The first official week of summer brings us warm temperatures in the upper-80s (low-90s interior). Early in the week, there will be chances each day for scattered showers and thunderstorms, particularly over inland areas. South facing shorelines should enjoy cooler temperatures with the possibility of sea breezes developign. A cold front passes Wednesday, bringing chances for more organized precipitation. Behind this, skies should clear up but temps remain warm.
Rest of today – mostly sunny with high temperatures around 90ºF. Chance for scattered showers and thunderstorms in the afternoon. Coverage would be spotty at best but with plenty of moisture available, any storms could produce heavy rain. Overnight lows around 70ºF.
Weather Prediction Center surface forecast for 8PM Tuesday.
Tuesday – similar to today, with high temperatures peaking near 90ºF and mostly sunny skies to start, then more clouds and some scattered showers and thunderstorms possible later in the afternoon. Overnight lows in the low-70s.
Wednesday – a cold front approaches from the west and brings us a better chance for organized showers and thunderstorms later in the day. These storms may be weakening as they hit the area if they arrive late in the day with sunlight diminishing. High temperatures again around 90ºF. Overnight lows in the low-70s.
GFS model 500 mb height, relative velocity, valid for 2PM Thursday.
Thursday– behind the cold front, skies should clear up as high pressure builds. However, temperatures will remain warm in the mid-80s with downsloping westerly winds. Overnight lows around 70ºF.
A slow moving low pressure and upper level low will result in the potential for isolated thunderstorms through the weekend with temperatures in the low-80s. Best chances for these diurnally driven thunderstorms would be in the afternoon hours. There’s a good amount of moisture in the air this weekend with steady southerly flow, so these storms could produce heavy rain, though severe weather is not anticipated. Past this weekend, a warmup to the mid-upper-80s (90s in interior) is forecast as upper level ridging and high pressure builds next week.
Saturday – fog early with cooler, marine flow. Temperatures warm into the low-80s with chances for scattered showers and thunderstorms particularly north and west of the city. Overnight lows in the upper-60s.
Weather Prediction Center surface forecast for 8AM Sunday
Sunday – Similar pattern to Saturday with partly sunny skies, isolated showers and thunderstorms developing later in the day particularly west of the city. Overnight lows in the upper-60s.
Monday – this pattern persists with partly sunny skies, highs in the low-80s and chances for isolated PM thunderstorms. Overnight lows in the low-70s.
GFS model 500 mb temperature, height, and wind forecast for 8PM Tuesday
Tuesday– high pressure builds offshore, with upper level ridging and 500 mb temperatures increasing, we should see sunny skies and very warm temperatures nearing 90ºF. Overnight lows in the mid-70s.
We have a muggy, strormy, and warm start to the weekend with temps in the 80s. Tomorrow, a cold front sweeps through in the afternoon. This will bring relief from the humidity and heat. High pressure builds in going into next week with temperatures back to seasonable ranges in the 70s. We should see an extended period of dry, sunny weather as a result.
Rest of today – mostly cloudy overall with high temperatures in the low-80s. Some shortwaves and surface troughs moving through will serve as the focal point for thunderstorm development. Plenty of moisture in the atmosphere today to tap, so storms could produce heavy rainfall, and if enough hit the same locations via training/backbuilding there is potential for localized flooding. Overnight lows in the upper-60s as storm chances continue with fog possible late.
GFS model precipitable water at 8PM today, with values as high as 2.00″ around NYC.
Saturday – clouds diminishing during the day with high temperatures in the mid-80s. A cold front moves through in the afternoon, but will not have the benefit of having as much moisture as today to tap into. Still, an isolated thunderstorm is possible. Downsloping winds behind the cold front should help dry and warm things up. Overnight lows in the low-60s.
Sunday – high pressure starts to build and skies remain mostly sunny with high temperatures in the mid-70s. Overnight lows around 60ºF.
Weather Prediction Center surface forecast for 8AM Sunday
Monday– high pressure continues to build and provide us another sunny day with high temperatures in the mid-70s. Overnight lows in the low-60s.
