12:00 PM (Fri.) | *Strong-to-severe thunderstorm threat late today/tonight along I-95…weather update for the SpaceX launch planned for Saturday…potential tropical activity in the Gulf of Mexico*
Paul Dorian
High-resolution forecast map by the 12Z NAM depicts one line of showers and thunderstorms associated with the pre-frontal trough near the I-95 corridor and a second line near the surface cold frontal boundary zone. Map courtesy NOAA, tropicaltidbits.com
Overview
A pre-frontal trough of low pressure will become the focal point for showers and thunderstorms late this afternoon and early tonight in the Mid-Atlantic region and some of the storms can reach strong-to-severe levels as they approach the I-95 corridor. A strong surface cold front will arrive in the same corridor late tonight, but it will encounter a more stable atmosphere likely not resulting in additional showers or storms. A much cooler air mass will arrive in the Mid-Atlantic region tomorrow night and Sunday and the month of June could actually begin with temperatures in the 40’s early Monday in some of the northern and western suburbs in the I-95 corridor. Elsewhere, unsettled weather continues across the Southeast US over the next couple of days and there can be some shower and thunderstorm activity in Florida on Saturday, but prospects for the 3:22 PM SpaceX launch at Cape Canaveral are perhaps a bit higher than they appeared yesterday. Looking ahead, there are indications that tropical activity may develop over the Gulf of Mexico in about a week to ten days and we’ll monitor those prospects in coming days.
Mid-morning surface (pressure) analysis reveals the positioning of the surface cold front in the Ohio Valley and a pre-frontal trough of low pressure over the Appalachian Mountains. Map courtesy NOAA
Evening strong-to-severe thunderstorm threat in the I-95 corridor
A strong cold front is crossing the Ohio Valley at mid-day and there is a pre-frontal trough of low pressure out ahead of it currently over the Appalachian Mountains extending from central Pennsylvania to West Virginia. This pre-frontal trough will actually become the main focus area for the I-95 corridor in terms of potential late day and evening shower and thunderstorm activity. As the atmosphere de-stabilizes later today, showers will expand in coverage in the vicinity of the pre-frontal trough and embedded thunderstorms could reach strong-to-severe levels by the time they close in on the I-95 corridor region at the end of the afternoon or early tonight. The best chance for strong-to-severe thunderstorms will likely be from Route I-95 and points to the west of there with the least chance of severe weather along coastal sections of New Jersey. I expect severe thunderstorm watches will be issued by the National Weather Service later today for much of the Mid-Atlantic region from Route I-95 and points west of there. By the time the surface cold front arrives in the I-95 corridor in the overnight hours, the atmosphere will likely have stabilized some reducing the chance for additional showers and thunderstorms.
A much cooler-than-normal air mass pushes into the Mid-Atlantic/NE US later this weekend and some suburban locations could start the month of June with temperatures in the upper 40’s early Monday. Map courtesy NOAA, tropicaltidbits.com
A cool air mass will arrive in the region tomorrow night after a warm day on Saturday and temperatures on Sunday and Monday will be below-normal for this time of year. In fact, there is the chance that some northern and western suburbs along the I-95 corridor start the month of June with temperatures in the upper 40’s early Monday.
12Z NAM forecast map for tomorrow afternoon with only isolated showers indicated across Florida. Map courtesy NOAA, tropicaltidbits.com
SpaceX launch attempt on Saturday afternoon
It has been 9 years since the US has sent its own astronauts into orbit and that drought was expected to end on Wednesday with a Florida rocket launch, but it was postponed until Saturday afternoon due to numerous showers and thunderstorms in and around the Kennedy Space Flight Center at Cape Canaveral. The next attempt will come at 3:22 PM on Saturday afternoon and while there is a chance for scattered showers and thunderstorms, it doesn’t look quite as threatening as it did a day or two ago. If the weather does cause a second postponement, a third attempt window will come on Sunday. Once the launch takes place, it will return the US to the business of human spaceflight in a public-private partnership (SpaceX/NASA). Not since the retirement of NASA’s space shuttle fleet in 2011 has the US possessed the capability to send its astronauts into orbit and the success of this mission known formally as SpaceX Demo-2 may shape the direction of spaceflight for a generation.
00Z Euro forecast map for 8PM, Saturday, June 6th with activity over the Gulf of Mexico. Map courtesy WSI, Inc., ECMWF
Potential tropical threat in the Gulf of Mexico in a week-to-ten days
The Madden-Julian Oscillation (MJO) is a tropical disturbance that propagates eastward around the global tropics with a cycle on the order of 30-60 days. It is a large-scale coupling between atmospheric circulation and tropical deep convection (thunderstorms). The movement of the MJO not only has wide ranging impacts on the patterns of precipitation, surface temperatures, and atmospheric circulation in the tropics, but it also influences precipitation and temperature patterns across the globe.
Research and empirical observations have found that the location or “phase” of the MJO is linked with certain temperature and precipitation patterns around the world. The MJO phase diagram illustrates the progression of the MJO index through different phases, which generally coincide with locations along the equator around the globe. When the index is within the center circle, the MJO is considered weak, meaning it is difficult to discern. Outside of this circle, the index is stronger and will usually move in a counter-clockwise direction as the MJO moves from west-to-east. The latest computer model forecasts of the MJO index generally propagate it into phases 1 and 2 during the first ten days or so of the month of June and this tends to favor tropical activity in or near the Gulf of Mexico region this time of year.
Meteorologist Paul Dorian
Perspecta, Inc.
perspectaweather.com
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