CPC Forecasts: Current Methods and Future Requirements Ed O’Lenic NOAA-NWS-Climate Prediction Center Camp Springs, Maryland , ext 7528

Outline - overview Weather versus climate Current status of CPC’s forecast system Schematic of CPC’s forecast system Schematic of the forecast process Outline – over-view

Outline – 30-and 90-day long lead outlooks Seasonal and monthly forecasting Forecast schedule and leads Outlook category and probability formats Maps and bulletins Forecast tools Canonical Correlation Analysis (CCA) Optimal Climate Normals (OCN) Ocean-Atmosphere Model Operations Concept Sample seasonal forecast using actual tools Outline – 30- and 90-day

Outline: 6-10 day and week 2 Forecast schedule and leads Outlook category and probability formats Maps and bulletins Tools Dynamical models Natural analogs Teleconnections Downscaling techniques Sample forecast using actual tools Outline /week 2

Outline - Threats Forecast schedule and leads Definition of Threats Outlook formats Maps and bulletins Tools Dynamical models Composites

WEATHER vs. CLIMATE Smooth curve = 30 year mean (climatology) Wildly oscillating curve = daily “weather” Subtracting the climatology and performing a 31-day running mean reveals the low-frequency signal or short-term climate variations we are trying to predict.

Climate Prediction Center Forecast System SchematicClimate Prediction Center Forecast System Schematic

Forecast Process Schematic Dynamical model forecasts/multi- model ensembles Recent observations Historical observations.. Verifications/Statistical tools Downscaling, Analogs, Composites WEB PAGES/AUTOMATED DATABASES Peer-reviews of the forecast tools and of the penultimate forecast via web/telephone conference with partners and through local discussions (map discussions,sanity check, conference calls, etc…) Forecaster-created or automated products Dissemination to public

Monthly and Seasonal Outlooks

Seasonal/Monthly Outlook Schedule/Leads Each month, near mid-month ( CPC prepares a set of 13 outlooks for 3-month “seasons” (any set of 3 adjacent months) for lead times ranging from ½ month, 1 ½ months, 2 ½ months, 3 ½ months, …, 12 ½ months. The outlook for each successive/prior lead time overlaps the prior/successive one by 2 months. This overlap makes for a Smooth variation from one map to the next. A monthly outlook is prepared at the same time as the seasonal. However, it is for a single lead time, ½ month.

Outlook Categories and Probabilities  Seasonal and monthly outlooks are prepared for average temperature and total accumulated precipitation category (please see sonal_outlooks/color/seasonal_forecast.html ) sonal_outlooks/color/seasonal_forecast.html Three categories are used (terciles). These are BELOW-,NEAR- and ABOVE-normal, for temperature, and BELOW-, NEAR-and ABOVE- median for precipitation. Regions where the likelihoods of the three categories are the same (33.33…% each) are designated as “CL”, for climatology. Note that, at any given location and time, the sum of these three probabilities is 100%. This is true for non-CL regions, too. In non-CL regions the labels on the contours give the (positive) difference between the probability of the indicated category and 33.33…%, i.e., they are probability anomalies. The simple rule that applies here is: For A or B, the likelihood of the indicated category is 33.33…% plus the contour value, while, the likelihood of the opposite category (B or A) is 33.33…% minus the contour value. The value of N remains 33.33…%. Finally, when N is favored, its value is 33.33…% plus the contour value, while the likelihoods of both A and B are 33.33…% minus ½ the N contour value.

Forecast Maps and Bulletins Each month, near the 15 th, CPC issues a set of 13 seasonal outlooks. These are formulated by two forecasters. There are two maps for each of the 13 leads, one for temperature and one for precipitation for a total of 26 maps. Each outlook covers a 3-month “season”, and, for leads 2-13, overlaps the next and prior season by 2 months. The seasonal outlook is accompanied by 2 bulletins: the prognostic discussion for the seasonal outlook over North America, FXUS05, and, for Hawaii, FXUS40. The lead seasonal forecaster writes the first bulletin. The monthly forecaster writes the second. The monthly outlook is issued at the same time as the seasonal outlook. Formulated by a single forecaster, it consists of a temperature and precipitation outlook for a single lead, 0.5 months. The monthly outlook is accompanied by a single bulletin, FXUS07. All maps are sent to AWIPS. Sample seasonal outlook maps for the 0.5 month lead (lead 1) forecast valid November- December-January

