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LU9DCE > ALERT 07.12.20 16:01z 171 Lines 9332 Bytes #999 (0) @ WW
BID : 42549_LU9DCE
Read: GUEST
Subj: STORM PREDICTION CENTER 07 12
Path: HB9ON<IW8PGT<IZ3LSV<IK5FKA<IK5FKA<LU9HGS<LU9DCE
Sent: 201207/1600Z 42549@LU9DCE.TOR.BA.ARG.SOAM LinBPQ6.0.20
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ESTACION DE PACKET RADIO - BUENOS AIRES (GF05OM)
BOLETINES INFORMATIVOS PROGRAMADOS (BIP)
CASTILLOEDUARDO@OUTLOOK.COM.AR
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MD 1838 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR THE FL
KEYS AND EXTREME SOUTH FL PENINSULA
Mesoscale Discussion 1838 NWS Storm Prediction Center Norman OK
0404 AM CST Mon Dec 07 2020
Areas affected...The FL Keys and extreme south FL Peninsula
Concerning...Severe potential...Watch unlikely
Valid 071004Z - 071130Z
Probability of Watch Issuance...5 percent
SUMMARY...An eastward-moving cluster may pose a risk for 40-60
mph wind gusts as it spreads east from the Dry Tortugas across the
Keys through about 13Z. Additional showers forming over the Upper
Keys might deepen into a supercell, but more likely should over
the Florida Straits.
DISCUSSION...A longer-lived convective cluster/short-line segment
near the Dry Tortugas has been steadily moving east around 35 kt.
This activity will likely spread across much of the Keys between
11-13Z. While surface winds are predominately southwest across the
Keys, robust speed shear with a nearly unidirectional wind profile
as indicated by the Key West VWP may support embedded small-scale
bowing segments capable of producing strong surface wind gusts amid
1000-1500 J/kg of MLCAPE per 06Z Key West and 08Z Miami RAOBs.
A confluence band of showers has also recently formed in a
north/south-orientation just east of the longitude of Marathon.
Surface winds have become increasingly veered across the greater
Miami metro area since the 08Z sounding, which is a trend also noted
in time-series of the VWP. That has likely resulted in decreasing
low-level hodograph curvature. Nevertheless, it is possible that
a transient supercell may develop out of this band of showers,
before they shift east off the coast into the Straits.
..Grams.. 12/07/2020
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MFL...KEY...
LAT...LON 24818208 25158123 25318078 25478023 25348014 24868032
24568089 24438162 24448216 24818208
SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0113
AM CST Mon Dec 07 2020
Valid 091200Z - 101200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY... Thunderstorms are not expected on Wednesday.
...Synopsis...
An upper ridge will shift eastward across the central and into the
eastern CONUS on Wednesday. At the surface, high pressure will
persist over much of the country, and continental trajectories
will result in dry and stable conditions. A shortwave trough will
dig across the Pacific Northwest and merge with the upper low
off the southern CA/northern Baja coast. This larger-scale trough
will develop eastward across the western U.S., extending from the
northern Rockies to AZ and northwest Mexico by 12z Thursday. Strong
southwesterly deep layer flow will spread across northwest Mexico
and southern AZ/NM, with midlevel moisture increasing toward
the very end of the period. Showers will likely increase across
parts of AZ/NM after 00z, however meager instability will limit
thunderstorm potential.
..Leitman.. 12/07/2020
Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK
0331 AM CST Mon Dec 07 2020
Valid 101200Z - 151200Z
...DISCUSSION... An upper trough over the western states will
shift eastward into the Plains through Day 5/Fri. In response to
height falls, lee cyclogenesis is expected, and a surface low will
develop eastward across the central/southern Plains vicinity on
Thursday into early Friday. Southerly low level flow ahead of the
surface low and attendant cold front will bring modest Gulf moisture
northward across east TX into the Ark-La-Miss on Friday. This system
will continue to develop eastward across the Midwest and Southeast
on Day 6/Sat and early Day 7/Sun.
