Easing back on temperatures in the Ohio Valley and lower Midwest for the summer, but still looking for hot spells; still looks wet early southern Plains
1. We are leaning more toward a rather hot summer for the nation as a whole despite periods of wet weather in the spring across the Plains into the Ohio and Tennessee valleys. The heat will come differently and at different times during the course of the summer which will be explained in the body of the discussion. Two of my analog years, 2007 and 1983, were hot summers for the nation with agriculture impacts. The drought concerns will be smaller around the Great Lakes and Ohio Valley as of this update, but dryness in July could be concerning stressful on crop areas. (Moderate confidence)
2. Dryness and heat has been slower to develop in parts of the Midwest and Ohio Valley from earlier thinking. We still feel the northern Plains, Upper Midwest and Lakes will be dry and hot overall. Farther south and east, the dry and heat will come in spells. The length of those spells will tell the story. There still can be episodes of wet weather cooldowns in June and possibly July to break up the long streaks. For the Northwest, once it becomes dry and hot, it will stay for a while through mid- and late summer. (Moderate to High confidence)
3. It seems the confidence has lowered a bit from original forecast on a significant fire season, more fires than what we have seen in the past few years, for the Ohio Valley and Midwest. I would still be concerned about the interior Northeast, Upper Midwest and northern Plains. Also need to watch the stress on agriculture, crops and animals going forward with any significant long dry spells during the middle of the summer. (Low to Moderate confidence)
4. Severe weather can make more impacts across the Rockies and the central and southern Plains to the mid- and lower Mississippi Valley. It can be less active compared to normal for the northern Plains, Midwest and Great Lakes. The severe weather can be spotty, but strong weather events for parts of the Northeast and mid-Atlantic in June and July and in Florida during June. (Moderate confidence)
5. Long-term drought holds for Southern California where rainfall was not enough to end the drought. There have been big improvements in northern California and the Northwest which should hold back the frequency of fires early in the season, but concerns of dryness in August and warm waters off the coast can lead to periods of hot, dry weather during the summer which could lead to increase fire danger and perhaps short-term drought conditions mid- and late summer again. (Moderate to High confidence)
6. Periods of wet weather will occur in the Rockies, the south-central Plains and along the Gulf coast. However, these same areas will go through drier periods as well which is explained more in the month-to-month breakdown section. Temperatures may not be as hot compared to normal, but we do not expect significant negative departures because of the changes throughout the season. (Moderate confidence)
7. The tropics can heat up quickly in August, right around the peak of the season. With a trend toward La Nina, warming waters and less shear at this time, we feel that storms will develop quickly and lead to impacts along the Gulf coast, including the east coast of Florida. We also need to watch Southern California and Arizona earlier in the summer from possible tropical moisture impacts. There is a slight concern for a late May or early June storm which would impact the far southeast. (Low confidence)
1. Temperatures were taken up more in the western U.S., especially western Nevada and California.
2. Reduced the plus 4 temperature departures in the northern Plains and Upper Midwest. June can bring another cooldown which could bring down the departures in the Upper Midwest and over the Lakes and Northeast especially.
3. Due to increase moisture in the Ohio Valley, Tennessee Valley into the central Appalachians, the departures may not be as extreme for this area. We adjusted temperatures down but kept above normal for this area.
4. Went drier in Southern California and Nevada and less drier in New England. There is still concern for more fronts in June and perhaps a couple of thunderstorm complexes in July for the Northeast.
1. May has been a little wetter than expected across the Ohio Valley, interior northeast and parts of the Midwest. Soil moisture has even improved in the central and southern Appalachians including the mid-Atlantic. This could hold back the idea of extreme early heat, but it still looks like there will be hot spells, a little more than often. There is a chance for a cooldown for these areas in late week one/week two June and perhaps some breaks from extended heat in July based on the upper air pattern look ahead. This can lead to more changes in the temperatures departures from the changes on this update. Watching the PDO will be crucial. Warm PDO can lead to more ridges in the Northwest and troughs in the East. Weakening to neutral of the PDO can lead to basically anything.