Sample 90-day bulletin PROGNOSTIC DISCUSSION FOR LONG-LEAD OUTLOOKS CLIMATE PREDICTION CENTER NCEP NATIONAL WEATHER SERVICE WASHINGTON DC 3 PM EDT THURSDAY OCTOBER BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOK THESE OUTLOOKS REFLECT THE EXPECTED U.S. CLIMATE ANOMALIES FOR ENSO-NEUTRAL CONDITIONS... THE LONG-TERM TREND AS ESTIMATED BY OCN AND FORECASTS OF OCEANIC AND ATMOSPHERIC CONDITIONS FROM DYNAMICAL MODELS. EQUATORIAL PACIFIC SSTS ARE NOW SLIGHTLY ABOVE NORMAL IN THE WEST AND CENTRAL PACIFIC AND BELOW NORMAL NEAR SOUTH AMERICA. MOST STATISTICAL AND DYNAMIC PREDICTIONS OF NINO 3.4 SSTS INDICATE ANOMALIES VERY NEAR ZERO THROUGHOUT THE UPCOMING COOL SEASON WITH SLIGHT WARM EPISODE (EL NINO) CONDITIONS BY LATE IN THE SPRING OR EARLY IN THE SUMMER OF WHILE IT IS LIKELY THAT EQUATORIAL PACIFIC SSTS NEAR AND JUST WEST OF THE DATELINE WILL BE ABOVE AVERAGE... THE ANOMALIES ARE EXPECTED TO BE WEAK AND NOT LIKELY TO PRODUCE THE LARGE-SCALE ATMOSPHERIC EFFECTS ASSOCIATED WITH STRONG EL NINO EVENTS THIS COOL SEASON. THE ABSENCE OF SIGNIFICANT ENSO-RELATED INFLUENCES SUGGESTS THE UPCOMING COOL SEASON MAY BE MARKED BY SIGNIFICANT MONTH-TO-MONTH VARIABILITY...WHICH MAY BE ENHANCED IF THE CURRENTLY STRONG SERIES OF MADDEN AND JULIAN OSCILLATION (MJO) WAVES CONTINUES OVER THE PACIFIC. CURRENT ATMOSPHERIC AND OCEANIC MODELS ARE NEAR-NORMAL IN THE TROPICAL PACIFIC IN SEPTEMBER. SST ANOMALIES ALONG THE EQUATOR CURRENTLY ARE NEAR +1.0 DEG C WEST OF THE DATELINE AND ARE AROUND -1.O DEG IN THE EASTERN PACIFIC - EAST OF ABOUT 130W. ABOVE NORMAL OCEAN TEMPERATURES EXTEND FROM THE SURFACE OR NEAR THE SURFACE TO OVER 200 M DEPTH OVER MOST OF THE CENTRAL PACIFIC OCEAN AND TO 100 M DEPTH AS FAR EAST AS 130 W. ENHANCED MJO ACTIVITY HAS BEEN NOTED DURING THE LAST SIX MONTHS. THIS IS EXPECTED TO CONTINUE AND WILL HAVE AN IMPACT ON SSTS IN THE CENTRAL EQUATORIAL PACIFIC. WITH WARM SSTS FARTHER EAST THAN LAST WINTER THERE IS A BETTER CHANCE STRONG MJO WILL MAKE IT TO THE DATELINE AND HAVE AN OPPORTUNITY TO IMPACT PRECIPITATION IN THE WESTERN UNITED STATES PROGNOSTIC DISCUSSION OF SST FORECASTS NEAR-NEUTRAL ENSO CONDITIONS ARE PREDICTED FOR MUCH OF THE WINTER. MOST DYNAMICAL MODELS (NCEP - SCRIPPS) GRADUALLY INCREASE NINO 3.4 SSTS BEGINNING IN THE SPRING. THE CONSTRUCTED ANALOG AND INVERSE MODEL PREDICT NEUTRAL OR COOL NINO 3.4 SSTS FOR THIS COOL SEASON WHILE CCA PREDICTS MODESTLY ABOVE NORMAL SSTS. A MARKOV SST MODEL INDICATES PERSISTENCE OF CURRENT SSTS THROUGH THE SPRING WITH WARM ENSO CONDITIONS DEVELOPING DURING APRIL THROUGH JUNE A CONSOLIDATION OF THREE NCEP TOOLS BASED ON THEIR PAST PERFORMANCE INDICATES NEAR NORMAL CONDITIONS WILL PREVAIL THROUGH THE WINTER WITH GRADUALLY INCREASING ANOMALIES THAT REACH AROUND +0.5 DEGREES C BY LATE NEXT SPRING. