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April 2020


donsutherland1
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1 hour ago, ict1523 said:

I might be in the minority but I do not think this spring has been that bad so far. We've actually had a solid number of dry, sunny days in between the rain. 

Does anyone know where to find the charts that show monthly cloud cover at various stations?

I agree-lots of sun this spring despite the cooler temps-some years we end up with days and days of overcast....

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Tuesday looks like a strong to potentially severe squall line that could change to snow over the higher elevations of the interior Northeast. Very strong cold front for this time of year. Could be another -10 temperature departure on Wednesday. April could be the first month with 3 days to reach -10 since November.

Northeast...
   A powerful upper trough will take on a negative tilt Tuesday as a
   cold front surges east across NY, PA, and southern New England.
   Rapid cooling aloft will occur in association with the left-exit
   region of a cyclonically curved upper jet, with the core of the
   strong lift swinging east/northeast across NY and New England.
   Forecast soundings ahead of the cold front indicate SBCAPE up to
   100-200 J/kg (depending on the model) is likely within a narrow
   north-south zone during the day, fueling shallow convection. Long
   hodographs may sustain convection, with a large cross-boundary
   component to the deep-layer shear vectors. Given the strength of the
   system, at least isolated damaging wind gusts will be possible, even
   with minimal SBCAPE. Cellular storm mode may be present as well
   given the long hodographs, and small hail is possible. Any severe
   risk on Tuesday will be highly dependent on instability, and an
   increase in probabilities cannot be ruled out in later outlooks.

9BE6FC00-896B-4179-AB50-CB3BAB05949E.thumb.png.1b3c21960724f3f7e8a8959e614e0c77.png

6A2BA9FF-F552-415A-B774-5C5179EA1C02.png.8449328953f14049d02e8cdbc62ebc03.png

 

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Yesterday's storm was likely the last glancing blow of the feeble winter of 2019-2020. Snowfall totals across the Middle Atlantic and southern New England regions were far below normal. Near final seasonal snowfall totals include:

Albany: 49.6" 10.2" below normal
Baltimore: 1.8" 18.3" below normal (lowest since 2011-12: 1.8")
Boston: 15.8" 27.8" below normal (lowest since 2011-12: 9.3")
Harrisburg: 5.1" 25.4" below normal (***lowest on record***)
New York City: 4.8" 20.9" below normal (lowest since 2001-02: 3.5")
Newark: 6.9" 21.5" below normal (lowest since 2001-02: 3.6")
Philadelphia: 0.3" 22.0" below normal (lowest since 1972-73: Trace)
Washington, DC: 0.6" 14.8" below normal (lowest since 1997-97: 0.1")

In contrast, Caribou has received 137.9" snow, which is 31.3" above normal. Winter 2019-20 was the 3rd consecutive winter during which 130" or more snow fell at Caribou. That last time that happened was winters 1970-71 through 1972-73.

After a cold start, temperatures moderated this afternoon. Readings topped out in the upper 50s and lower 60s across much of the region. High temperatures included:

Allentown: 64
Atlantic City: 61
Bridgeport: 59
Harrisburg: 60 (daily low: 29 tied the daily record set in 1904)
Islip: 57
New York City: 63
Newark: 63 (daily low: 33 tied the daily record set in 2001)
Philadelphia: 64

Overnight through tomorrow a storm will pass to the south spreading clouds across the region. A frontal passage could bring some rain or showers on Tuesday.

Through at least April 24, readings could average generally below normal to near normal with a few warmer than normal days across the Middle Atlantic and southern New England regions. Warmer than normal conditions could return during the closing days of April. However, uncertainty has increased, as some of the more recent guidance delays the return of the warmth.
 
Past cases that saw the NAO average -0.750 or below during April 1-5 with warmth in the East, as occurred this month, saw the development of a trough in the East after April 10. That trough typically persisted in the means for 1-2 weeks.

Looking ahead to May, 73% of cases that saw one or more days where the NAO fell to -1.000 or below during April 1-10, 1950-2019, as was the case this April, wound up with a warmer than normal May. In addition, two-thirds of cases that saw the MJO reach Phase 8 at an amplitude of 2.000 or above during the April 5-20 period, as happened this month, saw a warmer than normal May.

The ENSO Region 1+2 anomaly was +0.8°C and the Region 3.4 anomaly was +0.6°C for the week centered around April 8. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.72°C and the ENSO Region 3.4 anomaly has averaged +0.58°C. Neutral and occasionally warm ENSO conditions will likely prevail through at least the end of April.

The SOI was +15.14 today.

Today, the preliminary Arctic Oscillation (AO) figure was +1.181.

On April 18, the MJO was in Phase 1 at an amplitude of 1.453 (RMM). The April 17-adjusted amplitude was 1.391.

February 2020 saw the ENSO Region 1+2 anomaly increase by more than 0.50°C. Such a development has typically occurred before a warmer than normal summer. In all such cases, a warmer than normal spring was followed by a warmer than normal summer. Therefore, a warmer than normal summer is currently more likely than not. Should Spring wind up warmer than normal, a warm or even hot summer will be very likely.

