Archive for June, 2013

A MOIST FLOW CONTINUES BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS… THE BERMUDA HIGH IS EXPECTED TO BUILD WESTWARD TOWARDS THE MID-ATLANTIC COAST

The unsettled weather pattern continues across the Mid-Atlantic States and it is expected to continue for a few more days. (See my Saturday post for the causes of the increased rain chances across Hampton Roads). My Virginia Beach neighborhood has not received any significant rainfall so far since this pattern developed. However, there is an area of rainfall currently to our south and southwest over NC which may bring some rain later this morning if it survives the trip northeastward. Parts of Northeastern NC have received heavy rainfall in recent days. As I mentioned yesterday, the weather systems may actually retrograde over the next few days. This is expected to bring the Bermuda High pressure area closer to our area. Rain chances may drop somewhat as we head towards the 4th of July. However, there is a great deal of uncertainty with this forecast. We will still be in a very humid air mass so the slightest trigger can produce heavy rainfall. As I stated yesterday, it is very difficult to predict the timing and location of the rainfall in a pattern like this… The tropical Atlantic is quiet for now.

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AN UNSETTLED WEATHER PATTERN WILL MAINTAIN A CHANCE OF SHOWERS AND THUNDERSTORMS FOR SEVERAL DAYS

The combination of a stalled frontal boundary to our west, a trough of low pressure, and a moist flow around a high pressure ridge in the Western Atlantic will keep our weather quite unsettled for several days to come. You may have noticed that the chances of rain keep changing each day. This is due to the uncertainty that exists as to where and when the showers/storms will develop. For example, yesterday (Friday), there was a line of storms approaching Hampton Roads. The line north of the VA/NC border weakened while the line south of the border stayed intact for the most part. My Virginia Beach neighborhood only saw a period of light rain. Another area of light rain moved through during the night. This morning, a heavy thunderstorm moved just south of my area missing us again. There will be plenty more opportunities for rainfall but it is nearly impossible for forecasters to predict who will get the rain and when they will get it. The pattern is stagnant and the front may even retrograde to the west at some point. So, expect warm and very humid conditions to continue for several days with a continued chance of showers/storms. During rain-free and sunny periods, it will feel quite oppressive due to the relatively high dew points. Some localized flooding is possible so be alert and monitor the local media and NWS forecasts… Note that while there is a trough in the eastern part of the nation, there is an extensive ridge in the western states which is causing the intense heat out there.

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AN EXTENDED PERIOD OF UNSETTLED WEATHER SEEMS LIKELY AS A FRONT STALLS NEARBY AND A TROUGH IMPACTS THE AREA

It appears that we are in for an extended period of higher rain chances as a front stalls nearby. The combination of waves of low pressure developing along the front, a trough of low pressure setting up to our west and a very humid flow of air from the south and southwest should bring some opportunities for rainfall beginning later today or tonight through the next several days. While it will not rain much of the time, there should be occasional showers and thunderstorms, some of which could be heavy. It is impossible for weather forecasters to pinpoint when and where the rain will occur in a pattern like this. There may be some flooding issues as this pattern develops. The sun will be out at times, and during the dry and sunny periods, it will become very uncomfortable with all the humidity around. I know that this type of forecast creates problems for folks with outdoor plans but as I said before, it is very difficult to predict exactly when the rainy periods will occur. As it looks now, Saturday morning is likely to be one of those periods but that could change. So pay attention to your local forecast and monitor radar trends. Over the weekend, I will discuss the 4th of July forecast.

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WARMER TEMPERATURES RETURN TO HAMPTON ROADS… AS HUMIDITY LEVELS RISE AND A FRONTAL SYSTEM APPROACHES, RAIN CHANCES WILL INCREASE

Father’s Day should be a nice day overall with warm temperatures. A southwesterly flow around high pressure off the coast will bring in warm and increasingly humid air. Areas to our north and west will see a slightly better chance of showers and thunderstorms later Sunday. The current thinking is that most of Hampton Roads will be dry during the daylight hours on Sunday. Rain chances increase on Monday and on Tuesday showers and thunderstorms will be a good possibility. As I mentioned in yesterday’s post, there are some difference as to what the computer models are forecasting regarding rainfall chances and amounts Monday and Tuesday. Speaking of rainfall, most of Hampton Roads is running about average in total precipitation this year. Of course, we are now at the time of year when rainfall amounts can vary widely across the area due to the hit and miss nature of late spring and summer showers/storms… The frontal system should clear the area by Wednesday bringing drier weather, if the current forecast holds. Cooler temperatures along with lower humidity levels are expected to follow the front but I don’t believe it will be as cool as it was this past Friday.

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SATURDAY WILL BE A PLEASANT DAY WITH LOW RELATIVE HUMIDITY FOR THIS TIME OF YEAR… SOUTHWEST WINDS ON SUNDAY WILL BRING A RETURN TO WARM CONDITIONS WITH SLOWLY INCREASING HUMIDITY

The frontal system that blasted through the Mid-Atlantic States on Thursday brought very strong winds to the area. This resulted in extensive tree damage which caused power outages to many areas. There was some structural damage caused by trees or tree branches falling on homes and various buildings. Some folks are still without power as of this writing. In Hampton Roads, the peninsula was hit harder than the South-side. Winds gusted to hurricane force in some areas. The change in air masses was quite remarkable. Thursday was brutally hot and humid and Friday was cool, breezy, and much less humid. Strong winds aloft and the difference in the air masses were big factors in making this frontal system very potent. Rainfall varied across the area. My neighborhood didn’t pick up that much rainfall… less than a quarter inch.  This weekend will be very pleasant as high pressure builds into the region. The high will move offshore and the clockwise flow will result in a southwest wind on Sunday. A southwest wind at this time of year normally brings us warmer air temperatures and increasing humidity. No widespread showers or storms are expected this weekend but as I stated in previous posts, whenever you have very warm and humid conditions, it doesn’t take much to trigger a storm. So, don’t be surprised if there is a very isolated thunderstorm on Sunday but odds are, your area will not see any rain. Rain chances increase on Monday as a frontal system approaches. However, there is some uncertainty as to the chances of rain on Monday and Tuesday. I will have an update on Sunday on that. The tropical Atlantic is quiet for the most part right now.

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