July 2018 Weather Outlook
July 3, 2018
We have now reached the month of the summer where temperatures are at their warmest. Average highs in July range from the upper 70s to near 90 in the northern areas, to the 90s across most of the South, with 100s in the Desert Southwest. Daylight hours begin to slowly decline, though it will be hardly noticeable until late in the month. Daylight lengths range from 13 hours across the South to 14 to 15 hours in the North.
June has turned out very warm across a large portion of the country. The epicenter of the heat was located across the Plains, the southern Rockies, and the Mid-Mississippi Valley where readings were 4-8 degrees above normal. Lesser warm anomalies occurred across the Desert Southwest and Southeast. More seasonable weather impacted the Pacific Northwest and the Northeast with only brief heat episodes. A wet pattern set up across the northern Rockies, central Plains, the Ohio Valley, and the Mid-Atlantic. Flooding rains impacted portions of the Mid-Atlantic. Dry weather remained stubborn across most of Texas through the Middle/Lower Mississippi Valley. Bone dry weather occurred in California through the Great Basin. The tropics were relatively quiet with no named storms in the Atlantic Basin.
July 2018 should see the main upper level ridge start in the eastern half of the country, but retrograde into the West during the second half of the month. This should result in continued hot weather across the southern Plains through the Lower Mississippi Valley where readings could be 3-7 degrees above normal. Additional warmth should stretch northward through the Upper Midwest through the Great Lakes/Ohio Valley. Even modest warmth is possible in the Northeast. It is worth noting that the warmest weather relative to normal across the northeastern quadrant of the U.S. may be the first two weeks of July. There are signs that cooler air will attempt to press southward into the Upper Midwest through the Northeast during the second half of July, especially toward the end. This should allow warm anomalies to be reduced somewhat overall. A warmer month is expected across the Pacific Northwest, especially the second half. More seasonable temperatures should occur across the Desert Southwest and the Southeast Coast.
The heat will come with dry weather across the southern Plains through the Mississippi Delta and perhaps into Missouri. This should result in an expansion of drought conditions across most of these areas, especially away from Deep South Texas. The northern/central Plains will see a more variable precipitation pattern with localized rainfall as thunderstorm complex locations will largely control the rainfall patterns. This means localized areas will see excessive rains while others get missed. This should balance out to somewhat above normal rainfall. Meanwhile, a wetter July should occur from the Mid-Atlantic through the Southeast Coast. There could be enough rain for localized flooding at times. We should see the monsoon season begin to expand across the Four Corners Region with above normal precipitation. The Upper Midwest through the Northeast should see dry weather during the first half of July. Rainy weather should pick up a bit during the second half of the month, which should eat into deficits for many. The Northeast is the area that could see the best chance of dry weather. The Pacific Northwest and northern California will see below normal rainfall and an expansion of regional drought conditions.
The first week of July will feature the best chance of severe weather conditions overall and the most likely location will be in the northern Plains. Otherwise, a relatively benign severe weather month should unfold. This should keep the 2018 tornado count near the 15 year low.
July looks like a very quiet month in the tropics. Water temperatures are below normal over the main development region in the tropical Atlantic. In addition, the upper level pattern will be unfavorable for tropical systems through most, if not all, of the month. This is a strong signal. However, water temperatures in the eastern Gulf of Mexico and off the Southeast Coast are above normal. This means that we have to be on the lookout for close-in development in these areas. The risk is low, but it bears watching. These systems, should they occur, are likely to be weak and short-lived. However, they could produce an excessive rain threat.