2/22/17

Deep Low Pressure System and Attending Strong Upper Air Dynamics Pushing Through The Region Friday Night

   . . .SEVERE WEATHER UPDATE - 2/24/17 AT 12 NOON FRIDAY . . .
 ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    SOUTHERN LOWER MI...EASTERN IN...WESTERN AND CENTRAL OH...AND
    NORTHERN KY...  
 ...SUMMARY...
    Severe thunderstorms are forecast to affect areas from Lower
    Michigan southward to Tennessee, mainly this afternoon through
    tonight.  The primary threat appears to be damaging wind, but some
    hail and a few tornadoes will also be possible. 
 ...Southern Lower MI/Northern IN...
    Only minor changes have been made to the ongoing forecast.  Water
    vapor loops show a large upper trough over the Central Plains, while
    a deep surface low tracks northeastward across northern IL.  The
    initial severe concern will be ahead of the surface low and into the
    vicinity of the warm front lifting northward into MI.  Relatively
    strong heating and low level moisture advection will result in
    MLCAPE values around 1000 J/kg along and south of the boundary.  12z
    model solutions are consistent in developing scattered thunderstorms
    along this corridor this afternoon and early evening.  Forecast
    soundings suggest a favorable vertical shear profile for discrete
    supercells capable of large hail and damaging winds.  This portion
    of the outlook area holds the greatest concern for supercell
    tornadoes later today.

Previous 2/22/17 Write-Up and Update....

A strong spring-like system will be surging through the Great Lakes and Upper Ohio Valley Friday into Saturday. The unseasonably warm, spring-like temperatures that have affected Southeast Lower Michigan for the past several days will be rudely pushed east of the later Friday night and Saturday.

Ahead of the front; this clash of the spring-like and winter air masses will also bring the potential for strong damaging winds as showers and thunderstorms barrel through the area Friday afternoon into early Saturday morning. This storm system, more typical of a classic late March or April storm system, will also bring the risk of a rather unusual event of severe weather for February.

The set-up Friday night based on Latest NAM, 00Z - 022317

The deep low will occlude and move through Lower Michigan Friday afternoon into the first half of Friday night. Heavy to very heavy showers and scattered thunderstorms can be expected to charge ahead of the cold front and along the warm front. Very strong gusty winds will accompany the activity with gusts in excess of 50 mph are likely in the worst of the storms.























All severe weather parameters (and some not shown) paint the best instability, bulk shear, lapse rates and unusual (for February), surface based CAPE over Southern and Southeast Lower Michigan. The nose of an 80knot Bulk Shear coming into the Southern Great Lakes, certainly draws attention to the potential of realized damaging winds any heavy shower or storm could bring down. At the very least, the idea of a "thunder-less" line of heavy showers with potential severe winds would also be a threat with this system.

A potential for short-fused severe weather event is in the wings from Friday evening into the first half of the night till about 2am EST Saturday morning at this early juncture. Strong low pressure system and attending warm and cold fronts will be barrelling across Southern Lower Michigan at that time.

 
                                                From the Storm Prediction Center



...Southern Great Lakes and Ohio Valley...
Low-level moisture is forecast to slowly increase on strong
southerly flow with boundary-layer dewpoints forecast to range 52-58 degrees F. Although cloud cover will retard strong surface heating, cooling mid-level temperatures to around -19 degrees C will contribute to weak buoyancy (ranging from 250-1000 J/kg MUCAPE) within the northward expanding warm sector during the day. As strong forcing for ascent (DCVA) approaches and overspreads the western parts of the area, a band of thunderstorms will likely develop and intensify. Strong effective shear around 50 kt will act to organize updrafts and strengthening 700-mb flow to the 55-60 kt range will contribute to cold pool's organization and upscale growth. Downward momentum transport via damaging winds are the predominant severe risk. However, some forecast soundings show relatively moist low levels with strong 0-1 km shear in excess of 25-30 kt. A tornado risk may develop with the maturing squall line and/or pre-frontal supercell(s) that eventually merges with the line. A gradual weakening in buoyancy by the early to mid evening into the overnight will likely lead to a lessening in the damaging-wind risk as storms rapidly move east and northeastward after dark.


Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian




2/20/17

Roller-coaster Pattern of the Winter About to Get Revved Up Again

It's been a slow winter for potential storm discussions but as we turn the calendar from February into March, our various models have been in overdrive trying to peg potential storms from the last weekend of February into the first two weeks of March.