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOK THE STATISTICAL TOOLS... CCA... OCN AND SMLR... WERE CONSULTED AT ALL LEAD TIMES. ENSO-NEUTRAL COMPOSITES WERE ALSO CONSULTED. THESE WERE SUBJECTED TO A HIGH-PASS FILTER PRIOR TO ISOLATE INTERANNUAL SIGNALS FROM LONGER TIME SCALES. FINALLY DYNAMICAL MODEL FORECASTS FROM NCEP - EC HAMBURG - NASA AND NCAR - INITIATED FROM ATMOSPHERIC AND OCEANIC CONDITIONS FROM LATE SEPTEMBER - WERE ALL CONSULTED. ALTHOUGH THE INITIAL ENSO STATE IS NEAR ZERO - THERE WAS AGREEMENT AMONG 3 OF THE 4 DYNAMICAL MODELS ON A WAVE-TRAIN EMANATING FROM THE ABNORMALLY WARM POOL OF WATER IN THE WESTERN TROPICAL PACIFIC WHICH APPEARS TO CAUSE A PERSISTENT PATTERN OVER NORTH AMERICA. THIS PATTERN FAVORS POSITIVE UPPER AIR HEIGHT ANOMALIES OVER THE GULF OF ALASKA AND NEGATIVE ANOMALIES OVER EASTERN NORTH AMERICA. THE TEMPERATURE FORECASTS FROM THESE DYNAMICAL MODELS ARE IN OVERALL AGREEMENT WITH MANY OF THE STATISTICAL TOOLS - INCLUDING THE ENSO-NEUTRAL COMPOSITES AND CCA - BOTH OF WHICH PREDICT BELOW NORMAL TEMPERATURES IN THE NORTHEASTERN US AND ABOVE NORMAL IN THE SOUTHWEST DURING THE COLD SEASON. IN PARTS OF THE EAST WE GAVE GREATER WEIGHT TO THESE TOOLS THAN TO THE TREND (OCN) - LEADING TO FORECASTS OF CL IN THE SOUTHEAST AND BELOW NORMAL IN THE NORTH-CENTRAL AND NORTHEASTERN U.S PROGNOSTIC DISCUSSION OF OUTLOOKS - NDJ TO NDJ TEMPERATURE: MOST FORECAST TOOLS INDICATE WARMER-THAN-NORMAL TEMPERATURES FOR NDJ THROUGH NDJ IN THE SOUTHWEST U.S. THIS SIGNAL IS THE STRONGEST TREND SIGNAL ON THE MAP AND THE PROBABILITIES ARE ACCORDINGLY HIGH. MIXED SIGNALS APPEAR OVER ALASKA AND CLIMATOLOGICAL PROBABILITIES ARE OFTEN PREDICTED THERE. ONE MAJOR FACTOR INFLUENCING THE SEASONAL CLIMATE ANOMALIES OVER THE EASTERN U.S. THIS WINTER WILL BE THE PHASE OF THE NAO- WHICH IS NOT YET PREDICTABLE BEYOND ABOUT 1-2 WEEKS IN ADVANCE. ENSO-NEUTRAL COMPOSITES INDICATE COOLER THAN NORMAL TEMPERATURES OVER MUCH OF THE CENTRAL AND EASTERN U.S. - WHICH OPPOSES RECENT WARM TRENDS. BELOW-NORMAL TEMPERATURE WHICH CCA PREDICTED FOR ALASKA IN NDJ AND DJF IN LAST MONTHS FORECAST HAVE BEEN REMOVED - SINCE OCN AND CMP BOTH PREDICT WARM. BEYOND FMA 2002 CCA AND OCN ARE THE PRIMARY TOOLS. THESE SHOW THE WARM TREND IN THE WESTERN AND SOUTHERN U.S. DURING THE WARM SEASON AND A COOL TREND IN THE NORTH-CENTRAL U.S. DURING THE LATE SUMMER PRECIPITATION: CCA AND OCN PREDICT ABOVE-MEDIAN PRECIPITATION OVER TEXAS FOR NDJ THROUGH JFM AND SUB-NORMAL RAINFALL OVER FLORIDA AND PARTS OF THE SOUTHEAST FOR NDJ THROUGH DJF. WHILE MJO ACTIVITY IS EXPECTED TO BE STRONG DURING THE COLD SEASON AND SUCH ACTIVITY CAN BE ASSOCIATED WITH HEAVY PRECIPITATION EVENTS ALONG THE WEST COAST - THE TOOLS CURRENTLY GIVE MIXED INDICATIONS IN THAT REGION AND CL IS PREDICTED THERE. ODDS FOR ABOVE-MEDIAN PRECIPITATION INCREASE IN THE NORTHWEST IN AMJ AND MJJ DUE TO LONG-TERM TRENDS. BEYOND MJJ PREDICTABILITY OF PRECIPITATION IS LIMITED TO SCATTERED SMALL REGIONS ASSOCIATED WITH LONG-TERM TRENDS. THE BIGGEST CHANGES FROM LAST MONTHS OUTLOOK ARE REMOVING ABOVE-MEDIAN PRECIPITATION FROM THE NDJ THROUGH JFM FORECASTS FOR THE PANHANDLE OF FLORIDA AND FORECASTING SUB-MEDIAN PRECIPITATION FOR NDJ AND DJF FOR FLORIDA AND PARTS OF THE SOUTHEAST. THIS SIGNAL COMES FROM CCA AND THE DYNAMICAL MODELS - WHICH INDICATE THAT THE SIGNAL FADES RAPIDLY AFTER DJF. LAST MONTHS FORECAST OF BELOW-MEDIAN IN THE SOUTHWEST FOR NDJ AND DJF HAS BEEN MODIFIED TO CL IN LIGHT OF DYNAMICAL MODEL FORECASTS OF ABOVE-MEDIAN RAINFALL. ABOVE MEDIAN PRECIPITATION PREDICTED FOR ALASKA IN DJF THIS MONTH COMES FROM THE DYNAMICAL MODEL FORECASTS. FORECASTERS: ED OLENIC AND HUUG VAN DEN DOOL

