Strong high pressure in the upper atmosphere will remain over Iowa through mid week. Hot and humid conditions will likely persist into Thursday, making this heat wave the most prolonged in over 20 years across central Iowa. Isolated thunderstorms will brush northeast Iowa today through Tuesday, bringing some temporary relief in those areas. A cold front will move into the state this weekend, with rain chances increasing.
NATIONAL WEATHER SERVICE HEAT WARNING...........
EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM CDT THURSDAY...
* TEMPERATURE...AFTERNOON HIGH TEMPERATURES WILL BE IN THE MID TO UPPER 90S UNTIL THURSDAY...AND OVERNIGHT LOWS WILL ONLY FALL INTO THE MID TO UPPER 70S EACH NIGHT. SWELTERING HUMIDITY THROUGHOUT THE PERIOD WILL PRODUCE HEAT INDEX READINGS FROM 110 TO 115 DEGREES ACROSS MUCH OF THE AREA EACH AFTERNOON AND EVENING.
* IMPACTS...SEVERAL DAYS OF DANGEROUSLY HIGH HEAT AND HUMIDITY WITH LITTLE RELIEF AT NIGHT CAN CAUSE SIGNIFICANT PHYSICAL STRESS AND CREATE CONDITIONS FAVORABLE FOR HEAT RELATED PROBLEMS. PRECAUTIONS SHOULD ALSO BE TAKEN TO PROTECT PETS AND LIVESTOCK.
10 Day Temp and Precipitation Forecast:
TEMP:
Today thru 25 July: Well Above Normal - Becoming Near Normal by the 23rd.
26 July thru 3 Aug: Normal Highs.
PRECIP:
Today Thru 25 July: 3/4" - 1".
26 July thru 3 Aug: Less Than 1/4".
Today thru Thurs 18th-21st: Dry/Hot/Very Humid - Temps Mid/Upper 90's (Heat Index 100-115) - Isolated Tshowers Thurs.
Fri and Sat 22nd/23rd: Dry thru Fri - Tstorms Fri afternoon/Overnite into Mid Day Sat - Temps 92/90.
Sun and Mon 24th/25th: Tstorms Sun - Day Mon - Temps near 90.
Tues and Wed Fri 26th/27th: Dry - Mid/Low 80's.
Thurs and Fri 28th/29th: Dry - Mid/Upper 80's.
Sat and Sun 30th/31st: Dry - Mid 80's.
Mon and Tues Aug 1st/2nd: Tshowers.
IOWA PRELIMINARY MONTHLY WEATHER SUMMARY – JUNE 2011
General Summary. Iowa temperatures averaged 70.4° or 0.6° above normal while precipitation totaled 6.25 inches or 1.61 inches above normal. This ranks as the 53rd warmest and 27th wettest June among 139 years of records.
Temperatures. The wide swings in temperature that has characterized Iowa’s weather over the past several months continued in June, but with less frequent fluctuations. Warmer than normal weather prevailed for seven of the first eight days of the month with temperatures reaching 100° at Atlantic, Little Sioux, Onawa, Shenandoah, Sioux City and Spencer on the 6th and again in Algona, Pocahontas and Swea City on the 7th.
Cooler than usual weather predominated on 17 of the final 22 days of the month with Cresco
reporting the lowest temperature of the month with a morning low of 42° on the 12th. Daytime high temperatures were only in the 60s across all or part of Iowa on the 9 th-14th, 21st-23rd and 25th. However, very warm and humid weather returned for the last day of June with actual temperatures peaking at 97° at Sioux City while the heat index climbed to 111° at Des Moines on the 30th.
Precipitation. Relatively dry weather prevailed for the first week of June allowing the completion of nearly of all of the corn and soybean planting. However, rainfall was frequent and sometimes excessive from the 8th through the 22nd. Heaviest rains fell over northern Warren County on the 9th-10th with an unofficial two-day total of 9.31 inches just south of Norwalk. Rainfall frequently was heaviest over south central and southeast Iowa with record totals for any month set at Keosauqua (16.14 inches, old record 14.89 in June 1905 among 123 years of data) and at Bloomfield (14.60 inches, old record 14.31 in
August 1970 among 92 years of records). Fortunately much of the heavy rain fell
outside of the Missouri River watershed where excessive winter snowpack and very heavy spring rains in upper reaches of the basin brought record to near-record flooding along the Iowa-Nebraska border. A record crest on the Missouri was set at Plattsmouth, Nebraska (adjacent to Mills County, Iowa) on June 30 and at Nebraska City, Nebraska (adjacent to Fremont County, Iowa) on June 28. Meanwhile rainfall was less than normal over much of northeastern Iowa where Cresco reported their driest June since
1989 with only 2.39 inches of rain.
Severe Weather. The very active 2011 severe weather season in Iowa finally slowed
down a bit in June with a preliminary tornado total of eight (30-year average of 15). The most widespread severe weather outbreaks for the month came on the night of the 20th (23 counties, mostly over the west) and the night of the 26th (31 counties, all southwest one-half).
Harry J. Hillaker, State Climatologist
Iowa Dept. of Agriculture & Land Stewardship
Wallace State Office Bldg.
Des Moines, IA 50319
Telephone: (515) 281-8981
E-Mail: Harry.Hillaker@IowaAgriculture.gov
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