All indications are the "ole' sling-shot pattern" (a strong jet stream that digs south from western Canada into the southern California and/or Rockies & Plains before loading and shooting northeast somewhere in the Midwest/Lakes) will be a major player in the roller-coaster pattern prevalent so much this winter.



 More to follow....

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian


2/6/17

Digging Further into January's Weather Records Bring's More Rareness and Oddities - January 2017 Update

There's no doubt about it; besides the more typical climate statistics for the month of January ("warmest, wettest, etc etc), January 2017 had more to offer than the usual headlines.

True, January 2017 was the 12th warmest January on record at Detroit and Flint, while being the 15th warmest at Saginaw. Abundant rainfall of 3.13" made January the 6th wettest in Flint and while both Detroit and Saginaw had above normal rains, the top 20 list was not breached. Snowfalls were near to slightly below normal in most regions.

Elaborating on the oddities mentioned in the my article on January recently (below); January 2017 was also a stand-out month for any January (and other months) with cloud cover, lack of sunshine, dense fog and thunderstorms. Digging back over my records for Detroit, show that January 2017 was indeed lacking in sunshine due to the cloud cover. The sunshine normals or historical data is available up through June 1995. The sunshine switch was then removed from DTW and placed in at DTX. However, due to frequent errors in readings after the move, it was later terminated and dismantled. Past sunshine minutes, percentages and normals were last printed in the 1995 DTW Annual LCD. Again, this was after the NWS moved out of  DTW and DTW became a Contract Station.

January's cloud cover, sunrise to sunset /sr - ss/ is on the monthly F6 below and totaled 8.8 or rounded off  to 9, out of a possible 10. January 2017 had 26 cloudy or mostly cloudy days, 3 partly cloudy days and just 2 clear or mostly clear days. This compares to the averages or normals for January sky conditions/as follows: the 125 year ave /1871-1995/ amount of cloudy days in January sunrise - sunset /sr-ss/ averages to 20,  there are 7 partly cloudy days and 4 for clear. The 105 year average /1891-1995/ of possible sunshine in Detroit for January stands at about 36% while the 110 year average /1886-1995/ cloud cover for January is around 7.5 tenths.

Therefore yes January was a gloomy month - but a record? 


PRELIMINARY LOCAL CLIMATOLOGICAL DATA (WS FORM: F-6)

                                          STATION:   DETROIT MI
                                          MONTH:     JANUARY
                                          YEAR:      2017
                                          LATITUDE:   42 13 N
                                          LONGITUDE:  83 20 W

  TEMPERATURE IN F:       :PCPN:    SNOW:  WIND      :SUNSHINE: SKY/WX :PK WND
================================================================================
1   2   3   4   5  6A  6B    7    8   9   10  11  12  13   14  15   16   17  18
                                     12Z  AVG MX 2MIN
DY MAX MIN AVG DEP HDD CDD  WTR  SNW DPTH SPD SPD DIR MIN PSBL S-S WX    SPD DR
================================================================================

