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Official 90-day Outlooks are issued once each month near mid-month at 8:30am Eastern Time. Please consult the schedule of 30 & 90-day outlooks for exact release dates.

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More Outlooks
    0.5mn MAM 2020
    1.5mn AMJ 2020
    2.5mn MJJ 2020
    3.5mn JJA 2020
    4.5mn JAS 2020
    5.5mn ASO 2020
    6.5mn SON 2020
    7.5mn OND 2020
    8.5mn NDJ 2020
    9.5mn DJF 2020
   10.5mn JFM 2021
   11.5mn FMA 2021
   12.5mn MAM 2021
    0.5mn Mar 2020


Tools Used (see Discussion for explanation)
   CCA
   OCN
   CMP
   SMT
   POE
 
HOME> Outlook Maps>Seasonal Forecast Discussion
 
Prognostic Discussion for Long-Lead Seasonal Outlooks 
NWS Climate Prediction Center College Park MD
830 AM EST Thu Feb 20 2020

SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS

ENSO-neutral conditions continue across the equatorial Pacific Ocean, as
represented in current oceanic and atmospheric observations. The official CPC
ENSO forecast indicates that ENSO-neutral is most likely through the Northern
Hemisphere spring 2020 (~60 percent chance) and summer 2020 (~50 percent
chance).

The March-April-May (MAM) 2020 temperature outlook favors above normal
temperatures from central and southern portions of the West, across the
southern tier of the CONUS, northward to Great Lakes, and to the East Coast
states. Increased chances for below normal temperatures during MAM are forecast
across the northern Great Plains. Equal chances (EC) of above, near, or below
normal temperatures are indicated across the remainder of the CONUS. Above
normal temperatures are favored throughout much of Alaska, with the highest
odds from the Seward Peninsula to about Point Lay.

The MAM 2020 precipitation outlook indicates enhanced probabilities of above
normal seasonal total precipitation amounts from the Mississippi Valley to the
East Coast.  West of the Mississippi Valley, above normal seasonal total
precipitation amounts are favored from the Northern Rockies to the Central
Plains. Below normal seasonal precipitation amounts are favored across
southwestern Oregon, California, southern Nevada, Arizona, New Mexico, and
parts of West Texas. Equal chances (EC) are forecast among areas where seasonal
precipitation amounts are expected to be similar to climatological
probabilities. In Alaska, there are elevated probabilities of above normal
seasonal total precipitation amounts from about the Alaska Range northward to
the Arctic Coast. Elevated odds for below normal seasonal total precipitation
amounts are confined to the southernmost portions of the Alaska Panhandle,
while EC are indicated for southern coastal areas and Aleutians.

BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOKS
Note: For Graphical Displays of the Forecast Tools Discussed Below See:
http://www.cpc.ncep.noaa.gov/products/predictions/90day/tools/briefing

CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS

ENSO-neutral conditions persist across the tropical Pacific Ocean. The Oceanic
Nino Index (ONI) was at 0.6 degrees C for Nov-Dec-Jan of 2019-2020.  The weekly
Nino 3.4 index value peaked at +0.8 degrees C during the fall, but this was
largely related to the Madden-Julian Oscillation (MJO). The current weekly
values for Nino3.4 is 0.1 degrees C, which is slightly lower than most values
for the past 3 months, and likely an short-term dip as intraseasonal
variability has resulted in a slight increase in trade winds near 140W.
Subsurface waters are warmer than normal from about 170E to 140W down to 150
meters, with the only reservoir of colder than average waters west of 170E and
centered at approximately 150 meters below the surface. OLR anomalies show
enhanced precipitation right along the Date Line, with suppressed convection
over the Maritime Continent. From about 160W to the eastern Pacific, anomalies
in OLR are very small.

According to the National Snow and Ice Data center, ice extent was below
average over parts of the Bering Sea, the Sea of Okhotsk, and the East
Greenland Sea at the end of January. Sea surface temperatures along the
southwest coast of Alaska were also below normal in the latest pentads, but
those are highly variable this time of year.

PROGNOSTIC DISCUSSION OF SST FORECASTS

The CPC SST consolidation forecast, which includes three statistical forecasts
along with the CFS model, predicts a continuation of ENSO-neutral conditions
through the early spring before the CFS and statistical models slightly
diverge. The North American Multi-Model Ensemble (NMME) ensemble mean forecast
for the Nino-3.4 SST anomaly is near +0.5 degrees C through March, then a slow
decline through the neutral region to near -0.5 degrees C by Sep 2020, though
the spread of the ensemble means by Sep 2020 ranges from -1.2 to +0.3 degrees
C, so uncertainties are large.

PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS

The temperature and precipitation outlooks for MAM 2020 were based on dynamical
model guidance. Statistical tools that include global SST anomaly patterns, a
canonical correlation analysis that uses the evolution of SST and sea-level
pressure as predictors, and trends . Additionally, statistically calibrated
combinations (consolidations, and consolidations via bridging techniques) of
those tools were used throughout the forecast period. Long-term climate trends
were considered for all leads but were relied on more heavily from autumn 2020
through the next winter 2020-21. Implied soil moisture conditions,
corresponding with predicted precipitation patterns were also considered during
Summer 2020.

PROGNOSTIC DISCUSSION OF OUTLOOKS - MAM 2020 TO MAM 2021

TEMPERATURE

The temperature outlook for MAM 2020 relied on dynamical model guidance and the
consolidation of SST-CA, CCA, NMME, and trends . The resultant outlook is
slightly cooler than the consolidation of those tools as intraseasonal
variability is likely to tilt much of March toward below normal temperatures.
Shorter-term vartiability and trends favor below normal temperatures for the
Northern Plains.  Those intraseasonal variations are likely to reverse later in
the first 3 months, which would also coincide with some stronger trends for
above normal temperatures in the Northern Plains, so odds for below normal
temperatures are modest, with more increased uncertainty south and east of
where the early cold is predicted. Trends and most dynamical models favor above
normal temperatures from the Mid-Atlantic, to the Gulf Coast and westward to
the Four Corners and Pacific Coast states. Progressively earlier ice melt out
in the spring heavily favors above normal temperatures, but this outlook has
lower probabilities than recent trends would support, as the sea ice is near
normal along the west coast of Alaska.

Through late spring and early summer 2020, trends favor above normal
temperatures across the Southwest, peaking in JJA. Equal chances are indicated
across the Northern and Central Plains as trends are weakest in this area
Additionally, the late spring precipitation outlooks favor above normal
precipitation, which, during the warm season, is negatively correlated with
temperatures in the following months, especially across the Great Plains and
Midwest.

For the remaining seasons, ASO 2020 through MAM 2021, the seasonal outlooks
were heavily tilted toward historical climate trends , as incorporated into the
statistical consolidation tool (which does not include the NMME guidance).

PRECIPITATION

The precipitation outlook for MAM 2020 favors above normal seasonal total
precipitation from the Mississippi Valley to the East Coast, with the highest
probabilities from the Tennessee Valley to the Ohio River Valley. Trends and
dynamical model output with a largely progressive pattern favor wetness for the
aforementioned region. The potential for a dry March limits the odds for above
normal precipitation for the Great Lakes, but the March signal is likely
related to the intraseasonal cold signal, and likely to reverse throughout the
period. Persistent ridging along the West Coast during March favors below
normal precipitation for the southwest, as April and May are largely dry
months, while that signal weakens in California where April remains wet. Models
again favor below normal precipitation for Oregon, but then little to no signal
for Washington, so EC is indicated there. Ridging over the eastern Pacific is
likely to steer storms into mainland Alaska, favoring above normal
precipitation for interior Alaska and drier than normal conditions for the
southern Alaska Panhandle.

Through late spring, below normal precipitation is favored from the Pacific
Northwest to the Four Corners region, aligning with the northward progression
of the trend signal.  The northern Plains and east of the Mississippi are
favored to remain wetter than normal, consistent with model guidance and
potential for persistent early wetness to feedback into later months.  By the
end of the summer, the precipitation outlooks largely resemble trends , which
would be the dominant mode represented through next autumn if the ENSO neutral
conditions persist as the NMME models indicate. For next winter, trends
dominate the predicted patterns.

FORECASTER: Matthew Rosencrans

The Climatic normals are based on conditions between 1981 and 2010, following
the World Meterological Organization convention of using the most recent 3
complete decades as the climatic 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.

For a description of of the standard forecast tools - their skill- and the
forecast format please see our web page at
http://www.cpc.ncep.noaa.gov/products/predictions/long_range/tools.html
(Use Lower Cas e Letters)
Information on the formation of skill of the CAS forecasts may be found at:
http://www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/US/Outlook/outlook.shtm
l
(use lowercase letters)
Notes - These climate outlooks are intended for use prior to the start of their
valid period.  Within any given valid period observations and short and medium
range forecasts should be consulted.

This set of outlooks will be superseded by the issuance of the new set next
month on Mar 19 2020


1981-2010 base period means were implemented effective with the May 19, 2011
forecast release.
$$

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Page last modified: January 17, 2006
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