We have summery temperatures in the low-80s to start the weekend. Some storms are possible overnight as a cold front swings through. Saturday sets up to be another nice day with high pressure building. Sunny skies and more seasonable temperatures in the mid-70s. By Sunday, a storm system approaches bringing possible showers. Next week, we may see a prolonged period of wet weather, in part affected by tropical moisture from a potential Tropical Storm Arthur.
Rest of today – a warm front has already pushed through the area earlier this morning. Warm, southwesterly winds will help temperatures rise well into the upper-70s and low-80s. Clouds are likely to increase as a cold front approaches slowly from the northwest. Overnight lows in the low-60s as the cold front moves through, bringing low chances for showers and thunderstorms.
Weather Prediction Center surface forecast for 8PM Saturday
Saturday – high pressure builds in behind this cold front. This should yield a sunny day with high temperatures in the mid-70s. Overnight lows in the low-50s.
Sunday – a storm system will be approaching from the west. Rain chances will increase late with mostly cloudy skies and cooler temperatures in the mid-60s. Overnight lows in the low-50s.
Monday– rain chances continue due to the influences explained below. High temperatures remain cool, in the low-60s, with mostly cloudy skies expected. Overnight lows in the low-50s.
Potential Subtropical or Tropical Storm Arthur’s Impact on Our Weather
Next week, we may be in for an extended period of dreary, wet weather as the storm system mentioned above interacts with a potential tropical storm that’s currently forming over the Florida Straits. Actually, regardless of whether this becomes a full-fledged tropical or subtropical storm (which would be named Arthur, and the first named storm of the 2020 Atlantic Hurricane Season), it would still have the potential to bring tropical moisture our way. The interaction between these two storm systems, plus the forecast for a an area of blocking high pressure forming north of them means that we could see chances for rain well into mid-week next week.
National Hurricane Center’s forecast outlook for the Atlantic Basin, showing an 80% chance for a disturbance over the Florida Straits to become a subtropical or tropical cyclone
GFS model 1000-500 mb thickness, surface pressure, and precipitation for Tuesday, showing this offshore storm interacting with one over land
GFS model 4-panel prog valid for 8PM Sunday, showing conditions favorable for tropical cyclogenesis: low wind shear, high vorticity, and decently moist low-mid levels.
A couple storm systems will impact NYC this week. The first of these could bring some thunderstorms and gusty conditions tomorrow afternoon. Later this week on Thursday, a second storm bringing steadier rain will move through. Temperatures throughout this period will be generally 5ºF below normal. Tuesday and Wednesday overnight lows could bottom out in the upper-30s.
Rest of today – mostly cloudy, with clouds diminishing later, high temperatures in the upper-50s. Overnight lows in the mid-40s.
Weather Prediction Center surface forecast for 8AM Tuesday
Tuesday – quick moving storm will push a warm front and then a strong cold front through Tuesday afternoon. Showers should begin in the afternoon and a line of thunderstorms is possible with the cold front. High temperatures around 60ºF with southwesterly flow ahead of the cold front. Overnight lows in the mid-30s.
Wednesday – the low bringing the rain and thunderstorms on Tuesday continues to strengthen. The pressure gradient will tighten around this low and bring windy conditions but with sunny skies. High temperatures cool off into the low-50s. Overnight lows in the upper-30s.
GFS 2-meter above ground level temperature anomalies for 2AM Thursday. A cold night in store for many parts of the Northeast!
Thursday– partly sunny skies with high temperatures climbing into the upper-50s. Overnight lows around 50ºF with rain developing.
A powerful storm tracking over the Great Lakes that brought a deadly outbreak of severe weather and strong tornadoes to the Deep South will continue tracking northeast over the Great Lakes. A warm front and cold front associated with this storm could bring thunderstorms, though regardless, dangerously strong winds will be present. After this storm passes, this gives way to a cooling pattern with a second, weaker storm coming Wednesday. Temperatures during this period start above normal in the 60s to below normal in the low-50s.
