Seasonable temperatures to start the weekend won’t last as a cold front dives through and Canadian high pressure builds behind it Saturday. Cooler flow from the northeast will set up as the high sets up north of us and moves east. Winds will increase in intensity as an approaching coastal storm from the south leads to a tighter pressure gradient. This storm is currently tracking well offshore. However, we may still see some rain from the outer bands of the storm Monday. Aside from Saturday, temperatures will largely range 10-15°F lower than normal during this period.
Rest of today – sunny with high temperatures in the low-50s. Overnight lows around 30°F with winds increasing.
Weather Prediction Center surface forecast for 7AM Saturday
Saturday – with high pressure in control, we should see sunny conditions, but temperatures will be cooler with steady northeast winds of 20-25 mph. High temperatures around 40°F. Overnight lows in the low-30s.
Sunday – increasing clouds with high temperatures in the low-40s. Chances for rain possibly going overnight into Monday. Low temperatures in the upper-30s.
GFS model output for 7PM Monday, depicting a glancing blow from a coastal storm moving northeast well offshore of the area.
Monday– chances for showers with high temperatures in the mid-40s. Mostly cloudy otherwise. Overnight lows around 40°F. Persistent northeast flow may lead to coastal flooding concerns.
Record setting cold is on the way mid-week. Overnight lows in the mid-20s and daytime highs hovering around freezing Wednesday will make this week feel more like January than mid-November. Luckily, this bitter cold snap will be short-lived, with temperatures rebounding back into the 50s by the end of the week.
Rest of today – temperatures will be falling through the 40s during the day. Precipitation should end as an Arctic front pushes through. Temperatures will continue dropping into the 30s throughout the evening and bottoming out in the mid-20s. Precipitation should end before it gets cold enough to produce snow. Winds will become stiff with the parent low strengthening and a tight pressure gradient forming between that and an incoming high pressure center.
Weather Prediction Center surface forecast for 7AM Wednesday
Wednesday – sunny with record low high temperatures in the low-30s as a frigid Arctic air mass takes hold. Overnight lows continue to be cold, in the upper-20s.
Thursday – temperatures start to rebound into the upper-40s as a warm front approaches and we enter the warm sector of the next storm. Return flow around the western edge of the high pressure exiting east will also assist in helping move some warmer air in. Overnight lows in the mid-30s.
GFS model 500 mb temperature, height and wind at 1AM Wednesday, note the closed 500 mb low and the strong troughing over much of the Northeastern US
By 7PM Friday, the 500 mb trough is forecast to have flattened out considerably, allowing for temperatures at this level and at the surface to rebound
Friday – the warm-up continues, with temperatures reaching back into seasonable levels in the low-50s. A moisture starved cold front passes through late bringing overnight lows back down to the low-30s
Very cold temperatures kick off the weekend, followed by a return to milder temperatures. The reprieve is brief though, with the outlook for next week looking equally cold, especially on the heels of another storm system possibly impacting the region Monday night through Tuesday. Behind this, a reinforcing blast of cold air will reintroduce much below average temperatures to the region. High temperatures will start off ~15°F below normal for this time of year, the moderate to just a couple degrees below normal by Veterans Day.
Rest of today – mostly sunny, strong winds from the northwest ranging 25-35 mph with higher gusts. High temperatures only in the low-40s with this cold wind. Overnight lows may approach record lows, in the upper-20s. This will be aided by winds dying down and clearing skies as the high pressure center shown below continues to build and move closer to us. This should allow for potentially strong radiational cooling before dawn.
Weather Prediction Center surface forecast for 7AM Saturday
Saturday – very cold start to the day, temperatures will struggle to climb into the low-40s, close to the record coldest high temperatures for this time of year. The plus side will be calmer winds, eventually shifting to the southwest as the high pressure above moves off to the east. This should help “warm” things up a bit, with overnight lows recovering into the mid-30s.
