May 2020 cold snap; record cold, possible snow?

[michsnowfreak]

Decided to start a thread as it looks like record cold may be seen in many places and the novelty May snowflakes may fall as well. Feel free to add local stats on May snow (or cold) as well, Im sure I can count on at least Chicago stats haha. Will look into the magnitude of cold once we get closer.

Did some research on May snow at Detroit. Its actually quite rare, WAY more so than Oct snow. While the first flakes of the season are seen in October half the time, the last flakes are rarely in May. The frequency of May snow from 1902-1912 (7 of the 11 years) is an interesting sore-thumb type of anomaly.

 

Percent chance of a trace or more of snow in……..Percent chance of measurable snow in…

October – 50.0%  (70 out of 140 yrs)                        October – 10.7%  (15 out of 140 yrs)

November – 97.9%  (137 out of 140 yrs)                November – 86.4%  (121 out of 140 yrs)

December – 99.3%  (139 out of 140 yrs)                 December – 99.3%  (139 out of 140 yrs)

January – 100.0% (140 out of 140 yrs)                    January – 100.0%  (140 out of 140 yrs)

February – 100.0%  (140 out of 140 yrs)                 February – 99.3%  (139 out of 140 yrs)

March – 100.0%  (140 out of 140 yrs)                      March – 98.6%  (138 out of 140 yrs)

April – 95.7%  (134 out of 140 yrs)                            April – 73.6%  (123 out of 140 yrs)

May – 18.7%  (26 out of 139 yrs)                               May – 5.8%  (8 out of 139 yrs)

 

YEARS WITH MEASURABLE SNOW IN MAY (Chronologically)

1883 – 5.0”

1902 – 0.5”

1907 – 0.2”

1909 – 0.4”

1912 – 1.5”

1923 – 6.0”

1954 – 0.1”

2005 – 0.1”

 

YEARS WITH ANY SNOWFALL IN MAY (Chronologically)

1883 – 5.0”

1900 – T

1902 – 0.5”

1906 – T

1907 – 0.2”

1908 – T

1909 – 0.4”

1910 – T

1912 – 1.5”

1923 – 6.0”

1925 – T

1929 – T

1945 – T

1947 – T

1954 – 0.1”

1960 – T

1961 – T

1963 – T

1970 – T

1973 – T

1974 – T

1976 – T

1989 – T

1994 – T

2005 – 0.1”

2016 – T

 

SNOW SEASONS WHEN DETROIT SAW SNOW FALL IN 8 CONSECUTIVE MONTHS (OCT-MAY)

1901-02

1906-07

1907-08

1909-10

1922-23

1928-29

1959-60

1960-61

1962-63

1969-70

1972-73

1988-89

1993-94

2015-16

 

[Hoosier]

Measurable snow has fallen 9 times (cue the principal in Ferris Bueller) in May in Chicago, with the last occurrence being in 1989.  There is certainly an increased risk of some flakes if not something measurable in the upcoming pattern, so we'll see if we can add a 21st century year to the list.

List of May measurable snow is below.  If expanded to include trace, it would add in a lot more years.

1940:  2.2"

1907:  1.3"

1923:  0.6"

1989:  0.5"

1954:  0.2"

1966:  0.2"

1888:  0.1"

1911:  0.1"

1976:  0.1"

[beavis1729]

Re-posted from other thread...

12z GFS has 510 thicknesses over Bo's house on 5/8 (hour 102).  

In N IL, it looks like the coldest days will be 5/8 and 5/9.  As of now, it looks like the sun will be out at least part of these days...in which case daytime temps will probably be mild even if the thickness levels are anomalously low.  The sun angle is equivalent to early August. 

If Friday night can clear out with either strong cold advection or radiational cooling, some places in N IL may drop below freezing on Saturday morning 5/9.  That's probably the best chance for a record to be broken...although the record low is 27 in both Rockford and Chicago.

Rockford

5/8:  Record low max 41 in 1960; record low 30 in 1947

5/9:  Record low max 41 in 1960; record low 27 in 1966

Chicago

5/8:  Record low max 42 in 1960; record low 29 in 1983 

5/9:  Record low max 42 in 1966; record low 27 in 1983

[michsnowfreak]

10 minutes ago, Hoosier said:

Measurable snow has fallen 9 times (cue the principal in Ferris Bueller) in May in Chicago, with the last occurrence being in 1989.  There is certainly an increased risk of some flakes if not something measurable in the upcoming pattern, so we'll see if we can add a 21st century year to the list.

List of May measurable snow is below.  If expanded to include trace, it would add in a lot more years.

1940:  2.2"

1907:  1.3"

1923:  0.6"

1989:  0.5"

1954:  0.2"

1966:  0.2"

1888:  0.1"

1911:  0.1"

1976:  0.1"

While thats true that trace amounts add quite a few more years, I was really surprised how much more rare May snow is than October snow, at least at Detroit. Snow has fallen in 7 of the past 8 October's, and 10 of the last 20....but only 2 of the last 20 Mays.

