Saturday August 1 2020 Forecast

61 Comments

8:04AM

DAYS 1-5 ( AUGUST 1-5)

First of August, and first the weekend for discussion. Your pick of the weekend is today, which will feature plenty of sunshine and moderate humidity, light winds and coastal sea breezes. The only “thing” to watch for is the remote risk that enough lift is provided by a sea breeze boundary near or inland from the South Coast to pop an afternoon shower or two. This is a low risk and I would not cancel any outdoor plans over it. Sunday starts with sunshine but clouds will become dominant as the day goes on, this due to a warm front approaching the region. This front may generate a few showers as well, but for now it appears we will get through the majority of the day rain-free, with shower activity most possible late-day and mostly to the west. Some heavier thunderstorms will likely have formed west of the WHW forecast area closer to the warm front during the afternoon of Sunday, and if that is the case, we’ll have to watch for a couple of them trying to survive their way into portions of the region sometime Sunday night. Once the front passes, the humidity spikes and the heat returns for Monday, which will feature a risk for a few showers and storms popping up later in the day mainly well west and northwest of Boston well in advance of a cold front. This cold front will serve as a running board for tropical moisture heading northward up the Atlantic Coast in advance of Isaias, forecast to be a Category 1 Hurricane as it moves out of the Bahamas and parallels the coast of Florida over the weekend, then continuing its re-curve as it weakens to a tropical storm, center staying offshore of Georgia and South Carolina Monday, accelerating and probably moving over eastern North Carolina Monday night and continuing to accelerate while moving northeastward along (anywhere from just inland to just offshore of) the Middle Atlantic Coast Tuesday., at which time we may see tropical showers become more widespread along the front ahead of the system. With the typical track uncertainty to be taken into account, the current official forecast track brings the center of Isaias as a tropical storm, transitioning to post tropical, across southeastern New England late Tuesday night / very early Wednesday, at which time any rain and wind impact would be at maximum. We won’t know the details on either of these until we’re a little bit closer to the event, so the forecast below will reflect the forecast track, but expect tweaks to be made! Either way, expect rapid improvement as the system accelerates away so that Wednesday ends up as a very nice day.

TODAY: Mostly sunny to partly cloudy. Slight risk of isolated showers just inland from the South Coast during the afternoon. Highs 80-87. Wind variable up to 10 MPH with sea breezes.

TONIGHT: Clear. Lows 61-68. Wind variable under 10 MPH.

SUNDAY: Increasing clouds. Risk of mid to late afternoon showers, mainly west of the I-495 belt. More humid. Highs 78-85, coolest coastal areas. Wind SE up to 10 MPH.

SUNDAY NIGHT: Variably cloudy. Risk of showers. Slight risk of a thunderstorm. Humid. Lows 65-72. Wind S up to 10 MPH.

MONDAY: Partly sunny. Isolated showers and thunderstorms possible late-day, mainly outside the I-495 belt. Humid. Highs 86-93, cooler South Coast. Wind S-SW 5-15 MPH.

MONDAY NIGHT: Variably cloudy. Slight risk of a shower or thunderstorm. Humid. Lows 65-72. Wind variable 5-15 MPH.

TUESDAY: Mostly cloudy. Increasing risk for showers and a slight risk of thunderstorms. Humid. Highs 73-80, coolest coastal areas. Wind S-SE 5-15 MPH.

TUESDAY NIGHT: Cloudy. Widespread showers or rain likely. Chance of thunderstorms. Humid. Lows 65-72. Wind variable 15-30 MPH with potential stronger gusts, direction to be determined by the exact track of Isaias.

WEDNESDAY: Mostly sunny to partly cloudy. Humid. Highs 83-90. Wind W-SW 5-15 MPH, higher gusts.

DAYS 6-10 (AUGUST 6-10)

Most of this period should feature nice August weather. A frontal boundary may be close enough for at least some cloudiness and possibly a few showers around August 7 with another disturbance near the end of the period, but overall the majority of the time looks rain-free, but typically humid and warm.

DAYS 11-15 (AUGUST 11-15)

A weak block may form in the atmosphere (low pressure to south, high pressure to north in upper levels). This promotes surface high pressure to the north with a general maritime air flow (northeast to east) at the surface. Whether this persists the entire period is unclear. The general idea would be mostly dry weather but a lack of significant heat with this pattern. It’s also a low confidence forecast.

61 thoughts on “Saturday August 1 2020 Forecast”

  2. Good morning and thank you TK.

    A few questions related to The front Monday/Tuesday and the passage of Isaias.

    1. The Euro “almost” depicts a predecessor rain event. As of the last run, it looks like one, except the rain amounts do not meet criteria. Any chance of one developing, especially in conjunction with that approaching front.
    2. Is there any chance of tornadic activity depending upon the exact track of Isaias.

    Inquiring minds need to know these things.

    Many thanks

    1. I think we’ll kind of get a “HALF-PRE” sometime Tuesday during the day before whatever the core of the system has in store. The thing about that is it could just as easily set up west of this area.