Sunday – much warmer with high temperatures in the low-50s despite more cloud cover, both due the influence of southwesterly flow. Overnight lows warming into the mid-40s.
GFS model 2 meter above ground level temperature anomalies for 7AM Saturday
Corresponding GFS 500 mb heights, vorticity. Troughing at the mid-levels here will allow for the continued influx of cold air into the Eastern US. Note how the western US, which is under a 500 mb ridge is expected to experience above normal temperatures.
Climate Prediction Center temperature outlook for Nov 13-17, showing a very high probability for continued colder than average conditions for much of the Eastern US.
Monday(Veterans Day) – partly sunny with high temperatures in the mid-50s. Overnight, a system will approach from the west and could bring rain with lows bottoming out in the low-40s.
During my time taking classes as part of Penn State University’s Undergraduate Certificate in Weather Forecasting, we were taught that understanding the climatology of the location you are interested in is an important prerequisite for making accurate forecasts. This post continues on this theme, adding a climatology for November.
City Name / Station ID: New York, NY (LaGuardia Airport – KLGA)
Local Geography and Topography
Station Elevation: 10 feet above sea level.
Station Location: LaGuardia Airport (KLGA) is situated on the north shore of Queens along the East River, approximately 6 miles east-northeast of Midtown Manhattan.
KLGA’s location within the broader NYC area, as seen in a Google Maps terrain view
Important Topographical Features: New York City is located in the extreme southeastern corner of New York State, bordering suburban New Jersey and Connecticut. These suburban regions combined with those in Long Island comprise the Greater New York City Metropolitan Area, which is the most populous urban agglomeration in the United States and one of the populous urbanized areas in the world with an estimated population of 18 million. New York City itself sprawls across the coastal plain around the Hudson River estuary. The terminal moraine formed by glaciers of the last Ice Age result in a ridge of higher terrain that cuts a swath from southwest to northeast across the boroughs from northern Staten Island, northern Brooklyn, southwestern through central and northeastern Queens. Otherwise, the city itself is low lying. This ridge varies in height between 200-400 feet, rising sharply from south to north, but tapering more gently north. North and west of the city (about 30-50 miles away), lie significant elevations of the Catskills (north), Poconos (west), Taconics that are part of the broader Appalachian Mountain Range. The elevations of the lower foothills can range from 1000-1500 feet. Some of the elevations in the Poconos and Catskills, west and north of KLGA respectively, peak between 2000-3000 feet. The open expanse of the Atlantic Ocean lies south of KLGA and New York City. Long Island Sound also lies east-northeast. The vast urbanized area of the NYC metropolitan region has significant effects on local microclimates via differential heating (urban heat island effect). KLGA is in a low-lying area sensitive to UHI effects and marine influences.
On winter mornings, ocean temperatures which are warm relative to the land reinforce the effect of the city heat island and low temperatures are often 10-20 degrees lower in the inland suburbs than in the central city. The relatively warm water temperatures also delay the advent of winter snows. Conversely, the lag in warming of water temperatures keeps spring temperatures relatively cool. One year-round measure of the ocean influence is the small average daily variation in temperature.
National Weather Service – NYC Office
Wind Patterns
Below is a wind rose – you can read more about how to interpret this chart here.
Frequency (percentage) of the single most common wind direction: Due northwest (12%).
Directions that are most and least common: Other most common wind directions include west-northwest (10%), due west (8.5%), and due southwest (8.25%). Least common wind directions are east-southeast (1.5%), due southeast (1.75%), and south-southeast (2.75%).
Direction(s) most likely to produce the fastest winds: Winds in excess of 21.4 knots (~25 mph) are most frequently found coming from due northwest. West-northwest, north-northwest, due northeast, east-northeast, and due south directions can also see less frequent winds over 21.4 knots.
Direction(s) least likely to produce the fastest winds: As is the case with several other months, the least common wind directions of due east, east-southeast, and due southeast also rarely seen winds in excess of 16.4 knots.
