Northwest Florida Weather - Rain Brings Good News and Bad News

Total rainfall through midnight Wednesday night predicted by the NAM (North American Mesoscale) model.

There is a good chance of something we haven't seen much of in Northwest Florida for quite some time. Rain! While this likely won't be drought-busting rain, 0.5 to 1 inch is not out of the question during the next couple of days. And, besides, it's more rain than we've seen in quite some time. Unfortunately, there is a down side to this rain, and that's the possibility of severe weather.

The Convective Outlook from the Storm Prediction Center (SPC) showing the possibility of severe weather across the state of Florida. This map is valid until 6:00 AM CST Tuesday.

Yes, we have the potential of severe weather tonight (Monday night) into Tuesday morning here in northwest Florida. The Storm Prediction Center (SPC) has outlined areas generally west of Highway 331 (including Escambia, Santa Rosa, and Okaloosa Counties) in a "Marginal Risk" of severe weather, meaning that isolated severe thunderstorms are possible in that area. This risk is valid through 6 AM Tuesday morning. The environment isn't too supportive of severe weather for tonight, but some thunderstorms are in the forecast. Let's take a dive into a bit of meteorology.

from pivotalweather.com & SHARPpy. This is a model sounding from the HRRR (High-Resolution Rapid Refresh) model. The solid red line in the upper left diagram is the temperature profile through the atmosphere, and the solid green line is the dew point profile. The closer the lines are to each other, the more moist the atmosphere is. On the left, the pressure levels are labeled in millibars (mb) decreasing with height, and the temperatures are labeled on the bottom in degrees Celsius. Winds are labeled on the right hand side of the upper left diagram in knots.

This model sounding (from SHARPpy) shows what the HRRR thinks the atmosphere will look like at 3 AM CST at KVPS (Eglin AFB). Let's go through some things working in favor of severe weather tonight.

• Sufficient moisture at and below 700 mb.
• Strong winds around 850 mb (winds around 40-45 knots, 45-50 mph)
• Warm air advection
• Sufficient helicity
• Sufficient shear
• Decent instability

So, we pretty much checked off all of our severe weather ingredients. But, keep in mind, this is just one run of one model, and the atmosphere doesn't always behave like we want it to. Let me discuss a bit about models. Models ingest data before their run. The model already has its initial forecast planned out, then it uses the observations and data it ingests to adjust its forecast. The model can either adjust its forecast to come closer to the observation or reject the observation. The model rarely, if ever, accepts an observation as absolute truth. This already causes inherent error. Plus, observations aren't taken everywhere, especially upper air observations. Thus, we as meteorologists have to try to figure out if the model is performing well with interpreting and interpolating data. You can see where a lot can go wrong already, but this topic is for another time. Back to severe weather.

So, with one run of one model, it looks like severe weather is a decent possibility. One thing to note is that this sounding indicates a "possible hazard type" of tornado. I generally use the "possible hazard type" as the worst-case scenario of what could happen. Remember, that is also dependent on if there are storms around. Let's look at the same model run to see what it predicts as far as future radar.

Same run of the HRRR as the model sounding came from. This is the 1 km above ground level reflectivity forecast. Essentially, this is a future radar product. This is valid through 9 AM CST Tuesday morning.

The model shows a broken line of showers and thunderstorms moving through the Florida Panhandle early Tuesday morning. Now, notice that the line in general appears to weaken as it moves further east. So, if you're in Panama City or Marianna, your severe weather chance will be lower. Before we move on, let's look at one more just to show the uncertainty.

This is the 4 km NAM (North American Mesoscale) model valid through 9 AM CST Tuesday. Showing the same product as depicted in the HRRR model animation.

You can see, this model nearly completely dissipates the line of storms before getting here. This is why there's still quite a bit of uncertainty, even in the short term forecast.

Overall, I think our severe weather threat is low tonight and tomorrow morning. Gusty winds will be the main threat with the stronger storms tonight. I can't fully rule out an isolated tornado, but I think the better chance of that happening would be to our north and west.

Going into Tuesday and Wednesday, we still do have a risk of severe weather across northwest Florida. Here are the convective outlooks from the Storm Prediction Center.

SPC's convective outlook valid from 6 AM Tuesday through 6 AM Wednesday.

SPC's convective outlook valid from 6 AM Wednesday through 6 AM Thursday

The second threat of severe weather looks to be primarily Wednesday morning across northwest Florida. Again, damaging winds look to be the primary threat with severe thunderstorms. An additional blog post will be published on this possible severe weather threat tomorrow afternoon.