Estado de la Clima en Mayo 2018 Antes del Pronostico por Verano

Dr. Art DouglasProfessor Emeritus Creighton University

Outline

1. The impressive reversal in the April-May climate system in 2018.

2. The new climate regime 2014-18

3. Rapid shift from La Nina to El Nino in May and early June.

4. The Analog Forecast for Summer and Fall.

Abrupt Transition in April to May Weather PatternsThe Northern Hemisphere Climate System Experienced a Jolt That May Have Helped Kick-In El Nino Development

ABRIL

MAYO

May 2018 Climate Indices: 700mb

Height Anomalies (top) and SST

Anomalies (bottom)

Major centers of action are framed by black boxes. Indices from these 14 centers of action are analyzed in a cluster analysis to determine past years with similar climate patterns. Years with significant correlations across the indices are Analog Year candidates.

May 700mb HTS

May SSTs

Outline

1. The impressive reversal in the April-May climate system in 2018.

2. A new climate regime 2014-18.

3. Rapid shift from La Nina to El Nino in May and early June.

4. The Analog Forecast for Summer and Fall.

SST Anomalies in the Recent Period 2014-18 Warm PDO and Cold AMO

Top figure shows the mean anomaly for November-April 2014-18. Bottom figure shows the mean anomaly for May-October 2017. The anomalies are relative to the means of 1998-2013 which was the last period of a Negative Phase of the PDO and a Positive Phase of the AMO.

The 700mb Height Anomalies for November-April 2014-18 and May-October 2014-17.

The upper level circulation in the past 4 years has been very stable and appears to be driven by SST anomalies though a synergistic feedback may also be at work.

Outline

1. The impressive reversal in the April-May climate system in 2018.

2. A new climate regime 2014-18.

3. Rapid shift from La Nina to El Nino in May and early June.

4. The Analog Forecast for Summer and Fall.

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10121416

Diff

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ce (m

b)

Date

Pressure DifferenceEaster Island Minus Liberia,

Costa Rica

The Cross Equatorial Flow Index Has Entered El Nino Territory

The gradual decline in the equatorial pressure index from February to April was followed by a sudden collapse in May. With the collapse of the pressure index the Trade Winds weakened and the piling of water towards Asia ceased. An internal ocean wave near the Dateline progressed to the east.

Aletta

World SST Anomalies on June 4, 2018

With the collapse of the cross equatorial trade winds La Nina conditions are now replaced with El Nino warming. The North Pacific and North Atlantic have “El Nino” compatible SST patterns left from the 2014-16 mega El Nino event.

March

OLR Anomalies over the Past 30 days Remain in a La Nina Pattern

An early advance of the Indian monsoon and reduced convection in the central Equatorial Pacific are typical of La Nina. As equatorial warming expands expect strong impacts from El Nino.

NOAA CFSv2May 27th

ECMWFMay 1st

NOAA and ECMWF El Nino Forecasts through Fall 2018

NOAA is now forecasting El Nino warming by mid summer while the European model (ECMWF) forecasts stronger warming . A moderate El Nino event is now likely by late fall or early winter. Compared to the ECMWF, the NOAA CFSv2 model has been very poor over the past four years per the timing of El Nino.

March and FebruaryForecasts

In March the CFSv2 persisted La Nina while the ECMWF broke the March forecast with a forecast of warming.

March 1, 2018 ECMWF forecast of SST anomalies for August-October 2018. The ECMWF model has been forecasting equatorial warming since late last winter. The NOAA CFSv2 has been less consistent in NINO 3.4 forecasts but now forecasts El Nino by the fall.

The March 1st Analog SST Forecast For August 2018The analog forecast system showed minor warming along the equator west of Peru by mid summer. The forecast warming was equivalent to a “weak” El Nino event for Nino Regions 1&2 and 3.

March

The current El Nino first appeared with minor warming off Peru in March and with the development of an internal oceanic wave near the Dateline. The wave has moved east and weakened. The recent weakening of the trade winds has allowed the warm water pool off Peru to deepen and build. A new wave is likely this fall.

The NOAA CFSv2 forecast of depth section SST anomalies June-February 2019. The model strengthens the internal ocean wave east of the Dateline and moves the wave east by December. A second wave builds December-February near the Dateline suggesting an extended El Nino event.