Impacts of wind direction on local weather: November wind patterns are a marked shift from the prior two months. Winds coming from the northwestern quadrant become prominent. Meanwhile, winds from the south and southwest decline in frequency.
In general, northwesterly winds bring cooler, drier Canadian air into the region following cold fronts. Northwesterly winds will tend to warm slightly because of compressional warming as they downslope coming off the higher terrain of the Catskills, and Poconos outside of the city. This can sometimes lead to warmer temperatures than would normally be expected for this wind direction. Northeasterly winds, on the other hand, are often related to backdoor cold fronts sweeping from the Canadian Maritimes, the onshore flow ahead of an advancing warm front, or a passing coastal storm to the south.
The pattern of winds in November suggests the prevalence of classic frontal systems moving through, where warmer southwesterly winds precede the passage of a cold front, behind which strong, gusty westerly and northwesterly winds pick up. Northeasterly winds are, as pointed out above, a sign of passing coastal storms.
Maximum observed two-minute wind speed for the month: 41 knots (47 mph).
Temperature and Precipitation Averages/Records
Temperature units are in Fahrenheit and precipitation is in inches.
Worth noting: Average high temperatures in November start falling into the 50s, while lows fall into the upper-30s. November is the first fall month in which no record high temperature exceed the 90°F.
The week after we set our clocks back for the fall will see a shift to the coldest temperatures we’ve yet seen this season. High temperatures will trend from normal levels to slightly below normal (upper-50s to low-50s) before plummeting into the 40s following the passage of a low pressure center and cold front. The chilly air following this system will begin a longer term trend of below average temperatures going into the middle of the month at least.
Rest of today – mostly cloudy with a chance of showers as a cold front passes through later in the day. High temperatures on the mild side in the low-60s as we’ll be in the warm sector of the parent low bringing the cold front through. Overnight lows in the low-40s.
Weather Prediction center surface forecast for 7AM Wednesday
Wednesday – sunny with cooler high temperatures in the low-50s. High pressure depicted above will keep things nice and dry. Overnight lows in the low-40s.
Thursday – starting off mostly sunny with high temperatures in the mid-50s. A storm system will approach later in the day and bring the chance for rain at first, with rain and snow mixing possible overnight as lows drop into the mid-30s.
Climate Prediction Center temperature anomaly forecast for November 10-14
An anomalously low area of 500 mb heights will produce cold temperatures at the surface
Friday – the real cold sets in with high temperatures only in the low-40s. Rain/snow should taper off early giving way to sunny conditions, with winds picking up due to the low bringing this weather strengthening as it continues moving off to the northeast. Overnight lows are shaping up to be below freezing, near 30°F with winds forecast to die down and skies clearing allowing for some good radiational cooling.
NASA satellite Moderate Resolution Imaging Spectroradiometer (MODIS) image of the Getty Fire on October 28, 2019, shortly after the fire began. Smoke is visible billowing offshore to the south.
“Extremely critical” fire weather conditions are forecast to impact a large part of Southern California, with the strongest Santa Ana wind event of the year possibly occurring Wednesday before some improvement Friday. Affected areas include the entire Los Angeles metro area, where the Getty Fire continues to burn. Wind gusts at or above 70 mph in higher elevations coupled with very dry air (relative humidity less than 10%) will make it incredibly difficult to make any progress towards containing this fire, and presents a high risk for new fires to start.
Weather Prediction Center surface forecast for 5AM PDT Wednesday
Weather Prediction Center surface forecast for 5PM PDT Thursday
Synoptic Set Up Believe it or not, the strength of the Santa Ana winds will be tied directly to the very cold air mass moving into the Great Basin. A low along the leading edge of this cold air has caused a massive ongoing snowstorm across much of Colorado. Behind this, cold, stable air will move in along with a strong area of high pressure with surface pressures forecast above 1040 mb. At the same time, a coastal low will sweep south along the northern and central CA coast along the leading edge of the colder air accompanying this high pressure. This will set up a tight pressure gradient at the coast favoring strong offshore east-northeast winds, with local forecast offices citing model output of as much as 10-12 mb gradient from Barstow to LAX, over a distance of only 200 miles.