 1  41  23  32   6  33   0 0.00  0.0    0  5.9 14 210   M    M   2 18     17 190
 2  43  27  35   9  30   0 0.08  0.0    0  6.4 12  90   M    M   9 18     17  90
 3  45  38  42  16  23   0 0.36  0.0    0  8.1 18 290   M    M  10 12     24 280
 4  38  19  29   3  36   0 0.01  0.2    0 19.3 24 280   M    M  10        46 280
 5  20  12  16 -10  49   0 0.03  0.7    T 12.2 21 250   M    M   9 8      24 270
 6  17   8  13 -13  52   0    T    T    T  9.1 16 240   M    M   8 18     29 270
 7  17   5  11 -15  54   0 0.02  0.7    T 11.2 21 310   M    M   7 89     28 310
 8  18   8  13 -13  52   0 0.00  0.0    1 10.0 17 290   M    M   5        23 280
 9  31  16  24  -2  41   0    T    T    1 12.4 21 210   M    M  10        25 220
10  49  27  38  12  27   0 0.53  3.0    3 20.2 41 250   M    M  10 1246   53 260
11  57  29  43  17  22   0 0.13  0.0    0 13.9 33 250   M    M   9 138    42 240
12  58  29  44  19  21   0 0.40  0.0    0 11.4 29 230   M    M  10 13     42 220
13  29  20  25   0  40   0 0.00  0.0    0  8.1 17 280   M    M  10        23 280
14  33  23  28   3  37   0 0.00  0.0    0  4.4 10  80   M    M   8        13  90
15  34  18  26   1  39   0 0.00  0.0    0  3.9  9 200   M    M   3 18     12 220
16  36  19  28   3  37   0 0.15  0.0    0  3.3 13 100   M    M   9 168    16 100
17  48  33  41  16  24   0 0.42  0.0    0  8.6 18 250   M    M   9 1236   23 240
18  43  35  39  14  26   0    T  0.0    0 11.0 18 220   M    M  10 1      24 210
19  38  33  36  11  29   0 0.00  0.0    0  7.8 17 240   M    M  10 18     21 240
20  42  33  38  13  27   0 0.16  0.0    0  5.7 13  60   M    M  10 12     16  60
21  59  40  50  25  15   0    T  0.0    0  3.2 10 170   M    M   7 128    13 180
22  49  40  45  20  20   0 0.00  0.0    0  3.9  9  80   M    M  10 12     11  60
23  46  41  44  19  21   0 0.11  0.0    0  7.3 13  60   M    M  10 12     16  50
24  42  39  41  16  24   0 0.04  0.0    0  7.2 17 310   M    M  10 12     22 300
25  48  36  42  17  23   0 0.01  0.0    0 10.1 29 230   M    M  10 18     35 220
26  42  35  39  14  26   0    T    T    0 16.1 26 230   M    M  10 4      32 250
27  35  28  32   7  33   0 0.01  0.1    0 14.7 24 260   M    M  10 46     32 240
28  31  28  30   4  35   0 0.02  0.5    T 13.8 20 230   M    M  10 189    25 240
29  30  25  28   2  37   0 0.05  2.0    1  7.2 15 300   M    M  10 18     19 310
30  27  18  23  -3  42   0 0.06  1.4    2  7.0 14 190   M    M   9 1      19 240
31  36  26  31   5  34   0 0.24  3.2    6  9.1 17 270   M    M  10 18     32 280
================================================================================
SM 1182  811      1009   0  2.83    11.8 292.5          M      274
================================================================================
AV 38.1 26.2                               9.4 FASTST   M    M   9    MAX(MPH)
                                 MISC ---->  # 41 250               # 53  260
================================================================================
NOTES:
# LAST OF SEVERAL OCCURRENCES

COLUMN 17 PEAK WIND IN M.P.H.

PRELIMINARY LOCAL CLIMATOLOGICAL DATA (WS FORM: F-6) , PAGE 2

                                          STATION:  DETROIT MI
                                          MONTH:    JANUARY
                                          YEAR:     2017
                                          LATITUDE:   42 13 N
                                          LONGITUDE:  83 20 W

[TEMPERATURE DATA]      [PRECIPITATION DATA]       SYMBOLS USED IN COLUMN 16

AVERAGE MONTHLY: 32.1   TOTAL FOR MONTH:   2.83    1 = FOG OR MIST
DPTR FM NORMAL:   6.5   DPTR FM NORMAL:    0.87    2 = FOG REDUCING VISIBILITY
HIGHEST:    59 ON 21    GRTST 24HR  0.57 ON 16-17      TO 1/4 MILE OR LESS
LOWEST:      5 ON  7                               3 = THUNDER
                        SNOW, ICE PELLETS, HAIL    4 = ICE PELLETS
                        TOTAL MONTH:  11.8 INCHES  5 = HAIL
                        GRTST 24HR   3.2 ON   M    6 = FREEZING RAIN OR DRIZZLE
                        GRTST DEPTH:   6 ON 31     7 = DUSTSTORM OR SANDSTORM:
                                                       VSBY 1/2 MILE OR LESS
                                                   8 = SMOKE OR HAZE
[NO. OF DAYS WITH]      [WEATHER - DAYS WITH]      9 = BLOWING SNOW
                                                   X = TORNADO
MAX 32 OR BELOW:   9    0.01 INCH OR MORE:  19
MAX 90 OR ABOVE:   0    0.10 INCH OR MORE:   9
MIN 32 OR BELOW:  20    0.50 INCH OR MORE:   1
MIN  0 OR BELOW:   0    1.00 INCH OR MORE:   0

[HDD (BASE 65) ]
TOTAL THIS MO.  1009    CLEAR  (SCALE 0-3)   2
DPTR FM NORMAL  -214    PTCLDY (SCALE 4-7)   3
TOTAL FM JUL 1  2987    CLOUDY (SCALE 8-10) 26
DPTR FM NORMAL  -533

