Severe Storm Outlook Narrative (AC)
Issued by NWS

Current Version | Previous Version | Graphics & Text | 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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
ACUS11 KWNS 281738
SWOMCD
SPC MCD 281737
ILZ000-WIZ000-IAZ000-MOZ000-281930-

MESOSCALE DISCUSSION 0769
NWS STORM PREDICTION CENTER NORMAN OK
1237 PM CDT SAT MAY 28 2016

AREAS AFFECTED...PARTS OF NERN MISSOURI/ERN IOWA AND ADJACENT AREAS
OF IL/WI

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 281737Z - 281930Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...THE RISK FOR SEVERE STORMS IS EXPECTED TO GRADUALLY
INCREASE THROUGH THE 20-22Z TIME FRAME.  TIMING REMAINS A BIT
UNCERTAIN...BUT A WATCH SEEMS PROBABLE AT SOME POINT THIS AFTERNOON.

DISCUSSION...AN AREA OF LARGE-SCALE ASCENT /PIVOTING AROUND THE
SOUTHEASTERN PERIPHERY OF THE MID-LEVEL CLOSED LOW OVER THE MID
MISSOURI VALLEY/ IS READILY APPARENT IN SATELLITE
IMAGERY...SPREADING NORTHEASTWARD ACROSS SOUTHERN IOWA AND NORTHERN
MISSOURI.  THIS IS ALREADY CONTRIBUTING TO SCATTERED DEEPENING
CONVECTIVE DEVELOPMENT...WHICH PROBABLY WILL CONTINUE TO GRADUALLY
INTENSIFY WHILE APPROACHING THE MISSISSIPPI RIVER THROUGH 20-22Z.

INSOLATION ACROSS NORTHEAST MISSOURI INTO EASTERN IOWA AND ADJACENT
PORTIONS OF THE MISSISSIPPI VALLEY IS CONTRIBUTING TO STEEPENING
LOW-LEVEL LAPSE RATES.  BOUNDARY LAYER INSTABILITY AS CHARACTERIZED
BY CAPE IS ALSO INCREASING DESPITE SOMEWHAT MODEST MID-LEVEL LAPSE
RATES...THOUGH DIFFERENTIAL UPWARD VERTICAL MOTION AND PERHAPS WEAK
MID-LEVEL COLD ADVECTION MAY CONTRIBUTE TO FURTHER STEEPENING
THROUGH LATE AFTERNOON.

GIVEN THESE TRENDS...IN THE PRESENCE OF SUFFICIENTLY STRONG DEEP
LAYER SHEAR FOR ORGANIZED CONVECTIVE DEVELOPMENT...AND MODEST
STRENGTHENING OF 850-700 MB FLOW TO 30-40+ KT...A GRADUAL INCREASE
IN SEVERE WEATHER POTENTIAL IS EXPECTED THROUGH THE AFTERNOON.  A
TORNADO OR TWO MAY NOT BE OUT OF THE QUESTION IN THE MORE DISCRETE
INITIAL STRONGER STORMS.  HOWEVER...THE RISK FOR MARGINALLY SEVERE
HAIL TRANSITIONING TO MORE GENERAL POTENTIALLY DAMAGING SURFACE
GUSTS APPEARS MORE PRONOUNCED...WITH UPSCALE CONVECTIVE GROWTH INTO
AN EVOLVING ORGANIZED CLUSTER OF STORMS BY LATE AFTERNOON.

..KERR/CORFIDI.. 05/28/2016

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

ATTN...WFO...MKX...LSX...DVN...ARX...DMX...EAX...

LAT...LON   42049291 42719227 43029103 42349021 41299037 39929115
            40049258 41199311 42049291




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