30-,90-day Forecast Tools Examples of the variety of tools used in preparing the 30-day 0.5 month lead 30-day outlook and the multi-lead 90-day outlooks may be found at: These forecast tools consist of 3 types: 1.Statistical: CCA, OCN, MLR 2.Dynamical: Coupled GCM, AGCM, ensembles 3.Physically-based composites.

Statistical tools: Canonical Correlation Analysis (CCA) CCA is used to find predictive relationships among variables. For long-range forecasting the variables used include tropical Pacific Ocean sea-surface temperatures (SSTs), 700 hPa heights, (the predictors*) and U.S. surface temperatures (T) and precipitation (P) (the predictands) (* The SST fields are weighted twice a much as the 700 hPa heights in the CCA) When CCA is developed, relationships are found between observed U.S. T and P for a given season, say, January-February-March (JFM) and the predictors for the prior four non-overlapping seasons, in this case, OND, JAS, AMJ and JFM of the prior year. This is done for the entire available historical record of data, roughly To make a forecast, the relationships found in the developmental dataset are applied to the most recent observations of the predictors to produce T and P forecasts for the target season.

Statistical tools:Optimal Climate Normals (OCN) OCN, as it is used as a tool at CPC is, quite simply, a measure of the trend. For a given station and season, the OCN forecast is the difference between the seasonal mean temperature during the last 10 years and the 30 year climatology. As the amount of time between the last year in the climatology and the current year increases the difference trend gets larger (aging climatology). This continues until a new climatology is implemented, at which time, the impact of the trend suddenly drops and begins anew its growth as the climatology ages. The ‘Optimal’ in OCN refers to optimal number of years to use in the trend calculation to optimize skill when OCN is used to make forecasts. Very often this number, called k, is less than 30 years. When it is, the tool has value in making forecasts.

Dynamical tools: Operations Concept for Ocean/Atmosphere Model NCEP currently uses dynamical coupled ocean-atmosphere models in combination with statistical models to produce seasonal outlooks with ½ to 5 ½ month leads and, to a lesser extent, monthly outlooks with ½ month lead. Enhanced model operations which include increased numbers of ensemble members, more frequent model runs and enhanced capability to include the influence of within-season variations in SST and OLR will be used to: - Produce more highly resolved distributions of predicted variables, - Produce forecasts which increasingly and more appropriately reflect the influence of intra-seasonal variability on middle latitude climate, - Produce improved week 2 and monthly outlooks and develop and implement new outlook products for the week 3-4 period. - Develop and implement new products to predict seasonal variations in frequency of extreme events, primarily during ENSO.

Detailed operations concept for ocean- atmosphere model Currently, coupled dynamical model forecasts are one of several tools used in preparing long-range outlooks. NCEP’s model is run to produce one set of ensemble forecasts per month during the first week of the month. This is done in a two-tiered system, in which first, an ensemble of 16 ocean forecasts are created using a coupled GCM. The average of these is used as the official SST forecast. This SST forecast is then used as the lower boundary for an AGCM to create a set of 20 atmosphere ensemble members. The forecasts are run out to 9 months. A 20-year run of the AGCM is created each month. The seasonal means from this run are used as the climatology to create anomaly maps from each of the ensemble members. The means of these anomaly maps are used as the forecast tools which are presented to the forecasters. The forecasters use the NCEP model tools, together with other model tools to subjectively create outlook maps of the probability of monthly and seasonal mean temperature and total precipitation category.

NCEP Two-Tier Climate Modeling System INTEGRATED OCEAN MODEL- DATA ASSIMILATION SYSTEM COUPLED OCEAN- ATMOSPHERE GCM AGCM FORECASTS STATISTICAL TOOLS: CCA, CA STATISTICAL TOOLS SSTTOPEXXBTTAO OCEAN INITIAL CONDITIONS STRESS EVAP- PRECIP FLUX SSTA SSMI/ERS-2 HEAT FLUXES OFFICIAL SST FCST OFFICIAL PROBABILISTIC T,P OUTLOOKS FORECASTERS SURFACE T, P ANOMALIES IRI CDC

Forecast tools web page

Forecast tools page Web-based display of forecast tools gives ready-access to a wide variety of tools. A bi-weekly telephone conference call brings together participants to assess the current status of the climate system. Participants and contributors include: CPC, CDC, IRI, GFDL, University of Washington, Scripps, FSU, COLA and others Web-based tools

Sample Outlook Using Actual Tools

Atmospheric GCM (AGCM) T Forecasts

Atmospheric GCM (AGCM) NDJ T Verification

CCA 0.5 Mo lead NDJ T Outlook

OCN 0.5 Mo lead NDJ T Outlook

AGCM 0.5 Mo lead NDJ T Outlook

AO-ENSO-T composites

OFFICIAL NDJ T Outlook

AGCM P Forecasts

AGCM NDJ P Verification

CCA 0.5 Mo lead NDJ P Outlook

OCN 0.5 Mo lead NDJ P Outlook

AGCM 0.5 Mo lead NDJ P Outlook

AO-ENSO-P composites

ENSO-Neutral Composite

Official NDJ P Outlook

Temp Skill

Precipitation Skill

El Nino Global Impacts Current dynamical models accurately forecast gross ENSO properties. Future models must be able to predict more subtle event-to-event differences and underlying statistics of weather, including extreme events.