Based on sensitivity analysis applied to the latest guidance, there is an implied 70% probability that New York City will have a cooler than normal April. April will likely finish with a mean temperature near 52.0°.

 

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On 4/1/2020 at 8:52 AM, donsutherland1 said:

For purposes of looking at the GFS (FV3) cold bias, the model blend I use for my sensitivity analysis has a departure of +1.5° for the April 1-17 period vs. the GFS's -2.0°. It will be interesting to see the actual number.

Verification:

The April 1-17 mean temperature in New York City was 51.2. That was 0.5 degrees above normal. The model blend was 1.0 degrees too warm; the GFS was 2.5 degrees too cold.

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The next 8 days are averaging 52degs., or about 3degs. BN.

Month to date is  -0.3[50.8].            Should be about  -1.2[51.0] by the 28th.

53* here at 6am.         52* by 10am.        53* by Noon.        59* by 4pm.      51* by 10pm.

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68 degrees will be the high temperature in NYC for the first 20 days of April. This is -15 below the average maximum of 83 degrees since 2010. 

Time Series Summary for NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.
Ending Date
Highest Max Temperature Apr 1 to Apr 20
Missing Count
2020-04-20 68 1
2019-04-20 80 0
2018-04-20 82 0
2017-04-20 87 0
2016-04-20 82 0
2015-04-20 80 0
2014-04-20 77 0
2013-04-20 82 0
2012-04-20 88 0
2011-04-20 81 0
2010-04-20 92 0
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14 hours ago, donsutherland1 said:

Verification:

The April 1-17 mean temperature in New York City was 51.2. That was 0.5 degrees above normal. The model blend was 1.0 degrees too warm; the GFS was 2.5 degrees too cold.

For all the talk of cool weather it's basically been average. Of course when every month is in the top 5-10 even average feels cold.

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If the NAM is correct, then we may be under a severe thunderstorm watch on Tuesday. Very impressive squall line potential with steep midlevel lapse rates and some surface based instability. Could also see an embedded  meso spin up in the line with high helicity values.

1ACAE990-3702-48CD-89FA-DE40EB98EA24.png.a10890b5bb07be436c4ffc3362a9cdeb.png

EF08EC69-3252-4224-AD4B-34135D005785.png.76a89da6982ea44f72d56f606bb0ddb8.png

A1DE625E-A166-4907-A23A-09FD1296A6AA.png.08feb5f608cd7e253c98bbfcf7ecab3a.png

 

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22 hours ago, bluewave said:

A wild card moving forward may be all that warm water over the Eastern IO. MJO 3 is associated with a trough over the East this time of year. During the summer this pattern can produce a trough over the Midwest or Great Lakes. But the Atlantic and Gulf record SST’s support a strong WAR  pattern. How far west this ridge is able to build will determine whether we have a 0 to +2 summer or warmer. In any event, looks like it could be wet and humid if such a pattern sets up. So maybe warmer summer minimums and clouds preventing more frequent 100 days of 2010 to 2013. Be interesting to see how things turn out.

DF7FE091-7A52-4141-BD87-DE2C2A008C09.gif.52512f722990616a700f80bab04ac60f.gif

27AF4DB9-ED8E-4E89-8D3D-9B8091038F74.png.28d0f780863b39f98e7d4360387abf6e.png

8CABD434-429D-4F16-B0E3-FB2364356989.png.0e069875c0400aa60b177785e42c7acc.png

 

Yep, phase 3 in April is cold cold. Perfect storm now with blocking, mjo, -epo, and +pna. 

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48 minutes ago, uncle W said:

the blocking from the ao/nao isn't forecast to be that strong or lengthy...still we will be looking at the coldest temp for April 2020 this week...

The +PNA takes over once the NAO and EPO flip positive. So we still get a lingering trough over the Northeast. It will probably stay in place as long as the MJO remains around phase 3.

CBD73B1B-AD96-4287-97D7-7B35453A8879.thumb.png.37c3a08b8d15a9376897541f8ea396b0.png

FABDE73F-7ABF-4235-AB91-0A656205CDDC.gif.48b47165bb064065a15687dabbaf91d5.gif

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Wind Advisory

URGENT - WEATHER MESSAGE
National Weather Service New York NY
351 PM EDT Mon Apr 20 2020

CTZ005-006-009-010-NJZ002-004-006-103>108-NYZ067>075-078-080-
176>179-211015-
/O.NEW.KOKX.WI.Y.0008.200421T2100Z-200422T0600Z/
Northern Fairfield-Northern New Haven-Southern Fairfield-
Southern New Haven-Western Passaic-Eastern Passaic-Hudson-
Western Bergen-Eastern Bergen-Western Essex-Eastern Essex-
Western Union-Eastern Union-Orange-Putnam-Rockland-
Northern Westchester-Southern Westchester-New York (Manhattan)-
Bronx-Richmond (Staten Island)-Kings (Brooklyn)-
Northwestern Suffolk-Southwestern Suffolk-Northern Queens-
Northern Nassau-Southern Queens-Southern Nassau-
351 PM EDT Mon Apr 20 2020

...WIND ADVISORY IN EFFECT FROM 5 PM TUESDAY TO 2 AM EDT
WEDNESDAY...