[michsnowfreak]

22 minutes ago, beavis1729 said:

Re-posted from other thread...

12z GFS has 510 thicknesses over Bo's house on 5/8 (hour 102).  

In N IL, it looks like the coldest days will be 5/8 and 5/9.  As of now, it looks like the sun will be out at least part of these days...in which case daytime temps will probably be mild even if the thickness levels are anomalously low.  The sun angle is equivalent to early August. 

If Friday night can clear out with either strong cold advection or radiational cooling, some places in N IL may drop below freezing on Saturday morning 5/9.  That's probably the best chance for a record to be broken...although the record low is 27 in both Rockford and Chicago.

Rockford

5/8:  Record low max 41 in 1960; record low 30 in 1947

5/9:  Record low max 41 in 1960; record low 27 in 1966

Chicago

5/8:  Record low max 42 in 1960; record low 29 in 1983 

5/9:  Record low max 42 in 1966; record low 27 in 1983

I was born the evening of May 8, 1983. My mom remembers how cold and rainy it was. That night we had a record low for May 9th.

 

Detroit dailies

 

May 8th:

Record low max: 38 in 1947 (May record)

Record low: 30 in 1976

Record snow: T in 1947

 

May 9th

Record low max: 39 in 1923

Record low: 29 in 1983

Record snow: 6.0" in 1923 (May record)

 

May 10th

Record low max: 42 in 1902

Record low: 25 in 1966 (May record)

Record snow: 0.5" in 1902

 

May 11th

Record low max: 43 in 1960

Record low: 30 in 1907

Record snow: 0

 

May 12th

Record low max: 44 in 1966

Record low: 32 in 1934

Record snow: 0

[beavis1729]

For Chicago, here are the late-season measurable snow benchmarks to beat:

- Latest 0.5+" event:  May 8-9, 1923 (0.6")

- Latest 0.1+" event:  May 11, 1966 (0.2")

I think ORD will see a Trace of snowfall over the next week, but nothing measurable.  Maybe I'll be surprised. 

[beavis1729]

LOT discussion below.  Even if ORD doesn't break the daily record low of 27 on Saturday 5/9, a low of 30 would still make it the 3rd coldest temp on record so late in the season.

Later Thursday night or Friday morning, strong cold front is
progged to sweep across the area and allow some unseasonably cold
air to spill south into region. There remain some modest
differences amongst the medium range guidance in the details, but
the general idea of an extremely anomalous lobe of cold air moving
into the Great Lakes is a consistent theme with all the model
guidance. Low and mid level thermal fields are progged to be at or
just below recorded mins for this time of year, with record or
near record low 500mb heights as well. All of this would seem to
support the idea of both daytime and nighttime temps getting into
the territory of records.

The NBM guidance again resides in the upper echelon of the spread
of guidance and have made some downward adjustments to both
Friday`s high temps and Friday night`s low temps. Worth noting,
that the normally very reliable ECMWF has highs in the mid 40s
Friday afternoon with lows in the mid-upper 20s and a hard freeze
Friday night. Despite the ECMWF`s run-to-run consistency and
stellar track record with forecasting such anomalous events, have
only trended temps in that direction, but not all the way there
just yet. Certainly seeing growing support for a freeze for most
of the CWA Friday night outside of the urban heat island, with the
threat for a hard freeze (<= 28F) plausible.

[weatherbo]

I'm going to see accumulating snow, I already know. 

MQT:

Core of the coldest air will drop across the area on Fri. As an indication of how anomalously cold it will be, the NAEFS and ECMWF ensembles indicate 850mb temps falling to around -12C on Fri which will be outside the 1979-2009 climatology for this time of year, or stated in another way, none of the reanalsyses btwn 1979 and 2009 for this time of year showed 850mb temps as low as currently fcst. As for pcpn, expect little if any until Thu night/Fri when the coldest air arrives. It`s extremely unusual to see LES in May, but if the degree of cold verifys along with the shortwave swinging across the area, there will be some lake enhanced snow or at least a springtime hybrid type LES where land based instability supports further development inland downwind of the lake.

[Stebo]

4 minutes ago, weatherbo said:

I'm going to see accumulating snow, I already know. 

MQT:

Core of the coldest air will drop across the area on Fri. As an indication of how anomalously cold it will be, the NAEFS and ECMWF ensembles indicate 850mb temps falling to around -12C on Fri which will be outside the 1979-2009 climatology for this time of year, or stated in another way, none of the reanalsyses btwn 1979 and 2009 for this time of year showed 850mb temps as low as currently fcst. As for pcpn, expect little if any until Thu night/Fri when the coldest air arrives. It`s extremely unusual to see LES in May, but if the degree of cold verifys along with the shortwave swinging across the area, there will be some lake enhanced snow or at least a springtime hybrid type LES where land based instability supports further development inland downwind of the lake.