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

CLOUD COVER & SUNSHINE

RECORD NUMBER OF CLOUDY DAYS /AVERAGE FOR MONTH/ AT DETROIT FOR *JANUARY AND **ALL TIME

      MONTH  &   YEAR          NUMBER
 *    JANUARY      1960            9.3
1-**NOVEMBER 1985              9.3
   **JANUARY     1960              9.3
   **DECEMBER 1929               9.3
2-**NOVEMBER 1992               9.2
9-   JANUARY      2017             8.8
      (JANUARY      1932            8.6)



RECORD FOR LEAST AMOUNT OF SUNSHINE AT DEROIT FOR *JANUARY AND *ALL TIME
      MONTH & YEAR          NUMBER
*     JANUARY    1932            14%
1-**DECEMBER 1929              7%
2-**NOVEMBER 1985            13%
?   JANUARY     2017            N/A


November 1985, January 1960 and  December 1929 all tie for the cloudiest month ever in Detroit.  January 2017 doesn't even come close to the cloudiest month nor cloudiest January with 8.8 cloud cover /9th place/.

Looking at the previous sunrise-sunset cloud cover records and least sunshine records above, we can basically be assured that January 2017 would not have placed for the least sunniest month (December 1929 has that honor). How about the least sunniest January?  

January 2017 is a just a contender for the least sunniest January by the following reasoning...

Obviously, it's difficult to say how much sunshine Detroit had in January 2017 since it wasn't recorded locally and doesn't always correlate or is the inverse of cloud cover. Case in point from above: Lowest sunshine on record for January is 14% in 1932 but this occurred with less cloud cover at 8.6 as opposed to the 16% of sunshine in January 1960 with a higher amount of cloud cover at a record 9.3! If one was only to go by a direct correlation by cloud cover and subsequent lack of sunshine alone; then there is a higher chance, January 2017 contained less sunshine than January 1932.  However it isn't always that simple...

Here's where being an older-timer weather observer has its merits, so try to follow along...

It really has to do more to do with the type of clouds and their thickness observed during the day/month and resulting opaqueness.  In the "old days" of the NWS, observations of cloud cover was recorded in both total coverage and opaqueness of the total; say for example 10/10 of cirrostratus (usually a high but partially thin cloud cover) and its opaqueness, might be 10/5. Therefore the observation read something like; 200-OVC (or in the teletype days when I started, it was 200-O with a cross in the middle - sent out and read on teletype but not displayed on a weather map). The symbol (-) was read as thin, when the opaqueness of a cloud cover was half or less. Basically meaning; one could discern the blue sky above (or stars/moon at night). With the advent of ASOS, the thinner parts of all types of cloud cover was lost in the observation. This is where the human element of a weather observation was better to discern the actually cloud cover and its thickness. Clouds above 12,000ft are not officially observed on ASOS therefore some mid clouds and all high clouds are lost - and certainly their opaqueness! This was/is crap to most pre-ASOS days weather observers and many other weather aficionados. Wtih ASOS, sometimes the higher clouds are still augmented  (edited)  into the ASOS where human observers are co-located with ASOS.

Ok, back to the subject at hand...

The absolute dreariest month for sunshine happened after the stock market crash of 1929 when December 1929 had only 7% of the possible (well below anything other month).  I guess mom nature got in on the mood around metro Detroit and the country. Keep in mind, the month of December 1929 has the least amount of possible sunshine during any given December and month. Therefore; December 1929 with just 7% of the possible was indeed, the gloomiest month. Another interesting tidbit for December 1929; however was its Christmas was one of the whitest in Detroit's history with 11 1/2" of snow on the ground.
 
And talk about down right depressing:

It should be noted that November and December 1972 have the record for the gloomiest period /60 days/ in what I could find in both cloud cover and subsequent sunshine (or lack there-of).

    MONTH  &   YEAR          NUMBER  
NOVEMBER      1972                 9.1
DECEMBER      1972                 9.0

    MONTH  &   YEAR         SUNSHINE (%)    

 NOVEMBER      1972               13%
 DECEMBER      1972               13%

So, you see this past January wasn't so bad. There were other times during the 1970s in the winter I recall cloudy, dreary months around here and stats back me up; November 1977 /9.1/ December 1974 /8.7/ and actually it didn't end there in the monthly stats. The whole year of 1972 had 7.1 cloud cover for the cloudiest year on record at Detroit with 1984 a close second at 7.0. More 1970's show up here for cloudier years too, 1970 and 1973 at 6.9, 1974 at 6.8. Actually it sort of follows; being that some of the years in the 1970s, tended to be a bit more stormy in both winter and severe weather seasons...there'd also be more cloud cover. And, that leads me to thunderstorms in January...