Impacts With the tight pressure gradient forecast above, forecasters are calling for the possibility of gusts in excess of 70 mph in the mountain ranges near the coast with, with lower wind gusts of 35-40 mph at lower elevations. The influx of cold air already less capable of holding moisture that will downslope off coastal ranges and towards the ocean will yield relative humidities of 3-8% (as the air dries further during downsloping due to compressional warming). Santa Ana winds of this magnitude along with such dry conditions easily warrant the Storm Prediction Center designation of extremely critical fire weather.
GFS model output forecast sounding for KLAX at 11AM PDT Wednesday. Note the huge gap between the green dew point line and red environmental temperature line at the surface (5°F dew point, 64°F temperature). This will result in extremely low relative humidity values.
Storm Prediction Center fire weather outlook for Wednesday
Timing Peak potential for winds appears to be during the overnight hours through morning and early afternoon Wednesday. This is the time when the pressure gradient will be maximized. The high pressure referenced above is forecast to weaken overnight into Thursday, while the coastal low should also dissipate. The high pressure is forecast to continue weakening into the weekend, thus ending the most dangerous period of fire weather.
This weekend starts off with fair and dry weather. A storm developing along the Gulf Coast of Texas, tracking north along the Mississippi and Ohio Valleys into the Great Lakes, then east towards our area will bring a prolonged period of steady rain on Sunday. As of 11AM today, National Hurricane Center has designated this storm as Tropical Depression Seventeen. This storm should pull out of the area before the start of next week. Temperatures during this period should be at or above average for this time of the year in the low-mid 60s.
Rest of today – partly sunny to mostly cloudy with a cold front weakening, then stalling and returning north as a warm front. High temperatures in the mid-60s. Overnight lows in the low-50s with decreasing clouds as high pressure builds in.
Weather Prediction Center surface forecast for 8AM Saturday
Saturday – high pressure builds briefly and should give us mostly sunny skies with high temperatures in the mid-60s. Overnight lows in the low-50s with increasing clouds and chances for rain.
Sunday – much like last weekend, a storm with tropical origins will bring rain and lots of moisture to the area. The extratropical remnants of Tropical Depression Seventeen will track north towards the Great Lakes during this period. A warm front attached to it will bring a shield of steady stratiform rain over the area. Mostly cloudy with highs in the upper-60s as winds turn to the south. Steady rain continuing into the early overnight hours until the storm’s trailing cold front finally sweeps through and drier air works in. Lows in the mid-50s.
NAM model output for relative humidity and wind at 850 mb for 5PM Sunday. Note the nearly saturated nature of the lower levels of the atmosphere.
NAM model output for wind at 850 mb for 5PM Sunday. Note the high wind speeds at this level, indicating the presence of an 850 mb low-level jet (LLJ)
NAM model output for precipitable water at 2PM Sunday. Note the high values above 1.50″. This makes sense, given the tropical origins of the storm that will impact us Sunday.
Projected track of Tropical Depression Seventeen
Monday – high pressure and calmer conditions return with highs in the mid-60s and mostly sunny skies. Overnight lows in the mid-50s with mostly cloudy skies.
Sunny and seasonable weather with highs in the mid-60s will be punctuated by the passage of a strong frontal system mid-week. The timing of this frontal passage should bring the bulk of the rain through overnight Tuesday, such that Wednesday ends up still being a nice day. Looking ahead, a second cold front is forecast to move through late in the weekend but is not expected to bring significant rain at this time. Temperatures throughout this forecast period and beyond are looking to be at or above normal in the low-60s/
Rest of today – mostly sunny, with highs in the mid-60s. Overnight lows in the low-50s.
