February 6, 2012

Monday Weather Update

A handful of records went down over the weekend – mainly high temperature records, but also a rainfall record in Key West because the Caribbean apparently thinks we’re approaching June? Also, a dry stretch at Vero Beach ends in 2nd place at 39 days thanks to 0.01” of rain, but Melbourne’s continues into a 40th day.

Estimated rainfall for the weekend – with essentially all the rain from the frontal system shunted north of the state, and with the development of 90L, the rainiest spot in the state actually ended up being in the south. Unfortunately, the really good rain has stayed mostly offshore of mainland Florida.

Statewide: A cold front lies across the peninsula this morning – HPC’s last analysis put it from Jacksonville to Perry, but it has since slid south somewhat. Behind that front, high pressure more or less dominates the bulk of the country. Over the weekend, we saw very light, very scattered showers ahead of the cold front, and ultimately little to note. In the meantime, we have Atlantic Invest 90L (yes, that’s right – a tropical designator in February) working towards Florida from the Yucatan channel. It brought over four inches of rain to Key West, not only breaking a 140 year old daily record, but also the all-time February daily rainfall record. Unfortunately, not much of the rainfall from 90L is really pushing up into mainland Florida, with only scattered showers reaching up the east to Indian River County. While 90L had a brief chance yesterday to become a Subtropical Storm and wipe our first name off the 2012 list, it should get sucked up into the cold front/upper trough moving in from the north.

The cold front is likely to stall out at some point in its push through the peninsula. Out west, yet another weak surface low spawned by a cut-off low will shoot by to our north, bringing a mid-week cold front, and potentially another this weekend. Cumulatively, this may finally bring some chilly, dry air into the northern part of the state for the late week.

It looks, however, like we’re really starting to lose the potential for much modification down into the peninsula from frontal systems. That’s not to say no more are possible, but it will take a much stronger push of arctic air than we’ve been seeing lately to pull it off.

However, we may need to turn an eye to our south. With fronts stalling out across the Gulf and Caribbean, there is a potential (albeit a small one) for extratropical or maybe even subtropical lows to form off the old boundaries and slide up to Florida in a similar fashion as 90L is doing.

NWS rain probability forecast for today and tomorrow. With 90L skirting by, rain chances are higher for the peninsula. By tomorrow, 90L will be dispersed, and lower chances for rain will exist on or near a stalled front.

Regions 1-2: No serious fire weather concerns in the short term with high enough humidity, light to moderate winds, and dispersions well short of 75. Wraparound flow from 90L may keep moisture high enough for fog the next night or two in Northeast Florida.

However, a string of weak fronts and high pressure keeping generally northerly flow this week should eventually work in enough dry air to allow for some afternoon minimum RHs around or below 35% late this week. With no other RFW criteria expected to be met, however, no fire weather watches or warnings are currently expected.

Wind and RH forecast from the NWS for late this afternoon – despite a cold front moving into the state, we’re not expecting to see much in the way of wind, or very dry air moving into the state.

Regions 3-4: With weak frontal boundaries expected to stall out at some point over the peninsula, its fairly safe to say that we’re not expecting a strong modification of the airmass over the southern bulk of the state. In addition, winds are currently forecast to remain light to moderate, and dispersions lower this week, further mitigating fire weather issues.

We may see a repeat of 90L again later in the week if another low can get formed off of an old, stalled frontal boundary. However, it’s no sure thing, so rain chances in general will remain low – but not zero - after today. Even now, it looks like the bulk of 90L’s rainfall will remain offshore, so that’s a bit disappointing.

Tropical: So, did you miss this section? Not too much to say that I haven’t already mentioned earlier in the email, but it looks like 90L’s short window to become Alberto yesterday has closed. This is probably mostly a fluke, but with cold fronts more likely to begin stalling, it’s possible to see another interesting low pop up over nearby tropical waters in the future. Apparently conditions are decent enough to at least force us to pay attention to the potential for development, although anything actually happening is clearly a long shot for several months yet.

Sean Luchs, Meteorologist - Florida Forest Service

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