Weekend Forecast Outlook

Update Fri @ 12:58 PM — Last night’s models continue to show showers developing in the entrance region of a jet streak as an upper air vorticity develops. The HREF on this with its simulated radar forecast superimposed on the currently forecast jet streak position—

HREF forecast for 1 PM Saturday shows jet streak (enhanced wind speed of the jet stream) and the simulated radar in the white box area (the left entrance region of the jet streak.) The reason—there is enhanced upward vertical motion in this entrance regions. Notice that the position of the jet streak is somewhat further east than yesterday’s graphic, showing that the position of the showers will be further to the east than previous forecasts. (Click on image for a larger view.)

The position of the jet streak may change again and so will the forecast. Currently, most models have a mix of sun and clouds for Saturday with widely scattered showers mostly mid-day and early afternoon.

For Sunday another jet streak approaches as a ridge in the center of the country moves eastward. This time we will be in advancing exit region of the jet streak which also has enhanced upward motion. A warm front slowly moves through with this feature and we’ll have the chance of thunderstorms and showers. Details unclear at this time. Based on the NBM, Sunday will be cloudy in the morning, then a mix of clouds/some sun and thunderstorms during the early and late afternoon.
The latest models suggest the possibility of strong storms Sunday

GFS forecast for Sunday 7 PM. Another jet streak approaches along with a warm front. Enhanced upward vertical motion (this time) in the in this region will result in showers and thunderstorms. Timing details unclear at this time.

Check back for my regular “Weekend Weather Forecast” this evening.

Updated Thu 11:26 PM — Tonight’s models continue with a limited period of showers on Saturday. Not all areas will see showers. The most likely period is 11 AM-2PM. The models differ on the location, The NBM is the most aggressive with the shower coverage .

Update Thu @ 9:04 AM —The latest models have backed off considerably on the rain forecast for Saturday. A much weaker surface low expected to form, triggered by a jet stream level trough. Just some showers expected. This forecast may continue to change.

ECMWF forecast for Saturday at 2 PM. Dip in the jet stream with moderately strong jet streak places us in the “left entrance region” of the jet streak (white box), an area of upward motion. (Click on image for a larger view.)

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