Summary – Seasonal/Monthly Outlooks CPC long-lead seasonal outlooks are produced using, in order of perceived reliability: ENSO composites, trend, soil moisture, statistical models, dynamical models (DM). Frequent model changes hamper perceived reliability of DMs. Lack of information about model biases and calibration reduce perceived reliability of DM forecasts. Weather/climate impacts of AO, MJO, PDO are known. Prediction of AO, MJO, PDO is not yet possible. DMs cannot yet predict subtle differences among ENSOs. Stratospheric annular mode (SAM) is a link to AO prediction. DMs ability to predict SAM is unknown/doubtful. Relationship of Indian Ocean to predictable signals is unclear. Relationship of QBO, Southern Hemisphere mid-latitude circulations to predictable signals is unclear.

Six-to-Ten Day and Week 2 Outlooks

6-10 DAY/WEEK 2 OUTLOOK SCHEDULE/LEADS Each day, CPC prepares and disseminates outlooks for 6-10 days (lead time of 5 days) and week 2 (days 8-14, lead time of 7 days). Each of these outlooks is accompanied by forecast maps of –1) 500 mb height and 500 mb height anomalies over the Northern Hemisphere, forecast maps of –2) surface temperature and –3) precipitation for the continental U.S. and Alaska and a single bulletin, FEUS40, giving a prognostic discussion for both forecasts and a table of state- by-state forecasts for each forecast. On Monday through Friday, including holidays, the outlooks are prepared by a forecaster who draws the maps, writes the bulletin and composes the table. On Saturday and Sunday only automated versions of the maps and the tables are disseminated.

6-10 day/week 2 Outlook Categories, Probabilities 6-10 day/week 2 outlooks are prepared for 5-day/7-day average temperature and total accumulated precipitation category. Three categories are used (terciles). These are BELOW-,NEAR- and ABOVE-normal, for temperature, and BELOW-, NEAR- and ABOVE-median for precipitation. The contours on the maps depict the TOTAL probability of the occurrence of the indicated category. Contours of the climatological normals are also shown.

Recent Changes to Procedures From 3 times/week to daily in October 2000 Automated weekend forecasts from October 2000 Percent probability format from October 2000 Alaska and week 2 added October 2000 Automated weekend forecasts improved October 2001—neural net tool omitted and consistency with weekday forecasts added Bias-corrected precipitation forecast tool and other improvements added in the fall of 2001

6-10 day/week 2 process schematic Multi-model ensemble 9:00 AM Weighted average of model 500 hPa height Downscale: get surface weather from 500 mb height via analogs, regression, neural network. RR Forecaster formulates maps of predicted T, P, PMD bulletin Disseminate via web, AWIPS, FOS 3-4 PM R = Forecaster reconciliation of tools required

Forecast Maps and Bulletins Each day,between 3 and 4 PM Eastern Time, CPC issues a set of 6-10 day and week 2 outlooks. These are formulated by a forecaster (Monday through Friday) and are automated on weekends. There are two 500 mb height maps, two surface maps and a single bulletin. Sample 6-10 day outlook 500 mb height and anomaly forecast map from CPC web page.

Sample 6-10 day average T outlook

Sample 6-10 day 5-day total precipitation outlook from CPC web page. Sample 6-10 day T outlook