Rest of today – a powerful surface low over tracking over the Great Lakes with minimum central pressure below 984 mb will bring a period of dangerous winds to the region. The pressure gradient between this low and high pressure over the Atlantic will be very tight, as you can see below. This will result in sustained winds easily in the 30 mph range, with stronger gusts of 60-65 mph possible due to the very strong winds aloft. Both the warm front and cold fronts of this storm could touch off some isolated elevated thunderstorms, though instability will be modest at best. High temperatures should peak in the upper-60s with robust warm air advection due to these strong winds eventually turning southwest. Overnight lows in the mid-40s as this storm pulls away.
Weather Prediction Center surface forecast for 2PM Monday
Tuesday – skies clear up overnight into the morning. Partly cloudy to mostly sunny skies should prevail with high pressure building. High temperatures in the upper-50s. Overnight lows around 40°F.
Wednesday – a second, weaker low is forecast to form over the northern Gulf of Mexico along the southerly extremes of the cold front from this first storm. This low then slides northeast along the coast. Although this second storm will pass far to the south of us, it could still bring some rain during the day. With clouds, rain, and an onshore northeasterly/easterly flow, temperatures will struggle to hit 50ºF. Overnight lows in the upper-30s.
GFS model 500 mb height anomalies for 2PM Thursday. Negative height anomalies at the 500 mb level can often translate to below normal temperatures at the surface.
Thursday– temperatures remain cool despite more sun, only reaching into the low-50s. Overnight lows around 40ºF.
We have a stormy start to the forecast period with the Storm Prediction Center putting us under a slight risk for severe weather this afternoon. Behind this storm, windy conditions will prevail Friday with the pressure gradient tightening between an incoming high pressure and the departing low. This pressure gradient eases Saturday as high pressure moves more directly overhead. Decent weather continues Sunday before another storm rolls in Monday. Above normal temperatures for Thursday in the low-60s. Temperatures drop below normal in low-50s this weekend before picking up Monday into the upper-60s.
Rest of today – lighter stratiform rain in the morning hours with a warm front moving through. This will be followed up by a possible round of strong to severe thunderstorms in the afternoon hours (most likely around 1-2PM). The primary risk for severe weather comes from the potential for damaging wind gusts, with very fast winds aloft potentially mixing down to the surface. High temperatures in the low-60s. Overnight lows around 40ºF as gusty winds bring in strong cold air advection. See this detailed forecast for more info about today.
Storm Prediction Center convective outlook for Thursday, showing us in a slight risk area for severe weather later today.
Friday – despite a high in the low-50s, strong winds around a deepening low will make it feel significantly cooler. Clouds should gradually diminish during the day. Overnight lows cool, in the upper-30s.
Weather Prediction center surface forecast for 8AM Friday. A strong low pressure cetner is indicated tracking northeast out of Maine.
Saturday – winds ease as an area of high pressure moves more directly over us. High temperatures should range in the mid-50s with plenty of sun. Overnight lows will be in the mid-40s.
Sunday– clouds increasing with high temperatures in the upper-50s. Overnight lows will warm into the low-50s.
It’s been nearly three months since my last detailed forecast, so forgive me if I’m a bit rusty. Thursday in NYC will be an active weather day. A rather complex picture will unfold, with a warm front passing early, then a triple point passing nearby, followed by a trailing cold front that could bring the potential for thunderstorms later in the afternoon. Strong winds will be in the picture, and these winds will persist (if not increasing in intensity) into Friday.
My Forecast High: 61°F | Low: 49°F | Max sustained winds: 33 mph | Total precipitation: 0.24″ – verification will come from METAR data for the period between 2AM Thursday and 2AM Friday (06Z Thursday to 06Z Friday) at LGA (LaGuardia Airport), and the KLGA Daily Climate Report.