* WHAT...Northwest winds 20 to 30 mph with gusts up to 50 mph
  expected.

* WHERE...Portions of northeast New Jersey, southern Connecticut
  and southeast New York.

* WHEN...From 5 PM Tuesday to 2 AM EDT Wednesday.

* IMPACTS...Gusty winds could blow around unsecured objects.
  Tree limbs could be blown down and a few power outages may
  result.
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On account of a storm's passing south of the region, most of the area saw considerable clouds into the afternoon today. Temperatures continued to run somewhat below normal.

Tomorrow will be somewhat milder in advance of a cold front as a strong storm moves eastward from Ontario across Quebec. The storm's associated cold front will likely cross the region during the late morning or early afternoon with a round of showers and possibly thunderstorms. Strong winds are likely during the day. Noticeably cooler air will likely follow.

Readings will likely average generally below normal to near normal with a few warmer than normal days across the Middle Atlantic and southern New England regions through most of the remainder of the month. Warmer than normal conditions could return near the end of the month.
 
Past cases that saw the NAO average -0.750 or below during April 1-5 with warmth in the East, as occurred this month, saw the development of a trough in the East after April 10. That trough typically persisted in the means for 1-2 weeks.

Looking ahead to May, 73% of cases that saw one or more days where the NAO fell to -1.000 or below during April 1-10, 1950-2019, as was the case this April, wound up with a warmer than normal May. In addition, two-thirds of cases that saw the MJO reach Phase 8 at an amplitude of 2.000 or above during the April 5-20 period, as happened this month, saw a warmer than normal May.

The ENSO Region 1+2 anomaly was +0.1°C and the Region 3.4 anomaly was +0.7°C for the week centered around April 8. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.55°C and the ENSO Region 3.4 anomaly has averaged +0.62°C. Neutral and occasionally warm ENSO conditions will likely prevail through mid-May. ENSO Region anomalies could begin a steady cooling during late April or May.

The SOI was +8.00 today.

Today, the preliminary Arctic Oscillation (AO) figure was +1.181.

On April 19, the MJO was in Phase 1 at an amplitude of 1.678 (RMM). The April 18-adjusted amplitude was 1.451.

February 2020 saw the ENSO Region 1+2 anomaly increase by more than 0.50°C. Such a development has typically occurred before a warmer than normal summer. In all such cases, a warmer than normal spring was followed by a warmer than normal summer. Therefore, a warmer than normal summer is currently more likely than not. Should Spring wind up warmer than normal, a warm or even hot summer will be very likely.

Based on sensitivity analysis applied to the latest guidance, there is an implied 77% probability that New York City will have a cooler than normal April. April will likely finish with a mean temperature near 52.0°.

 

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11 hours ago, NJwx85 said:

Mesoscale models have an area of "showers" moving through early afternoon before the main show. Worried that might severely limit the amount of CAPE available. The 18z NAM backed off quite a bit on instability. 

200-400 j/kg of surface based cape will be more then sufficient. Elevated cape will be there as well. With the strong winds aloft this can definitely produce some nice winds in areas.

 

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The next 8 days are averaging 50degs., or about 5degs. BN.

Month to date is  -0.4[50.9].         Should be about  -1.7[50.7] by the 29th.

47* here at 6am.     48* at 7am.      53* by 9am.          Storms at 12:20pm and 3:15pm.         44* by 10pm.

NYC WIND ADVISORY:

HEADLINE: Wind Advisory issued April 21 at 3:29AM EDT until April 22 at 2:00AM EDT by NWS New York City - Upton

DESCRIPTION: ...WIND ADVISORY REMAINS IN EFFECT FROM 5 PM THIS AFTERNOON TO
2 AM EDT WEDNESDAY...
* WHAT...Northwest winds 20 to 25 mph with gusts up to 50 mph
expected.
* WHERE...Portions of northeast New Jersey and southeast New
York.
* WHEN...From 5 PM this afternoon to 2 AM EDT Wednesday.
* IMPACTS...Gusty winds could blow around unsecured objects.
Tree limbs could be blown down and a few power outages may
result.

INSTRUCTIONS: Use extra caution when driving, especially if operating a high
profile vehicle. Secure outdoor objects.

Issued By: NWS New York City - Upton (Long Island and New York City)

Some rain by 1pm and the Jackpot around 3pm?:

nam3km_mslp_pcpn_frzn_neus_13.png

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First time since 2000 that we are getting a cool April after such a warm March.

Top 5 warmest Marches in NYC since 2000

Monthly Mean Avg Temperature for NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.
Year
Mar
Apr
Season
2012 50.9 54.8 52.8
2016 48.9 53.3 51.1
2010 48.2 57.9 53.0
2020 48.0 50.9 49.1
2000 47.2 51.0 49.1

 

 

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