April 23: Latest Storm Discussion, Rain Map

Today was a nice day across the area, with temperatures generally in the 60s and mostly sunny skies. Tomorrow should not be much different, in fact it should be even slightly warmer, however these nice conditions won’t last for long as the next storm approaches.

Tomorrow’s Forecast:

As with today, we are looking at dry and mild conditions across the area, though temperatures should be slightly warmer than yesterday in the area. We are looking at high temperatures in the mid to upper 60s in the north and western parts of the area, and in the upper 60s to the lower 70s for the New York City area. The immediate coast should not be as warm, with high temperatures in the mid 60s.

Meanwhile, rain should start to approach the area from our southwest. An intensifying storm that should bring us a wet start to the week is going to slowly move towards the northeast, bringing rain up to Washington DC, and thunderstorms in southwestern Virginia. This rain will eventually reach us on Saturday night.

Storm Discussion: Heavy Rain To Return

***A Red Alert remains in effect for this storm, indicating a greater than 70 percent chance of significant rainfall. Click here for more details.***

As I have previously mentioned, a large storm is going to affect the area between Saturday night and Tuesday, bringing heavy rain once again to the area. Making my forecast today was slightly more difficult, as the models have slightly changed with the timing of the storm, which I will show in more details below.

Rain is expected to begin affecting the area tomorrow night, spreading from our southwest. However, instead of the heavy rain beginning to fall on Sunday morning, the latest model runs now have the heavy rain starting late on Saturday night, and lasting through Sunday afternoon. At this time, in my 5-Day Forecast, I kept my forecast the same for Saturday night, however for Sunday I changed around the forecast, expecting heavy rain before noon followed by light rain, instead of going the other way.

Making Monday’s forecast was more complicated. We should continue to see light rain as the low pressure from Ohio approaches the area, however a few NAM runs have added another low pressure for Monday morning, which would bring an additional 1/4 to 1/2 inch of rain. While at this time I do not think that we should see this scenario, I am waiting at least until tomorrow to see if this solution is still shown.

The part of the forecast that has a higher confidence is that the low pressure in Ohio is eventually going to approach the area, redeveloping off the coast by Monday night. This is expected to bring another round of rain, possibly heavy at times, until Tuesday morning, which is when the rain is expected to slowly end. An additional 1/4 to 1/2 inch of rain is possible from this additional round of rain.

By the time that the storm exits the area on Tuesday night, we are looking at a general 1 to 2 inches of rain across the area, mainly in the higher end of that range, with locally higher amounts possible. After looking at both the latest and previous model runs, I created the rain map below. I considered the GFS as an outlier for the northern extent of the heavy rain, which it brings over an inch of rain well into Maine. The “Areas of 1.5″+” zone is where the best chance of over 1.5 inch of rain exists, though it does not mean that the entire area should be seeing over 1.5 inch of rain.

Longer Range: Potential Warm Spell

After the early April warm spell, temperatures have been generally near average, occasionally below average. This storm is expected to bring high temperatures in the mid to upper 50s, which is below average. Afterwards, however, it appears that we may see a warm up once again, starting in the middle of next week.

A storm in the Midwest is expected to bring a much warmer air mass into the area by that time, allowing for warmer temperatures. By Friday, high temperatures have the potential to return into the 70s, and in the warmer case scenario, as a few models have been showing, 80+ degrees may be possible once again on Saturday, however this is still uncertain.

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