2. The development of the upper high in the middle of the country looks weaker compared to past years, which can impact rainfall in the northern Plains, the monsoon and southern Plains weather. Any strengthening can impact these factors in the opposite direction to what we are thinking. A strong ridge means less drought in the north and more thunderstorms, less heat as well. Also, hotter and drier conditions in the southern Plains and a stronger monsoon with heavier rain in the Rockies. Staying on this idea, we felt that rainfall had a higher chance in June for the southern Plains and lower Mississippi Valley and less chance with a stronger ridge in July. However, the analogs and some of the modeling does not show this idea. We may be too dry in July for southeastern Texas.
3. Every summer, we know that tropical moisture or storms can affect the forecast for a certain area. Those concerns are early for Southern California and Arizona, which could wind up wetter if an eastern Pacific storm has influence. The other area is the central Gulf Coast to the Tennessee Valley in August. But some modeling and the overall pattern in late May and early June support a potential storm from the Bahamas to Florida.
Last summer, there was quite bit of rain across the Midwest, Ohio Valley and Great Lakes early on which made a bit impact on overall temperatures departures (much lower than normal). We are not expecting this to occur this year but we are backing off on the percentages of drought in the lower Midwest region, Ohio Valley and southern Great Lakes. The bigger concern for drought is farther north and especially into Canada which can lead to higher temperatures. Across the Northwest, conditions were very dry already heading into the summer last year. This year will be a little different where winter and spring rain and snow has led to an increase in soil moisture but more development of vegetation. So, with a warm PDO still, this area should dry out again this summer, and by midsummer, heat and fires can return. With the increase in vegetation, we do not want to play down the fire season.
The graphics below show last summer, comparison April summer outlook and May update, and standing along our updated summer forecasts (temperatures and precipitation).
Here is our 2016 summer temperature forecast
Here is the comparison from April update
Here is our 2016 summer precipitation forecast
Here is the comparison from April update
The change in ENSO can have some impact on the summer, although the greatest may come for the late fall and winter. However, the tropics and overall upper pattern in the Pacific can influence the moisture and temperatures in the U.S. A weaker ENSO signal and strong positive PDO can influence the drought and heat across the northern tier of the nation. The warm PDO signal may take over at least through the first half of the summer. Also, a quicker decline of El Nino can contribute to more tropical storms (but other factors are involved).
The next two sections will deal with models and analogs. I will show some comparisons. I have changed my ideas on the analogs each month and see differences among other mets. We are in a period of extremes this past year with a PDO value up toward the top of the charts and record tying El Nino which is weakening fast, based on water temperature anomalies. The AO and EPO continue to be factors in the forecast even this far into the warm seasons. Now the QBO is going through some incredible changes, heading from a short period of positive to negative. Finding matches to all of this is pretty tough.
I have looked at all the models with exception of the IMME and IRI. I have see some differences but a common theme is slightly wetter from the central Plains to the Ohio and Tennessee valleys. The European leans heavily that way with area of above normal now in the Tennessee Valley and Ohio Valley which impact the temperatures (lower) in this region as well. We have made similar changes in our forecast as well.
We continue to favor the trends of ENSO, the strength of the PDO and soil moisture as key players in the summer forecast. The PDO could be more dominating in the summer as ENSO heads for neutral conditions. This could mean the new analogs that I have chosen for this update may lean too much toward a weaker PDO and strong change of ENSO. Analogs show wetter and cooler Northwest and drier and hotter interior Southeast. I believe on both area will see less extremes on both ends.
Staying with the analogs, I used these years to help predict 90-plus days for selected cities. We favored the warmer analogs but not to the extreme of 1988. The upper pattern does not support the numbers shown in that year. Here is a look at the table.
We made some changes to the charts. We decided to take down eastern areas; however, they are still above the norm. We also dropped Chicago by a small number based on some of the wetness so far in spring. We took up Phoenix which looks to be on average a little hotter than we initially called for.