Sample 6-10day/week 2 bulletin PROGNOSTIC DISCUSSIONS FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS CLIMATE PREDICTION CENTER NCEP NATIONAL WEATHER SERVICE WASHINGTON DC 3 PM EDT FRI OCT DAY OUTLOOK NOV MODEL COMPARISONS: 6-10 DAY MODELS - MRF - MRF ENSEMBLE MEAN ARE IN VERY GOOD AGREEMENT TODAY... WITH THE ECMWF SOMEWHAT DIFFERENT AS IT BUILDS THE RIDGE OVER THE GREAT LAKES AND SOUTH CENTRAL CANADA MUCH STRONGER AND HAS A SLIGHTLY DIFFERENT SOLUTION ALONG THE WEST COAST. WEATHER ACROSS MUCH OF THE CONUS WITH EITHER SOLUTION WILL BE MAINLY MILD AND DRY FOR EARLY NOVEMBER EVERYWHERE EXCEPT ALONG THE WEST COAST... WHERE NORMAL TEMPERATURES AND BENEFICIAL RAINS ARE STILL EXPECTED. ALL MODELS CONTINUE TO FORECAST A DEEP LOW OVER ALASKA... EXTENDING INTO WESTERN CANADA. THE BLENDED PATTERN... WHICH RELIES MORE STRONGLY ON THE MRF ENSEMBLE MEAN HAS ABOVE NORMAL HEIGHTS COVERING THE ENTIRE CONUS EXCEPT FOR THE PACIFIC NORTHWEST AND FLORIDA. THIS PATTERN IS VERY WELL TELECONNECTED... AND THE COMPOSITE ANALOG CORRELATES AT A VERY HIGH 0.94 WITH THE FORECAST HEIGHT PATTERN. CONFIDENCE IN TODAYS FORECAST IS ABOVE AVERAGE FOR THE SEASON... RATED 4 ON A SCALE OF 1 TO 5. THE OFFICIAL 500-MB HEIGHT PROG USES 60 PERCENT OF TODAYS MRF ENSEMBLE MEAN CENTERED ON DAY PERCENT OF THE ECMWF MODEL CENTERED ON DAY 7... AND 25 PERCENT OF TODAYS MRF CENTERED ON DAY 8. MODEL OF THE DAY: ENSEMBLE MEAN THE TEMPERATURE OUTLOOK IS BASED MAINLY ON THE KLEIN SPECIFICATIONS FROM THE 500- MB BLEND AND FORECAST TEMPERATURES BASED ON THE 10 BEST HISTORICAL ANALOGS. THE PRECIPITATION OUTLOOK IS BASED ON THE MRF MODEL OUTPUT CORRECTED FOR RECENT BIASES... SPECIFICATIONS FROM THE NEURAL NET AND PRECIPITATION BASED ON THE COMPOSITE OF THE 10 BEST HISTORICAL ANALOGS DAY OUTLOOK FOR NOV THE MRF AND MRF-BASED ENSEMBLE MEAN ARE AGAIN IN GOOD AGREEMENT TODAY WITH BOTH MODELS SHOWING A BROAD FLAT RIDGE CENTERED IN THE MIDDLE OF THE COUNTRY EXTENDING FROM COAST TO COAST... WITH TROUGHS LOCATED OFF THE WEST COAST AND IN THE WESTERN ATLANTIC. MAIN DIFFERENCE BETWEEN MRF AND ENSEMBLE MEAN CONCERNS THE WESTERN ATLANTIC TROUGH... WITH THE MRF RETROGRADING THE TROUGH INTO THE NORTHEAST. THE BLENDED MAP MAINTAINS ABOVE NORMAL HEIGHTS ACROSS MOST OF THE CONUS... EXCEPT FOR RIGHT ALONG THE EAST COAST... THE SOUTHEAST... AND RIGHT ALONG THE PACIFIC NORTHWEST COAST. THIS SHOULD RESULT IN CONTINUED QUIET EARLY NOVEMBER WEATHER ACROSS THE US... WITH TEMPERATURES ABOVE NORMAL AND PRECIPITATION BELOW NORMAL. A DEEP LOW IS MAINTAINED OVER ALASKA WITH A TROUGH EXTENDING SOUTHWARD ALONG 140W... WHICH SHOULD RESULT IN CONTINUED BELOW-NORMAL TEMPERATURES OVER ALASKA. CONFIDENCE IN TODAYS FORECAST IS ABOVE AVERAGE FOR THE SEASON... RATED 4 ON A SCALE OF 1 TO 5. THE OFFICIAL 500-MB HEIGHT PROG USES 75 PERCENT OF TODAYS ENSEMBLE MEAN CENTERED ON DAY 11 AND 25 PERCENT OF TODAYS MRF MODEL CENTERED ON DAY 11. THE TEMPERATURE PROG IS BASED ON KLEIN SPECIFICATIONS FROM THE OFFICIAL HEIGHT PROG. THE PRECIPITATION IS BASED ON THE SPECIFICATIONS FROM THE NEURAL NET AND THE LIKELY STORM TRACKS INDICATED BY THE 8-14 DAY MEAN 500-MB CIRCULATION FORECASTER: M. HALPERT

6-10 day/week 2 Forecast Tools Examples of the variety of tools used in preparing the 6-10 Day and week 2 outlooks. These forecast tools consist of: 1.Statistical: Klein, Neural Network, analogs, teleconnections 2.Dynamical: hrMRF, MRF ensembles, ECMWF, dAVA

Archive of 23 years of daily forecasts (1 forecast/day) out to week 2, October 1978-present (MRF T62) Operations: Run a 15-member ensemble in real-time using the same model as is used to create the archive. Ensemble mean for 6-10, 8-14 days Calculate anomalies using the 23-year model climatology (bias corrected) Compute the climatology of spread for this model, I.e. assume the mean week 2 spread is determined by the error variance of the 23-years of forecasts. A Simple Calibration Scheme – J. Whitaker, CDC

6-10-day/Week 2 Outlook Using Actual Tools

ECMWF, MRF Ensembles The first step in making a 6-10 day forecast is to formulate a forecast of upper-air height, which is easier to forecast accurately than surface parameters. The forecasters main tasks are to reconcile differences between different models, account for biases in individual models and become satisfied the models are performing properly. Teleconnections are useful to determine whether a given predicted circulation pattern has occurred often or infrequently in the past. Infrequent patterns are less likely to persist and are more difficult for models to predict accurately. The opposite is true for persistent patterns.

ECMWF upper-air height forecasts, analog

MRF Ensemble upper-air- height forecasts, analog

Official 6-10 day 500 hPa forecast

Teleconnections (TC) Definition: Composite of those maps, for a calendar month, with largest + (top 10%) or – (bottom 10%) 500 hPa height at a specified space point from (~150 maps). Forecasters compute TC on the major anomaly centers (base points) of 500 hPa forecast maps. If there is a strong relationship between the base point centered at the largest anomaly, and distant points, the TC map will display large correlation values at the base point and at the distant centers. If there is no strong historical relationship, only the correlations at the base point will be large. Weak TC indicate the pattern is probably transient and not as likely to be well predicted by the model as would a persistent (strong TC) pattern.