IND PACIFICO ATL IND PACIFICO ATL IND PACIFICO ATL

Outline

1. The impressive reversal in the April-May climate system in 2018.

2. A new climate regime 2014-18.

3. Rapid shift from La Nina to El Nino in May and early June.

4. The Analog Forecast for Summer and Fall.

North American Percent Normal Precipitation for the past 7, 30 and

90 days ending June 4, 2018

The Southwest Drought has expanded into Texas. The last vestiges of La Nina hold on with above normal precipitation in the Northwest. The corn belt is peppered with dry spots. Kansas has gradually improved but probably not fast enough to help the wheat crop.

90 DAYS

30 DAYS

7 DAYS

The Vegetation Health Index for North America onJune 3, 2018 (top) and the Observed Index Change from a Year

Ago (bottom)

Stressed Very Healthy More Stressed Improved

Change 2017 to 2018

The Vegetation Health Index for Mexico June 3, 2018 (left) and the Observed Index Change from a Year Ago (right)

Drought conditions are very intense in Sonora, Sinaloa, Chihuahua and Durango. Dry soils have lead to record high temperatures and the development of an early monsoon high pressure along the Mexican border.

More Stressed Improved

Change 2017 to 2018

Stressed Very Healthy

Weekly Change in the Mexican Vegetation Health Index on June 3, 2018

From May 27 to June 3, 2018 the Vegetation Health Index in Mexico lagged the normal greening during the normal start of summer monsoon. The stressed vegetation across Mexico will help to create local feed back mechanisms with dry areas suppressing rainfall processes.

Outline

1. The impressive reversal in the April-May climate system in 2018.

2. A new climate regime 2014-18.

3. Rapid shift from La Nina to El Nino in May and early June.

4. The Analog Forecast for Summer and Fall.

May 2018 Climate Indices: 700mb

Height Anomalies (top) and SST

Anomalies (bottom)

Major centers of action are framed by black boxes. Indices from these 14 centers of action are analyzed in a cluster analysis to determine past years with similar climate patterns. Years with significant correlations across the indices are Analog Year candidates.

May 700mb HTS

May SSTs

The June 2018 Analog Year Forecast

The final analog years are highlighted in yellow. Correlations with the various runs are high, but this is typical when circulation patterns are actively shifting to El Nino. Volcanic eruptions that reached the stratosphere occurred in 1963, 1982 and 1991-94. Only the 1991 analog year was kept since the dust cloud from this volcano did not impact the Western Hemisphere until later in the summer.

YEAR BASE SST HGTS PAConly ? ATLonly Rvladiv RPAC40-50 R SW AZNMTATL40-50 RGreenICE ?Y15 0.69 0.63 0.77 0.57 2.66 0.87 0.00 4.00 5.00 4.00 5.00 18.00

Y91 0.61 0.47 0.96 0.53 2.57 0.79 0.00 5.00 2.00 5.00 5.00 17.00

Y94 0.57 0.67 0.41 0.47 2.12 0.71 2.00 4.00 5.00 0.00 0.00 11.00

Y86 0.57 0.70 0.41 0.39 2.07 0.82 5.00 1.00 5.00 0.00 0.00 11.00

Y16 0.53 0.53 0.51 0.44 2.01 0.76 1.00 4.00 5.00 5.00 3.00 18.00

Y72 0.50 0.28 0.89 0.30 1.97 0.77 0.00 3.00 3.00 0.00 0.00 6.00

Y03 0.45 0.30 0.58 0.33 1.66 1.00 2.00 4.00 0.00 3.00 3.00 12.00

Y63 0.41 0.22 0.63 0.33 1.59 0.52 2.00 4.00 0.00 4.00 4.00 14.00

Y82 0.29 0.27 0.46 0.50 1.52 -0.35 3.00 4.00 2.00 5.00 5.00 19.00

Figure 4. A Decision Tree Forecast approach to predicting TC frequency and seasonal distribution (timing) of storms in the EastPac and Caribbean-Gulf of Mexico. The TC activity of 2009 followed the left branch of the forecast tree (El Nino) with low frequency and a later season in the East Pacific but an early season with low TC frequency season in the Caribbean-Gulf of Mexico.