Summer Drought Analysis:
Main Points:
- Drought returns over Pacific Northwest this summer - Drought rebuilds over all of California and the Desert Southwest - Significant dry weather to moderate drought develops northern Plains and northern Great Lakes, gradually across the central Plains and Rockies - Wetter-than-normal conditions dominate Arklatex and Gulf Coast
The Pacific Northwest has, as predicted, experienced a wetter-than-normal winter thanks to El Nino conditions and an active northern branch. Rainfall in Washington, Oregon, Idaho, Montana and parts of the surrounding regions received above- to well-above-normal rainfall throughout the winter. Given that the drought going into fall was substantial to extreme, conditions at the end of winter appear to have reversed. Portions of the interior Northwest remain abnormally dry at the soil level, with a few pockets of lingering drought. As spring transitions to summer, the arrival of a neutral ENSO combined with a PDO that should remain generally positive will result in the return of drier and warmer-than-normal conditions. Snowpack in the Cascades has improved but will obviously provide only limited relief into the early portions of summer, after which the lack of rainfall and warmer conditions will present significant drying conditions.
Farther south, the El Nino has contributed but not enough. Almost all of California, with the exception of northern California, has not had drought reversal, with the Central Valley agricultural complex having the most persistent conditions. In fact, over a third of California's drought was still considered "exceptional" by the end of March. Precipitation this summer is expected to be near to below normal, with slightly above-normal temperatures. Even near-normal precipitation especially during the summertime is not enough to reverse a California drought. This will extend into Arizona, New Mexico and the Great Basin but to a less extreme extent. Abnormally dry conditions already present in eastern New Mexico, the northern Texas Panhandle, and southwestern Kansas are also expected to persist, although there will be enough chances for rain to prevent conditions from deteriorating to widespread significant drought.
In the northern Great Lakes and the Upper Midwest, current conditions would indicate a general absence of drought. Conditions are expected to become abnormally dry, however, heading into summer with a large mass of warmer-than-normal conditions spreading down from the Canadian Prairies. The combination of drought with some of the warmest potential departures from normal temperatures will lead to considerable drying heading into summer. Due to current conditions, it is not likely that widespread drought develops, but patches of moderate drought could populate the region with most of the region seeing abnormally dry conditions.
With its recent history of flooding rain, the one area of the country that could stand to be drier than normal is the Gulf Coast; however, the abnormally wet conditions across the region are expected to continue. Moisture levels should not be excessive and the flooding risk should not be significant, especially considering the lack of snowmelt in the river system this year. In fact, the latter part of the season may tend to be drier outside of any tropical impacts in August.
Summer Wild Fire Analysis:
-- Higher Fire Risk from the Northwest to the central Plains, Portions of the Great Lakes and interior Northeast -- Higher Fire Risk from the California through New Mexico -- Lower Fire Risk from the eastern Arklatex through the southern Appalachians
A large portion of the northern half of the country will have a considerable fire threat this year compared to normal. The returning drought in the Northwest and developing drought in northern Rockies will lead to an increased fire danger to the region during the summer. With that said, the season may start later than normal and end earlier than normal, meaning the season could be short but fierce, with 100-hour and 10-hour fuel moisture being the primary fuels.
While precipitation across the Southwest should be near normal from late spring into summer, the fuel moisture levels across the region are extremely low; 1,000-hour fuel moisture, that of the largest fuels and those that take the longest to recover, are severely low and recovery is doubtful. Combined with a potentially fast-moving southern branch of the jet stream into summer across the Southwest providing for wind events, the fuel load will be too much to ignore.
Winter precipitation and March warmth has led to above-normal greening already this spring across much of the Southeast and with precipitation trends expected to continue, the resulting wildfire threat should be significantly lower.
For many of these areas, the primary fire weather season is late summer into fall.
