Johnny BOSS

Current/Near Term

A beautiful Patriot’s Day is on tap as mostly sunny skies and warm temperatures surround the area. Current satellite imagery shows mostly sunny skies with a few clouds located in western MA. Temperatures are already near record highs in parts of the forecast area with a strong south/southwest flow. A red flag warning is currently in place for much of the area as warm, dry, and windy conditions will be in place through at least 0Z.

Short Term (Tonight-Wednesday)

GFS/NAM are in good agreement with moving a low pressure through southern Canada well north of the forecast area. A cold front will drag through the area in connection with this low between 03Z and 12Z. Both the GFS/NAM brings this front through the area mostly dry. Frontogenetical forcing is relative weak as the front crosses the area. A dry forecast seems plausible at this time with the passage of the front.

For Tuesday, the cold front will continue to move off to the east as CAA moves into the area. 1000-500mb thickness levels decrease slightly but it is not until Wednesday that cooler temperatures can be expected. Highs Tuesday will still manage upper 70s with mostly sunny skies.

Wednesday will see high pressure and cooler temperatures under mostly sunny skies. GFS and NAM MOS are in fair agreement with lower to mid 60s inland with cooler temperatures near the immediate coast.

Long term (Thursday-Monday)

Shortwave will pass to the south of the region Thursday with minimal moisture available. Will go with dry conditions with temperatures rebounding slightly from Wednesday into the upper 60s to lower 70s.

Much uncertainty remains in the Friday-Saturday timeframe. A shortwave trough will dig south and slowly track northeast through the period. Model ensembles remain very uncertain in the timing and track in pushing two low pressures through the area. However, the potential for a fair amount of precipitation looks possible during this time period.

Verification

Boston reached a high of 87 on Monday breaking the old record of 84 set in 2003. Models had a good handle on bringing extreme temperatures into the region. Red flag warning criteria was not meet as per the requirements by the NWS. Not all of the following were met: 1) a sustained wind average 15 mph or greater 2) relative humidity less than or equal to 25 percent and 3) a temperature of greater than 75 degrees F.Temperatures did surpass 75 but sustained winds averaged 9 mph while the RH averaged 59% with a low of 34% at 2:00pm.

Short Term

Both GFS/NAM did a good job with moving the cold front through the area dry as not enough forcing was in place for precipitable accumulation. For the Boston area, high temperatures for Tuesday reached 84. This was higher than the models predicted. Mid-April mostly sunny skies attributed to this. With that being said, models showed a significantly cooler day for Wednesday which was experienced. BOS hit a high of only 62 which both the GFS and NAM MOS handled well.

Long Term

Models are still having difficulty in the evolution and development of the short wave trough which will affect the area during this time frame. Models develop a cutoff low across the Southeast and into the Gulf of Mexico this weekend and then diverge in its evolution. 12Z GFS ejects the cutoff and moves it northeast into our area in the Sunday time frame. GFS has a less amplified trough and moves the low further east than the other models. On the other hand the ECMWF UKMET and CMC all have similar solutions on slowing the progression of the low and moving it into our area Monday. For now, GFS is the outlier as it appears to not be handling this situation all to well. As is often the case with cutoff lows, the GFS looks to be the faster solution.

With that said, all models bring in rather significant QPF into the region. At this time, best rainfall chances appear to be Monday-Monday night as eastern portions of the area could see a greater than 1 inch event. As the low moves up the coast, a strong pressure gradient will lead to increased winds. This will have to be monitored.