Severe Storm Outlook Narrative (AC)
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
000
ACUS02 KWNS 210537
SWODY2
SPC AC 210536

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1236 AM CDT THU AUG 21 2014

VALID 221200Z - 231200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
A FEW STRONG STORMS WILL BE POSSIBLE ACROSS PARTS OF THE CENTRAL AND
NORTHERN PLAINS INTO THE MIDDLE MISSOURI VALLEY FRIDAY AFTERNOON
INTO THE OVERNIGHT HOURS. GUSTY WINDS AND HAIL WILL BE THE MAIN
THREATS WITH ANY STORMS THAT DEVELOP.

...SYNOPSIS...

THE CENTRAL U.S. UPPER RIDGE WILL CONTINUE TO AMPLIFY OVER THE MS
RIVER ON FRIDAY. AT THE SAME TIME...UPPER LOW OVER AZ WILL BECOME
ABSORBED IN LARGER-SCALE TROUGH WHILE ANOTHER UPPER LOW FORMS OVER
THE PACIFIC NORTHWEST. AS THIS OCCURS...THE EMBEDDED SHORTWAVE OVER
THE FOUR CORNERS REGION WILL PIVOT NEWD TOWARD THE CENTRAL
PLAINS...RESULTING IN MODEST HEIGHT FALLS DURING THE OVERNIGHT HOURS
AND SEVERAL VORTICITY MAXIMA TRACKING OVER THE SRN/CNTRL HIGH PLAINS
INTO THE CENTRAL AND NRN PLAINS. AT THE SFC...A LEE TROUGH WILL
EXTEND SWD ACROSS THE CENTRAL HIGH PLAINS WITH A W-E ORIENTED WARM
FRONT OVER THE MID-MO VALLEY INTO THE GREAT LAKES. THIS FRONT WILL
NOT MOVE MUCH THROUGH THE PERIOD AS A COLD FRONT BEGINS TO TRACK S/E
OVER THE NRN PLAINS.

...NRN/CNTRL PLAINS INTO THE OHIO VALLEY...

SCATTERED STORMS OR POSSIBLE MCS MAY BE ONGOING...ALBEIT
WEAKENING...ACROSS PARTS OF THE OHIO VALLEY EARLY IN THE PERIOD AS
WARM ADVECTION CONTINUES AND OVERNIGHT LLJ BEGINS WEAKENING. STORMS
MAY REDEVELOP DURING THE AFTERNOON ALONG ANY OUTFLOW BOUNDARY LEFT
FROM THIS EARLY CONVECTION...BUT SEVERE POTENTIAL WILL BE LIMITED BY
POOR LAPSE RATES DUE TO WIDESPREAD CLOUD COVER IN ADDITION TO
POTENTIAL SUBSIDENCE AS SHORTWAVE IMPULSE SHIFTS SE OVER THE CENTRAL
APPALACHIANS TO THE CAROLINAS. HOWEVER...PW VALUES NEAR 2 INCHES AND
MODEST MLCAPE /LESS THAN 1500 J PER KG/ WITH 0-6 KM SHEAR AROUND
25-30 KT COULD RESULT IN SOME STRONG/MARGINALLY SEVERE STORMS WITH
SMALL HAIL AND PERHAPS A WET DOWNBURST.

FURTHER WEST ACROSS THE PLAINS INTO THE MID-MS VALLEY...ANOTHER
COMPLEX SCENARIO IS EXPECTED. SOME ISOLATED SHOWERS AND
THUNDERSTORMS COULD BE ONGOING ACROSS PARTS OF THE CNTRL/NRN HIGH
PLAINS AND ALSO OVER THE MID-MO AND MID-MS VALLEYS DURING THE
MORNING...BUT SHOULD DIMINISH BY MIDDAY. CLOUD DEBRIS ASSOCIATED
WITH THIS CONVECTION COULD POSE PROBLEMS FOR STRONGER AFTERNOON
DESTABILIZATION. ADDITIONALLY...CAPPING COULD BE A CONCERN AS
MIDLEVEL TEMPERATURES WILL BE QUITE WARM /-6 TO -4 AT 500 MB/.
SO...CONVECTION MAY BE FAIRLY ISOLATED THROUGH PEAK HEATING. DURING
THE NIGHTTIME HOURS...MODEST WARM ADVECTION WILL OVERSPREAD THE
REGION ATOP THE WARM FRONT AND SEVERAL WEAK SHORTWAVE IMPULSES WILL
EJECT FROM THE CNTRL/SRN ROCKIES INTO THE CNTRL/NRN PLAINS. THIS MAY
BE SUFFICIENT FOR ISOLATED TO SCATTERED ELEVATED STORMS TO DEVELOP
IN THE VICINITY OF THE WARM FRONT AND A DIFFUSE DRY LINE/COLD FRONT
OVER CENTRAL NEB AND PERHAPS SRN SD AND NRN KS. SOME HAIL AND GUSTY
WINDS WOULD INITIALLY BE POSSIBLE WITH THESE STORMS BEFORE POSSIBLY
TRANSITIONING TO MORE OF A HEAVY RAIN THREAT AFTER MIDNIGHT.

..LEITMAN.. 08/21/2014



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.