Northwest Florida Weather - 11-17-2016 - Drought Worsens with Little to No Relief

Latest Drought Monitor for Northwest Florida. Map data provided by the National Drought Mitigation Center (NDMC), United States Department of Agriculture (USDA), and the National Oceanic and Atmospheric Administration (NOAA).

The latest drought monitor was released today, and it does not bring good news. Unfortunately, the drought has worsened. Much of Northwest Florida is now in a "Severe Drought." While there are no official burn bans in effect right now, outdoor burning is strongly discouraged. In fact, the Florida Forest Service is not issuing any authorizations for acreage or pile burning in the Blackwater Forestry District (Escambia, Santa Rosa, and Okaloosa Counties). The drought is highly affecting our soil moisture as well.

The Keetch-Byram Drought Index (KBDI) essentially measures the soil moisture. Above is the average value by county across Northwest Florida.

This is the Keetch-Byram Drought Index (KBDI) data from the Florida Forest Service. The KBDI assumes that the top 32 inches of soil can hold up to 8 inches of water. A KBDI of 0 means that the soil is water-logged and can't hold any additional water; on the other hand, A KBDI of 800 means that the soil is completely dry. Right now, Okaloosa, Walton, and Holmes Counties are the driest counties not only in Northwest Florida, but the entire state. This dry soil can lead to an enhanced wildfire danger. Unfortunately, there is very little in the way of rain in the forecast.

12Z (6 AM CST) run of the GFS model. Black solid lines represent isobars (lines of constant pressure). Red and blue dashed lines represent 1000-500 mb thickness. Shaded areas represent 6-hour precipitation accumulation. Fronts drawn in by myself.

While we do have a cold front moving through, it looks like rain will fall apart as it approaches. I am forecasting only a 10% chance of rain, and that might be a bit optimistic. Even if we do see rain, totals will be less than 0.10". Very dry air will follow behind the cold front as well as breezy conditions.

This is a model skew-T from the 12Z (6 AM CST) run of the GFS at KVPS (Destin-Fort Walton Beach Airport). Focus on the upper left diagram. The dashed white diagonal lines are temperatures in degrees Celsius. The solid white horizontal lines are pressure. As you head up the diagram, you go up in the atmosphere, and pressure decreases. The solid red line is the temperature profile through the atmosphere, and the solid green line is the dew point profile through the atmosphere.

Let's look at the above model skew-T. This is valid as of noon CST on Sunday at the Destin-Fort Walton Beach Airport in Valparaiso. It will be rather cool with this particular model only showing mid-50s at the surface at this time. But check out the dew point: 11 degrees Fahrenheit. That is bone-dry. If we go up just a little bit in the atmosphere (roughly 4,500 to 5,000 ft.) at 850 mb, it's even drier. The temperature at 850 mb is 47.3 degrees F., but the dew point is -35.5 degrees F. That is an 82.2 degree difference between the temperature and dew point.

After a bunch of math that I won't bore you with, you get this:
Relative humidity at the surface: 16.4%
Relative humidity at 850 mb: 2.2%

In other words, very, very dry conditions are expected after the cold front passes through. That coupled with winds around 10 mph could produce very dangerous conditions for wildfires. Fire Weather Watches or Red Flag Warnings may become necessary.

But that's not the only threat. Some of the coldest air of the season so far will be filtering in behind this front. Many areas could see their first freeze of the season. Here is a look at Saturday Night's forecast:

This already would be the coldest air of the season for most areas. Widespread 30s can be expected across much of Northwest Florida. But, the winds will prevent the temperatures from falling below freezing for most places. Now, not to outdo Saturday night, here's Sunday Night's forecast:

Even colder temperatures possible on Sunday night. With decreasing winds, it will allow our temperatures to fall quite a bit more. Many areas north of the bays could see their first freeze of the season. The National Weather Service in Mobile (which covers Escambia, Santa Rosa, and Okaloosa Counties) said this in their latest forecast discussion:

It will then be dry and cold over the weekend in the wake of the front and surface high
pressure building in from the north. Will monitor for likley [sic] Freeze
Watches and Warnings over the weekend...

Low temperatures Saturday night behind the cold front will fall into
the mid to upper 30s, with lows Sunday night ranging from 25 to 32
degrees inland areas, and from 32 to 38 degrees along the immediate
coast.

So, in summary, very little, if any, rain is expected through the weekend. A cold front will move through on Saturday, which will bring the coldest air of the season. Freeze Watches/Warnings will likely be issued this weekend. Very dry air and breezy conditions this weekend will lead to dangerous wildfire conditions, and Fire Weather Watches/Red Flag Warnings may be required.

NW FL Weather (11/15/2016) - Sunny & Dry, But Turning Cooler

The forecast sounds like a broken record: sunny and dry. Drought conditions continue across Northwest Florida. In fact, much of Northwest Florida is under a "Moderate Drought" (except for a small sliver of northern Santa Rosa County where there is a "Severe Drought").

Current Drought Monitor for the State of Florida. Map courtesy of the National Drought Mitigation Center (NDMC), U.S. Department of Agriculture (USDA), and the National Oceanic and Atmospheric Administration (NOAA)

This map will be updated on Thursday. Without any rainfall in the next 7 days, our drought will continue to gradually worsen. The drought is taking a serious toll on soil moisture. Here is the Keetch-Byram Drought Index for Northwest Florida.

Current Keetch-Byram Drought Index from the Florida Forest Service. Used Blackwater and Chipola Forest District maps.

The Keetch-Byram Drought Index (KBDI) measures the amount of water in the top 32" of soil. It is assumed that the maximum amount of water in that top layer of soil is 8" of water. The index goes from 0 (absolutely wet) to 800 (absolutely dry). So, Okaloosa County is currently the driest county on average according to this index with a value of 666. This means that there is 6.66" of water missing from the soil. Unfortunately, with the dry soil, this helps provide fuel for wildfires.

Without rain in our forecast, we focus purely on the temperatures. As the cold front moves through Saturday morning, it will not bring a substantial rain chance (right now, less than 10%). But, the front does bring cooler, drier air.

Animation of the 18Z (12 PM CST) run of the GFS model showing mean sea-level pressure (black solid lines), 1000-500 mb thickness (red and blue dashed lines), and 6-hr. precipitation accumulation (shaded). Fronts drawn in by me.

The cold front will move through Northwest Florida on Saturday morning. Temperatures will be warmer the further east you are, but will fall once the front passes. Here are your 7-day forecasts for inland and coastal regions (updated since video above):

The National Weather Service in Mobile does note that Frost and/or Freeze Warnings may be required by Sunday night. Several areas could see their first frost and first freeze of the season. Interestingly, Crestview has already had their first freeze of this season (November 11):

Believe it or not, Crestview #FLwx dropped to 32° degrees this morning, making it the first freeze this season. pic.twitter.com/Nv5QB3Jm2p

— Cameron Young (@wx_cam) November 12, 2016

So, prepare for more dry weather. Cooler weather will make its way back down to the Gulf Coast by this weekend and early next week.