Teleconnection on 500 hPa weighted mean anomaly center at 10W/56N (+)

Teleconnection on 500 hPa weighted mean anomaly center at 88W/55N (+)

Teleconnection on 500 hPa weighted mean anomaly center at 140W/53N(-)

Composite of observed T, P anomalies associated with teleconnection on hPa anomalies at 56N 10W

Composite of observed T, P anomalies associated with teleconnection on hPa anomaly at 55N 88W

Composite of observed T, P anomalies associated with teleconnection on hPa anomaly at 53N 140W

T prediction analog maps

MRF precipitation bias correction

Official 6-10 day T, P forecast The final forecasts of temperature and precipitation. The forecasters reasoning is given in the bulletin (next slide).

6-10 day Prognostic Map Discussion  CLIMATE PREDICTION CENTER NCEP NATIONAL WEATHER SERVICE WASHINGTON DC 3 PM EST THU NOV DAY OUTLOOK NOV MODEL COMPARISONS: 6 TO 10 DAY MRF...MRF ENSEMBLE MEAN...AND ECMWF ARE IN FAIRLY GOOD AGREEMENT TODAY. ALL THREE MODELS HAVE A MEAN 500 MB TROUGH OVER ALASKA EXTENDING SOUTH OVER THE EASTERN PACIFIC... A RIDGE COVERING MOST OF CENTRAL NORTH AMERICA...A TROUGH EXTENDING SOUTHWARD FROM EAST OF LABRADOR AND A BLOCKING RIDGE NEAR THE BRITISH ISLES. IT IS NOW THE ECMWF WHICH GIVES THE MOST AMPLIFIED SOLUTION... ESPECIALLY THE RIDGE OVER NORTH AMERICA... PLACING A STRONG POSITIVE ANOMALY CENTER NEAR THE SOUTH SHORE OF HUDSON BAY. THE MRF DOES HAVE A SECOND BUT NOT STRONG POSITIVE ANOMALY CENTER OVER NORTHERN CANADA... AND AS USUAL THE MRF ENSEMBLE MEAN WAS SIMILAR TO THE MRF BUT HAD WEAKER ANOMALIES. ALL MODELS ARE BASICALLY DRY... EXCEPT FOR GIVING RATHER HEAVY PRECIPITATION ALONG THE PACIFIC NORTHWEST COAST DUE TO STRONG ONSHORE FLOW SOUTH OF A SERIES OF INTENSE STORMS IN THE GULF OF ALASKA. ANOMALY CORRELATIONS OF THE MODELS WITH THE CONSENSUS OF THE 10 BEST ANALOGS WERE ONLY IN THE RANGE OF.82 TO.86 TODAY... AND SURPRISINGLY THE ANALOG COMPOSITE FOR THE MRF SOLUTION WAS RATHER DIFFERENT FROM THE ENSEMBLE MEAN ANALOG COMPOSITE. THE OFFICIAL 500 MB PROG HAS RIDGES WITH STRONG POSITIVE ANOMALIES CENTERED BETWEEN THE GREAT LAKES AND HUDSON BAY... AND ALSO NEAR THE BRITISH ISLES... FLANKED BY TROUGHS EXTENDING SOUTHWARD FROM THE GULF OF ALASKA TO JUST NORTH OF HAWAII... WITH A NEGATIVE ANOMALY CENTER NEAR 52N/142W AND ANOTHER TROUGH EXTENDING SOUTHWARD FROM THE GREENLAND-DAVIS STRAIT AREA INTO THE NORTH ATLANTIC NEAR 50W. WEAKLY BELOW NORMAL HEIGHTS COVER MOST OF MEXICO AND THE GULF OF MEXICO. CONFIDENCE IN TODAYS FORECAST IS NOW ONLY AVERAGE FOR THE SEASON... RATED 3 ON A SCALE OF 1 TO 5 - FOR FAIRLY GOOD MODEL AGREEMENT AND ANALOG CORRELATIONS BUT HINTS THAT THE PATTERN MAY BE ABOUT TO CHANGE. THE OFFICIAL 500-MB HEIGHT PROG USES 40 PERCENT OF TODAYS MRF ENSEMBLE MEAN CENTERED ON DAY PERCENT OF TODAYS ECMWF MODEL CENTERED ON DAY PERCENT OF TODAYS MRF CENTERED ON DAY 8... AND 10 PERCENT OF YESTERDAYS ECMWF CENTERED ON DAY 6. MODEL OF THE DAY: SLIGHT PREFERENCE FOR MRF ENSEMBLE MEAN. THE TEMPERATURE OUTLOOK IS BASED ON A CONSENSUS OF THE KLEIN... ANALOGS... AND NEURAL NETWORK SPECIFICATIONS FROM THE OFFICIAL HEIGHT PROG... WHICH WERE IN GOOD AGREEMENT IN MOST AREAS. THE PRECIPITATION OUTLOOK IS BASED MAINLY ON THE MRF ACCUMULATED PRECIPITATION ADJUSTED FOR RECENT BIASES - ANALOGS TO THE PREDICTED UPPER AIR HEIGHT PATTERN AND THE NEURAL NETWORK.  THE MRF-BASED ENSEMBLE MEAN CONTINUED TO SHOW RATHER WEAK ANOMALIES IN MOST AREAS... SUGGESTING THAT THERE IS A LOT OF SPREAD AND UNCERTAINTY IN THE FORECASTS OF THE INDIVIDUAL MEMBERS. THE MRF PROG SHOWS A SIMILAR PATTERN...BUT WITH STRONGER NEGATIVE HEIGHT ANOMALIES OVER THE SOUTHEASTERN U.S. CONSISTENT WITH THE APPEARANCE OF THE DAILY PROGS BEYOND THE 6-10 DAY PERIOD. THE OFFICIAL 500 MB PROG MAINTAINS ABOVE NORMAL HEIGHTS ACROSS THE NORTHERN PART OF THE COUNTRY WITH A TREND TOWARDS LOWER HEIGHTS OVER THE SOUTH. THIS IS CONSISTENT WITH A TREND THAT ALL THE MODELS HAD TO A GREATER OR LESSER EXTENT OF JOINING THE BRITISH ISLES BLOCK WITH THE NORTHEASTWARD BUILDING RIDGE OVER CANADA... WHILE BEGINNING TO SEAL OFF THE BOTTOM OF THE TROUGH SOUTHEAST OF THE CANADIAN MARITIMES. IF THIS TREND IS CORRECT AND CONTINUES... COLDER WEATHER WILL EVENTUALLY DEVELOP OVER THE U.S. WITH A REVERSAL IN PHASE OF THE NAO. THE DAILY MRF PROGS NEAR THE END OF THE FORECAST PERIOD HAVE A DECIDEDLY COOLISH LOOK... ESPECIALLY OVER THE SOUTHEASTERN U.S. THE RIDGE OVER THE WESTERN U.S. ALSO BUILDS SOMEWHAT... AND THE TROUGH OVER THE EASTERN PACIFIC RETROGRADES WITH THE ASSOCIATED NEGATIVE ANOMALY LOCATED NEAR 40N/156W. THIS WILL ALLOW THE TREND TOWARD MILDER WEATHER OVER ALASKA TO CONTINUE...EVENTUALLY ENDING THE LONG COLD PERIOD OVER THE STATE. CONFIDENCE IN TODAYS FORECAST IS SOMEWHAT BELOW AVERAGE FOR THE SEASON... RATED 2 ON A SCALE OF 1 TO 5... DUE TO HINTS OF CHANGES IN THE PATTERN. THE OFFICIAL 500-MB HEIGHT PROG USES 40 PERCENT OF TODAYS MRF ENSEMBLE MEAN CENTERED ON DAY PERCENT OF TODAYS MRF CENTERED ON DAY PERCENT OF YESTERDAYS MRF CENTERED ON DAY AND 20 PERCENT OF TODAYS ECMWF 5 DAY MEAN CENTERED ON DAY 7. THE TEMPERATURE PROG IS BASED ON KLEIN AND NEURAL NETWORK SPECIFICATIONS FROM THE OFFICIAL HEIGHT PROG WHICH WERE IN GOOD AGREEMENT. THE PRECIPITATION PROG IS BASED ON THE NEURAL NETWORK SPECIFICATIONS FROM THE OFFICIAL HEIGHT PROG WITH CONSIDERATION OF THE MRF ACCUMULATED PRECIPITATION. BOTH FORECASTS WERE SUBJECTIVELY MODIFIED SOMEWHAT ON THE BASIS OF THE DAILY MRF PROGS. FORECASTER: A. J. WAGNER

