 12Z will
continue northeastward and reach the Great Lakes by early evening.
At the surface a warm front will move northward into southern MS
where it will likely stall, while a cold front advances eastward
through the central Gulf Coast region. Dewpoints in the upper 60s
to near 70 F will likely reside in the moist warm sector beneath
modest 6-6.5 C/km mid level lapse rates, contributing to 800-1200
J/kg MLCAPE. The 00Z RAOB and point-forecast sounding data show a
modest inversion around 700 mb. Given that deeper forcing for ascent
attendant to the shortwave trough will remain well to the northwest
with only neutral height tendency in warm sector, this inversion
could persist through the morning. A band of scattered thunderstorms
will likely continue developing within warm conveyor belt along
and just east of the cold front across the lower MS Valley. The
southern extent of the band from LA into southern MS will be rooted
near the surface within the moist warm sector where a window will
exist this morning with large 0-1 km hodographs supporting a threat
of supercells with low-level mesocyclones and perhaps a tornado
or two. The limiting factors will continue to be weak low-level
lapse rates and presence of remnant mid-level inversion which could
limit updraft strength. The threat will diminish this afternoon as
the low-level jet shifts northeast away from the warm sector.
SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1136
PM CST Tue Feb 19 2019
Valid 211200Z - 221200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY... The risk of severe thunderstorms appears negligible
across the U.S. Thursday through Thursday night.
...Discussion... Mid-level subtropical ridging centered near/east
of the Bahamas appears likely to remain a prominent feature. Some
westward and northwestward expansion across the Gulf Coast states,
and Mid South, into the Ohio Valley is forecast during this period,
coinciding with further building of broad ridging within the
mid-latitude westerlies to the north.
Models indicate that this will occur as large-scale upstream
troughing over the Southwest undergoes further amplification, in
association with vigorous short wave trough digging into its base.
After progressing across southern California, models suggest that
the smaller-scale perturbation will gradually pivot across the
international border area, as another short wave trough digs toward
the British Columbia coast. Although not quite yet coming in-phase
with a belt of westerlies emanating from the subtropical eastern
Pacific, it may become increasingly so toward the end of the period.
In lower-levels, a frontal zone is expected to trail a developing
cyclone, near/east of the northern Mid Atlantic coast at 12Z
Thursday, across the Mid Atlantic and southern Appalachians through
the lower Mississippi Valley and Texas Gulf coast. It appears that
this feature may still be a focus for continuing weak thunderstorm
development early Thursday, particularly in a corridor above/to
the cool side of it, aided by weak destabilization associated with
continuing moisture return off the Gulf of Mexico.
As the cyclone deepens and migrates away from the Northeast coast,
the frontal zone is expected to shift southward through the Mid
Atlantic. However, to the west, beneath the building mid-level
ridging, the frontal zone will shift/redevelop northward, likely
providing a continuing focus for lift and weak destabilization in the
presence of returning moisture. By late Thursday afternoon, highest
thunderstorm probabilities may exist in a corridor across northern
Louisiana, Mississippi and Alabama, before shifting northward through
the Tennessee Valley and developing west-southwestward toward the
Ark-La-Tex by late Thursday night.
Weak thunderstorm activity is also possible Thursday night across
parts of the Rio Grande Valley into central Texas, supported by
elevated moisture return and destabilization associated with the
subtropical stream. A few additional thunderstorms are possible
Thursday near the southern California coast, and across parts of
central Arizona, associated with the digging short wave trough.
...Eastern Gulf Coast and South Atlantic Coast states... Near and
just south of the surface front, in the vicinity of the categorical
(10 percent probability) thunder line across southern portions of
Louisiana, Mississippi, and Alabama, into north central Georgia and
perhaps the South Carolina piedmont, there may be a corridor of weak
boundary-layer destabilization Thursday. Although forcing for the
initiation of storms remains unclear, there is some signal in the
model output that isolated to widely scattered diurnal thunderstorms
are possible. If this occurs, deep layer vertical shear may be
sufficient for storms capable of producing marginal severe wind and
hail. However, at the present time, this potential still seems low,
with severe probabilities being maintained at less than 5 percent.
...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: <5%
- None Hail: <5% - None
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK
1254 AM CST Wed Feb 20 2019
Valid 201200Z - 211200Z
...Synopsis... As a well-defined mid-level trough exits the Central
Plains and traverses the Great Lakes area during the day, a second
mid-level shortwave trough will deepen across the southwest CONUS,
with a weak surface lee trough developing along the High Plains
during the afternoon hours. Breezy, dry surface westerlies will
become prevalent across the southern High Plains by noon, fostering
modest potential for fire spread given drying fine fuels in place.
...Portions of eastern New Mexico into west Texas... As temperatures
rise above 50F with the onset of diurnal heating and associated
boundary-layer mixing, westerly surface winds will increase to 15+
mph, coincident with 10-20% RH. These elevated conditions will first
be realized shortly after noon east of the Caprock Escarpment, with
elevated conditions becoming more apparent across the Llano Estacado
a few hours later. By evening, nocturnal cooling will promote surface
RH recoveries and weakening winds, lessening the wildfire threat.
...Please see www.spc.noaa.gov/fire for graphic product...
In Marseilles they make half the toilet soap we consume in America, but the
Marseillaise only have a vague theoretical idea of its use, which they have
obtained from books of travel.
-- Mark Twain
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