Tropical downpours Friday, Flash Flood Watch Issued; Refreshingly mild pattern to take hold

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Fast moving south to north moving showers are around early Thursday evening but many may still remain rain-free or mostly dry this evening.  Showers and a few thunderstorms are to ramp up late tonight and early Friday morning.  Rainfall will increase Friday morning to as much as 70% coverage but that will be the peak.  The rain will shift east and depart starting Friday afternoon.  We look for improvement from northwest to southeast by Friday evening.



The combination of highly humid air, remnants of tropical storm Cindy and a approaching cold front will combine to activate shower and thunderstorms starting early Friday.  Drenching downpours are likely at times especially early on Friday.  There is a threat that very heavy rainfall will occur and at such a rate flash flooding could develop.  A Flash Flood Watch has been issued through 8 pm Friday.

Rainfall will not be evenly distributed so rainfall amounts will vary widely before ending Friday late afternoon and early evening.  Off a 9 computer model average for Indianapolis, we calculated a rainfall of 1.96".  However the amounts vary widely from as little as .25" to as much as 3.22".  Convection - that is thunderstorms and where they roam will lend itself to the higher totals.  Underneath any storm and repeat offenders the rainfall will be greatest.


The weather will really improve starting after the passage of a cold front later Friday afternoon.  We bracket the hours of 4 pm to 7 pm for a FROPA (frontal passage).  That is the leading edge of the the cooler and much less humid air that surges into the state on a northwest wind.  The weekend will open with a refreshing brand of air and a rather mild brand for the first weekend of summer.


The cooler pattern will be reinforced as a new front drops through the state Monday.  Even cooler air will arrive for Monday and Tuesday as high temperature run as much as 12-degrees below normal.  It is still looking very possible that early morning temperature will reach the upper 40s by Tuesday and Wednesday morning!