Weather Prediction Center surface forecast for 8PM tonight. We will be wedged between the storm that brought steady rain yesterday to the east and an approaching frontal system with a parent low over the Upper Midwest.
Tuesday – increasing clouds with high temperatures in the low-60s. Rain chances increasing especially later in the day. Bulk of the rain accompanying the cold front should arrive overnight. Overnight lows in the mid-50s.
Wednesday – rain should clear the area. Temperatures expected to rebound back into the mid-60s under sunny skies with some downsloping westerly flow behind the front. Overnight lows in the upper-40s with a cooler, drier airmass working in.
Climate Prediction Center temperature outlook for Oct 26-30. We will be in an area with about equal chances of above or below normal temperatures up to 33% for warmer than normal temperatures.
Thursday – another really nice day with high temperatures in the mid-60s and mostly sunny skies. Overnight lows around 50°F.
Soaking rains from Wednesday’s nor’easter have long since exited east, yet we will continue to feel the impact of this low with windy conditions to start the weekend. As the low continues moving east, an area of high pressure will build in and take its place. Winds will relax and we should enjoy a nice, sunny day for Saturday. Clouds are expected to build back in as a potential extratropical remnant low of what could become Subtropical Storm Nestor this weekend pass south of the region. Temperatures during this period are expected to be at or just below normal in the low-60s with a warm up going into next week.
Rest of today – windy conditions continue as the pressure gradient between a building area of high pressure to the west and the low that brought us rain Wednesday which is now over the Canadian Maritimes. High temperatures around 60°F with partly cloudy skies. Overnight lows expected to be quite cool, in the low-40s with skies looking to clear up and winds dying down – conditions that could lead to some strong radiational cooling.
Weather Prediction Center surface forecast for 8AM Saturday
Saturday – high pressure builds in and gives us a sparkling, sunny, fall day with high temperatures in the low-60s. Overnight lows milder around 50°F.
Sunday – although the extratropical remnants of what could be Subtropical Storm Nestor are forecast to pass well south of the area, this storm is expected to have a broad cloud shield to its north, and some outlying rain bands could even result in a couple scattered rain showers for the area. High temperatures should be similar to Saturday in the low-60s, because even with clouds, overall flow will be from the south. Overnight lows around 50°F again.
GOES satellite imagery of Potential Tropical Cyclone Sixteen
National Hurricane Center’s latest forecast track guidance for this storm
Monday – with this low exiting east, we’ll see more southerly flow ahead of the next incoming storm system. High temperatures should respond by warmingin into the upper-60s with mostly sunny skies. Overnight lows in the mid-50s with mostly cloudy skies.
The week starts off with warm temperatures for this time of year, followed by entry of a cooler airmass. A storm system is forecast to bring rain mid-week. Temperatures will cool even more behind this storm with high temperatures dropping to slightly below normal levels in the low-60s by the end of the week.
Rest of today – mostly sunny, with highs in the low-70s. Overnight lows in the low-50s.
Weather Prediction Center surface forecast for 8PM Tuesday
Tuesday – a dry cold front passes over the region later today, leading to cooler high temperatures in the low-60s for Tuesday on the back of colder northwest winds behind the front. It should be a sunny day. Overnight lows in the low-50s.
Wednesday – a low pressure system over the Great Lakes will track east towards the area. Mostly cloudy skies will prevail with highs warming into the mid-60s due to a shift in winds to the south and southeast. Rain should start to overspread the area later in the afternoon and continue overnight. Overnight lows in the low-50s and even cooler possibly in the upper-40s. A secondary coastal low forming off the Carolina coast will become the primary low as energy transfers from the inland storm.
GFS model output for 1000-500 mb thickness and precipitation valid 2PM Wednesday
GFS model output of the same metrics for 2AM Thursday
Thursday – rain should clear out before the start of the day but winds will be breezy from the northwest. This will bring in cooler air again with high temperatures in the upper-50s and partly sunny skies. Overnight lows around 50°F.
