Prognostic Discussion for Monthly Outlook 
NWS Climate Prediction Center College Park MD 
300 PM EDT Fri May 31 2019 
 
 
30-DAY OUTLOOK DISCUSSION FOR JUNE 2019 
 
For the month of June, El Nino is expected to continue, with a 70% chance that 
El Nino conditions continue through Northern Hemisphere summer.  The 
Madden-Julian Oscillation (MJO) is highly amplified, with the convectively 
active phase over the eastern Indian Ocean. Linkages from the MJO to CONUS and 
Alaska impacts are generally weak during June, so canonical downstream impacts 
from an MJO are not a significant factor in the outlook. Recent heavy rains 
leading to very high soil moisture and flooding are likely to play a role in 
the evolution of temperatures over the central and southern Great Plains during 
June, while recent dryness is likely a factor further north. 
 
The updated temperature outlook maintains high chances of above normal 
temperatures across Alaska. Contributing factors include above normal 
sea-surface temperatures near the coast, trends , and shorter-term predictions 
that have high confidence for warmer than normal conditions. Above normal 
temperatures are still favored from California to Washington, though the odds 
are slightly reduced due to a predicted colder than normal period during 
Week-2, sandwiched between periods predicted to be warmer than normal. Recent 
and predicted dryness favor above normal temperatures in the Northern Plains. A 
period of warmth is predicted to move across the northern tier of the CONUS, so 
the area where below normal temperatures are favored is shifted southward, and 
now aligns with the most likely area of above normal precipitation. 
 
The highest odds of above normal precipitation are from the Rio Grande Valley 
into the central Great Plains, where predicted 7 day precipitation totals are 
greater than the threshold for below normal precipitation for the climate 
divisions in those regions. Probabilities have been increased from the 
mid-month outlook. Model guidance depicts below normal precipitation across the 
northern CONUS from the Great Plains to the Northeast, with the strongest 
signal centered over North Dakota. This signal is an addition from the initial 
outlook. Slight tilts toward drier than normal conditions in the Pacific 
Northwest and wetter than normal in southern Alaska were in the initial 
outlook, and reasoning remains unchanged. 
 
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The previous discussion for the June 2019 outlook, issued May 16, follows 
below: 
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The June 2019 outlook is based on various forecast tools, including dynamical 
and statistical models, and observations of current boundary conditions. El 
Nino is likely to continue through June, and the active phase of the 
Madden-Julian Oscillation (MJO) is likely to have residual impacts across the 
Americas, early in the month. Soil moisture conditions and the connection to 
temperatures in following months are also taken into consideration for the 
outlooks. 
 
The temperature outlook for June reflects the dynamical model guidance from the 
NMME suite, which includes the CFS, and the Week-3/4 outlooks from the CFS and 
the ECMWF. The monthly mean output from those modeling suites indicate little 
to no signal for many areas of the CONUS, and where there are stronger signals  
on monthly time scales, lagged impacts from the active MJO would destructively 
interfere. That destructive interference, along with the weak signals  in the 
models, results in large areas of Equal Chances in the outlook. The Week-3/4 
model output have slightly stronger signals , which cover the first 1-2 weeks of 
June. 
 
The signal for above normal temperatures across the Northwest is supported by 
the dynamical models  and trends , as well as potential feedback from recent 
dryness in the Pacific Northwest. A residual impact from the MJO would support 
troughing across the Western CONUS at the start of the month, so the signal for 
above normal temperatures is scaled back, when compared to model output and 
trends, across the Southwest and Great Basin. Model guidance and trends  support 
above normal temperatures from the Gulf Coast to the Northeast. 
 
Across the center portions of the CONUS, near record to record level soil 
moisture values are likely to have lagged impacts favoring below normal 
temperatures. Those correlations are highest in the Plains, from South Dakota 
to Texas, though there are some weaker signals  that extend eastward to the Ohio 
Valley. 
 
The precipitation outlooks from the dynamical models  have a distinct signal 
from the Southern High Plains to the Northern Great Plains and Northern 
Rockies. High Soil moisture and precipitation are positively correlated in the 
Plains, while El Nino supports the signal into the Rockies. One area where the 
June monthly outlook differs from the June-July-August outlook is over southern 
Arizona and California.  The potential for a the active MJO to help trigger a 
late May tropical cyclone, leading to a surge of moisture in the Gulf of 
California is highlighted in some statistical model tools. The June outlook 
reflects that wetter signal during a relatively dry month for that area, while 
the seasonal outlook has to consider the entire summer season. 
 
Above normal temperatures are favored for Alaska, where trends  are quite 
strong. Odds are highest along the west coast of Alaska where sea ice is at 
record lows and sea surface temperatures (SSTs) are above normal. The 
precipitation outlook for Alaska has significantly less certainty than the 
temperature outlook. The NMME suite has little to signal in the calibrated 
model guidance for mainland Alaska. Some of the statistical tools favor below 
normal precipitation for the Alaska Panhandle, and that signal is included. 
Above normal precipitation is forecast for south-central and southwest Alaska, 
though the signal is spotty and weak. 
 
FORECASTER: Matthew Rosencrans 
 
The climatic normals are based on conditions between 1981 and 2010, following 
the World Meteorological Organization convention of using the most recent 3 
complete decades as the climate reference period.  The probability anomalies 
for temperature and precipitation based on these new normals better represent 
shorter term climatic anomalies than the forecasts based on older normals. 
 
The next monthly outlook...for Jul ... will be issued on Thu Jun 20 2019 
 
These outlooks are based on departures from the 1981-2010 base period. 
$$