Monday, October 28, 2013

Halloween Week Forecast: Warmer through Wednesday, then a stormy Halloween

To start your week off, we're going to focus on weather through Halloween. The big picture is increasing moisture with warmer temps each day, then a frontal passage and precipitation for Halloween. Get the details below.

Visible Satellite Imagery at 1402 UTC (9:02 AM CDT)
We started this morning off with a large area of fog across the Mid-South. As a result temps will sit near 60 for much of the morning but as fog starts to clear, expect peaks of sun this afternoon which will help bring temps into the low 70's. Southerly wind will slowly increase moisture tonight, this combined with mostly cloudy conditions will limit temperatures from falling much below 60 in the metro.

Weather Prediction Center's 60 hour surface forecast. This map shows the Mid-South well into the warm sector with a warm front far to our north and a cold front still well to the west at 12Z Wednesday (7 AM CDT)
Tuesday looks quite similar to today, with the main difference being less fog in the morning. This will allow for periods of sunshine much earlier and as a result higher temperatures (near 80). As for overnight conditions, expect low temperatures to be warmer as a result of clouds, higher moisture content at the surface, as well as light to moderate winds. Wednesday is nearly a carbon copy of Tuesday with both days seeing an isolated to slight chance of a shower.

Storm Prediction Center Day 4 Outlook, highlighting the Mid-South in an area with a 30%+ chance for severe weather on Halloween.

Thursday is when things start to get tricky (pun intended!). An approaching cold front will provide the lift mechanism necessary for thunderstorms, while plenty of moisture (dewpoints in the 60s), modest instability, and strong wind shear should be present to fuel them. Details including intensity and timing will still need to be refined, but as of now plan on a wet and stormy Halloween with both heavy rain and severe storms a possibility. Currently, the majority of activity looks to occur during daylight hours, but we cannot quite rule out a lingering shower or thunderstorm Halloween evening. We'll have more details by Wednesday.

--William Churchill (Social Media Intern)

Addendum by MWN meteorologist Erik Proseus:

This time of year is not off-season for severe weather. In fact, November into early December is considered "secondary severe weather season" in the south. As seasons transition, it's not unusual to have strong fronts move through. In these transitions seasons of spring and fall, typically the jetstream is stronger and low and mid-level wind is also stronger, providing more fuel for the storms in the form of wind shear. The key ingredient that (sometimes) is not as plentiful is instability. Showers ahead of the main storms, timing offset from peak heating, and other factors can play a negative role in instability.  With the upcoming system, instability seems to be the biggest question mark, though we expect there will be enough to fuel storm activity. The more instability, the higher the potential for strong to severe storms.

Now is a great time to review your severe weather safety plans as we enter a season that can bring hazardous weather.  It's been some time since we've had to exercise those plans, so review ahead of time. Here is a good place to start.  School administrative personnel should also review how they get their severe weather information and what their plans are in case action needs to be taken during the school day.

You should also know where you will get your severe weather information. If you have the mobile app, now is the time to go ahead and spend the few extra dollars to add StormWatch+ to your app in the Alerts tab, then program in the specific locations you want alerts for. Links to our apps are available below if you do not yet have the app.

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