Virginia Weather: Christmas Eve

Yesterday was cool, still, and mostly cloudy.

It has been a rainy day in Jersey, VA, thus far.  The weather is slightly warmer than yesterday, as the cloudy evening prevented a large temperature fluctuation at night.

The National Weather Service (NWS) in Albuquerque forecasts a cloudy day today, with a high temperature of 51 F. The winds will be 6-9 mph from the west.  This evening will be rainy after 1 am, with a low temperature of 35 F.  Winds will be light and from the west.

The visible satellite imagery shows overcast skies organized in bands over the entire state today.

The enhanced infrared satellite imagery shows that some of the bands are relatively thick; the band structure of these clouds is apparent in this image.

The water vapor imagery shows a large frontal boundary draped across New England and the Midwest, with most of the moisture piled up ahead of this boundary.

The 12Z sounding from Sterling, VA, shows that the atmosphere was saturated all the way up to about 600 mb.  Above this level, the air is still quite humid.  There was 1.03 inches of precipitable water present in the column. There was no Convective Available Potential Energy (CAPE) and no Convective Inhibition (CINH).  There was a large, deep thermal inversion near the surface, and the 0-3 km average lapse rate was 1.9 C/km.

The hodograph shows 48 kts of low-level shear (mostly directional changes) and 60 kts of deep-layer shear (mostly speed changes).

The surface observations (from the SPC Mesoscale Analysis Map) show cool temperatures, cloudy skies, high humidity (as told by low surface dewpoint depressions) and light southwesterly winds.  There are no major frontal boundaries present over the state so far today.

The surface pressure chart shows that the high pressure system from yesterday has continue moving east, leaving us under moderately high pressure (1022 mb).  There are no strong pressure gradients over the state this morning.   The RAP shows that the pressure will stay relatively constant, and no strong gradients are expected to develop over the next six hours.

Synoptically speaking, the 300 mb NAM chart (from Unisys) shows strong zonal flow over the state.

The 500 mb NAM chart shows a stripe of stronger vorticity passing through the central part of the state.  Embedded in this stripe is a small vorticity maxima that will pass through Northern Virginia later this evening, contributing to some Positive Vorticity Advection (PVA).

The 700 mb NAM chart shows some rapidly-rising air over the state today.  It is not very strong, but is centered over the Richmond area this afternoon.

The 850 mb NAM chart shows some Cold Air Advection (CAA) moving in from the northwest from West Virginia by 0Z.

The Precipitation chart shows that our area should experience somewhere around 0.25 inches of rain, most of which has already fallen.

I expect the rain to taper off through the late afternoon and early evening hours here in Jersey, VA, though Northern Virginia may see a little more as the vorticity maxima passes through.  I do expect the skies to remain cloudy tonight, the winds calm, and the temperature to drop only slightly, with the heavier cloud cover.  In the western part of the state, the temperature may drop a little lower, given the approaching CAA.

I think I left the White Christmas back in New Mexico, if you can believe that.

Thank you for reading my forecast.

The upper air soundings and mesoscale analysis plots are from the Storm Prediction Center website.
The forecasted upper air soundings are from
The surface observation and upper level charts are from Unisys Weather.
The satellite data is from NASA – MSFC


About highplainschasing

This blog is about my tales in storm chasing. My name is Seth Price and I am an instrumentation instructor at New Mexico Tech. My amateur radio call sign is N3MRA.
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