Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 011917
SWOMCD
SPC MCD 011916
OKZ000-KSZ000-012145-

MESOSCALE DISCUSSION 1657
NWS STORM PREDICTION CENTER NORMAN OK
0216 PM CDT MON SEP 01 2014

AREAS AFFECTED...PORTIONS OF NORTHERN OKLAHOMA AND SOUTHERN KANSAS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 011916Z - 012145Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...PORTIONS OF NORTHERN OKLAHOMA AND SOUTHERN KANSAS ARE
BEING MONITORED FOR WATCH ISSUANCE. WHILE WATCH ISSUANCE IS LIKELY
BY THIS EVENING...IT IS ALSO POSSIBLE THAT ISSUANCE WOULD BE NEEDED
DURING THE NEXT FEW HOURS. CONVECTIVE TRENDS WILL CONTINUE TO BE
MONITORED.

DISCUSSION...OBSERVATIONS FROM THE OKLAHOMA MESONET INDICATE A SFC
LOW APPROXIMATELY OVER WOODS COUNTY OK. A STATIONARY FRONT EXTENDS
SW OF THE LOW INTO W-CNTRL OK AND THE ERN TX PANHANDLE...WHILE AN
OUTFLOW BOUNDARY EXTENDS E/ESE OF THE LOW THROUGH THE TULSA AREA
INTO NW AR. STRONG INSOLATION BETWEEN A WEAK SFC TROUGH E OF THE
STATIONARY FRONT HAS ALLOWED SFC TEMPERATURES TO RISE INTO THE
MIDDLE/UPPER 90S OVER WRN OK. A CORRIDOR OF 7.5-8.0-C/KM SFC-3-KM
LAPSE RATES CURLS INTO THE SERN SEMICIRCLE OF THE LOW S OF THE
OUTFLOW BOUNDARY. CORRESPONDINGLY...VIS SATELLITE IMAGERY INDICATES
BOUNDARY-LAYER CU DEVELOPMENT AT THE ERN/NRN EDGES OF THE STEEPER
LAPSE RATE PLUME...EXTENDING FROM N-CNTRL OK NWWD INTO BARBER AND
COMANCHE COUNTIES IN KS.

MODIFICATIONS TO THE 12Z OUN RAOB AND RAP FORECAST SOUNDINGS SUGGEST
THAT...WITH SFC TEMP RISES OF ANOTHER 1-2 DEGREES...ISOLATED DEEPER
CONVECTION COULD BLOSSOM FROM THE ONGOING CU FIELD BY 21-22Z -- AND
SPREAD E/ESE. AS THE OUTFLOW BOUNDARY CONTINUES TO RETREAT
NWD...MLCAPE VALUES OF 1500-3000 J/KG WILL LIKELY EXTEND NWD INTO
FAR SRN KS...AIDED BY STEEP MID-LEVEL LAPSE RATES SURMOUNTING UPPER
60S/LOWER 70S SFC DEWPOINTS. WHEN COMBINED WITH 30-45 KT OF
EFFECTIVE BULK SHEAR...ORGANIZED CONVECTIVE STRUCTURES INCLUDING
SUPERCELLS WITH LARGE HAIL MAY EVOLVE. VNX VWP DATA SUGGEST
LOW-LEVEL SHEAR IS ONLY MODEST AT PRESENT. HOWEVER...WITH SOME
DIRECTIONAL VARIABILITY IN THE FLOW BELOW 3 KM AGL ENHANCING SRH --
ESPECIALLY NEAR THE OUTFLOW BOUNDARY -- A TORNADO COULD OCCUR GIVEN
THE STEEP LAPSE RATES IN PLACE. AMPLE INHIBITION N OF THE OUTFLOW
BOUNDARY IN NERN OK AND SERN KS AS EVIDENCED BY
VIS-SATELLITE-IMPLIED BILLOWS SUGGESTS THAT INITIAL STORMS MAY
QUICKLY BECOME ELEVATED AS THEY POTENTIALLY DEVELOP INTO A MORE
STRONGLY CAPPED BOUNDARY LAYER.

ULTIMATELY...THE SVR-TSTM RISK DURING THE NEXT FEW HOURS IS HIGHLY
CONDITIONAL...AS DEEP-LAYER FORCING FOR ASCENT IS WEAK AND AT LEAST
SOME CAPPING ALOFT PERSISTS. CONFIDENCE IN SEVERE-TSTM DEVELOPMENT
THROUGH 22Z IS MODEST...BUT IS HIGHER INTO THE EVENING WHEN
LOW-LEVEL MASS FLUXES BECOME BOLSTERED IN ASSOCIATION WITH A
STRENGTHENING LLJ STREAM AND NOCTURNAL BOUNDARY-LAYER WIND MAXIMUM.

..COHEN/HART.. 09/01/2014

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...SGF...TSA...ICT...OUN...DDC...

LAT...LON   36199705 36449821 36799878 37299898 37599828 37669625
            37589525 37249468 36509470 36169520 36199705




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