ENSO Neutral or La Niña

El Niño

IAS TC Activity

Low TC Frequency East Pacific Late Gulf/Caribbean Early

Negative PDO

Positive PDO

High TC Frequency East Pacific Early Gulf/Caribbean Late

EPAC Warm Pool Cold

1

2

3

Normal TC Frequency Normal Seasonal Timing

EPAC Warm Pool Neutral/Warm

Low TC Frequency East Pacific Late Gulf/Caribbean Early

1

Dependent sample: 1921-1988; used 1989 to 2008 for verificationVariables considered:ENSO Index (June-Sept)PDO phaseAMO phaseEPAC Warm pool (Mar-May)

Caribbean Warm pool (Mar-May)

Since 1979, Volcanic forcing is responsible for half of

the observed warming (based on global MSU Satellite

temperatures). Last volcanic event 1991.

Food for Thought: Long term warming after the last major volcanic eruption with Pinatubo in 1991. Previous warming 1830s-1850s.

The 18 Synoptic Climate Regions in Mexico

Month PeriodMeanJun Jul Aug Sep Oct

Regions

1 360% 7% 61% 33% 19% 37%

2 21% 47% 92% 78% 133% 84%

3 99% 109% 120% 151% 66% 115%

4 86% 101% 93% 105% 164% 103%

5 125% 144% 110% 102% 69% 115%

6 122% 149% 85% 153% 130% 126%

7 78% 84% 65% 109% 94% 88%

8 142% 55% 41% 90% 59% 81%

9 76% 72% 96% 80% 120% 85%

10 73% 86% 78% 76% 124% 84%

11 127% 106% 85% 100% 104% 104%

12 141% 114% 77% 107% 109% 110%

13 106% 75% 98% 85% 123% 94%

14 113% 94% 79% 117% 121% 105%

15 87% 72% 93% 104% 114% 92%

16 84% 57% 73% 66% 139% 77%

17 74% 55% 74% 53% 76% 65%

18 88% 68% 109% 87% 69% 86%

All 97% 85% 88% 92% 107% 92%

Percent Normal Precipitation

1986, 1991, 1994

BCNBCSSONSON-SINSINCHIHDURCOAHNL TAMPSNAYCOLIMAJALGTO MEX PUEBALSASTAMPS VCVC norteVC OAX norteOAX surCHIAPISYUC

The Analog Forecast of 700mb Height Anomalies Summer 2018

Upper level heights will be above normal from Africa to Mexico and this indicates weakened tropical wave activity and reduced tropical storm development in the Atlantic. The main moisture flow will be north through Florida with a dry north flow into Tamaulipas. A strong high pressure ridge from off Baja to Canada will favor a strong summer monsoon in northwest Mexico. Tropical storms in the Pacific will be offshore and far south of normal.

SUMMER 700MB HEIGHT ANOMALIES

SUMMER 850mb SURFACE WIND ANOMALIES

Anomalous easterly flow is forecast south of Mexico for the summer. This indicated a southward displaced ITCZ with reduced cyclonic shear and decreased storm activity near the south coast of Mexico.

SUMMER OLR ANOMALIES

The OLR Anomalies indicate a dry zone from the Caribbean into the eastern Tropical Pacific. This dry zone is associated with strong easterly trades invading the region. Above normal moisture is indicated from the Meseta central to Sonora as convection is enhanced on land.

Summer Surface VorticityLong Term Normals (left) vs. Summer 2018 Forecast (right)

Normally the main zone of cyclonic vorticity lays south of Mexico (left). The forecast for the summer shows the anomalous vorticity shifted south and anomalous anticyclonic along the coast. This favors interior thunderstorms and dry coastal mountains.

The Analog Forecast of 700mb Height Anomalies for Fall 2018

The fall flow pattern will favor moisture entering eastern Mexico from the Caribbean and Gulf of Mexico. A weak trough in Arizona will facilitate the flow of Pacific moisture into western Mexico. This forecast indicates a much wetter fall after a dry summer through southern and eastern Mexico.

FALL 700MB HEIGHT ANOMALIES

FALL 850mb SURFACE WIND ANOMALIES

Anomalous westerly flow is forecast along the equator which reflects the strong warming and the eastward movement of the internal ocean wave. Easterly flow from the Caribbean with intersect the Pacific westerlies favoring cyclonic turning.

FALL OLR ANOMALIES

The OLR Anomalies indicate a dry zone from the Caribbean into the Yucatan. This dry zone is associated with strong easterly trades invading the region. A tongue of deep moisture develops west of Moisture with an advancing MJO wave coupled to the warming SST