A Wet Week in Many Places

A Wet Week in Many Places:

Monday, July 8th brought record-setting rainfall to the Washington, D.C. area where Ronald Reagan Airport set a new daily record of 3.44 inches. Wallops Island, VA reported 3.26 inches, and Hagerstown, MD reported 2.71 inches. Flash flooding and street closures were common that day throughout the D.C. Metro Area.

Over July 8-9, 2019 many parts of northwestern Minnesota reported record or near record thunderstorm rainfall. Fargo, ND set a record with 2.20 inches, while across the border in Minnesota Georgetown (Clay County) reported a record 4.47 inches, Hallock (Kittson County) a record 3.58 inches, and Thief River Falls (Pennington County) a record 2.31 inches. Elsewhere places like Moorhead, Fergus Falls, New York Mills, Detroit Lakes, and Ottertail all reported over 2 inches.

Then on July 10th (Wednesday) bands of clouds associated with the formation of Tropical Storm Barry in the Gulf of Mexico brought 3-4 inch rains to portions of Louisiana, flooding may streets there and closing some highways.

July Rainfalls Above Normal Already:

The following locations in Minnesota now report above normal rainfall amounts for the entire month of July, even though only 12 days have passed.

Georgetown 7.96”, Redwood Falls 6.58”, Milan (Chippewa County) 5.71”, Artichoke Lake (Big Stone County) 5.66”, Canby (Yellow Medicine County) 5.32”, Windom (Cottonwood County) 4.98”, Hallock (Kittson County) 4.83", and Dawson (Lac Qui Parle County) 4.50”.

Weekly Weather Potpourri:

The NOAA-National Hurricane Center was closely monitoring Tropical Storm Barry in the Gulf of Mexico this week, as it was expected to develop into a category 1 hurricane just before landfall on Saturday. It will bring strong winds and heavy rainfall to Louisiana. Some areas of that state may see 10-15 inches of rainfall through the coming weekend.

NOAA scientists announced this week that for the period from July, 2018 to June, 2019 across the contiguous USA it was the wettest 12 month period in history. This surpassed the previous records which had been from June, 2018 to May 2019, which had surpassed the previous record of from May, 2018 to April of 2019. The same 12-month periods historically ranked quite high in Minnesota as well:
July 2018 to June 2019 4th wettest in history
June 2018 to May 2019 tied for wettest in history (with 2010-2011)
May 2018 to April 2019 3rd wettest in history
All 12 month periods delivered an average 12-month precipitation well over 32 inches.
So the widespread wet weather pattern across the country which has caused a great deal of flooding on many rivers appears to have some persistence. In 2019 many climate stations may record their wettest year.

A recent article in Nature Communications finds that according to climate model projections, even if the Paris Agreement on limiting global temperature change to 1.5°K holds, the melting of Artic Sea Ice will continue at a rapid pace and it may be ice-free during the month of September most years (end of the Northern Hemisphere summer).

With support from the National Integrated HeatHealth Information System (NIHHIS) and CPO’s Communication, Education, and Engagement Division, community organizers in 8 U.S. cities are preparing to run citizen-science field campaigns to map Urban Heat Islands (UHI) this summer. Cities were selected for support based in part on their readiness to mobilize community members to run the mapping campaign and on their ability and willingness to use the heat maps produced by the campaign to build resilience to extreme heat.

NOAA recently reported that Alaska recorded its 2nd warmest June in history, following its warmest spring (March-May) in history. So far in July of 2019 Anchorage is reporting an average monthly temperature that is 11°F above normal. So the trend continues.

MPR listener question:

Please settle a bet for us. What is the highest dew point temperature measured in the Twin Cities as well as the highest measured in the state? We think it has to be in July.

Answer:

Yes, the record dew point for the Twin Cities is 82°F measured on July 19, 2011 and on the same date a statewide record dew point of 88°F was measured at Moorehead, MN. Both occurred between 4pm and 5pm in the afternoon. In the Twin Cities climate record a dew point of 80°F or greater has only been measured on 11 dates, all but one (June 22, 1983) in the month of July.

Twin Cities Almanac for July 12th:

The average MSP high temperature for this date is 84 degrees F (plus or minus 7 degrees F standard deviation), while the average low is 64 degrees F (plus or minus 7 degrees F standard deviation).

MSP Local Records for July 12th:

MSP weather records for this date include: highest daily maximum temperature of 106 degrees F in 1936: lowest daily maximum temperature of 67 degrees F in 1926; lowest daily minimum temperature is 48 degrees F in 1941; highest daily minimum temperature of 83 degrees F in 1936; record precipitation of 2.93 inches in 1912; and no snow has fallen on this date.

Average dew point for July 12th is 61 degrees F, with a maximum of 80 degrees F in 1995 and a minimum of 39 degrees F in 1926.

All-time state records for July 12th:

The state record high temperature for this date is 111 degrees F at Canby (Yellow Medicine County) in 1936. The state record low temperature for this date is 27 degrees F at Tower (St Louis County) in 1975. State record precipitation for this date is 5.45 inches at Buffalo (Wright County) in 1961; and no snowfall has occurred on this date.

Past Weather Features:

The worst Heat Wave historically occurred in July of 1936, and on the 12th nearly every spot in Minnesota reported an afternoon temperature of 100°F or greater. The coldest spot in the state was 98°F at Two Harbors. It was 106°F as far north as Littlefork (Koochiching County), and the overnight low never dropped below 81°F in Itasca State Park.

One of the worst Heat Waves in the modern record occurred over July 12-14, 1995. Dew point spiked into the mid 70s to low 80s F across Minnesota, producing Heat Index Values from 105°F to 117°F over the three days. In central Minnesota there were reports of hundreds of thousands of turkeys killed by the heat. In the city of Chicago, hundreds of citizens died during this Heat Wave.

July 12-13, 1995 also brought strong thunderstorms and a derecho (straight line wind storm) to many parts of northern Minnesota. Many areas reported wind gusts of 70 mph to 100 mph. Especially hard hit was Itasca State Park where many ancient trees were uprooted or broken off by the high winds. The park had to be closed for a time. Many climate stations reported 1.5 to 2.5 inches of rain.

Outlook:

Southerly winds and bright skies will amplify daily temperatures, keeping them above normal over the weekend and much of next week. High temperatures will be in the 90s F many places over the Sunday through Wednesday period, with overnight lows in the 60s and 70s F. Some Heat Advisories may be released by the National Weather Service during this period. There will be chances for thunderstorms later on Monday, and some widely scattered thunderstorms through next week.