USA 20./21. 05. 2019 OK / TX
geschrieben von: Eike
Datum: 19. Mai 2019 21:09
" Moderate Warnung " mit 3 Tagen Vorlauf.
Das ist jetzt die 2 Tages Vorhersage:
SPC AC 191729
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 PM CDT Sun May 19 2019
Valid 201200Z - 211200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM NORTHWEST
TEXAS INTO CENTRAL OKLAHOMA...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM FAR EASTERN
NEW YORK INTO SOUTHERN NEW ENGLAND...
Severe thunderstorms capable of all severe hazards, including strong
tornadoes, are expected across portions of the southern Plains on
...SIGNIFICANT SEVERE WEATHER EVENT POSSIBLE ACROSS THE SOUTHERN
PLAINS ON MONDAY...
A complicated, yet potentially higher-end severe weather scenario
will unfold across the southern Plains throughout the forecast
period. Height falls associated with an approaching longwave trough
centered over Arizona will overlie a strong surface dryline along
the New Mexico/Texas border, resulting in a north-south oriented
band of storms in that area around 12Z or so. These storms will
migrate northeastward and contain a threat for hail and damaging
wind gusts throughout the morning due to steep mid-level lapse rates
and supercellular wind profiles. A tornado threat may also exist on
the southern end of this activity - especially where convection can
become surface-based and remain discrete amidst with slightly higher
boundary layer moisture (i.e., upper 60s to 70s dewpoints).
The evolution of this early morning complex will impact the severe
risk in downstream areas of Oklahoma and northwest Texas through the
afternoon and evening. A variety of operational models and CAMS
suggest that some portions of this MCS will interact with the
northward-moving surface warm front and possibly retard its movement
into northern portions of the outlook area (near the OK/KS border
area). Meanwhile, most model solutions suggest the development of
isolated convection out ahead of any ongoing MCS activity - with
this risk most evident across portions of southwestern Oklahoma and
vicinity. These storms are expected to reside in a environmental
parameter space supportive of all severe hazards, including
significant hail and strong tornadoes, and this risk should be
maximized as long as discrete, cellular convection can persist
through the forecast period. This risk will become further enhanced
by an increasingly strong low-level jet across the region during the
early evening should storms maintain a relatively discrete mode.
Farther downstream across eastern Oklahoma and vicinity, uncertainty
remains regarding specific positioning of the warm front, although
most model solutions persist in developing convection across the
region via either an upstream MCS moving into the region and/or
isolated convection forming along and south of the front. The
potential for isolated convection is plausible given surface
heating, weak mid-level inhibition, and broadly confluent
warm-sector low-level flow - even in the absence of any forcing for
ascent aloft. The environment along and south of any warm front or
convective outflow will support all severe hazards, including strong
tornadoes. The inherited risk areas have been expanded eastward
into western Arkansas to account for severe potential in those
North of the warm front (across Kansas and vicinity), steep
mid-level lapse rates and strong vertical shear will support
primarily elevated storms with a threat of large hail. Steep
mid-level lapse rates will also exist in portions of Colorado,
although the development of any substantial surface-based
instability will depend on convective evolution across the Texas
Panhandle and vicinity. Storms in that area will have at least a
threat for large hail.
Late in the forecast period (after about 06Z Tuesday), an ejecting
mid-level trough over the Four Corners vicinity will take on a
negative tilt while moving toward the High Plains. Sustained
low-level advection across the warm sector (and resultant moderate
instability) should result in development of another line of storms
across the Texas South Plains/Panhandle vicinity. These storms
should reach the I-35 corridor of Oklahoma and north Texas by the
end of the forecast period, with damaging wind and isolated
tornadoes remaining possible.
...Mid-Atlantic and Northeast...
Surface heating ahead of an approaching cold front near the
Appalachians will result in steepening low-level lapse rates and
weak instability. Mid-level lapse rates will be relatively poor,
although the glancing influence of an approaching wave over the
eastern Great Lakes will result in development of a few convective
cells along and ahead of the front. Strong flow aloft and downward
transport of that momentum near storms will result in a few damaging
wind gusts. This risk should wane with eastward extent in response
to nocturnal stabilization.
...MAXIMUM RISK BY HAZARD...
Tornado: 15% SIG - Moderate
Wind: 45% - Enhanced
Hail: 30% SIG - Enhanced