[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 200024
SWOMCD
SPC MCD 200020 
SDZ000-NDZ000-NEZ000-KSZ000-200215-

MESOSCALE DISCUSSION 2249
NWS STORM PREDICTION CENTER NORMAN OK
0720 PM CDT SUN SEP 19 2004

AREAS AFFECTED...W CNTRL NEB THROUGH THE CENTRAL DAKOTAS

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 200020Z - 200215Z

POTENTIAL FOR DAMAGING WIND GUSTS APPEARS LIKELY TO INCREASE A BIT
NEXT FEW HOURS.  TRENDS ARE BEING MONITORED.  IT CURRENTLY APPEARS
MORE WIDESPREAD WIND THREAT MAY BE SHORT IN DURATION...AND WW IS NOT
ANTICIPATED AT THE PRESENT TIME.  01Z OUTLOOK UPDATE WILL REFLECT
THIS THREAT WITH A SLIGHT RISK ACROSS PARTS OF THE NORTHERN/CENTRAL
PLAINS.

INCREASE IN CONVECTIVE DEVELOPMENT IS ONGOING ACROSS THE HIGH
PLAINS.  PRIMARY ACTIVITY OF INTEREST IS FORMING ALONG LOW-LEVEL
THERMAL RIDGE AXIS EXTENDING EAST OF THE COLORADO FRONT RANGE
THROUGH THE BLACK HILLS INTO CENTRAL NORTH DAKOTA.  THIS IS WHERE
LAPSE RATES ARE MAXIMIZED...AND STRONG INFLUX OF MID-LEVEL MOISTURE
OF LOWER LATITUDE PACIFIC ORIGINS IS ONGOING.

FORCING FOR ACTIVITY MAY BE AIDED BY WEAK/LOW AMPLITUDE SHORT WAVE
TROUGH EMBEDDED WITH STRONG SOUTHWESTERLY FLOW AHEAD OF LARGE-SCALE
WESTERN U.S. TROUGH.  MODELS SUGGEST THIS FEATURE WILL CONTINUE TO
LIFT RAPIDLY NORTHEASTWARD THROUGH THE NORTHERN PLAINS THIS
EVENING...AND MAY EVENTUALLY SUPPORT EVOLUTION OF MORE ORGANIZED
SQUALL LINE.  NARROW BAND OF CONVECTION WILL BE BASED AT TOP OF
FAIRLY DEEP MIXED BOUNDARY WITH CAPE MOSTLY ON THE ORDER OF 1000
J/KG OR LESS.  THIS WILL TEND TO MARGINALIZE HAIL THREAT...BUT
POTENTIAL FOR DAMAGING WIND GUSTS MAY INCREASE FOR A FEW HOURS THIS
EVENING.

ACTIVITY LIKELY WILL BECOME ORIENTED ALONG WESTERN FRINGE OF
SOUTHERLY LOW-LEVEL JET...WHICH IS INTENSIFYING IN EXCESS OF 50 KT
FROM WEST CENTRAL NEBRASKA INTO THE EASTERN DAKOTAS.  GIVEN SIZABLE
TEMPERATURE-DEW POINT SPREADS BELOW CLOUD BASES...EVAPORATIVE
COOLING MAY AID DOWNWARD TRANSFER OF HIGHER MOMENTUM TO THE SURFACE.
 DAMAGING WIND THREAT LIKELY WILL DIMINISH LATER THIS
EVENING/OVERNIGHT...AS CONVECTION SPREADS DEEPER INTO THE PLAINS AND
WEAKENS IN COOLER LOW-LEVEL ENVIRONMENT WITH MORE STABLE MID-LEVEL
LAPSE RATES.

..KERR.. 09/20/2004

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

ATTN...WFO...FGF...FSD...ABR...GID...BIS...LBF...UNR...GLD...

41730234 43170253 44610241 46120148 47399993 47879920
45729830 43409847 41019931 39720025 39730092 40460167
40710187 41900258 

WWWW