SNOW FOR HAMPTON ROADS? Possbily…
Yes believe it or not it looks like there are going to be two ** POSSIBLE ** snow events in the Hampton Roads area over the next 2 days. L:et me explain and pay attention.
As many of you probably know there is such a weather phenomenon known as Lake Effect snow. This is found most commonly in and around the Great Lakes but there are other places around the CONUS (Continental 48 states) where we see the same kind of weather forces at work that create Lake Effect or in some cases BAT effect snow. One location is in southeastern Massachusetts around Cape Cod. When the Arctic air is extremely strong and you have due north winds coming down from Maine across Cape Cod that area will CAN get pounded by OCEAN/ BAY eEffect snow. But there are specific sets of criteria that must be met that will trigger Bay effect snows in the Cape Cod Massachusetts region.
Another area where this happens is in the Chesapeake Bay which of course leads to Hampton Roads. This phenomenon has been studied frequently and there are certain set of specific criteria which must be met. The high-resolution short-range models as well as the actual atmosphere itself indicate that there are going to be 2 chances or opportunities for effect snow events for Chesapeake Bay snow squalls.
The criteria involves a certain set of specific atmospheric conditions.
FIRST the winds must be North in the Bay straight southward into Hampton Roads. By NORTH we mean anywhere from 340° to 020 but the ideal wind is 360° or due north. (for those of you who are really SCIENCE illiterate and or don’t know anything about directions when meteorologists say North Winds — we mean the wind is blowing FROM the North to the South).
The other criteria that must be met is a significant temperature contrast between the sea surface temperatures in the Chesapeake Bay and the Arctic air in the atmosphere near the surface. The difference between the two must be at least 13 degrees Celsius.
It should be obvious that in order to have Chesapeake Bay snow squalls or snow showers you MUST have Arctic air in place across Eastern Virginia/ the Chesapeake Bay/ and the Delmarva.
This satellite image shows you what typically happens when you have moderate to heavy Chesapeake Bay snow squalls during Optimum conditions.
Here are some fairly recent radar images of heavy snow squalls in the Chesapeake Bay over the years which have developed because of the due north winds coming down the bay and the Arctic air in place.
FIRST POSSIBLE EVENT FRIDAY EVENING IN HAMPTON ROADS
As the coastal storm pulls away from the Middle Atlantic Coast … Arctic air will rush in to the coastal areas of the Middle Atlantic region. A strong spoke of energy or vorticity Max in the upper levels of the atmosphere around the circulation of the coastal storm may spark a localized heavy snow shower or snow squall Friday evening between 7–9PM.
High resolution 3km NAM model which is designed to handle very small features like this in the atmosphere is detecting a heavy rain and snow showers around 6–7pm in the Williamsburg Newport News area.
By 8 or 9 PM there is a localized heavy snow shower or snow squall impacting Norfolk and the northern portions of Virginia Beach.
Assuming that the model depiction of this Friday evening snow shower snow squall in Hampton Roads is correct ….this event is not a true Chesapeake Bay Lake Effect occurrence. However, the next event on Saturday morning is.
SATURDAY MORNING CHESAPEAKE SBAT SNOW SQUALLS?
This image shows the forecasted Temperatures at 1 miles above the ground (850mb) and as you can see they are extremely cold at around -14 and — 15c with even colder air coming southward from Baltimore down the Bay. The contrast between the relatively warm BAY water temperatures in the Chesapeake Bay and this Arctic air is greater than the 13° C requirement for the occurrence of snow squalls in the Chesapeake Bay moving into Hampton Roads and the lower Virginia Eastern Shore regions.
This text image shows the actual WIND Field which I have highlighted in Black across the entire Chesapeake Bay. Notice the wind barbs — — the direction of the Winds in the southern portions of the Chesapeake Bay — around 340° or 350°. Again this meets the criteria for Chesapeake Bay snow showers and snow squalls to develop in the southern portion of the day and impacting portions of Hampton Roads.
These next images are radar simulations from the Thursday midday 81z HRRR mesoscale model. Saturday morning 6AM there is a snow squall impacting Matthews and Gloucester in the Chesapeake Bay heading south reaching Cape Henry.
At Saturday 10 and 11am there is a full-on moderate or heavy snow squall impacting Williamsburg Jamestown New York James City Hampton Poquoson Newport News Norfolk Virginia Beach and Northern Chesapeake.
Exactly how long this activity will continue — assuming of course the model is correct — is uncertain. Aas long as the Arctic air is in place (it will be all day Saturday) and the winds that stay out of the perfect Direction across the southern half of the Chesapeake Bay… the snow shower and snow squall activity could continue into the afternoon hours.
Indeed the HRRR model is showing a snow accumulation up to 1 inCH in Hampton Roads from the snow showers and snow squalls