Incoming foot

[weatherbo]

1 minute ago, Stebo said:

Incoming foot

Haha... hush!  

If it hits overnight, nothing would surprise me.

[Stebo]

1 minute ago, weatherbo said:

Haha... hush!  

If it hits overnight, nothing would surprise me.

Hell why not have June snow at this rate. Horrible winter.

[weatherbo]

1 hour ago, Stebo said:

Hell why not have June snow at this rate. Horrible winter.

I felt it was a great winter.  Plenty of snow without the numbing cold.  My issue begins when winter extends beyond 7 months. Anomaly or not, any snow that falls will not impress me, but it comes with the territory and I like living here.  I'll just be grouchy and complain.   

[Stebo]

Just now, weatherbo said:

I felt it was a great winter.  Plenty of snow without the numbing cold.  My issue begins when winter extends beyond 7 months. Anonymous or not, any snow that falls will not impress me, but it comes with the territory and I like living here.  I'll just be grouchy and complain.   

Yeah a lot more synoptic snow this winter up there vs LES. Would have been interesting to see a core sample from when you had your max depth, just to see how much liquid was in that snow pack.

[cyclone77]

Euro continues to advertise snow showers/flurries for northeast IL on Friday.  Also much of MI.  Wish we could get in on it.  If it's gonna be so miserable outside might as well have something to show for it.  

[Hoosier]

9 minutes ago, cyclone77 said:

Euro continues to advertise snow showers/flurries for northeast IL on Friday.  Also much of MI.  Wish we could get in on it.  If it's gonna be so miserable outside might as well have something to show for it.  

Obv would take amounts with a grain of salt and treat this more as snow vs no snow

[Harry Perry]

From GRR this morning 

 

-- Widespread freeze possible record lows Saturday--

 

As we have been writing about for over a week now, the upper level flow brings us air that is currently over the Arctic Circle. The 500 mb heights fall to near 535 m, which suggest (long story) but highs should not get much over 40. All of the ensemble and long range models continue to forecast lows Saturday morning from around 20 north to the mid 20s near and east of US-131. This would be a killing freeze if it happens. Sunday morning may be nearly as cold too.

 

-- Next system Sun/Monday ????--

As I suggested yesterday, the upper low that brings us the cold air rotates around brings another shortwave from the northern stream into our area Sunday or Monday (depending on which model you choose or which version of which model you choose). The 00z run of the ECMWF is now bringing the system farther north, like the GFS did yesterday and continues to do today. That would bring rain and snow into the area Sunday or Monday. Given this is a northern stream system, it would not have Gulf moisture so precipitation amounts would be less than a 1/4 inch. Still, if it were to snow Sunday night we could see 2 to 4 inches on grass areas by Monday morning.

 

Handy. 

[michsnowfreak]

GFS hints at a reinforcing shot of cold early next week too. The cold definitely looks impressive.

 

For Detroit, the already-cold 1970s have quite a few records year-round that stand to this day from the days when DTW was a radiational cooling magnet as opposed to present-day UHI-influenced (thermometer placement also plays a role, I assume, as the south end of the airport is much colder/valleyed than the north side). But it was noted that since 1979, DTW has only seen 4 instances where the low temp in May fell to 31F or colder.

29F - May 9, 1983

30F - May 13, 2013

30F - May 3, 1986

31F - May 4, 2005

 

Stretching it out, some all-time late season cold may be seen. Since the cold here will be approx. May 8-13, lets look at cold records on and after May 8th.

Coldest temps on and after May 8th (since 1874)

25F - May 10, 1966 (coldest May temp on record)

29F - May 9, 1983

29F - May 9, 1923

30F - May 10, 2013

30F - May 8, 1976

30F - May 13, 1971

30F - May 9, 1966

30F - May 7, 1911

 

So if it officially drops into the 20s, it will only be the 4th time on record this late in the season. If it drops to 28F or lower, it will be 2nd only to the May 10, 1966 all-time May record. Not to take away from the 1966 record, but that was RIGHT after the official station moved from DET to then-rural DTW (Apr 1, 1966). fwiw the low at DET was 30F that day. Wind and clouds will likely play a role in just how colds it gets.

[Hoosier]

The NAM being the NAM?  Pretty bullish on evap/dynamic cooling

[snowlover2]

3 minutes ago, Hoosier said:

The NAM being the NAM?  Pretty bullish on evap/dynamic cooling

FWIW

[Hoosier]

Radical departure from previously so take with a million grains of salt.

[NTXYankee]

30 minutes ago, Hoosier said:

The NAM being the NAM?  Pretty bullish on evap/dynamic cooling

If that happens I am moving again, I don’t care if it lasts two hours on the ground and melts.  It’s May not March.  Disgusting.