      As far as a tornado threat it will come down to the exact track. East of centerline would be where you may see some kind of threat materialize. Based ONLY on the NHC forecast track, you’d have an early indication that if something like this were to occur, Cape Cod would be your greatest threat area.

  4. This loop looks pretty pathetic.

    https://www.weathernerds.org/satellite/?initsatsrc=On&initsatname=GOES16&initsattype=ir&initcscheme=ir1&initimdimx=1050&initimdimy=764&initrange=28.500000000000:-84.500000000000:20.000000000000:-70.500000000000&initloop=True&initnframes=20&initlightning16=On&initlightning17=Off&initltngfed=Off&initltngtoe=Off&initinterstates=On&initwarnings=On&initlatlon=On&initascata=Off&initascatb=Off&initascatc=Off&initascatamba=Off&initascatambb=Off&initascatambc=Off&initsst=Off

  6. Thanks TK
    I would not rule out an isolated tornado threat to the east if this makes landfall on the CT RI boarder as the NHC is showing at the moment. Areas to the west could get heavy rain.

  8. https://www.star.nesdis.noaa.gov/GOES/conus_band.php?sat=G16&band=09&length=12

    I agree that satellite presentation may not be great, but the Bahamas radar looks more impressive and the recon plane hasn’t shown a lot of weakening versus the storm’s baseline.

    I have some concern that there is a chance for easing shear when this thing is over water from northern Florida to first landfall in the Carolinas.

    Here’s why, east of a trof, there’s going to be a downstream ridge and I think that can be seen already on this water vapor loop. Then, once you get past NC, and it gets into the SW flow, that won’t necessarily be shear, in that sense that the storm will be moving in the direction of the winds aloft.

    And we are likely to be on the eastern side.

    1. That puts us in right front quadrant?? If that is so, does that area remain the strongest even in a post tropical storm?

      1. I believe that would put us with having more wind than rain which would mean more opportunities for tree damage and naturally, power outages.

  10. Wouldn’t be surprised if we have 75°-78° dew points especially on the east side of what is left of the circulation. Also probably some beautiful tropical clouds against a deep blue sky.

  11. The hurricane modesl, HWRF and HMON seems to want
    to take the center West of Boston. Could get interesting.

  12. Model followers: Don’t forget to discount the NAM until this thing is not really tropical anymore.

  13. Thanks TK.

    Based on satellite, Isaias appears to have collapsed. Not overly surprising given its environment. It did an effective job of fighting off shear and dry air yesterday, but once a storm falls behind in that battle if only for a moment, you risk disrupting the inner core and causing a total loss of organization. I suspect from here it will limp to the Florida coast as a weak to moderate tropical storm. Depending on the track, if it doesn’t go inland over FL, there may be a short window for restrengthening off the northern/central FL coast. But any chance Isaias had of ever exceeding Cat 1 intensity have ended this morning.

    Whether it goes inland or not, it’s still certainly in play to be a pretty big East Coast rainmaker, though still not sure how widespread the higher totals (2″+) will be.

    1. Thank you, WxW. Not that we have not known this for years, but you have one heck of a bright future. I’m beyond happy that you still post here.

      And Please know that is not to for one second diminish the many wonderfully knowledgeable folks here.

  15. GFS has stengthening in that window between northern FL and landfall in Carolinas. 1,006 to 996 mb. Not so focused on the actual pressures, just noting the projected pressure drop.

  17. 12z euro has a pressure drop btwn N Florida and landfall in the Carolinas. Not big, but the global models are consistent on that today.

  18. 1002 mb over east central mass at hr 96 with a 60 kt (850mb) jet right to the east of the track. Plenty warm, humid and unstable for decent mixing, would be my guess …..

  19. Thanks WxW!!
    I echo what the others have said.

    By the way, a fairly rare occurrence in that there has been more tropical activity in the Atlantic this season than the entire North Pacific. It is remarkably quiet in the North Pacific. In fact, the western North Pacific by only a couple of days missed setting the record for the all-time latest first tropical storm formation of the year.

    Worldwide tropical cyclone occurrence is only at 60% of its average through July. Quiet year!

    On a similar note, the US tornado count for July was at its second lowest on record. 1985 holds the number one spot for the least amount of tornadoes during the month of July.

    1. Hurricane Isaias inches toward COVID-19-weary Florida
      Hurricane Isaias gained momentum Saturday, swirling slowly toward Florida after hammering the Bahamas before dawn. Strong winds and heavy rain uprooted trees and ripped off shingles in an area that rings Nassau before heading back out to water for a 200-mile trek to Miami, and a possible march up the East Coast to New York. Forecasters at Miami’s National Hurricane Center estimated Isaias would make landfall late Saturday or in the wee hours of Sunday near Boca Raton, about 50 miles from the

        1. It’s from New York Post: Hurricane Isaias inches toward COVID-19-weary Florida

          Sent to me by a friend.

    2. I figured that area will receive 1 to 2 inches of rainfall, which is manageable. They will be west of the center of a very weak hurricane, which will take away from the wind intensity on that side. They probably get northerly winds shifting more to the west gusting in the 20 to 40 mph range most often with a few gusts into tropical storm force.

