risk of flooding and strong storms this weekend

– flash flood watch in effect – slight risk of severe storms Saturday and Sunday

1. This morning a period of heavy showers and thunderstorms should be ongoing across southern Indiana and western Kentucky as a upper level impulse travels northward along a very slow moving front. This area of showers and storms will be slow moving and produce torrential rainfall as it moves southeast toward our region, ahead of this period of showers and storms excessive clouds should limit instability which will keep the threat for strong to severe storms with a gusty wind threat to the scattered variety. By early afternoon this period of showers and storms or it’s outflow boundary should over the BowlingGreen area. The redevelopment of this thunderstorm complex or the development of new convection is likely during the afternoon, once again storms with strong wind gusts and heavy rain are the main threats. At this time hail potential looks low and any tornadic thunderstorms should be  very isolated. By evening the thunderstorm coverage should diminish across the region to just scattered showers . I expect between 1/2 and 1.5 inches of rain by Saturday evening. Further north in Louisville for the derby showers and thunderstorms will be steadier and more widespread through the afternoon making for a sloppy track.  This rain Saturday will likely set the stage for some flooding across the region Sunday.

storm prediction center severe outlook

MODELS ARE SUGGESTIVE THAT A WEAKENING MESOSCALE CONVECTIVE SYSTEM
   COULD BE ONGOING EARLY SATURDAY ACROSS PARTS OF KENTUCKY AND
   TENNESSEE.  SUFFICIENT PRE-FRONTAL MOISTENING IS EXPECTED AHEAD OF
   ACTIVITY TO SUPPORT WEAK TO MODERATE DESTABILIZATION IN THE PRESENCE
   OF 40 TO 50 KT DEEP LAYER MEAN SOUTHWESTERLY FLOW.  THE ENVIRONMENT
   APPEARS LIKELY TO BECOME FAVORABLE FOR THE INTENSIFICATION OF THE
   CONVECTIVE CLUSTER…OR RENEWED DEVELOPMENT EAST NORTHEASTWARD
   THROUGH THE UPPER OHIO VALLEY DURING THE DAY…ACCOMPANIED BY THE
   RISK FOR DAMAGING WINDS WITH FAST MOVING STORMS.

GFS model for Saturday

GFS 850 mb map showing the disturbance to our northwest

Thunderstorm cluster moving into our region by noon Saturday

Cluster diminishes and thunderstorms refire along the boundary left behind. Expect scattered to numerous coverage of these storms with locally heavy rains and gusty winds.

2. I’m expecting a lull for Saturday night across the region before a stronger impulse of low pressure moves along this stalled front across the region. With plenty of moisture influx from the gulf another band of heavy rain and thunderstorms will develop Sunday morning to our west.  Some strong to severe storms will be possible on the lead edge Sunday morning into the early afternoon with gusty winds again the main concern. This band of heavy rain and storms will move from north to south or actually move northwest at times  during the day and night. training of heavy showers and storms are likely with torrential rainfall. rainfall totals by Monday morning for the 24 hour period should range from 2 to 4 inches with local amounts to 6 inches. on top of the rain seen int he past week and the potential for heavy rainfall rates. Low elevations will need to keep an eye on rapidly rising water, streams and creeks may also overflow late Sunday.  If you see high water turn around and don’t drown. The nam model is spitting impressive rainfall totals Sunday and Sunday night. If this pans out a high impact flood event may occur in the Bowling Green region by Sunday night.  The band will finally move east by Monday morning.

SPC outlook for Sunday

COLD FRONTAL CLUSTERS OF STRONG-SEVERE TSTMS ARE EXPECTED TO BE
   ONGOING SUNDAY MORNING WITHIN A MOIST AND STRONGLY SHEARED
   ENVIRONMENT WHERE A THREAT FOR TORNADOES AND DAMAGING WINDS WILL
   EXIST.  THE NRN EXTENT OF THESE STORMS MAY TEND TO WEAKEN WITH TIME
   DUE TO THE PRESENCE OF WIDESPREAD CLOUDS AND PRECIPITATION WHICH
   WILL LIMIT DESTABILIZATION WITHIN AMBIENT INFLOW AIR MASS.
   HOWEVER…FARTHER S OVER THE LOWER MS VALLEY…AN INFLUX OF HIGH
   THETA-E AIR WILL BE MAINTAINED INTO ONGOING STORMS BY MODERATELY
   STRONG SLY LOW-LEVEL FLOW.  THE COMBINATION OF A MOIST/MODERATELY
   UNSTABLE AIR MASS AND STRONG VERTICAL SHEAR SUGGEST A CONTINUED
   THREAT FOR EMBEDDED SUPERCELL AND BOWING STRUCTURES CAPABLE OF
   TORNADOES AND DAMAGING WINDS SUNDAY INTO SUNDAY NIGHT.
  

Nam simulated radar, what the nam model thinks the radar will be at a time interval.

Sunday morning

Noontime

early evening

midnight Sunday night

yellow is for heavy rainfall, the nam is suggesting a 24 hour period of torrential rainfall for the region starting Sunday morning.

Nam rainfall totals for Sunday only

the nam has 3-6 inches of rain sunday alone for the region.

It should be noted that the gfs model is faster with pushing out the heavy rain sunday night which would cut down these totals a bit.

recap

– cloudy saturday morning

– band of thunderstorms to move in or reform as scattered to numerous showers and storms by mid afternoon with locally hvy rains and gusty winds ( around or just under 1 inch of rain total)

– lull saturday night

– heavy rain and storms all day sunday with training heavy showers and storms, leading edge of this activity may be strong to severe. Flooding possbily delevoping across the region Sunday night ( 2-4 with isolated 6 totals)

– temperatures should stay in the 70’s this weekend.

– Overall model prefrence was the gfs for the first event Saturday and leaned toward the nam on event 2 on Sunday

– updates to the images and comments will be made as needed this weekend

forecaster: MWG