[beavis1729]

LOT

A remarkably cold/deep mid-upper low will be located near
Ontario-Quebec border late Thursday night into Friday morning. A
short-wave wrapping around this ULL will bring a reinforcing surge
of anomalously cold air aloft into Friday morning. ECMWF has been
consistent in signal for showers driven by this wave and land/lake
convergence. Not all guidance has picked up on this yet, but with
consistency of ECMWF, added in slight chance PoPs for northeast
Illinois and far northwest Indiana. With very strong May sun and
extremely cold air aloft with low freezing levels, steep low level
lapse rates could yield graupel mix if not outright snow showers
in spots should the showers materialize. Outside of this, the main
story will be the temperatures likely staying in the 40s in many
areas with brisk northerly winds. In addition, northerly wind
driven waves and record lake levels could bring some risk for
lakeshore flooding to at least portions of IL/IN shore.

The unseasonably cold daytime temps followed by diminishing winds,
clearing skies Friday night and 850 mb temps bottoming out as cold
as -6 to -9 Celsius (among coldest 850 mb temps on record in May
at ILX and DVN) could set the stage for a rare May freeze (<32F)
everywhere but downtown Chicago and a hard freeze (<=28F) for
some locations. The last May freeze at O`Hare, Chicago`s climate
site was all the way back on May 3, 2004 when the low temperature
was 30 degrees. With the growing season now well underway after
the warm conditions this past weekend, this could be a damaging
freeze if it occurs. Should trends hold for temperatures Friday
night into Sat. AM, we`ll likely need to issue a Freeze Watch at
some point over the next few days.

The deep trough responsible for Friday-Sat AM cold will exit east
on Saturday, allowing for moderation back into the 50s for highs
(still well below normal) along with plenty of sun. Unfortunately,
model and ensemble guidance is coming into better agreement for a
clipper-like system to impact the area on Mother`s Day (Sunday).
There`s uncertainty at timing of precip. onset, with ECMWF on
slower side Saturday night, but felt signal is strong enough for
rain on Sunday that PoPs were bumped up to likely. The exact track
of the associated low pressure system will determine whether
temperatures will be merely well below normal (period of time in
"warm" sector) or in the 40s (low pressure track south of us).
Added in some slight chance thunder mention to account for the
brief period in warm sector scenario and fairly stout short-wave
with steep lapse rates).

Another shot of unseasonably cold air aloft (several degrees below
0C at 850 mb) could follow Sunday`s clipper system and depending
on how long it takes to exit the region, hate to say it but
couldn`t rule out some wet snow Sunday night before precip ends.

[Gino27]

A grain of salt would be a stretch.

[michsnowfreak]

On 5/4/2020 at 6:43 PM, weatherbo said:

I felt it was a great winter.  Plenty of snow without the numbing cold.  My issue begins when winter extends beyond 7 months. Anomaly or not, any snow that falls will not impress me, but it comes with the territory and I like living here.  I'll just be grouchy and complain.   

People like me and beavis do not enjoy the thaws and the periods of bare ground that come with the territory of a mild Winter. But for the casual citizen who hates any cold and Winter weather, this season has to be a nightmare. After late October snow, a record heavy November snowstorm and record smashing cold hit before mid November, then a wintry April is now followed by early to mid May snow chances and more record cold. In between, the actual Winter was quite mild compared to an average Midwest and Great Lakes Winter, but of course this still included plenty of cold and snows.

[Stebo]

2 hours ago, Hoosier said:

The NAM being the NAM?  Pretty bullish on evap/dynamic cooling

In the day time no less. I would absolutely pound the under on this one.

[Indystorm]

Ha Ha.....I;m tempted to say I'll eat my Covid-19 mask if this verifies.

[cyclone77]

3 hours ago, Hoosier said:

The NAM being the NAM?  Pretty bullish on evap/dynamic cooling

The ol' sun angle might have something to say about that lol. 

[Hoosier]

1 hour ago, Stebo said:

In the day time no less. I would absolutely pound the under on this one.

Yeah, there are some signals in the guidance of a potential changeover or flirting with a changeover, but the NAM is just going crazy with it.  

[snowlover2]

0z NAM holding on to the idea although amounts did lessen a little.

[madwx]

Looking at records for MSN most are probably unreachable but still interesting to note:

5/8:  Low-26  Low Max-41

5/9: Low-20 Low Max-40

5/10: Low-22  Low Max-41

5/11:  Low-29 Low Max-40

5/12:  Low-24 Low Max-44

 

The only one with a realistic chance of being broken at the moment looks to be Monday's record low of 29.  The rest look to be unreachable.

In addition the 8-11 all have measurable daily snowfall records so don't see any of those getting broken atm.