      I don’t know if the particular place is prone to any flooding when there is a quick heavy rainfall, but barring that, I don’t think your friend has much of anything to worry about.

  21. Looking at tad better?

    https://www.weathernerds.org/satellite/?initsatsrc=On&initsatname=GOES16&initsattype=vis&initcscheme=vis1&initimdimx=1050&initimdimy=766&initrange=29.250000000000:-85.500000000000:20.750000000000:-71.500000000000&initloop=True&initnframes=20&initlightning16=On&initlightning17=Off&initltngfed=Off&initltngtoe=Off&initinterstates=On&initwarnings=On&initlatlon=On&initascata=Off&initascatb=Off&initascatc=Off&initascatamba=Off&initascatambb=Off&initascatambc=Off&initsst=Off

    1. Love these loops JpDave.

      Yeah, it’s developing some thunderstorms on its northern side.

      Look at the storm over Miami and check out the citrus being ripped off to the east. Good west and southwest shear hitting Isaias

        1. At first I thought they had a bad thunderstorm with damaging winds wreaking havoc with the orange crop until I realized you meant cirrus. 🙂

  24. So, I think mid afternoon today, the hurricane hunters flew a high altitude dropsonde mission. If I recall correctly, they dropped 13 to 14 of them from 40,000 ft over the ocean just east of the Carolinas, down towards Georgia. That data should be in the 00z models. Looking forward to the set of runs and what they say.

  26. SpaceX’s Crew Dragon capsule departed the ISS at 7:34 this evening. There was just a fly-over starting at 8:37. My son and I went outside and were amazed that we were able to see both vehicles. The capsule was trailing the station by about a thumb’s width – an amazing sight!

  27. Looking at the recon plane data, I think one could argue the winds being brought down to 55 or 60 mph.

    I understand that the NHC does not like to make drastic changes and there is a lot of good in that philosophy.

    As I see their pre-11 pm advisory and outlook, the NHC shows this entity being a hurricane off the Fl coast and a tropical storm landfalling in SC

    I hope that doesn´t portend a casual attitude in SC because I think the models are showing the storm gets its act together some before landfall in SC/NC and I think what comes ashore in the Carolinas is likely to be a bit stronger than what is off the coast of FL currently.

    I believe the wind numbers should be greatest at SC landfall to try to get this idea across.

  28. https://www.pivotalweather.com/model.php?m=gfs&p=sfcwind_mslp&rh=2020080200&fh=36&r=conus&dpdt=&mc=

    https://www.pivotalweather.com/model.php?m=gfs&p=refcmp&rh=2020080200&fh=36&r=conus&dpdt=&mc=

    Weakest projection in pressure, radar simulation continues to look sheared

    https://www.pivotalweather.com/model.php?m=gfs&p=sfcwind_mslp&rh=2020080200&fh=54&r=conus&dpdt=&mc=

    https://www.pivotalweather.com/model.php?m=gfs&p=refcmp&rh=2020080200&fh=54&r=conus&dpdt=&mc=

    Pressure fall before SC landfall, radar simulation looks better, heavy echos wrapping around north semi circle

    https://www.pivotalweather.com/model.php?m=gfs&p=refcmp&rh=2020080200&fh=72&r=conus&dpdt=&mc=

    Radar simulation looks good with center over NYC, pressure has maintained fairly decently from landfall, still at 1,000 mb

    I still think this could be a sneaky 2-4 hr tropical storm wind event in eastern Mass.

    Onto the Euro 🙂

    All images courtesy pivotal weather

  29. Always be wary of the warm front. Cell in eastern PA this morning near Reading and Allentown made for an interesting end to my night shift. Issued my first 2 career tornado warnings for it. Will see when I wake this afternoon if it actually produced anything but it looked pretty good for quite awhile. That area is tough in terms of a lack of low level radar coverage. Extreme rainfall amounts in the Reading, PA area also with the city there setting a single day record for August. Bad flooding ongoing around there.

    1. Wow! Although I don’t want anyone hurt or anyone’s property
      damaged, at the same time I want your warning/forecast
      to be verified. Does that make any sense.

      Best of luck WxWatcher

      FWIW, the cell East of Allentown looks to be rotating.
      Don’t think it warrants a warning just yet, but it is a watcher, I think.

  30. Isaias looking much healthier this morning.

    https://www.weathernerds.org/satellite/?initsatsrc=On&initsatname=GOES16&initsattype=swir&initcscheme=vis1&initimdimx=1050&initimdimy=764&initrange=30.750000000000:-86.500000000000:22.250000000000:-72.500000000000&initloop=True&initnframes=20&initlightning16=On&initlightning17=Off&initltngfed=Off&initltngtoe=Off&initinterstates=On&initwarnings=On&initlatlon=On&initascata=Off&initascatb=Off&initascatc=Off&initascatamba=Off&initascatambb=Off&initascatambc=Off&initsst=Off

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