Isolated thunderstorm potential will increase across parts of the
southern Plains late Thursday night in a strong warm advection
regime associated with the deepening surface low and advancing
mid/upper trough. By Friday, some low-end severe potential could
exist across parts of east TX and persist eastward into the lower
MS Valley/Gulf Coast vicinity through Saturday. However, this will
largely depend on the quality of Gulf moisture return, which will
influence instability in an otherwise strongly-sheared environment.
As such, confidence remains low concerning organized severe potential
on Days 5-6/Fri-Sat, though probabilities could become necessary
in subsequent outlooks.
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK
0148 AM CST Mon Dec 07 2020
Valid 071200Z - 081200Z
...CRITICAL FIRE WEATHER AREA FOR HIGHER TERRAIN OF SOUTHERN
CALIFORNIA...
...Synopsis... An amplified upper-level flow pattern with high
pressure across the Rockies and Great Basin will flank an upper low
moving south along the California coast. Strong offshore winds are
expected across much of California, supporting very dry and windy
conditions. Critical fire weather is expected.
...Southern California... Critical fire weather conditions will
develop in response to increasing northeasterly winds early this
morning. With the upper-low moving overhead, easterly mid-level flow
will help reinforce the intensifying surface pressure gradient. By
the afternoon, widespread winds of 20-30 mph are expected with
higher gusts. Humidity values are forecast to drop to near 10%
through the day. The amalgamation of very dry fuels, low RH, and
strong surface winds may support localized extremely critical fire
weather conditions across the Transverse Ranges of Ventura and Los
Angeles counties. Here gusts greater than 60 mph may accompany single
digit RH supporting extreme fire behavior. A targeted extremely
critical upgrade maybe necessary should the much stronger wind
gusts and very low RH be sustained.
...Northern/Central California... Moderate northerly/northeasterly
downslope winds are possible across portions of the Bay
area and Sacramento valley with the potent offshore pressure
gradient. Overnight observations show moderate to strong humidity
recoveries (40-80%) occurring across much of the central Valley
and coastal areas. The increase in moisture should slow fire
weather potential during the day, despite the increasingly gusty
winds. However, with record dry fuels in some locations, localized
elevated/critical fire weather conditions may exist. The higher
terrain around the Bay Area would be the favored corridor for
overlap of low humidity and strong winds during the day.
..Lyons.. 12/07/2020
...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
0149 AM CST Mon Dec 07 2020
Valid 081200Z - 091200Z
...CRITICAL FIRE WEATHER AREA FOR SOUTHERN CALIFORNIA...
...Synopsis... High pressure over the Great Basin will drift to
the east as a cutoff low move south toward the Baja peninsula. The
pressure gradient driving offshore winds over much of California will
gradually weaken as the upper low drifts farther south. Widespread
critical fire weather conditions are expected Day2/Tuesday morning,
and will decrease through the remainder of the forecast period.
...Southern California... A moderate to strong offshore pressure
gradient will be ongoing Day2/Tuesday morning across southern
California. Widespread surface RH of 10-15%, with surface winds of
20-30 mph will support critical fire weather conditions across the
higher terrain and foothills. The presence of upper-level support
from 35-45 kt mid-level winds near the upper low, will bolster strong
surface wind gusts to 60+ mph for a few hours. With very dry fuels
and strong winds in place, localized extremely critical fire weather
conditions will be possible early Day2/Tuesday across portions
of the Transverse ranges. Decreasing upper-level support from the
southward moving upper-low will limit the potential for extremely
critical conditions to the first half of the forecast period.
Critical fire weather conditions may continue through the evening
and into the overnight with lingering offshore winds. A sharp drop
off in the stronger Santa Ana winds is expected Day2/Tuesday evening
as the pressure gradient rapidly decay. This suggests that only
localized critical fire weather conditions are likely overnight
and into early Day3/Wednesday.
...Northern Rockies/High Plains... Dry downslope winds of 15-20
mph are expected across portions of central/eastern Montana into
western South Dakota east of the strong surface high over the Great
Basin. Despite cool temperatures, diurnal RH minimums near 20-30%
will support locally elevated fire weather potential where cured
fuels are exposed.
..Lyons.. 12/07/2020
...Please see www.spc.noaa.gov/fire for graphic product...
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Somewhere, just out of sight, the unicorns are gathering.
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