Chantal’s Weird Pressure. Local Rain Again?

July 9th, 2013 at 9:06 am by under Weather

Each tropical system is different.  It’s so interesting to me to see how every system has its own unique qualities.  Sometimes it is the heavy rain.  Sometimes it is a weird path or structure.  In the case of Chantal (so far) it is the pressure.

tropics

The latest information has Chantal at a pressure of 1010 mb (millibars).  To you that may not seem like anything, but to me it really sticks out.  Tropical storms and hurricanes are areas of low pressure by definition.  A tropical storm usually doesn’t have too low of a pressure, but it usually at least closer to 1000 mb.  For another reference our current pressure around here is about 1018 mb.  So to have a 50 mile per hour wind is impressive at this point with that particular pressure.  The storm was located near Barbados, and it is still moving quickly to the WNW at 26mph.  It’s amazing that it is not only staying together, but is also forecast to strengthen in the short term.  It is moving into an area of higher wind shear. The forecast track takes it through the Leeward Island chain.  Then on to the Dominican Republic and Haiti.

Forecast Track

Forecast Track

There is a pretty high confidence of it moving to that location.  IF it survives Hispaniola, then it would likely come out the other side as a weaker tropical storm.  After that it would probably head northwest towards the Bahamas as a weak trough breaks down the strong ridge to the north (temporarily).  Towards the weekend, it looks like the ridge would build back in to the northeast of the storm over the western Atlantic Ocean.  This would push it westward into either Florida, Georgia, or South Carolina.  It would probably be able to strengthen a bit as it encounters the warm waters of the Gulf Stream. However, it would also be fighting some wind shear.  That’s something that it hasn’t really had to contend with yet.  It’s very possible that it won’t make it that far.  The computer models are in good agreement on the track up to Hispaniola.  Then they diverge quite a bit.

Forecast Track Models

Forecast Track Models

Last night’s 0z (Zulu time) run of the GFS model had it going into Florida during the weekend.  However, the latest run 6z has it falling apart shortly after Haiti.  The European model also is not very impressive during the whole course of the storm.  So there basically is a low confidence in the forecast beyond 36 hours.  The shear is increasing on the system right now.  So that could impact the lifetime of Chantal if it weakens before landfall in the Caribbean.  There is also some fairly dry air at mid-levels just west of the system.  So we’ll see what happens. If it does make it past Haiti, then it would likely bring us some surf as well has a higher threat for rip currents over the weekend.

Locally, we did have some more rain this morning across parts of northeast North Carolina.

Radar This Morning

Radar This Morning

The rain has tapered off a bit, but we could all see a few showers and storms later this afternoon.  We generally have high pressure around, but the heat and humidity will lead to a few pop up storms.  Tomorrow there is only a slim chance for a shower or storm.  Then the rain chances will go up on Thursday and Friday as a cold front approaches from the northwest and stalls out near the region.

Forecast of Fronts/Pressure valid Thu 12Z

Cold Front Moves In

Map is from the Weather Prediction Center.

Meteorologist: Jeremy Wheeler

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