Saturday Weather Blog: Milder Air Returns

By: Meteorologist Ray Hawthorne Email
By: Meteorologist Ray Hawthorne Email

A quick note: We are still having occasional issues getting the most recent data to our web site. This does not affect the MegaWatt Doppler, but it could affect some of the images under the WCTV Weather Maps section of the weather page. I am working (as we speak) with our vendor to resolve these issues. The routine forecast products should be updating normally.

We are in the process of undergoing about a 35-degree temperature swing from this past Wednesday (when the high was 42 degrees) to this upcoming Monday (when the forecast high is 78). The anomalously deep trough that was covering the Eastern United States and causing cold air to pour in straight from Hudson Bay has now flattened out. We are in a zonal (i.e. straight west to east) pattern, meaning a milder Pacific airmass has scoured out the Polar airmass. A weak impulse embedded within the zonal pattern near the Sabine River is sending occasional cirrus our way. The cirrus could thicken up a bit late this afternoon and evening as the upper air impulse moves in our direction. Moisture is still lacking, especially in the middle and lower layers of the atmosphere, so rain is not expected with this system. Highs should still reach the mid 60s on average.

The upper level moisture should depart before sunrise Sunday, so temperatures and fog become forecast issues. With clearing skies overnight, temperatures will reach the dewpoint, causing patches of radiation fog to form. The winds near the ground are expected to be more easterly than southerly and this usually does not favor a widespread dense fog event for our viewing area. The low temperature will depend upon the amount of lower stratus or stratocumulus clouds that can move into our area from the Atlantic and/or Gulf of Mexico. This is always difficult to forecast. There are clouds with lower bases already moving westward toward Northeast and East-Central Florida. If those make it here, temperatures may not get much colder than the mid 40s. On the other hand, clear (or nearly clear) skies would allow temperatures to plummet into the mid or upper 30s. I am splitting the difference and carrying lower 40s for now, but we will monitor satellite data throughout the day. Either way, a frost or freeze is not very likely.

A ridge through a deep column of the atmosphere will build over us Monday and Tuesday, which means temperatures will continue to warm up. We expect highs to reach the mid 70s Sunday and the upper 70s Monday. There is some disagreement among the models regarding our next weather system. The GFS shows a fast-moving shortwave passing through our area Tuesday night, then quickly departing on Wednesday morning. The GFS's depiction of the wave is such that a cold front will pass through first thing Wednesday. Meanwhile, the ECMWF holds on to the ridge over us a little longer, which would direct the above-mentioned shortwave well to our north. This would cause the cold front to stall over the northwest part of our viewing area on Wednesday with a chance of showers. The UKMET looks more like the faster GFS, which would give us a somewhat better chance of rain Tuesday night or early Wednesday, followed by the cold frontal passage. We are carrying a 40 percent rain chance early Wednesday and we will refine this as the models solutions coalesce.

The pattern forecast by the global models does not favor any polar surges making it this far south, but they do forecast a stormier pattern toward next weekend and the following week.

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