The most important factor in keeping the worst of the extreme heat to the west of our region is the historic band of rainfall and flooding that has established itself from Kansas City to St. Louis, southwestern Indiana east of Kentucky. Water cuts your temperature and can act as a wall to heat up via feedbacks from the surface to the atmosphere. It raises your dew point, but in the wetland and downwind of the wetland.
Parts of southwestern Indiana had their wettest July since 1875 with +13″ (much of it fell in 7 days in late July. Up to 16″ of rain fell in the east from Kentucky for the past 1.5 weeks.
Several observation sites saw their largest 24-hour rainfall totals on record and January 1937 rainfall totals were beaten in parts of Kentucky. Dozens of people were killed in the floods with the multi-billion dollar disaster from late July to early August.
An estimated 33% of the watermelon crop was lost in southwestern Indiana to flooding.
These floods occurred on the edge of extreme heat as deep Pacific moisture due to a very active eastern Pacific tropical season combined with tropical low-level flow from the Gulf of Mexico (water temperatures above much higher than normal).
By laying this strip of very, very wet ground with lush vegetation, he created a feedback loop by which the extreme heat of +100 to 110 is contained.
However, the wet ground caused our dew points to be incredibly high. Dew points at our WLFI observing site have exceeded 75 for 5 consecutive days. Some dew points have reached 82!
We still reached 91-97, but not 98-105. The heat indices nevertheless reached 112. The lack of heat advisories issued by the NWS was surprising in our area.
There’s the worst of the contained heat…it was as high as 112 in Kansas yesterday and as high as 102 in Iowa with a heat index at 120.
The heat continues in the northwest with temperatures reaching 97-101 for days.
You can see where the drought tends to linger long-term and where the historic rains and floods have completely put a stop to it:
This is another great perspective of rain flooding from the southwest and south to southeast of our area like a wall…..
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Despite the recent precipitation, the month of July will be particularly dry for certain parts of the observation area. The exceptions are Newton, Jasper, North Benton to White counties which experienced above normal precipitation at the end of the month.
Purdue Airport measured less than 1″ for July (0.58″), while I was only about 1″ at our WLFI viewing site.
There has been more precipitation in the past 7 days than at any time in August for the Greater Lafayette area, including Purdue Airport (0.68″) and our site. WLFI sighting (1.03″).
Drought conditions are still technically present in the central and southern part of the observation area.
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Highs today reached 87-95 with Heat Indexes peaking at 99-113.
Few isolated to sporadic showers are possible this evening-tomorrow morning. Skies appear to be mostly cloudy with lows of 73 to 78 this evening with a light southwesterly wind.
It will continue to be heavy to oppressive.
As for tomorrow, with a mix of cloud and sun, highs of 87-93 are expected with heat indices of 97-108. Winds will be from the southwest at 14-25 mph.
A few isolated or occasional showers are possible.
A disorganized broken line of thunderstorms is expected to develop in our northwestern counties and move southeastward into the evening. Coverage should be around 50%.
Lows near 70 are expected tomorrow evening with some showers and thunderstorms still possible Tuesday morning.
A slow clearing trend is expected in the afternoon with decreasing humidity and highs 77-83. Winds will be north-northwest at 10-25 mph.
After 58-63 Tuesday night, highs of 82-85 are likely Wednesday with tolerable humidity and northerly winds of 7-13 mph. The sky looks rather sunny.
After 59-64 Wednesday night, highs of 84-87 are expected Thursday with skies becoming partly cloudy.
A few isolated to irregular showers/thunderstorms are possible along a cold front in the afternoon, but coverage will only be around 25%.
This front will usher in a cooler breeze for Friday with highs 76-82 with low humidity, northerly winds and sunshine with some cumulus clouds.
The front then begins to move towards the northeast in the form of a warm front. Clouds will rise next weekend with highs back in the 83-87 range and lows in the 60s.
Humidity will also increase.
It looks like all showers/thunderstorms with this warm front will settle west of our region next Saturday night and Sunday night. They will tend to be nocturnal and fade during the day as the low level jet turns.
The heat will attempt to return to the east and northeast with high 90s by mid-August.
A warmer than normal pattern tends to dominate the second half of August.
Rainfall does not seem abundant and always seems to be lacking.
Nothing screams 105 degrees, but 90s to 100s are possible as our soils dry out and vegetation begins to lose its deeper green glow.
MJO is expected to enter Phases 1, 2, 3 as Saharan dust continues to thin, paving the way for robust tropical development in the Atlantic and western Gulf of Mexico over time.
The general trend is a warm horseshoe ridge from the west to the northern plains, from the Great Lakes, from the Midwest to the northeast.
Below normal to normal temperatures will reside in the southwest desert and southern plains where vigorous monsoon humidity will bring daily storms and the increasingly active gulf will bring heavier rainfall.
This is for a good part of August.
Missouri, Nebraska, Kansas to Texas and the desert southwest will see above normal precipitation, while the rest of the country overall appears to have below normal precipitation. This is for a good part of August.
September looks warmer and drier than normal with record heat potential.
We will monitor the active tropics. We will significantly catch up with the number of Atlantic hurricane season storms! With these persistent favorable MJO phases and the persistence La Nina and the cold PDO phase with the warm AMO phase, everything points to an active hurricane period in the Atlantic, Caribbean and Gulf of Mexico.
Still enjoying a warmer and wetter than normal October with later than normal foliage color change again this year. This will be the fourth year in a row with later than normal foliage change. Yesterday was particularly late (up to 3 weeks).