The rain continues

Synopsis:

An upper level low continues to hang tight over the Great Lakes while low level disurbances rotate around it toward New England. Today and Thursday will feature clouds and frequent showers with temperatures around 10 degrees below normal. A slow warmup through the weekend and next week will follow as the upper low lifts northeast.

Discussion:

Shortwave approaching from the lower Ohio Valley today will provide isentropic lift over the region today. With abundant low level moisture and PWATs climbing to 1.5" this afternoon, we'll see frequent showers today, heavy at times. Today will feature clouds through the day, keeping temperatures in the upper 60's to near 70 which will strongly limit surface based instability. However, with the cold pool of air aloft, elevated convection will be possible this afternoon, and some of these storms could produce hail and gusty winds. Certainly they will produce downpours, and we will likely see some flash flood warnings issued in the northeast once again today.

On Thursday, very similar conditions to today. The upper level low will be in the process of weakening and openning up, while advancing eastward. This will allow a front to cross the region, again increasing isentropic lift and triggering a round of showers and thunderstorms, downpours possible, as always. Persistent clouds as a warm frontal boundary remains to our south will keep highs again down around 70.

The upper low will continue openning and lifting to the northeast on Friday, however it will also continue to affect our region with cold air aloft, cyclonic flow, and abundant moisture keeping clouds and showers/thunderstorms in the forecast. However, temperatures will rebound back into the mid to upper 70's ahead of ... the next upper low.

On Saturday the next chapter of upper lows begins. The low will bring a reinforcing shot of cold air aloft, with a strong jet providing upper level divergence over the region. This will generate showers and afternoon thunderstorms. Winds out of the west will still try to bring a few periods of sun, and will help temperatures into the mid 70's.

Disagreement between the GFS and ECM comes into play by Sunday with the GFS keeping flow more zonal while the ECM is more robust with the amplitude of the upper low. Per the GFS, Sunday would be dry, with partial clearing. Per the ECM, clouds and showers remain. Monday, a second piece of energy rotates south into the region bringing clouds and showers. Tuesday, we could dry off, but temperatures will remain on the cool side behind the low. Wednesday, the ridging over the central US begins pushing eastward with surface high pressure moving into the Ohio Valley. This should be the start of a warm up back to seasonal or slightly above normal temperatures by the end of next week.