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CDC Discussions of the NOAA Official Monthly-Seasonal Long-Lead Outlooks
This week's Threats Assessment    CPC Outlooks Index    Current precipitation anomalies    Western region climatologies
NOAA/Climate Diagnostics Center        Colorado Climate Center (state climatologist)         NOAA/Climate Prediction Center
CDC Precipitation Monitoring and recent precip and temp conditions                                      Western Regional Climate Center
NOAA Colorado Basin River Forecast Center           USDA/NOAANational Drought Monitor
This page describes the latest official seasonal forecast issued by the NWS/Climate Prediction
Center last week, with a focus on the information provided by these on the Interior Western U.S. This page reproduces the maps discussed and provides active links to CPC pages. The these and other outlook maps are accessible from the CPC main page, look down to
"outlooks" and click on your preferred time scale, or access it from "index" on the next line.   I find the color maps are easiest to read, and these are accessed from clicking on
"monthly and seasonal". You can also look at black and white versions by choosing either "U.S.
monthly temp and ppt outlooks" (September), or "US seasonal" (Sept-Oct-Nov avg) . The official seasonal
forecasts are issued on Thursdays in the middle of the month; the next ones will be April 12th and May 17thth. Schedule for future outlooks.
These discussions are an experimental product developed by the NOAA-CIRES Climate Diagnostics Center (CDC), which is a NOAA research lab.
- Discussion of CPC forecast issued Thursday, 15 March, for April 2001 and following months
April and April-May-June forecast
Legend for colors
DISCUSSION: The climate outlook for temperature in April (above upper right)is for an increased probability of upper tercile temperatures (above normal) for much of the sourthern tier of the U.S,including west Texas, southern New Mexico, Arizona, and southern California. This region is expanded somewhat for the April-May-June (lower right). Note that this is for the *average* for the month of April and the three month average AMJ.
The climate outlook for precipitation for April '01 (above upper left) is for increased risk of lower tercile precipitation (below normal) for the lower Colorado Basin, western New Mexico (including the southern San Juan basin), and southern California. There is a slightly increased probability that the total precipitation for April in the lower Colorado Basin will be in the *driest* tercile.
The state of Colorado is in a region for which the outlook is CL, for "climatology," that is, there are about equal chances of each of the three categories, below noremal, near normal, or above climate normals
DEFINITIONS: 1) "terciles" refer to three equally probable categories of the distribution of precipitation or temperature for each area and each month or season. Climate data for a region and season are divided into the third (upper tercile, wettest or warmest), middle third (middle tercile, near normal), and lower third (lower tercile, driest or coolest). By chance, there's a 33% risk that any given year would fall in each of these terciles. On the outlook maps, these categories are A=above
normal; N=near normal, and B=below normal. In practice, N is rarely forecast in these outlooks. More commonly, and often misrepresented as normal, CL is indicated, which means "climatology." CL indicates that there are about equal chances that conditions will be below normal, near normal, or above climate normals. Another way of putting this is that there is no information on if there is an increased probability that conditions will be in any category.
To determine how much the probability is changed, you add the number on the map to the climatological probability of 33%. The medium yellow indicates a probability anomanomaly of 5-10%, which is added to 33%, thus the risk increases to between 38-43% that the accummulated ppt in that month or season will be in the category denoted by the letter, A= above normal, B-below normal. By the way, 10% increased risk may not seem like much, but it actually represents a fairly substantial increase as forecasts for precipitation go.
2) all the comparisons are made to a "base period" of 1961-1990; in the next several months, the base beriod for comparison will change to 1971-2000
Long-Lead forecast
Legend for colors
The long-lead outlooks for precipitation (above)for 3-month
overlapping seasons has little information for the Colorado Basin until the summer. For Colorado and New Mexico, there is a slightly increased probability of above normal precipitation in the July-Sept monsoon period.
Individual seasons can be viewed by clicking on the season you want from at this index. You can also read the technical long lead prognostic discussion .
Legend for colors
The long-lead outlooks for temperature (above) continues the outlook for the AMJ season for above normal temperatures in the southern tier, including Arizona,
(see the prognostic discussion of the long lead forecast, for a technical discussion)
Please feel free to contact me if you have futher questions, andrea.ray@noaa.gov, 303-497-6434. To see my description of last month's forecast, see below.
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