An active weather pattern brings yet another week of cool, rainy weather. Tuesday will be the only day with sunny skies and near normal temperatures with high pressure briefly building in. Otherwise, a couple slow moving storms will bring clouds and rain the rest of the week. This will result in temperatures largely running below seasonal averages. I suppose that’s some incentive for people to stay safe and quarantine at home?
Rest of today – early rain chances should diminish steadily. High temperatures cool, only around 50ºF under the influence of northerly flow as the slow moving coastal storm that impacted us yesterday and today moves off to the northeast. Clouds should start to diminish later in the day. Overnight lows in the low-40s.
NAM output forecast cloud cover for 11AM Tuesday
Tuesday – we should see a brief window of sunny skies and dry weather as high pressure builds and passes over for the day. This break in rainy weather should allow temperatures to climb into the low-60s. Overnight lows in the mid-40s.
Wednesday – the reprieve from dreary conditions barely lasts a day as yet another storm system takes aim at the area. With the high pressure Tuesday slow to move east, this next storm will be similarly as slow moving as this past weekend’s storm. The result for Wednesday, even if we don’t get too much in the way of rain, will be cloudy conditions and cool, southeasterly onshore flow ahead of an advancing warm front. This will cause temperatures to cool into the mid-50s. Overnight lows barely budge, and hover around 50ºF.
Weather Prediction Center surface forecast for 8AM Thursday
Thursday– the second storm of the week hits with steady rain and southeasterly onshore breezes. Warm advection could help temperatures stay slightly above 60ºF, with overnight lows in the low-50s.
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.
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.
We have an active weather pattern with two storms moving through NYC this first full week of spring. A nor’easter will pass offshore today, bringing mixed precipitation early then cold rain later. We get a lull Tuesday with temperatures rebounding into the mid-50s, before a second low hits Wednesday. This will bring another round of cold rain with temps back in the mid-40s. Temperatures rebound again Thursday after this second storm.
Rest of today – some light mixed precipitation has already moved through the region this morning. A second round of more consistent, moderate precipitation should hit around lunch. High temperatures only in the mid-40s. Overnight lows around 40°F.
High resolution rapid refresh simulated radar for 1PM Monday
Weather Prediction Center surface forecast for 8PM Monday
Tuesday – the nor’easter pulls away to the northeast and we get a brief period of calm with weak high pressure building in. Partly sunny skies expected with highs in the upper-50s. Overnight lows in the low-40s with rain chances picking up towards Wednesday morning.
Wednesday – a second storm system moves up from the south. This will bring us another round of cold rain, with highs back in the mid-40s. Overnight lows around 40°F.
GFS model 500 mb height and relative vorticity valid 2PM Wednesday. A shortwave trough is evident over the Northeast, providing upper-level divergence for the second storm to hit this week.
Thursday– similar to Tuesday with things drying out. Partly sunny skies with high temperatures in the mid-50s. Overnight lows in the mid-40s.
Near record warmth to start the week in the upper-60s to low-70s. A summer-like pattern with a strong high pressure center over the western Atlantic will keep warm, southerly winds coming our way. A cold front will approach Tuesday bringing chances for rain. Temperatures remain above normal in the 50s for the remainder of the week.
Rest of today – very warm with mostly sunny skies and highs in the upper-60s to low-70s. The record high for today at LGA is 75°F so this is definitely abnormally warm. Strong ridging over the western Atlantic is leading to very warm southerly flow coming our way. Overnight lows in the upper-40s.
Tuesday – an approaching cold front will bring clouds and some chances for rain especially later in the day. High temperatures will still be quite mild in the low-60s with continuing southerly flow ahead of the frontal passage. Overnight lows should be in the mid-40s.
Wednesday – behind the cold front, temperatures will dip into into the mid-50s, but that’s still 7-10ºF above normal for this time of year. Skies should also clear up. Overnight lows will drop into the low-40s.
Climate Prediction Center temperature outlook for Mar 14-18, showing the above average temperature trend continuing in many parts of the Eastern US while below normal temperatures are likely out west.
Thursday– similar day to Wednesday with high temperatures in the mid-50s, but with potentially more clouds as the next storm system approaches. Overnight lows in the low-40s.
First half of this week features much above average temps in the upper-50s slowly dropping to the low-50s after mid-week. A passing storm system could bring showers and isolated thunderstorms overnight tonight. Temperatures remain mild until later in the week. Another chance for rain/snow is possible overnight Friday into Saturday as another storm system passes by.
Rest of today – very mild, high temperatures in the upper-50s with the area in the warm sector of a low pressure system centered over northern Quebec. A secondary low will bring another reinforcing warm front through before the trailing cold front finally swings through. Rain chances increase towards the afternoon with a batch of rain possible around 3PM. A second, stronger round of rain is possible around 10PM. Overnight lows in the mid-40s.
Weather Prediction Center Surface forecast for 1AM Wednesday
Wednesday – despite the passage of a cold front, the air mass behind the front won’t be that much colder than today’s. Furthermore, downsloping westerly flow should keep things on the mild side with high temperatures expected in the mid-50s under mostly sunny skies. Overnight lows will dip into the upper-30s.
Thursday – another nice day with high temperatures still above normal in the low-50s, with mostly sunny skies. Overnight lows in the upper-30s.
Climate Prediction Center temperature outlook for Mar 8-12, showing a warm up yet again next week.
Friday– clouds build as a couple storm systems start making their way towards our area. Cloud cover and chances for rain during the day will keep temperatures closer to normal in the mid-40s. Overnight lows in the low-30s could allow for some rain to mix with snow before the storms clear our area.
Mild temperatures from this weekend carry over into the beginning of this week. High temperatures will remain in the 50s, well above normal, until the second half of the week. A couple storm systems will impact the area bringing rain, as well as a cool down in temperatures to end the week. The upcoming weekend will see temperatures drop to below normal levels with highs only in the 30s.
Rest of today – very mild, high temperatures in the upper-50s with persistent southerly flow. Increasing clouds towards the overnight hours. Rain chances increase towards day break with overnight lows in the low-40s.
Weather Prediction Center surface forecast for 7AM Tuesday
Tuesday – rain chances continue to increase as the storm above moves closer. High temperatures top out in the low-50s with mostly cloudy skies and rain chances throughout the day. Overnight lows in the low-40s with rain chances continuing.
Wednesday – rain starts to diminish but is still possible with this storm system being fairly slow to clear the area. High temperatures remain in the low-50s. Overnight lows in the mid-40s with one more slug of rain moving through.
GFS mean sea level pressure, and 10 meter above ground winds for 11PM Thursday
Thursday– clouds start to break and the rain finally clears the region. Winds will pick up as high pressure builds to the west with low pressure exiting east, creating the right pressure gradient depicted above. High temperatures dropping into the upper-40s. Overnight lows in the low-30s with cooler northwesterly winds.
