SPC AC 051252

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0752 AM CDT Fri Jul 05 2024

   Valid 051300Z - 061200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
   THE UPPER OHIO VALLEY INTO THE CENTRAL AND SOUTHERN APPALACHIANS...

   ...SUMMARY...
   Scattered severe thunderstorms will be possible midday into the
   afternoon across parts of the upper Ohio Valley into the central and
   southern Appalachians.  Damaging gusts 50-65 mph will be the primary
   severe hazard.

   ...Synopsis...
   Water-vapor imagery this morning shows a mid-level shortwave trough
   and associated low moving east across the mid to upper MS Valley and
   into the western Great Lakes.  A belt of strong southwesterly 500-mb
   flow (50-60 kt) will move through the base of the trough from the
   lower MO Valley east-northeastward through IN/OH and into the Lower
   Great Lakes through early evening.  Upstream of this disturbance, a
   lower amplitude shortwave trough will move southeastward from AB
   into MT during the day.  

   ...Eastern Great Lakes/Ohio Valley/Southern and Central
   Appalachians...
   A convectively augmented lead disturbance over the lower OH Valley
   will continue to progress eastward today ahead of a larger-scale
   trough forecast to pivot east across the OH Valley.  An ongoing
   squall line from southern IN to the AL/TN border, will move east
   into a very moist and destabilizing airmass.  Surface analysis shows
   a reservoir of lower to mid 70s deg F dewpoints from north-central
   AL north-northeastward through the central Appalachians and OH River
   vicinity.  A belt of stronger mid-level southwesterly flow will
   likely remain north of the OH River, but some enhancement to 2-6 km
   flow (reference Memphis, Paducah, Fort Campbell, and Evansville
   WSR-88D VADs) will likely spread downstream across TN/KY and into
   southern OH and WV.  Visible-satellite imagery denotes strong
   heating will occur ahead of the MCS, thereby contributing to upwards
   of 1500-3000 J/kg MLCAPE by early afternoon (2400 J/kg MLCAPE per
   Nashville 12 UTC raob).  Organized multicells (via the MCS) will be
   capable of scattered 50-65 mph gusts and wind damage.  Farther south
   into the southern Appalachians and Carolinas/VA Piedmont, weaker
   flow but very moist/unstable conditions later today will support
   scattered thunderstorms and an isolated risk for damaging gusts with
   the stronger wet microbursts.  

   Farther north, more uncertainty and potentially lower strong/severe
   storm coverage will extend from Lower MI across the southern/Lower
   Great Lakes into PA and west-central New York.  A hail threat
   may also develop in parts of Lower Michigan, ahead of the
   upper-level trough, where mid-level temperatures will be cooler
   which will aid in steeper mid-level lapse rates.  Localized damaging
   gusts will be the main severe risk.

   ...Eastern New Mexico...
   Southwestern periphery of stronger mid-level northwesterly flow will
   glance the southern High Plains in between a mid-level anticyclone
   centered near the northern CA coast and the larger-scale trough over
   the Midwest.  Strong heating and moist upslope flow (dewpoints near
   60 F) will contribute to initially isolated storms preferentially
   developing over the higher terrain by early to mid afternoon.  Model
   guidance shows MLCAPE peaking in the 1500 to 2000 J/kg range, with
   0-6 km shear around 30 kt.  Some organization of storms is possible,
   mainly via multicells and perhaps transient supercell structures. 
   Isolated severe gusts/hail may accompany the stronger thunderstorms.

   ...MT...
   Aforementioned mid-level impulse will move into central/eastern MT
   this afternoon/evening.  Strong heating amidst 40s dewpoints will
   yield weak buoyancy (500-1000 J/kg MLCAPE) but steep lapse rates.  A
   few stronger storms may be capable of locally severe gusts for a few
   hours late this afternoon before this activity subsides later this
   evening.

   ..Smith/Bentley.. 07/05/2024

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