RECORD NUMBER OF THUNDERSTORM DAYS FOR JANUARY

YEAR          NUMBER
2017                    3
1909                    3
1907                    2

Thunderstorm days in January while not unheard-of are fairly rare with an average since 1871 of just about .2 (or well less than one day in January). Therefore you can reason, that January thunderstorms days are few and far between.
RECORD NUMBER OF DENSE FOG DAYS DETROIT FOR *JANUARY AND **ALLTIME
DENSE FOG RECORDS


    MONTH & YEAR          MOST DENSE FOG DAYS

 * JUNE          1973                9
**JANUARY  1907                 8
   JANUARY  2017                 8 /TIED WITH 1907 & THUS SUPERSEDES/


There were 8 days total during the month of January (20-24th, 5 dense fog days in a row) which was also very rare. Occurrences of dense fog in January is 2 days on average. January 2017 totaled just one day less the the all time record for dense fog days which belongs to June of 1973. However; January tied for first place for the month of January with 8 days which was also observed in January 1907. Just for an extreme comparison; there were only 6 days in all of 2015 that dense fog was recorded at DTW. The annual average for the year is about 17 days for dense fog.

Previous Preliminary January write-up through January 22nd... 

"Strange January to Get back on Track Later This Week"

It's been an odd and very variable January this year. The first several days started out mild, then a cold blast commencing on the 5th reminded Southeast Lower Michigan inhabitants what month it really was with temperatures well below normal - but that didn't last long did it? We turned the corner by the 9th and again, it was off to the races to warmth with high temperatures basically in the 50s for three days before a slight 4-day cool down took hold through the 16th. Since then; readings have continually averaged above or well above normal through the 21st /yesterday/. In fact; Detroit's high on the 21st of 59 reached the peak reading thus far for the month, making that the third upper 50-degree temperature this month! Not to be a record however as that honor belongs to Jan 21st of 1906 with 65! If we're going to speak of records, Flint's high temperature of 54 on the 21st came within one degree of its 55 degree record in 1954.

In the midst of January's wild roller-coaster ride of frequent up and down temperature swings; came just as many resulting weather phenomena - some typically seen and some not during January. Snow and cold of course, ranks on the side of normalcy in January; whereas balmy spring-like temperatures interspersed through the month, thunderstorms and many dense fog days do not. Oh sure they happen in January; and if at any time, usually during our cyclical January thaw which comes regularly enough to nudge up temperature records in past data during mid to late month for several days. However, there's certainly been more than a weeks duration of thawing weather this January with several notable upward temperature swings during the month. So much so, that even with the bitter cold experienced earlier in the month, readings are averaging 4 - 5 degrees above normal and enough so; that we are beginning to enter the top 20 warmest January's list at all three stations in the bottom (upper teens to 20). Three thunderstorm days have ranked up this month thus far at Detroit, an unusual amount being its the dead of the winter. Dense fog days have just eclipsed (6/5-as of the 22nd) the number of snow days thus far in January with nearly a week total in days where visibilities at Detroit Metro Arpt dropped down to a 1/4 mile or less. Last night (21st-22nd) being the foggiest I've seen it in quite awhile around metro Detroit. Dense fog advisories have been carried/existed since Saturday evening /21st/ (now Sun eve night, 22nd).

The snow machine sputtered the first ten days of the month but then died completely after the tenth. What had been a relatively snowy winter thus far into early January went bye-bye since, with 4.6" recorded the first ten days at Detroit. Flint did a bit better with 5.7" and Saginaw topped it with 7.4" To be fair; all three climate stations still are above normal for the snow season of 2016-17 by about 2-4" - but don't look for much of any addition this week as temperatures hold basically above normal with mainly rain expected until about Friday. The better chances for any addition of light snow will be across the northern portions of Southeast Michigan but then, rain is expected to mix with the snow, which should cut down any appreciable accumulations. Actually more rain than snow days have been observed this month with all of Southeast Lower Michigan having a wet January thus far. Detroit is nearly an inch above normal (a decent departure for January); Flint is nearly an inch and a half above while Saginaw rests at about three quarters above average".


Note; Due to the lack of records for some weather items in Detroit's LCD since 1995, some records were estimated using very long term records which were then, updated.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian