RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Thu Jun 1 14:27:01 UTC 2023.
No Mesoscale Discussions are in effect as of Thu Jun 1 14:27:01 UTC 2023.
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 AM CDT Thu Jun 01 2023
Valid 011300Z - 021200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE SOUTHERN HIGH PLAINS...
...SUMMARY...
Severe hail and gusts, and perhaps a tornado, are possible across
portions of the southern High Plains this afternoon and evening.
...Synopsis...
The mid/upper-level pattern will remain characterized on the large
scale by western troughing, a ridge roughly from central MX across
the Ozarks and upper Mississippi Valley to Hudson Bay, and troughing
over parts of the Southeast and central/eastern Gulf. A shortwave
trough was apparent over AZ/UT, with embedded 500-mb low near the
Grand Canyon. This feature is forecast to weaken as it pivots
northeastward across the Four Corners region through 00Z, then over
western CO through the end of the period. Meanwhile, a southern-
stream/subtropical-branch perturbation -- evident in moisture-
channel imagery west of Baja between 125W-130W -- will move eastward
across Baja during the 00-06Z time frame, and across Sonora through
12Z tomorrow. An MCV was apparent in radar composites over western
KS, moving northward.
The 11Z surface chart again showed a muddled, nebulous pattern over
most of the CONUS east of the Rockies, outside of these features:
1. A meso-alpha-scale outflow area from prior and ongoing
convection that extended from southwestern KS and western OK to the
Llano Estacado. The boundary was drawn from west-central KS across
westernmost parts of the main body of OK, past CDS to between
LBB-HOB, then west-northwestward over southeastern to central NM.
The boundary should stall on the eastern end today, while stalling
then drifting northward over eastern NM and the TX South Plains on
the south and west sides.
2. A dryline south of the outflow area from central NM to near GDP
and west of PRS. This feature should mix eastward somewhat across
southeastern NM. A diffuse dryline/lee trough was evident farther
north over northeastern CO to the Black Hills vicinity and
southeastern MT.
...Southern High Plains...
Isolated to widely scattered thunderstorms are possible along and
north of the outflow boundary through this evening, with the
greatest severe potential being very near the boundary as it shifts
slowly northward. Severe hail/gusts and a conditional, low-end
supercellular tornado threat are apparent.
The severe potential today has some nontrivial uncertainties --
especially regarding initiation timing and overall coverage. Still,
the severe threat appears more spatially focused, due to weaker
shear and more-stable boundary layer with extent, weaker shear and
lapse rates eastward, drier/deeply mixed air westward past eastern
NM, and lack of substantial large-scale/upper-air forcing area-wide.
At least somewhat stabilizing low-level trajectories from ongoing/
morning areas of showers and isolated thunderstorms the southeast --
over west-central TX -- also may weaken the baroclinicity along part
of the boundary, in turn making associated lift more uncertain in
strength and timing with regard to diurnal convective potential,
amid gradual diurnal weakening of ambient MLCINH.
As the MCV moves away and the AZ/Four Corners perturbation moves
abeam of this region and weakens, two primary synoptic- to
subsynoptic-scale effects are expected aloft:
1. Height rises through the period, which should continue tonight
amid shortwave ridging that precedes the southern/stream/Pacific
trough, and
2. A related northward arching of the subtropical jet (STJ) across
west TX and southern NM, increasing upper winds over the outlook
area roughly south of I-40.
Given these factors, surface-based convective coverage/timing are is
uncertain along the boundary, and more improbable than previous days
to its south, given the ridging aloft and associated lack of
substantial large-scale UVV support. Any activity that does develop
along the boundary, however, will be well ventilated near anvil
level in the northward-arching STJ, and will access locally
maximized low-level vorticity/hodograph size/SRH. Such convection
also should benefit from strong veering of winds with height from
surface through midlevels, helping to offset modest midlevel
westerlies enough to yield 35-40 kt effective-shear magnitude.
Given the potential for a few supercells, the 15% hail/wind and 5%
tornado probabilities are maintained and somewhat reshaped toward
the expected boundary layout today, while the marginal probabilities
are tightened down on the north end, where airmass recovery is more
doubtful.
...North-central High Plains...
Isolated to scattered thunderstorms are possible this afternoon into
early evening, near the dryline/lee trough, from near I-80 northward
over the NE Panhandle and eastern WY toward the Black Hills. This
activity may be associated with a corridor of relatively maximized
large-scale ascent aloft, ahead of a minor shortwave trough ejecting
northward out of northern CO, atop diurnally minimized MLCINH.
Although mid/upper-level lapse rates will be seasonally modest over
this region. Surface dewpoints in the mid 40s to mid 50s F may
support pockets of 1000-1500 J/kg MLCAPE atop well-mixed layers.
Weak low-level and deep-layer shear are forecast. Marginally severe
hail and/or a few gusts near severe limits are possible.
..Edwards/Jewell.. 06/01/2023
Read more
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0924 AM CDT Thu Jun 01 2023
Valid 011700Z - 021200Z
The previous forecast remains on track with only minor expansion
needed across parts of far southwest NM where ensemble guidance has
trended towards higher probability for sustained elevated
conditions. See the previous forecast for additional details.
..Moore.. 06/01/2023
.PREV DISCUSSION... /ISSUED 0126 AM CDT Thu Jun 01 2023/
...Synopsis...
Modest mid-level winds will be maintained as the Four Corners trough
moves northeast and weakens today. A weak surface trough is also
expected to develop in eastern New Mexico. These features will
combine to promote 15-20 mph winds across parts of central New
Mexico. By the afternoon, RH of 10-15% will be possible. Some
precipitation occurred on Wednesday afternoon in some portions of
central/southeastern New Mexico. While dry and windy conditions are
possible farther north and east, mitigated fuel dryness should
reduce the overall fire potential. Elevated to perhaps locally
critical conditions are expected in portions of central New Mexico.
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
|
RSS Feed