bluewave

Looks like our first +3 SD MJO phase 8 since February 2017. That one was preceded by the blizzard of 2017. But much warmer conditions and a spring wavelength response didn’t allow for a similar wintery outcome. 2021 4 27 -2.8350327 1.1143280 8 3.0461676 2017 2 15 -3.0841775 0.94387865 8 3.2253771 https://www.weather.gov/okx/Blizzard_Feb92017

Just looking at the teleconnections, it appears like this should have been a cold April. But the warmer south based blocking continued like we saw during the winter. So it was a rare warmer than average -EPO, -AO, -NAO April.

This is one of the less common months when the high temperatures are driving the departures. NYC was +1.5 on the max and +0.3 on the min through yesterday. Frequent cold fronts and drier conditions have allowed the minimum temperatures to remain near normal while the high temperatures have been above average. CLIMATE REPORT NATIONAL WEATHER SERVICE NEW YORK, NY 435 PM EDT WED APR 28 2021 ................................... ...THE NEWARK NJ CLIMATE SUMMARY FOR APRIL 28 2021... VALID TODAY AS OF 0400 PM LOCAL TIME. CLIMATE NORMAL PERIOD 1981 TO 2010 CLIMATE RECORD PERIOD 1893 TO 2021 WEATHER ITEM OBSERVED TIME RECORD YEAR NORMAL DEPARTURE LAST VALUE (LST) VALUE VALUE FROM YEAR NORMAL ................................................................... TEMPERATURE (F) TODAY MAXIMUM 89 157 PM 90 1990 67 22 68 2009 MINIMUM 50 502 AM 33 1934 48 2 40 AVERAGE 70 57 13 54

Yeah, now the temperature is back down to 71° at LGA. Very impressive hourly and daily temperature jumps since late March on the wind shifts. The temperature on the South Shore back in late March rose from 57° to 80° in an hour.

Today was the 7th highest April diurnal temperature range for Newark at 38°.

When was the last time that Newark was 17° warmer than LGA at 2pm? Newark/Liberty PTSUNNY 88 53 30 SW14G21 LaGuardia Arpt PTSUNNY 71 46 40 NE9

Temperatures are off to the races for areas that get into a westerly flow like we are first seeing in Central New Jersey. WRI just experienced a 25° jump in just 3 hours. So our local spots that can go more westerly will quickly rise into the 80s.

This month is another example of the coldest departures focused around the Plains.

Looks like .47 so far in NYC. Matches the spring theme of mostly light to moderate events. While this spring is on the drier side of recent years, it’s still wetter than 2016 was. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Ending Date Total Precipitation Mar 1 to Apr 25 Missing Count 2021-04-25 5.88 0 2020-04-25 7.33 0 2019-04-25 7.26 0 2018-04-25 10.62 0 2017-04-25 8.69 0 2016-04-25 2.49 0 2015-04-25 6.80 0 2014-04-25 5.60 0 2013-04-25 4.17 0 2012-04-25 4.45 0 2011-04-25 11.23 0 2010-04-25 12.94 0

The system is moving pretty quickly. So the best chance for rain will be tonight into early Sunday. Looks like the afternoon could turn out nice with breaks of sun and 60s. KEWR GFS MOS GUIDANCE 4/24/2021 0600 UTC DT /APR 24 /APR 25 /APR 26 / HR 12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 00 06 X/N 71 51 63 41 65 TMP 53 64 68 68 64 58 54 53 54 54 59 61 56 53 48 43 46 55 62 59 47 DPT 36 32 30 31 33 36 40 42 44 44 43 38 34 33 30 26 24 19 17 19 25 CLD SC FW SC BK OV OV OV OV OV OV OV BK FW CL CL CL CL FW CL FW CL WDR 26 27 23 20 22 18 18 05 02 36 31 31 30 31 29 29 30 31 30 30 30 WSP 05 07 10 11 09 05 03 05 09 12 14 17 19 19 15 14 17 17 18 18 04

Quick wavelength changes coming up with the very strong MJO and typhoon recurve. Looks like we finally get our April 80° potential on Wednesday. But a near record amplitude MJO 8 for April doesn’t allow it to lock in for long. So it’s followed by a backdoor cold front and cooler on Thursday.

