HEADLINES ** 2 ND FROST POSSIBLE FOR THE SHEANANDOAH VALLEY THURSDAY MORNING 4/17??***

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1 HEADLINES DATA SHOWS CLOUDS WINDS VERY LOW DEW POINTS OVER NIGHT WHICH MAY SAVE THE DAY AND PREVENT MAJOR FROST FREEZE IN SOME AREAS WEDNESDAY MORNING ** 2 ND FROST POSSIBLE FOR THE SHEANANDOAH VALLEY THURSDAY MORNING 4/17??*** ====================================== It is now time to get down to Brass tacks..to make a good forecast and watch conditions see how developing the overnight hours and early on Wednesday morning. Of course I will be up especially early on Wednesday morning so I can track conditions by using something called the MESO -NET. This is a network of Weather stations which exists throughout the country but are not officially part of the NWS reporting stations. The MESO net reporting stations consist of people's own individual weather stations such as might exist at a vineyard or at a high school or along skyline drive or part of national park service or part of VDOT etc etc. Most of the reporting stations used in the MESONET are the high tech and very accurate and reliable. Unfortunately NWS and local TV stations very rarely take advantage of this fine network of information which is available for free... for people who know how to find it.

2 This image shows the way to short range weather model valid for dawn on Wednesday. As you can see the temperatures are impressively cold over much of West Virginia Virginia Southern North Carolina and much of central and Western Maryland. I have drawn in a blue line see you can see where the temperatures are at or below 25. This image seems to support strongly idea of a major Frost or Freeze which will hit much of these areas on Wednesday morning especially west of the Blue Ridge mountains. But there is some new data which is come up which may allow us to escape without a major hit.

3 In or to get a serious Frost and /or Freeze certain conditions have to happen. It is not simply a matter of getting a Min temperatures to drop below 28 for 3 hours or longer. That is a basic minimum requirement but there are complicating factors. 1. First skies have to be clear. It is the lack of cloud cover which allows the dew point condensation which produces a Frost. Keep in mind that a Frost is the same thing as morning Dew. The difference is that a Frost that occurs when the temperature at the ground is below 32. That's the only difference. 2. The winds have to be light and variable or Calm. You can have a temperature 25 for 5 hours at a particular location but if the winds stays up around 10 or 15 miles per hour...you will not get a Frosty of Freeze. That may be some scattered Frost but you will not see a Freeze condition. On the other hand you can have a temperature of 28 with no wind and you can get a serious Frost or Freeze. So the winds are very important. And on the small MESO weather features which might affect your farm or vineyard. 3. Tthe cold surface temperatures and the DEW point temperature HAVE to meet to produce the actual Frost. In other words if you have temperature of 25 but the Dew Point is you can have clear skies... and no wind but NO Frost. WHY? Because the surface temperature and the Dew point have "met"... There is NO saturation In other words there is air is cold but too dry to produce a Frost or Freeze. This next image is the latest radar picture. As you can see we slept significant rain over the eastern half of North Carolina Virginia Eastern Maryland up into the big cities the Northeast. The rain has ended over the western half of Virginia as well as far Western North Carolina and tlow West Virginia and Western Maryland.

4 This next image shows the latest surface map as of 6:00 PM. We can see the stalled front were slow moving cold front cutting through Western North Carolina... western Virginia...up into central Maryland... and eastern Pennsylvania. Notice the cold front is clearly marked on this map. However take a look behind the cold front-- over Kentucky Ohio and Indiana. I have highlighted with a thick brown line where the clearing vs. cloudy line is located and it's back and Western Tennessee and Western Kentucky. Notice that the temperatures are much colder...down into the low 30s in many locations. But there see extensive cloud cover all way back into eastern and central Illinois.

5 This means is that we still have a long way to go before skies clear out over Western Virginia... Western North Carolina and Western Maryland. ***The longer the sky stay cloudy during the overnight hours the less chance for a serious Frost or Freeze.** In addition take a look at the winds which remain fairly strong across the Ohio Valley. There are numerous reports of winds in Kentucky Ohio and Indiana gusting over 20 and 25 mph. This means that during the evening of overnight hours this area of strong winds will be moving into West Virginia...Virginia...North Carolina...and Maryland. ** The longer these winds stay up over 10 miles per hour the LESS chance of saying a significant Frost or Freeze early Wednesday morning. ***

6 In addition the short range weather models do not show the winds "de-coupling" or calming down until 5:00 AM over Western Virginia. This reduces the chance of saying a significant Frost / Freeze on Wednesday morning over most areas. Finally we can take a look at the forecasted Dew points. The short range models continue to pick up the nature of this cold and dry air mass coming in from the Midwest. As a result the data today showed due points are dropping significantly. Wednesday morning at Charlottesville Virginia of Wytheville Culpeper at 17 and Winchester and 14.

7 Yet the temperature forecast models show Winchester dropping to 23 by 7am. This separation of 9 between the temperature and the dew point is too far apart to support a widespread Frost/ Freeze. Take a look of Charlottesville with the temperature for Wednesday morning that is forecasted to be 27. Again with a Dew Point of The difference or spread between the two is 9 which again is too far apart to support a major Frost or Freeze. At Wytheville VA... The model forecast the morning low temperature of 20 and a dew Point of 18. Here the situation is ideal for a major Frost or Freeze... and that is the case throughout southwestern Virginia. In Culpeper the temperatures forecasted the 24 with the dew point of 18. These two numbers are fairly close to each other and this would support a light to Moderate Frost or Freeze SUMMARY Even though the morning temperature forecast for Wednesday morning wuld SEEM clearly support a major Frost or Freeze across much of the Virginia Piedmont...the Shenandoah Valley...southwest Virginia... the western third of North Carolina...the eastern third of West Virginia...central and western Maryland... there are some factors which may prevent a major damaging Frost or Freeze. The cloud cover is pretty deep and extends way back almost to the Mississippi River. The WINDS west of the Appalachian Mts are still quite strong and are going to take a long time before they calm down. As long as the winds stay " up" there will be no major Frost or Freeze. Third... the air mass in many areas is going to be too dry and too cold to allow for a major Frost / Freeze. The areas' most susceptible to a Frost or Freeze on Wednesday morning... Will be southwest Virginia and the northern portions of the Shenandoah Valley into central and Western Maryland.

8 The next full update of the around 7:00 AM WEDNESDAY. If you wish get Free samples of the kind forecasts I can produce for your SPECIFIC locations and /or more information about this potential FROST please feel free to me at the address below or on Besides this particular frost scare and the potential 2nd event around April we also have to deal with the developing El Nino which is going to come on like gangbusters and be a problem for the second half of the Summer and the Autumn. I would be more than happy to come out to your vineyard and take a look around and show you the various kinds of detailed forecasts I can produce which will help you stay ahead of the weather and could potentially save you from the big money problems. DT wxrisk.com OFFICE CELL