Verification High: 58°F | Low: 44°F | Max sustained winds: 44 mph | Total precipitation: 0.26″ – this ended up being a decent forecast for the high temperature. The cooler scenario depicted by NAM ended up being correct, and siding with a more conservative high was the right call. Amazingly, I was only 0.02″ off from the precipitation total! However, in my focus on that aspect of the forecast, I neglected some basic signs about the winds and low temperatures. These two ended up being connected. Winds in the wake of the cold front were likely boosted by subsidence (sinking cold air), and these provided a boost to cold air advection, leading to the low actually occurring around midnight, as opposed to the overnight hours going into the day. This was actually apparent in the statistical guidance, but was something I failed to spot. Lesson learned: never forget to check the entire data set – and when cold fronts with convective activity swing through, consider being aggressive about the winds associated both with the storms themselves, and behind the front.
Weather Prediction Center surface forecast for 2AM Thursday
Weather Prediction Center surface forecast for 8AM Thursday
Weather Prediction Center surface forecast for 2PM Thursday
Weather Prediction Center surface forecast for 8PM Thursday
Synoptic Setup At the surface, two lows will be influencing the picture, one centered further north over Ontario, and another tracking closer to the area. Early in the forecast period, a warm front associated with secondary low pushes through. This could lead to some lighter stratiform rain due to isentropic (overrunning) lift. After this, a triple point passes just north of the area in the afternoon, and this should provide a locus for some some enhanced lift. This will be followed shortly thereafter by a trailing cold front passing through in the late afternoon hours. This cold front could trigger some thunderstorms with NAM showing some instability, though GFS isn’t as aggressive.
GFS is less bullish on showing a saturated layer at 850 mb. NAM does have wetter conditions which explains why the QPF totals are higher with this model. One thing both models agree on is the presence of strong winds at this level, anywhere from 35-50 knots. Should moisture content be better upstream, we should see effective moisture transport from this low-leve jet.
Further up in the atmosphere at 500mb, a shortwave trough attached to a closed 500 mb low over Ontario/Quebec border is forecast pivot through the region. Models are suggesting very strong positive relative vorticity associated with this feature. This should lead to ample divergence aloft and enhanced lift potentially supportive of organized convective activity. Low-mid level lapse rates due to the presence of the closed low could also be decent enough to support convection.
Finally, at the 300 mb level, a jet streak with very fast core winds in excess of 140 knots looks to set up over the Ohio Valley. We will be in the favorable left exit region of this jet streak, a set up that further favors enhanced divergence aloft. This should likewise increase lift in the atmosphere. This is reflected by SREF that shows a decent probability of moderate to strong omega over the region during the passage of this storm.
NAM model 850 mb relative humidity and winds valid 2PM Thursday
GFS model 500 mb height and relative vorticity valid 2PM Thursday
GFS model 300 mb height and winds valid 2PM Thursday
High Temperatures There was a large spread between NAM and GFS statistical guidance, with NAM much cooler and coming in only in the mid-50s, while GFS came in with low-60s. Given that there should be some warm air advection with southerly winds ahead of the cold front, I tend to buy more into the warmer end of the guidance envelope. However, both sets of statistical guidance also show a period of winds backing to the ESE in the afternoon which would bring a characteristically onshore flow and introduce a marine air mass. That might cut into overall high temperatures. Some limited evaporational cooling and clouds could also keep a cap on temperatures warming too much. With all this in mind, I’m going with a high temperature of 61ºF.
Low Temperatures There is likewise a big spread between GFS and NAM on low temperatures. NAM is close to climatological averages for low temperatures in the low-40s while GFS is a full 10ºF warmer. Southerly winds are indicated during most of the overnight hours seem to suggest erring on the warmer end of guidance. I think that EKDMOS 50th percentile of 49ºF seems reasonable.
GFS MOS guidance for KLGA
NAM MOS guidance for KLGA
Max Sustained Winds Both GFS and NAM indicate that a well-mixed layer will form by the late afternoon. As referenced above, winds aloft at 850 mb will be quite strong. This mixed layer should enable these strong winds to work their way down to the surface. This will be aided by any downward momentum transfer effected by falling rain. Layer mean wind analysis shows max wind speeds well above statistical guidance, and I few reasons to disagree with this, so I’m calling for max sustained winds of 29 knots, or 33 mph.