6-10 day Monthly Average Skill Scores

Week 2 forecast tools from CDC

MRF Precipitation Bias Correction: Week 2

Z500 d+8 skill

Z500 d+11 skill

T850 d+8 skill

T850 d+11 skill

U.S. Threats Assessment

U.S. Threats Assessment Schedule, Leads The U.S. Threats Assessment (USTA) is intended to provide advance warning of extreme weather events to emergency managers, weather forecasters and planners at all levels of government. The USTA is issued each week on Tuesday. It covers days A preliminary version of the product is prepared and placed on a web site by noon on Monday. A web site is available to NWS field personnel to review the preliminary product and then send comments to CPC suggesting modifications. The product is updated often during the week following its release. A single forecaster prepares the product primarily using output from dynamical models, including the MRF, ECMWF, Canadian model, NOGAPS, etc… Each Wednesday, CPC hosts a telephone conference call which is open to the public. The call gives users the opportunity to discuss the product and its implications.

Definitions of Threats Listed at left are the nominal definitions of threats. Because prior conditions play a role in the impact of anomalies on the level of threat, the definitions listed are only guidelines, to be used along with knowledge of prior conditions, by the forecaster in assigning threats. Research is required to objectively determine thresholds for threats at a large number of locations.

U.S. Threats Assessment Web Page

Threats text: Summary of Forecasts and Threats

Threats Text: Discussion

Briefing sequence

Seasonal U.S. Drought Outlooks Prepared monthly following release of the long-lead outlooks

Seasonal U.S. Drought Outlook

New medium range automated products CPC and MDL have collaborated to create new MOS-based products which are produced and disseminated automatically. Heat index outlooks for 6-10 and 8-14 days Wind-chill outlooks for 6-10 days Average temperature outlooks for 6-10 days

Excessive Heat Outlooks

Excessive Heat probabilities

Wind-chill Outlooks

Average T Outlook

The End