My latest Weather Journal column looks at instances of “temperature whiplash” we’ve had in the last several months.

And that’s what we’re about to experience, again. After Tuesday morning’s scattered frost, temperatures are likely to be 15-20 degrees warmer to start Wednesday … and then shoot up into the 80s by Wednesday afternoon. It wouldn’t be totally out of the question for Roanoke to record its second 90-degree high of 2013 on Wednesday, though the forecast high is just a tad cooler. After a record-breaking low of 35 at Roanoke and record-tying low of 31 in Blacksburg on Tuesday morning, May 15 record highs of 92 at Roanoke (1962) and 88 at Blacksburg (1985) will probably be just a wee bit out of reach — but not inconceivable. Westerly winds blowing down the slopes of the Appalachians will enhance the effects of the strong warm air advection rolling in from the west to produce the high temperatures 10-15 degrees above normal for mid-May. We’re not the only part of the country experiencing temperature whiplash, or even the part experiencing it most severely — some parts of Nebraska, South Dakota and Iowa soared past 100 on Tuesday, just a couple of days after sub-freezing lows and less than 2 weeks after abnormally late and in some cases record-large snow for May. Omaha, Neb., for instance, has recorded its earliest 100-degree temperature and its heaviest May snow just 11 days apart.

Some hard-to-time disturbances and ill-defined fronts will begin to affect our weather by Thursday continuing well into next week. That’s why you see forecasts with chances of showers and thunderstorms stretching out for days. In time, those forecasts may become a little more focused on particular periods with higher chances of showers and storms.

The Hokie Storm Chasers, who left chilly Blacksburg on Tuesday morning, may see some severe storm action Wednesday afternoon/evening in north-central Texas, or somewhere reasonably nearby. Targets sometimes easily shift 100+ miles as new data develops on these trips. We’ll see if they come up with any memorable storm photos on the second day of this first trip.

Wednesday’s Weather Journal column looks at how tornado numbers have been low nationally for about the last year. The reasons have differed dramatically during the typical spring peak seasons — unseasonable warmth in 2012, and unseasonable chill in 2013. Some related reading to the latter is provided by the Washington Post’s Capital Weather Gang, which looks at the extraordinarily cold and snowy April in the north-central U.S. — including the interesting fact that Duluth, Minn., had more snow in April (51 inches) than any previous month on record — not any previous April, any previous month.

A surge of warmth is headed to Southwest Virginia on Wednesday that may carry us to temperatures in the mid 70s to low 80s, about 10 degrees above normal. But it will be a brief surge, as a cold front approaching from the west will return us to slightly below normal temperatures — 60s highs, 30s/40s lows — for Thursday and Friday. The front will not have much moisture to work with, and it’s possible that showers and storms diminish or die out entirely trying to cross the Appalachians from the west on Wednesday. But anytime a cold front pushes into air this warm, there is some chance of storms, and at least a marginal chance of strong to severe storms with locally gusty winds as the major threat.

A much larger and longer lasting warmth surge is due to effect much of the central U.S. early next week, with summerlike temperatures possibly pushing into some of the same Northern Plains/Upper Midwest areas experiencing record snowpack this week. That will cause flooding problems up there. We probably get in on that warmth surge in time, but its effects may be delayed a few (or several) days by a southern-stream low-pressure system over the weekend and early next week that may cut off and wobble around the Southeast/Mid-Atlantic for a few days. We’ll have a chance of showers for several days, and the combination of the low’s counterclockwise circulation and the position of the high bringing warmth to the central U.S. may circulate east to northeast winds to create a “wedge” effect that holds cooler air in against the Appalachians.

(Courtesy, National Weather Service, Blacksburg)

Roanoke’s official high temperature today was 90 degrees, setting a record for April 10 (previous record 88 in 1922) and marking the 8th earliest 90-degree reading in Roanoke’s weather history dating to 1912. The record earliest was March 19, 1945, and four of the five others date to the April 5-8 periods in 1929 and 1942. Roanoke also hit 90 degrees on April 6, 2010.

Blacksburg reported an official high of 83 degrees (measured at the National Weather Service office) breaking the record of 82 set for April 10 in 2001.

At 4 p.m. (EDT), the hottest temperatures in the United States were low 90s in south Texas and Virginia. Harlingen and McAllen in Texas were at 93, while Stafford, Va. was at 92. Roanoke and several other sites not far behind.

Photo by Matt Gentry / The Roanoke Times

Though it never delivered the “big’un,” we will not soon forget the 2012-13 snow season. Thursday added a dramatic final chapter — we presume — to the overtime session of the 2012-13 winter, as Gulf of Mexico moisture caught up to cold, dry air and evaporational cooling allowed snow to reach the surface for several hours Thursday afternoon and evening, providing a rare April snowstorm that was Roanoke’s first measurable April snow in 20 years and the region’s largest in at least 26 years. For the first time since 1971, the Roanoke and New River valleys experienced two significant calendar spring snowfalls, as this one followed on the heels of the March 24-25 “Palm Sunday” snow event. I hope to have some final numbers or maps on Friday regarding Thursday’s snow, but generally, it was a 3 to 7 inch snow across the New River Valley and along the Blue Ridge south of Roanoke, and a 1 to 3 inch snow in the Roanoke Valley and locations just north and east. The amounts did not extend northward as would often be the case, as regions farther north in the state actually warmed more during the day with thinner clouds, and the high pressure system helping to bank the cold, dry air against the mountains began moving eastward out to sea before the bulk of the moisture arrived. So Southwest Virginia was just far enough south to get a solid slug of moisture and just far enough north and west to have that moisture move into very dry air, which allowed evaporational cooling to occur, as heat was removed from the air to turn frozen and liquid precipitation into vapor. Eventually, warmer air aloft did win out, and precipitation turned to rain, but not before several inches of snow had fallen in many locations. I’m glad we were at least talking about the possibility of snow on this blog for a few days before — but the amount of snow that fell in parts of the New River Valley particularly was a surprise for me, just as for many other weather professionals.

One interesting tidbit is that Blacksburg experienced its first measurable snow on Oct. 29, 0.2 inch with Superstorm Sandy, and what we presume to be the last measurable snow on April 4, 157 days later. That breaks the record set in 1970-71, at 156 days, for longest stretch between first and last measurable snowfalls.  Also for Blacksburg, the official 5.4-inch measurement (at the weather service office — more was reported elsewhere nearby) made it the third largest April snowfall on record, trailing only the April 7, 1971, (10 inches) and April 27, 1978 (6 inches) events, just ahead of the 5.3 inches of April 3-4, 1987.  Roanoke’s official 1 inch was the seventh largest April snowfall on a single calendar day — but since the list splits the 1971 and 1987 April snows into two different calendar days,  combining those would pull Thursday’s snow up to the  fifth largest April snowfall.

But, as I noted on here earlier in the week, the pattern is changing dramatically. Thursday evening’s enhanced satellite photo shows the key players. First, near the East Coast, you see the storm system that dumped our snow. Over the western U.S. is a low pressure system that will initiate the southwesterly wind flow that will overtake much of the U.S., leading to much warmer, and more moist, air overspreading the nation. (While the eastern U.S. storm system was snowing on us, the western U.S. storm was spawning a tornado in northern California, of all places). Even farther west is a curve of clouds in the northern Pacific Ocean. This powerful dip in the jet stream will begin to carve out a trough of low pressure over the western U.S. that will lead to several days of southwesterly flow over the central and eastern U.S. This typical spring pattern means quickly rebounding temperatures for us — snow-melting 50s to near 60 Friday, widespread 60s Saturday, many 70s by Sunday and through the early part of next week — plus increased severe weather and rain chances through the central U.S.  So yes, I’m declaring the 2012-13 snow season to be OVER for Southwest Virginia. at least below 4,000 feet in elevation (higher locations sometimes get snow in May.) Spring is on, especially by Sunday. Soon, we’ll be talking severe weather risks, not snow threats.

WINTER WEATHER ADVISORY ISSUED SUNDAY MORNING THROUGH MONDAY MORNING, MOST OF ROANOKE AND NEW RIVER VALLEYS

Trends on forecast models today have been moving toward a colder and snowier direction for Sunday across  the Roanoke and New River valleys and much of Southwest Virginia. Even though high temperatures have been in the 40s and 50s today, much of the air above us is still unusually cold and dry for late March. As a feed of Gulf of Mexico moisture rams into that air early Sunday (beginning perhaps as early as 7 a.m. to 10 a.m.), it is expected to rapidly cool the atmosphere falling through the cold dry air, with a mix of rain, sleet and snow, possibly giving way to all snow in many locations. There are still a wide array of potential amounts, owing to variables with moisture and temperature, mixing of rain/sleet, and especially the marginal surface temperatures and ability of the ground to absorb solar warmth from a high sun angle even if it is cloudy. The National Weather Service in Blacksburg has put out a map showing 2-4 inches in most of the Roanoke and New River valleys, more to the northwest, less to the south and east. This is probably a good middle ground of the possibilities, which could range upward significantly if the moisture and temperature on some models is correct, but could range downward with more rain or sleet mix if more warm air streams in aloft. There will be potential for additional snow into Sunday night and early Monday as well with this complex spring storm system.

Stay tuned. It will become largely a “nowcasting” show soon.

UPDATE 12:40 AM, 1/2: I’m simply going to add a link to the Weather Journal column with my 5 picks for top weather events of the year in The Roanoke Times readership area — based on intensity of impact, breadth of impact, unusual nature of the event, meteorological records, newsworthiness, etc. Frankly, though, there was an obvious pick for No. 1 (June 29 derecho) and everything else is arguable below that.  Weatherwise, expect a few more showers — maybe even some snowflakes — overnight into Wednesday morning.  The next few days appear to be pretty placid, with near-normal temperatures (40s highs, 20s lows) and only a couple of weak disturbances that may trigger a few sprinkles or flurries, Thursday and perhaps over the weekend. We’ll look ahead more in depth in the next blog post sometime Wednesday evening. END UPDATE

Happy New Year, Weather Journal fans! It certainly was a wild 2012.  The National Weather Service in Blacksburg has released a list of what its meteorologists voted as the top five weather events in its forecast area for 2012. I’ll have my own list in Wednesday’s newspaper (and I’ll link it here) of the top five events in The Roanoke Times readership area, a much smaller area than the Blacksburg forecast area.

December finished with a 44.7-degree average for Roanoke — the 6th warmest December in the past 101 years, eight-tenths of a degree warmer than last December, and only two-tenths of a degree cooler than November — putting the year at 59.5 degrees. I’m checking with the National Weather Service about where this ranks the year as a whole — this online listing suggests it would be the warmest year on record, but I have another chart provided by the weather service office that shows 1930 as having a 59.6 average. Either way, a very warm year.

The radar has showed splotches of precipitation moving across Southwest Virginia all day on Monday, but very little has reached the surface. Dry air east of the Virginia-West Virginia border and I-77 corridor has been hard to penetrate by the weak overrunning flow of moisture from the west and southwest. Some will eventually get through, as the air slowly saturates, but amounts look to be rather meager. Because there is so much dry air, evaporational cooling may be sufficient for some sleet or snow, but enough milder air is filtering northward, without much of anything to fight it with cold air from the northeast, that most of the precipitation will probably be rain. I say “probably” because we’ve had a couple of precipitation events in  the last week that didn’t work as expected due to subtle changes in the atmosphere’s thermal profile. There may be another chance of some frozen precipitation late Tuesday as cold air filters in on the backside, but again, it just appears like amounts will be very light, less than a tenth of an inch of liquid for most, maybe a quarter-inch west of I-77.

We do have a milder pattern taking over for a while over the weekend and next week, as extremely cold air near Hudson Bay will remain wrapped up, for now, by a rapidly spinning area of low pressure. Whether the pattern changes to allow this cold air to surge southward later this month or early in February may be the single biggest determinant in how winter 2012-13 will end up being characterized. Locally, we’re actually off to a milder start in December than our second warmest winter on record a year ago, but nationally, there is more snow cover, and there are far more signs of Arctic air stirring to our north than this time last year. We’ll watch the push and pull of mild and cold the next several days to see if this ends up being a mild repeat or is overtaken by an Arctic surge.

Now about halfway through the month of December, the balmy start to the month has put back into play the possibility that 2012 could be Roanoke’s warmest year on record, something I wrote off as recently as Nov. 21. The first 15 days of the month averaged 48.2 degrees. The month as a whole would need to average 46.8 for 2012 to surpass the yearly average temperature of 59.6 from 1931. It would need to average 45. 6 to at least tie that mark. An expected cold shot of air next weekend will likely bring the month’s average down quite a bit, but it still has some room to drop, especially if we rebound to somewhat milder weather after Christmas. After the last 2 months of the second-warmest winter on record, the warmest March on record starting off the warmest spring on record, and then the hottest July on record splitting a summer that was fairly mild on the front and back end, it appeared that cooler weather in October and November had derailed the year’s obvious march toward record status. The first 60-degree average year appears to be off the table now, requiring a 50.4 average for the month. (Incidentally, 47.8 is the record warmest December for Roanoke, set in 1956. Last year’s 43.8 was the 8th warmest December … and the 31.3 average of the previous December in 2010 was the fifth coldest.)  But a record tying or setting year is still possible — unless next week’s cold spell hangs in for the balance of the year. Joining 1921, 1931, 1990 and 2007 as the fifth 59-plus degree year is very likely.  Nationally, 2012 is virtually assured to be the hottest year on record, dating to 1895.

Back to the here and now, with rain potential. The NAM (North American Model) and GFS (Global Forecast System)models — the two major U.S. forecast models — are fighting it out about whether Southwest Virginia will be a rain bullseye or rain shadow, respectively, in regard to the storm system the next couple of days. The Hydrometeorological Prediction Center has more or less split the difference, showing our region generally around the 0.5 to 0.75 inch range over the next 3 days — more than the GFS shows, less than the NAM shows. The reason such a configuration could occur is what often occurs here, with the best moisture staying to our south while the best storm dynamics to lift and condense moisture go around us to the west and north. If you’ve lived here a few years and paid attention to the weather map, you’re all too familiar with this two-step. The good news for those wanting moisture to ease the dryness is that we are likely to get at least some, as Gulf of Mexico moisture overruns cooler surface air on southwesterly mid-level winds overnight into Sunday, triggering some showers. By Monday, a low-pressure system and cold front will move closer, adding more lift to squeeze out the moisture. Roanoke’s biggest rain since Oct. 1-2 was only 0.41 on Nov. 12-13, so it wouldn’t take a whole lot of rain to make this the rainiest system in more than 2 months. Once the cold front passes late Monday or early Tuesday, a few mountain snow showers may develop on northwesterly upslope breezes, but the air mass behind it is not that all that cold, and southwesterly flow ahead of the next storm system tracking northwest of us may get us close to 60 again in some spots by Thursday.

Late week,  a surge of Arctic air remains likely Friday into the weekend, with blustery northwest winds, highs not topping 40 on at least a day or two, and the potential for a more vigorous round of upslope snow showers. Forecast models today do want to move low-pressure over the Great Lakes eastward a little faster, rather than stalling it, so a multi-day snow shower event appears less likely. Next week has lots of questions with it, but on the whole, it appears likely to be the coldest average-temperature week so far this month — not a terribly impressive feat, considering how mild it’s been, though there is at least some model support for a very cold Christmas week — with perhaps some potential for a storm system in the days after Christmas. Whether the temperatures rebound after next weekend’s cold surge, or remain at least seasonably cold, will go a long way to determining if a potential system after Christmas would bring wintry precipitation or mainly rain.

Latest Radar / Future Cast

UPDATE 6 AM, 8/19: Some heavy rain showers have developed this Sunday morning in the Roanoke and New River valleys and nearby areas as a wave of low pressure along the front has swept thick moisture atop a somewhat cooler air mass sliding in from the north and northeast. Additional showers are possible through the day across Southwest and Southside  Virginia as the wave moves by. High temperatures will be considerably lower in areas that get significant rain. END UPDATE

There will undoubtedly be plenty of folks who remember 2012 as one of the hottest summers because of that torrid June 28-July 9 stretch, when Roanoke topped 100 four times and every day but two among those 12 90-plus days also topped 95. But the climate records for this summer, based on averages over three months, are not going to corroborate those memories. The list of the 10 hottest summers based on average temperatures for Roanoke is topped by the last two summers and 2007, impressive and indeed anomalous that 3 of the hottest summers should occur within the most recent 5-year span. Beyond that are a scattering of years from 1934 to 1987, with three years in the 1950s on the list.  (NOTE: 1930 does not appear at all because of some missing dates. Considering it had 21 100-plus days, by far the most, it would most likely be somewhere near the top if records were complete).  If summer 2012 ended Saturday, its 76.7 average would put it in a 4-way tie for 5th on the list. But if the National Weather Service projected temperatures for the next week are accurate (they won’t be exactly, of course, but could be close), the summer average will fall off to 76.2 and drop out of the top 10, needing a steep last-week rebound to regain a top 10 spot. 2012 will likely finish among the top fifth of summers for average warmth, but it will not be a record breaker, because of cool to normal temperatures the first 3 weeks of June and again in much of August. Heat in 2012 has been a sprint; it was a marathon in the past 2 summers.

In a few months, news that a recently passed cold front is developing a wave of low pressure (Sunday evening projected weather map linked) that will throw moisture back over will be greeted with intense interest from snow lovers . In August, it’s kind of blah. It may provide some showers to folks needing rain, especially Sunday night and early Monday, but it appears the heaviest rain will generally stay south and east of Southwest Virginia. The extra humidity and clouds are going to stymie what could have been a couple of really good nights of radiational cooling, too — instead of widespread 50s and maybe a few 40s, lows will hang pretty close to normal, upper 50s to mid 60s, for Sunday and Monday mornings. But highs, which sunshine boosted to near normal levels today in the upper 70s to mid 80s across the region, may drop back a few or even several degrees in the 70s (some upper 60s possible on Monday if it gets really socked in by rain and clouds ). The temperature regime this week will remain pretty stable, with upper 50s/low 60s common for lows and upper 70s/low 80s common for highs through most of the week, maybe a few degrees cooler Tuesday or Wednesday morning if a reinforcing shot of Canadian air can find a calm, clear night.

A long way out, we may need to keep an eye on the tropical disturbance in the eastern Atlantic or possibly the one just now coming off Africa, as forecast models are rather consistent in bringing a tropical cyclone into the western Atlantic near Aug. 30. It’s much too early to nail down specifics on path or strength this far out, but it tis the season for this sort of thing, and the pattern may become favorable during that window.

UPDATE 8:20 PM: Easterly winds are banking relatively, cool moist air against the mountains. The upslope effects plus some temperature contrast are triggering small but heavy showers, perhaps accompanied by some thunder, in and around the Roanoke metro area, southward along the Blue Ridge through Franklin and Henry counties. (Radar linked here) Brief periods of heavy rain will be possible with these showers. As the easterly winds continue to bank moisture overnight, a layer of low clouds and scattered drizzle is likely to develop — such a layer kept much of northern Virginia in the upper 60s and low 70s throughout today. How long this layer can hold in place on Sunday will determine whether we have a cooler day with a high in the 70s or a warmer, sticky day in the 80s. END UPDATE

This weekend: Warm and sticky, highs mostly in the 80s, with scattered showers and storms possible as daytime heating interacts with a stubborn front and thick moisture. Some will get heavy rain (like Galax did Friday evening) and/or gusty winds, others will get lighter rain and a little thunder, and yet others will get sprinkles or nothing. Can’t really be much more specific than that. Same old midsummer dog days refrain.

We are 20 days into July, and Roanoke is on track for some possible monthly record heat. As with the record hot summer of 2010 and runnerup in 2011 (a merely normal June average temperature may make it hard for this summer as a whole to equal the previous two), it’s more about warm overnight lows than hot afternoon highs. Through Friday, Roanoke’s average high temperature for July is 91.9 degrees — that would rank fourth were it an end-of-month average. But more impressively, the average low has been only 71.2 degrees. Should a similar number be posted after 11 more days, it would crush the current July record of 69.9 degrees set just last year and even overturn August 2007′s record 70.6 for warmest average low for any month. Roanoke low temperatures have been no lower than 66 on any day this month and have been 70 or above on 12 of 20 days. The normal low is 67 — only July 12 at 66 has been below that, every other low has been 1 to 9 degrees above normal. Averaging the mean high and low together produces an average temperature for the first 20 days of July of 81.6 degrees, which, were it a month-end average, would set a new record for hottest July and be just less than half a degree off the 82.1-degree record warmth of August 2007 for hottest month on record. I bring this up now because we are two-thirds through the month with absolutely no sign of a significant weather pattern change. High temperatures go down with cloudy days like Friday (only 82 at Roanoke, 76 at Blacksburg) and passing cold fronts, but muggy low temperatures are hanging on even in the somewhat cooler periods because truly cool, dry air from Canada has been blocked from coming this far south.