GFS forecast sounding for KLGA valid 2PM Thursday. The presence of a well mixed layer is apparent from the surface up to just above 850 mb. This should allow for strong winds at this layer to mix down to the surface, something that would be enhanced by precipitation drag effects from rain falling.
Total Precipitation There is high bust potential for total precipitation forecasts here with convective precipitation in the picture. The earlier light stratiform precipitation with the warm front probably will not result in too much overall precipitation. However, just one strong thunderstorm/heavy downpour could wreck any forecast here. The blended GFS/NAM mean is about 0.25″ and SREF probabilities for precipitation greater than this are not a lock, despite the overall synoptic picture showing decent support for good lift. SREF gradients are quite sharp going south. In addition, onshore winds that are possible could help stabilize the area by bringing in a cooler marine layer. I don’t feel confident that we’d see more than 0.25″ unless a convective burst hits KLGA head on, so I am going with 0.24″ as a conservative play.
We have above normal warmth to start the week in the mid-60s. Clouds increase Tuesday going into Wednesday as a low is forecast to form along a warm front. This brings us the first chance for rain Tuesday night into Wednesday morning. There appears to be a brief pause in rain chances before before a more potent storm passes Thursday. As pointed out by forecasters, this storm looks to be associated with a vigorous upper low that should enhance lift. Some thunderstorms could be possible with this.. Temperatures will trend lower towards end of week.
Rest of today – high pressure in control with plenty of sun, high temperatures should rise into the mid-60s with downsloping northwesterly winds. Overnight lows in the mid-40s.
Weather Prediction Center surface forecast for 8PM Tuesday
Tuesday – a warm front associated with a low tracking into the Great Lakes makes its approach. Ahead of this low, clouds will increase, though temperatures should still be able to reach into the low-60s. Overnight lows around 50°F with rain chances increasing.
Wednesday – rain early in the day as the warm front lifts through the region. High temperatures still reaching into the low-60s. There may be possible partial clearing of skies in the afternoon as we get into the warm sector behind the warm front. Overnight lows in the upper-40s.
GFS model 500 mb height, and relative vorticity valid 2PM Thursday. This model depicts a closed upper low over the Great Lakes spawning very strong vorticity (and hence divergence and lift aloft).
Thursday– a second, more powerful storm hits the region. A closed upper low over the Great Lakes will provide enhanced lift for this storm as it pushes a cold front through the area later on Thursday. High temperatures in the upper-50s. Showers and possibly thunderstorms will accompany the cold front passage. Overnight lows in the low-40s.
It’ll be a cloudy start to the week with possible thunderstorms later today. Rain chances continue Tuesday with a surface low in our vicinity. Once this low moves off, our weather calms Wednesday. High pressure builds in Thursday and should bring us mostly sunny skies. High temperatures start off slightly below normal in low-50s with clouds and rain, and will warm into normal ranges in the mid-50s later on.
Rest of today – energy from an upper level low will support development of a surface low around its base. Surface troughs from this low may touch off some isolated showers and thunderstorms later this afternoon with the aid of a cold pool aloft (increasing lapse rates and increasing instability). Best chances for this activity will be north of the city. High temperatures in the mid-50s with clouds and rain. Overnight lows in the low-40s.
GOES East Geo Color satellite image. You can see the large area of cloudiness associated with the upper level low
High resolution rapid refresh simulated radar showing the possibility for some convective activity associated with a cold pool later this afternoon around 5PM
Tuesday – this surface low will help move a backdoor cold front through, bringing cool, damp, northeasterly flow to the area. With this air mass, we’re only expecting high temperatures in the upper-40s. Rain chances continue with the low in our vicinity. Overnight lows in the upper-30s.
Wednesday – the low affecting our weather to open the week finally moves off. We’ll get a dry day with diminishing clouds and high temperatures around 50°F. Overnight lows around 40°F.
Thursday– high pressure builds and brings us a mostly sunny day. High temperatures rebound into the mid-50s in response. Overnight lows in the mid-40s.