The major crops most impacted by the potential extreme weather will be corn and soybeans in the Upper MIdwest, especially from Minnesota to Wisconsin, extending into Michigan and parts of northern Indiana and Illinois. Late-spring rain has brought good topsoil moisture to the reach. With breaks in the rainfall in the near future, planting should finish right on time. However, our concern as always been mid-summer. The combination of below-normal rainfall and above-normal temperatures in July can likely stress the crops to the point where production will suffer. If we get a spell of very hot weather during the pollination period for corn (July), it will be impacted dramatically. From this vantage point that is still hard to be confident of occurrence, but its certainly a possibility. That did happen in the summer of 1983 and corn production suffered dramatically, lowering by 30% from the year before on a national basis. Soybean production for 1983 suffered as well, but by 15-17% rather than the 30% losses on corn.
So temperatures and rainfall over the Midwest pollination period, which is likely to fall in the period July 6-July 21 will be absolutely critical for the corn crop. Hay production may also be impacted this year. Hay is grown from April through Sept from the Plains to the Midwest and mid-Atlantic states, especially mid to late season, rather than early. The variety known as Alfalfa is primarily grown from the Dakotas to Pennsylvania and will be hit harder than the other varieties. In a dry year, there may only be 2-3 cuttings of hay, compared to 4-5 in a wetter or normal year. This lost production is likely to drive up the price of hay which is used to feed many animals, including beef cattle.
The southwest monsoon pattern will set in between July and early September. Typically, an early start leads to an above-normal monsoon season. However, there are other factors that can contribute.
1. Temperatures were eased back in the lower Great Lakes, Ohio and Tennessee valleys back to the mid-Mississippi Valley as the pattern is slow to change from May with more wetness than earlier expected. This will hold back departures by a degree or so for the month.
2. We reduced the below-normal area in the Ohio Valley while expanding the below-normal area in the Northwest and West.
1. We still favor drier-than-normal conditions in the Great Lakes and Upper Midwest but have less confident in the Ohio and Tennessee valleys, Northeast and southern parts of the Midwest. It still looks more back and forth through early June with some heat but also cooldowns behind fronts with more rain in the pattern. Any dry spells can lead to periods of hot weather. We still foresee an extended period of hot and dry weather, maybe late June, from the Midwest to the Northeast. (Moderate confidence)
2. Severe weather will be spreading out in June, similar to May. We feel more confident in a path of storms from the north-central Rockies to the south-central Plains into the Mid and lower Mississippi Valley. We feel the northern Plains, upper Midwest and Great Lakes miss out much of the time. (Moderate to High confidence)
3. Isolated severe weather events can occur in Florida and parts of the Northeast. It is not uncommon to see bad storms for these areas in June. However, we have seen some significant events in the Northeast in past El Nino severe weather season like 1998 in Pennsylvania and southern New England. Nine tornadoes touched down in southwestern Pennsylvania on June 2, 1998, with plenty of damage. (Moderate confidence)
4. Heat and dryness will return in the West starting in June. Remember, the Northwest and northern California are coming off a good winter and spring with rainfall and snowfall, so significant drought weather in northern areas can return, but mainly for the mid- and latter part of summer. Fire threat will increase for Pacific Northwest late-June severe drought continues in Southern California and parts of the Southwest. Onshore wind flow at times can lead to heat surges. Across the interior Southwest, there are some concerns for dust storms before tropical moisture spreads into the region in July. (Moderate to high confidence)
5. It does not look extremely hot for southern or southwestern Texas into the far interior Southwest. However, farther west in Arizona, California and Nevada, there will be more extreme periods throughout the month as far as heat. Despite above-normal rainfall, between events, temperatures can still be hot and the humidity can run high to keep nighttime lows above average for the month for the southeast and Gulf coast. (Moderate confidence)
6. Texas, central and western Gulf coast looks wet at times. (Moderate to strong confidence)
7. New England and mid-Atlantic will see there hot spells, but spoiled at times with occasional fronts and some rain. It looks a bit wetter than earlier thinking. (Moderate confidence)
8. Still see some rain on the Northwest coast but intensity decreasing east of the Cascades and later in June can be much drier. The PDO may have influence here during the mid Summer.
