[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 210618
SWOMCD
SPC MCD 210617 
IAZ000-NEZ000-210715-

MESOSCALE DISCUSSION 1806
NWS STORM PREDICTION CENTER NORMAN OK
0117 AM CDT THU JUL 21 2005

AREAS AFFECTED...IA

CONCERNING...SEVERE THUNDERSTORM WATCH 653...

VALID 210617Z - 210715Z

CURRENT TRENDS SUGGEST REMAINING VALID PORTION OF WW 653 MAY BE
CANCELLED BEFORE 09Z EXPIRATION...TRENDS WILL CONTINUE TO BE
MONITORED FOR INCREASING SEVERE THREAT AND POSSIBILITY OF NEW WW
DOWNSTREAM.

CONVECTIVE CLUSTER ACROSS THE MID MISSOURI VALLEY HAS BEEN SUPPORTED
BY WEAK MID-LEVEL SHORT WAVE...WHICH WILL CONTINUE SLOWLY MIGRATING
EAST SOUTHEASTWARD TONIGHT...AROUND NORTHEASTERN PERIPHERY OF
SUBTROPICAL RIDGE.  WITH BOUNDARY LAYER COOLING SOUTH OF SURFACE
WARM FRONT...INHIBITION NOW APPEARS TOO STRONG FOR NEW CONVECTIVE
DEVELOPMENT ALONG GUST FRONT SURGING INTO SOUTHEAST NEBRASKA.  

PRIMARY CONVECTIVE DEVELOPMENT SEEMS LIKELY TO BECOME CONFINED TO
THERMAL GRADIENT ALONG/NORTH OF SURFACE WARM FRONT...WHERE
CONVERGENCE/WARM ADVECTION ON NOSE OF LOW-LEVEL JET IS CONTRIBUTING
TO STRONGEST ASCENT.  UNCERTAINTY EXISTS CONCERNING STRENGTH OF
LOW-LEVEL JET...WHICH MODELS GENERALLY SUGGEST WILL WEAKEN BETWEEN
NOW AND 12Z.  IF THIS OCCURS...ACTIVITY MAY BECOME INCREASINGLY
BASED AT MID-LEVELS.  HOWEVER...EVEN FOR PARCELS REACHING LEVELS OF
FREE CONVECTION AT MID-LEVELS...MOST UNSTABLE CAPE APPEARS LIKELY TO
EXCEED 2000 J/KG...WHICH MAY MAINTAIN AT LEAST RISK OF ISOLATED
LARGE HAIL THROUGH THE NIGHT.

..KERR.. 07/21/2005

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

ATTN...WFO...DVN...ARX...DMX...FSD...OAX...

43159619 43399524 43479401 43139277 42799169 41849189
41369341 41279507 41609619 42229624 

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