May 21: Rain Chance Returns Sunday

Today was very warm across the area, with high temperatures reaching the mid to upper 80s. Starting from Sunday, however, the forecast becomes much more complicated, with significant changes made to yesterday's forecast.

Tomorrow's Outlook:

Tomorrow should already be colder than today, and with partly sunny skies, should lead to a comfortable Saturday, with high temperatures in the mid to upper 70s for most of the area except for Long Island, which should be in the upper 60s to lower 70s.

While the area should stay dry, clouds should begin to move in tomorrow afternoon ahead of a disturbance that should bring thunderstorms to western Pennsylvania and West Virginia.

**Longer Range Uncertainty**

For the longer range starting on Sunday, creating my forecast was harder than usual. The model solutions significantly differ on this time period on factors such as rainfall amounts and temperatures.

Instead of following the exact model solutions, I will look at each time frame in detail with the model solutions, then make my forecast based on my current thoughts on what the time period may end up being like. A summary of my thoughts can be found in my 5-Day Forecast, though the forecast will be discussed below in more details, including more possibilities.

Sunday And Monday (5/23-24):

For Sunday and Monday, the weak disturbance is expected to affect our area. What is likely at this time is that there should be cloudy skies, along with rain in at least parts of the area with the potential for locally heavy rain, which was also mentioned yesterday. What is uncertain, however, is where rain does or does not fall, the rainfall amounts if any, and the temperatures.

Reviewing the latest models, there is a wide variety in the rain amounts shown. The NAM, for example, has varied from a trace of rain on its 06z run, 1 inch on the 12z, 1/4 inch on the 18z, and more on the 00z. Looking at the overall scenario, we are going to have two rainmakers, the first being the disturbance to the west, and the second being an area of rain offshore that should move into at least parts of the area. As there is uncertainty with the exact rain location, I am currently going to mention a 60% chance of showers, locally heavy, which should produce 1/4 to 1/2 inch of rain, locally up to 3/4 inch.

Temperatures are also going to be colder. On Sunday, due to the clouds and rain, high temperatures are going to be chilly, though the temperatures are going to depend on where it rains or not. At this time, I am expecting Sunday's high temperatures to be in the mid 60s with some upper 60s possible, though if there is more widespread rain, possibly heavy, high temperatures should end up in the lower to possibly mid 60s. On Monday, due to remaining clouds and potential rain showers, temperatures are going to remain chilly, in the upper 60s to lower 70s.

Tuesday And Wednesday (5/25-26):

During this time period, we are going to see much warmer temperatures than Sunday and Monday. It is likely that we should not see rain during this time frame, though the main question is how warm it gets. I previously expected temperatures in the range of the upper 80s to lower 90s, however the majority of the models have trended colder, and some model runs do not even bring temperatures over the lower 80s.

For now, I slightly lowered my forecast high temperatures on Tuesday, expecting the lower to mid 80s, though it is possible that it could be slightly colder. At this time, I am leaning towards the warmer solution on Wednesday, as with 850 mb temperatures warmer than today, as well as a north wind, I do not think that Wednesday should be colder than today. I am currently expecting high temperatures in the mid to upper 80s, though if the models do trend warmer once again, high temperatures could be in the range of the upper 80s to lower 90s.

Wednesday Night Through Friday (5/26 Night - 5/28):

During Wednesday night, the model solutions have consistently shown a back door cold front approaching from our east. There is still uncertainty with the exact timing, meaning that it could end up reaching the area between Wednesday night and Thursday afternoon, though it should bring slightly colder temperatures along with the potential for scattered showers or thunderstorms. There is still a spread on high temperatures, especially due to timing differences, which could end up from the mid 70s to the mid 80s. At this time, I am leaning slightly warmer, expecting high temperatures in the lower 80s, though this can still change.

By Friday, the models show the warmer air mass briefly returning into the area before another cold front moves through. Warmer temperatures are likely to return on Friday, with widespread 80s possible again, however if the current model solutions verify, thunderstorms may be possible. This is still in the longer range and may still change, however this time period does have the potential to bring storms to the area.