Even Long Island should make it to at least 60° today. But as usual, Newark is the warm spot. Already 56° there with another 5 hours of warming to come. So mid 60s look like a good bet there. Newark Liberty MOSUNNY 56 21 25 W15G31

Another day with a big diurnal temperature range. Our high temperatures usually beat guidance with such low dewpoints and humidity. MOS numbers have mid 60s today in the warm spots. So maybe somebody can get close to 70°. KEWR GFS MOS GUIDANCE 4/23/2021 0600 UTC DT /APR 23 /APR 24 /APR 25 / HR 12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 00 06 X/N 65 46 68 51 63 TMP 42 53 62 65 62 56 51 48 53 63 66 65 62 57 54 53 54 56 60 56 49 DPT 22 18 17 19 23 29 31 32 35 33 32 34 36 40 43 44 45 45 45 38 33

The rotation in that cell prompted the NWS to issue a tornado warning.

These brief cool downs have only been able to last a day or two. NYC is +2.1 through the 21st. So temperatures should quickly rebound back to near to above average. The 0z OP Euro joined the EPS and GFS for 80s potential next week. KEWR GFSX MOS GUIDANCE 4/22/2021 0000 UTC FHR 24| 36 48| 60 72| 84 96|108 120|132 144|156 168|180 192 THU 22| FRI 23| SAT 24| SUN 25| MON 26| TUE 27| WED 28| THU 29 CLIMO X/N 54| 35 66| 47 69| 52 62| 44 66| 45 70| 54 74| 58 78 46 65

This may be close to the record for largest NYC hail in April. At 2:25 PM EDT, 2 SE Midtown Manhattan [Queens Co, NY] TRAINED SPOTTER reports HAIL of penny size (M0.75 INCH) https://mesonet.agron.iastate.edu/lsr/#OKX/202104211825/202104211825

Close to record midlevel lapse rates for late April on the 12z OKX sounding.

Steep surface to 500mb lapse rates in place for severe storms.

The forecast will come down to what happens with the low pressure system on Sunday. The EPS keeps it going far enough to our east so that we get into a deep SW flow at the end of the month. The OP Euro cuts it off east of New England with more of an onshore influence. If we can can get into a strong SW flow, then 80s will be possible.

Looks like an early round of showers next few hours. Then we’ll see how much we can destabilize going into the afternoon. The latest HRRR has a line of strong to potentially severe convection this afternoon.

Our next big temperature drop of the spring. From late March into early April it was 80s to 20s in 7 days. Now places like Newark will drop from 78° to the mid 30s in just 2 days. TEMPERATURE (F) YESTERDAY MAXIMUM 78 245 PM 91 1941 64 14 56 MINIMUM 48 550 AM 34 1953 45 3 42 AVERAGE 63 54 9 49

Yeah, not thinking that we see a repeat of last year. That was the first time the May monthly minimum temperature was lower than April. Quite a swing to warmer after that to the 2nd warmest summer behind 2010 near the coast. Monthly Lowest Min Temperature for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Apr May Season 1891 29 32 29 1874 20 33 20 2020 36 34 34 1947 33 35 33 1880 26 35 26 https://www.ncdc.noaa.gov/cag/divisional/time-series/3004/tavg/3/8/1895-2021?base_prd=true&begbaseyear=1981&endbaseyear=2010 201006 - 201008 75.2°F 126 3.5°F 202006 - 202008 74.4°F 125 2.7°F 201606 - 201608 74.2°F 124 2.5°F 200506 - 200508 73.9°F 123 2.2°F 201106 - 201108 73.9°F 123 2.2°F 199906 - 199908 73.7°F 121 2.0°F 201206 - 201208 73.4°F 120 1.7°F 201806 - 201808 73.4°F 120 1.7°F 201906 - 201908 73.2°F 118 1.5°F 201506 - 201508 73.1°F 117 1.4°F 194906 - 194908 73.0°F 116 1.3°F 200606 - 200608 73.0°F 116 1.3°F 200206 - 200208 72.9°F 114 1.2°F 201306 - 201308 72.9°F 114 1.2°F

Very active pattern for late April coming up. Severe threat Wednesday and big temperature drop to near freezing Thursday. Then a warm up followed by a slow moving coastal on Sunday.

The latest forecast soundings have some of the steepest surface to 500 mb lapse rates that we have seen in April. Looks like the potential for a severe squall line Wednesday afternoon,. Pretty impressive severe signal for April.