Drought begets more drought. Drought begets more heat. More heat begets more drought. Vicious cycle much of the U.S. is in. We’re on the eastern periphery of the real trouble (Thursday’s Drought Monitor map shows the darker colors mostly to our west), but until there are major pattern changes that can bring large-scale storm systems to soak at least some of the very dry areas, there will be little change to prevailing mostly hot, mostly dry weather. Short of a large tropical system moving deep inland, an unlikely event for now because of an infusion of Saharan dust that has tracked westward from Africa over much of the Atlantic basin, those kind of drought-busting events probably aren’t going to occur for at least another 45 days, if not longer, when seasonal changes in upper-air patterns begin to take hold. So we’re pretty much stuck with a dome of hot, dry air over the central U.S., expanding or wobbling eastward over us at times, and at other times aiding in pushing at least some fronts and disturbances southeastward into the Appalachians and Mid-Atlantic regions. The heat and lingering humidity (plus terrain factors in the mountains) will be sufficient at times to fire scattered afternoon storms, but at other times hot, dry air moving aloft will block upward growth of storm clouds. A dip in the jet stream into New England may be able to erode the heat dome near us in coming days and weeks, which might lead to a somewhat cooler pattern — but widespread, general rainfall remains doubtful.

UPDATE 5:25 PM: Roanoke’s official high through 5 p.m. was 103 degrees — the hottest day in 29 years, since it was 104-105-104 on Aug. 20-22, 1983. It’s tied for the second hottest high in June, trailing only 104 from June 30, 1936, and is the first high of 100 or higher in June since 1959. Blacksburg reached a high of 95, which is the hottest ever recorded in the month of June since records began there in 1954. Combined with very warm lows of 84 at Roanoke and 78 at Blacksburg, this is the hottest day by average temperature that either site has ever seen — but it’s possible the low temperature end of that will be affected by an area of storms moving rapidly through the Ohio Valley. Whether or not that “bow echo” storm cluster (radar image at left) moves directly through, an outflow from it may cause cooler temperatures than this morning’s lows before midnight, which would thus supplant those lows for the date. You can track it on the Radar / Future Cast at right. END UPDATE

UPDATE 3:30 PM: Roanoke has officially hit the 100-degree mark as of 3 p.m. It is the first 100 in June at Roanoke since 1959. END UPDATE

UPDATE 9:50 AM: The National Weather Service in Blacksburg has confirmed a morning low of 84 in Roanoke, which if it stands til midnight, would be the warmest low in Roanoke’s weather history by 4 degrees. However … before we etch that in stone .. the threat of evening thunderstorms appears to be on the increase, and it would probably take thunderstorm downburst winds to get it cooler than 80 by midnight. It is possible that a storm cluster may develop in the Upper Midwest/Ohio Valley today and rocket southeast, near or perhaps through Southwest Virginia. The Storm Prediction Center has placed much of our region from Roanoke northward in a slight risk of severe weather for this possible. Damaging winds would be the primary threat if this storm cluster — perhaps a “bow echo” or derecho — develops. Before any of that would occur, it’ still likely to reach or exceed 100 at Roanoke. It’s already 90 at 9 a.m. END UPDATE

This  morning’s low at Roanoke Regional Airport, based on the automatic observations available on the Web site linked here, was no cooler than 82 degrees (depending on when 82 occurred — it was low in 6 hours before 2 a.m., so it may have occurred before midnight, in which case, morning low may have even been warmer). The warmest low that has ever been recorded previously at Roanoke since 1912 is 80 on four different occasions in the 1930s and 40s. In more recent times, Roanoke had a low of 79 on Aug. 9, 2007, and 78 twice last summer.  If this is confirmed as official, it will stick as an all-time record if it doesn’t get below 80 by midnight — which would probably only happen if there were downburst winds in  an unexpected thunderstorm. Starting out so warm substantially increases the chances of reaching 100 degrees today, which has not happened in June at Roanoke since 1959. Widespread 92-104 high temperatures will occur today across most of Virginia aside from the highest ridgetops today.  A massive dome of hot, dry air, originating in the Desert Southwest, not the Gulf of  Mexico where we typically see hot and more humid air masses come from, is overspreading our region, and being forced downward by high pressure. West to northwest surface winds rotating around the hot high pressure system are blowing down the slopes of the Appalachians, further compressing and heating that air. It’s a scenario that has led to some of our hottest days historically.

Daily record highs for June 29 are 101 at Roanoke (1934) and 92 for Blacksburg (1954). Blacksburg’s record appears very likely to fall, as it’s already in the low 80s there this morning. Roanoke’s record also appears to have a better than even-odds chance of being tied or broken, now. While it has been at least 100 six times since 2000, Roanoke has only been above 100 twice since 1988 — highs of 101 and 102 on August days in 2007.

For those looking for relief — there are indications the hot high will be pulled westward and northward, allowing more of a northwest wind flow and some cold fronts, mid to late next week. But will be several very hot days between now and then.