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
000
ACUS03 KWNS 180732
SWODY3
SPC AC 180731

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0231 AM CDT THU SEP 18 2014

VALID 201200Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
THUNDERSTORM DEVELOPMENT IS EXPECTED ON SATURDAY FROM THE
INTERMOUNTAIN WEST EASTWARD TO THE GREAT PLAINS AND NORTHEASTWARD TO
THE GREAT LAKES REGION. SOME MARGINALLY SEVERE WIND GUSTS AND HAIL
WILL BE POSSIBLE WITH THE STRONGER THUNDERSTORMS FROM THE CENTRAL
PLAINS NORTHEASTWARD TO LOWER MICHIGAN. OTHER STORMS ARE EXPECTED TO
DEVELOP ACROSS PARTS OF THE GULF COAST STATES AND ALONG SOUTHERN
PARTS OF THE ATLANTIC SEABOARD.

...CNTRL PLAINS/MID TO UPPER MS VALLEY/GREAT LAKES...
A LOW-AMPLITUDE UPPER-LEVEL TROUGH IS FORECAST TO AMPLIFY ACROSS THE
UPPER MS VALLEY ON SATURDAY AS A SHORTWAVE TROUGH MOVES INTO THE
BASE OF THE LARGER-SCALE TROUGH. AT THE SFC...A COLD FRONT IS
FORECAST TO ADVANCE SEWD ACROSS THE CNTRL PLAINS AND UPPER MS
VALLEY. AHEAD OF THE FRONT...SFC DEWPOINTS SHOULD BE IN THE MID TO
UPPER 60S F AND MODERATE INSTABILITY SHOULD BE IN PLACE BY LATE
AFTERNOON. SFC HEATING AND INCREASING LOW-LEVEL CONVERGENCE ALONG
THE FRONT SHOULD RESULT IN THUNDERSTORM INITIATION BY LATE
AFTERNOON.

FORECAST SOUNDINGS AT 00Z/SUNDAY FOR CHICAGO IL AND ALPENA MI SHOW
0-6 SHEAR OF 45 TO 50 KT AND STEEP LOW-LEVEL LAPSE RATES.
HOWEVER...MODEL FORECASTS ARE IN DISAGREEMENT CONCERNING THE AMOUNT
OF INSTABILITY THAT WILL BE PRESENT. IF MODERATE INSTABILITY CAN
DEVELOP AS SOME MODELS SUGGEST...THEN A WIND DAMAGE AND HAIL THREAT
WOULD BE POSSIBLE LATE SATURDAY AFTERNOON. FURTHER TO THE SOUTHWEST
FROM NE KS INTO SE IA...DEEP-LAYER SHEAR IS FORECAST TO BE LESS THAN
IN THE GREAT LAKES REGION. IN SPITE OF THIS...STRONGER INSTABILITY
AND HIGHER SFC DEWPOINTS COULD HELP COMPENSATE FOR THE WEAKNESS IN
SHEAR...MAKING A MARGINAL WIND DAMAGE THREAT POSSIBLE AS WELL.

..BROYLES.. 09/18/2014



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