Alert archive / Arkansas / Mesoscale Discussions in 2019
Mesoscale Discussion 21
The Storm Prediction Center issued this mesoscale discussion at Jan 18, 2019, 5:50 PM CST for 35 counties in Arkansas; 7 parishes in Louisiana; Bolivar County, Coahoma County, Mississippi. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jan 18, 2019, 5:50 PM CST (23:50 UTC)
- Expired
- Jan 18, 2019, 8:15 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 44 counties
Arkansas County, AR, Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Clark County, AR, Cleveland County, AR, Columbia County, AR, Crittenden County, AR, Cross County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Faulkner County, AR, Grant County, AR, Hot Spring County, AR, Independence County, AR, Jackson County, AR, Jefferson County, AR, Lafayette County, AR, Lee County, AR, Lincoln County, AR, Lonoke County, AR, Monroe County, AR, Nevada County, AR, Ouachita County, AR, Phillips County, AR, Poinsett County, AR, Prairie County, AR, Pulaski County, AR, Saline County, AR, St. Francis County, AR, Union County, AR, White County, AR, Woodruff County, AR, Bossier Parish, LA, Claiborne Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Union Parish, LA, Webster Parish, LA, Bolivar County, MS, Coahoma County, MS
The radar
The Little Rock radar (KLZK), 71 km from the middle of the area, began a volume at 23:49 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Little Rock, AR (KBYH), launched 12:00Z, 11.8 hours before the alert went out and 185 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 592 m above ground
- 0-6 km bulk shear
- 57 kt
- 0-1 km storm-relative helicity
- 160 m²/s²
- 0-3 km storm-relative helicity
- 187 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
324
ACUS11 KWNS 182351
SWOMCD
SPC MCD 182350
ARZ000-MSZ000-LAZ000-190215-
Mesoscale Discussion 0021
NWS Storm Prediction Center Norman OK
0550 PM CST Fri Jan 18 2019
Areas affected...Northern LA...Much of Central and Eastern AR...Far
Northwest MS
Concerning...Severe potential...Watch unlikely
Valid 182350Z - 190215Z
Probability of Watch Issuance...20 percent
SUMMARY...Some isolated hail is possible from the Arklatex
northeastward into northeast AR and northwest MS tonight.
DISCUSSION...A combination of increased large-scale forcing for
ascent attendant to the approaching upper trough and strengthening
warm-air advection within the warm conveyor will result in an
increase in showers and thunderstorms from the Arklatex
northeastward into northeast AR and northwest MS. Gradually warming
and moistening low-levels beneath relatively cool mid-levels will
result in steep lapse rates (i.e. 7 to 7.5 deg C per km) across the
region. Consequently, MUCAPE values could exceed 1000 J/kg, which
could support some more robust, longer-lived updrafts.
Additionally, strong unidirectional flow is already in place. Recent
SHV VAD profiles sampled 0-6 km shear over 45 kt and objective
mesoanalysis estimates closer to 60 kt farther north across northern
AR. These values support the potential for a few rotating/more
organized updrafts, which could contribute to an increase potential
for hail. Much of this hail would likely be sub-severe but a few
instances of one inch hail are possible. Anticipated marginal and
isolated nature of the threat are expected to preclude the need for
a watch.
..Mosier/Hart.. 01/18/2019
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MEG...JAN...LZK...SHV...
LAT...LON 34959282 35799174 35539024 34379042 33569079 32459203
32719404 34959282Nearby
Mesoscale Discussions in Arkansas, 2019Mesoscale Discussions in Louisiana, 2019Mesoscale Discussions in Mississippi, 2019Every mesoscale discussion in 2019
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.