1. Temperatures were taken up more in the interior Northwest for July while temperatures were taken down in the Tennessee and Ohio valleys along with the Great Lakes.
2. Temperature were adjusted in the Southwest, warmer in Arizona but slightly cooler in central California.
3. Below normal precipitation was reduced in the Northeast based on possible thunderstorm events during the month.
4. Below normal area in eastern Texas was shifted a little farther west over central Texas.
1. Soil moisture by July is typically drier. What areas can run drier-than-normal are the Great Lakes, parts of the Ohio Valley and northern areas of the Midwest. Minor to moderate drought conditions may develop which can lead to above-average 90-degree days in this area and some 100-degree days with the drier soil. Cooling products will be in high usage this July for this area. (Moderate to High confidence)
2. An earlier section discussed the monsoon and our feelings on how this will impact the West. We feel it will be a weaker season compared to last year and compared to normal. It may start good in July but trail off in August. So we can expect normal to slightly above-normal precipitation in the Southwest, perhaps heavier storms in Colorado, Wyoming and Montana. (Low to Moderate confidence)
3. There can still be some severe thunderstorms with an occasional front or two in the Northeast The upper heights are not super high, meaning some cooler-than-normal air aloft which can lead to more active fronts. Also, the flow could turn to the north leading to cooler air at times.
The frequency will be low and disturbances could come down from Canada to produce isolated severe storms. Our temperature departures are more conservative compared to the Great Lakes and Ohio Valley. (Moderate confidence)
4. PDO still looks positive, perhaps even strongly positive. Look for conditions to worsen on the dry side in the Pacific Northwest which can lead to high fire danger. Big fires can erupt due wet weather from the winter and spring that has lead to better vegetation growth. June is expected to have near-normal rainfall, wetter than last year, but it can turn drier later in the month. Remember, the two previous years of June-July featured the biggest wildfire in Washington's history followed by an early and severe wildfire month of July in 2015. I do not feel this will the case in June but perhaps a later start. (Moderate to High confidence)
5. Central Texas looks drier compared to western Texas and the Four Corners in July. There are mixed signals from the models and analogs, but the positioning of the upper high may tell the story. If it does occur over the south-central Plains, then this scenario should work out. (Low to Moderate confidence)
1. Fewer changes made in August but temperatures were taken down a bit in the central Plains and I am concerned that I may be too dry in this area which can be looked at closer in the next month or so.
1. Hot, dry weather will hold over the Great Lakes, Ohio Valley and mid-Atlantic but will expand toward the Northeast and west across the south-central Plains. (Moderate to High confidence)
2. Not many areas will be below normal on temperatures across the nation. An area to watch is the central and southern Plains to the lower Mississippi Valley which could be a little more active as far as rainfall and thunderstorms. Plus this area may not be completely dried out from July. I lean toward near-normal temperatures, slightly below in a few spots. (Low to Moderate confidence).
3. Tropics will heat up and we will watch all of the Gulf Coast region and both west and east coasts of Florida. Florida is due, and it could come in multiple storms this year. The area from the central Gulf Coast to the Tennessee Valley has a higher chance that could lead to flooding. (Low to Moderate confidence)
4. The arrival of La Nina and intensity of the PDO will determine the pattern from the Northwest to the northern Plains. If La Nina develops faster and the PDO weakens considerably from what it is right now, then showers and thunderstorms can develop quicker in the Northwest moving into the northern Plains resulting in an easing of temperatures and fires (leaning toward late August and September). However, a later start to La Nina and a stronger PDO can hold the dry and hot weather in the Northwest, northern Rockies and northern Plains through August. (Low confidence)
5. Moisture in the eastern Four Corners region may taper down with the positioning of the upper high farther west over New Mexico and Colorado, shown by some modeling. However, it could turn wetter in Arizona and Southern California. Tropical moisture from the eastern Pacific may be pulled once or twice northward into this region. Across the central Rockies, we expect just spotty thunderstorms, but nothing to lead to above normal overall. (Low to Moderate confidence)
