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An Unusually Usual Weather Pattern for July Standards

This unusual and sluggish weather pattern for this time of the year means the unsettled weather will continue through parts of Wednesday. While the heaviest and most persistent plume of moisture stays closer to the East Coast, occasional showers and thunderstorms can still be expected for our region. (WCHS/WVAH)

Good Monday!

Unusual July Weather Pattern means Showers & Storms Will Continue

The words 'shower' and 'thunderstorm' go well with the month of July; this is typically when our region sees most of it's rain--at least from an accumulation standpoint (April typically sees the most days with rain). These showers and storms, however, have an unusual driving force behind them for mid-summer standards--a deep upper-air trough, something like you'd see in the spring or fall instead. While there's some heat and humidity to go around with these summer storms, too, that's not the 'only' reason they are forming like their typical summer counterparts. These showers and storms have plenty of deep moisture and lift to work with due to the unseasonably strong upper-air support. This means that not only are the downpours more widespread--but more persistent, too. With this, comes the potential for excessive rainfall for some areas. Let's take a look at the next several days.


TODAY: A mix of Sun & Clouds and humid with scattered showers and thunderstorms developing. High: 84.

  • After a dry start, expecting more activity to develop this afternoon thanks to sluggish, and spring-like, low-pressure system just towards our west. The counter-clockwise flow around this feature will continue to push moisture up from the south--along with some 'ripples' of energy rotating up around the low in the mid to upper-levels. The combination of these two mean shower and thunderstorm chances increase again--especially late this afternoon and evening when better moisture and lift arrives from the southeast thanks to an uptick to the low-level flow. A few storms will be capable of gusty winds, a good amount of lightning and heavy downpours in this time-frame, but the steering flow is fairly strong in the 15-25 MPH range--which should allow any action to move along. Still, considering the wet ground from weekend rains--will keep an eye on torrential downpours.
  • Even before 3-4 PM, though, can't rule out a pop-up shower and/or thunderstorm for some given a lack of a 'lid' overhead, moderate instability and some leftover boundaries from the weekend storms. The south-southeasterly flow in the lower atmosphere should favor the Eastern Mountains at first, though.


TONIGHT: Mostly cloudy with a scattered shower and/or thunderstorm possible. Low: 67.

  • Feel that any showers or thunderstorms left may persist a few hours after sundown here, as they will have some upper-air support via a few 'ripples' of energy moving up from the south--plus some instability and deep moisture to tap into. By around Midnight, however, should see most of the action fade--as instability becomes increasingly capped. With dewpoints in the upper 60's, expecting a humid night--and while boundary layer humidities may rise to near 100% again, not sold the fog will be too widespread and/or dense given a southerly wind-flow a few thousand feet of the ground. Typically, this keeps the fog fairly inconsequential and may even favor more of a stratus layer (low clouds). I suppose across the more-sheltered valleys and hollows--where the wind doesn't mix as much--some fog could develop.


TUESDAY: More clouds than sun & humid with showers and thunderstorms increasing. High: 83.

  • More Deja Vu here, as the largescale pattern essentially remains the same. In fact, this environment could be more capable of producing downpours and lightning--as the moisture appears deeper and more robust. With no lid overhead, nothing will prevent rising thermals from blossoming into thunderheads in the afternoon--so keep a close eye out if outdoors. These rising columns of air should be augmented by several pieces of energy rotating up from the south again in the mid to upper-atmosphere, so feel that the coverage should actually be more widespread and random. With dewpoints in the upper 60's to lower 70's, it will be muggy outside--so any brief sunshine in between the building clouds will make it feel especially warm. There looks to be some wind in the mid to upper-atmosphere to push any storms along--about 10 to 20 MPH of it--but a few tropical downpours over a given location may lead to localized high water, especially with the wet ground. There's some potential for slow-moving showers and storms by the evening-time, as the flow weakens right underneath the slowly departing low-pressure.


WEDNESDAY: Partly sunny and humid with scattered showers and thunderstorms. High: 83.

  • Don't really get the vibe that this day will be as active, as guidance suggests the best upper-level support and trough will gradually move east. Typically, after a fairly busy day--as I suspect Tuesday could be--you don't see another busy day the following one due to an overturned, or 'tired', atmosphere. However, it would be unwise to discount the potential for at least scattered showers and thunderstorms given the soupy airmass still in place--especially from near I-77 and east, where the best overlapping of deep moisture, upper-support and instability should be. In between the clouds, a bit of sun will peak through--which will make the atmosphere especially feel warm and humid given dewpoints hovering around 70 Degrees. Whatever storms do fire may be slow-movers, as forecast models only suggest about 10-15 MPH of flow aloft.


THURSDAY: Partly cloudy and drier! Turning hot in the afternoon, but not too humid. High: 88.

  • Expecting a quiet day here, as we get out ahead of another front back in the Midwest. This front will be associated with another strong upper trough (for this time of the year) and an area of low-pressure scooting across portions of Eastern Canada. While there does appear to be a hint of a moisture surge in the lower levels late in the day (sort of a Warm-Front), guidance still suggests a much drier atmospheric column along with no shortwave energy passing through and weak instability. As a result, feel that this day will remain dry with lower humidity under a mix of sun & some clouds. It will turn rather warm/hot, though, given a slight west-southwesterly wind.


FRIDAY: A mix of sun & clouds with scattered showers and thunderstorms developing. High: 86.

  • Looks like the front that was mentioned on Thursday back in the Midwest should move across here. As it does, moisture--both near the surface and aloft--should increase, leading to increased instability values for some showers & thunderstorms. With the mid to upper-level flow blowing more perpendicular to the front, wouldn't be surprised for this frontal passage to trend quicker in the coming days; this *may* bode well for Live on the Levee. Shear values look pretty decent in the 30-40 knot range per the NAM & ECMWF models--which may support a few strong to severe cells if fropa can occur near maximum heating. Otherwise, it will be a humid day with a slight breeze between a mixture of clouds and sun.


SATURDAY: Partly cloudy and warm, but not too muggy. High: 84.

  • Model guidance shows zonal flow with a weak high-pressure system building in behind the front here. While the atmosphere looks a lot drier, the fast west to east flow aloft should push some mid to high clouds in--especially late. It will turn a bit cooler in the wake of the front, and there should be a nice drop-off in humidity, too--this means the atmosphere looks mainly stable. Overall, it looks like a good day!


SUNDAY: More clouds than sun with a slight shower chance. High: 85.

  • The aforementioned west to east flow aloft suggests increasing mid to high clouds, so perhaps more of a filtered, or milky, look to the sky here. Despite less direct sunlight expected, should still be a warm day as the high-pressure moves into the Mid-Atlantic--which will allow our winds to shift more out of the southwest. This return flow should allow some moisture to increase, too--which may be enough for a shower or two--but there are still some timing issues in regards to a shortwave trough back in the lower Ohio Valley and how quickly energy and the deep moisture can return. Based on this, only have a slight shower chance in there for now, but it may trend upward in coming days. The humidity doesn't look to be too bad as of yet.


Have a Great Monday!

WCHS Storm-Team Meteorologist, Brandon Stover

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