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                U.S. DEPARTMENT OF COMMERCE
                                                             National Oceanic and Atmospheric Administration
                                                             NATIONAL WEATHER SERVICE
                                                             Silver Spring, Md. 20910

WSOM Chapter C-45 is a new chapter that incorporates coordination procedures and meteorological discussions for field offices and national centers. State Forecast Discussions (SFD) had been included in the superseded version of WSOM Chapter C-42, Winter Weather Warnings (TM 83-19, November 9, 1983). Discussions and coordination procedures by the Meteorological Operations Division of the National Meteorological Center had not been previously included in a WSOM. For completeness of the subject matter, discussions and coordination procedures for other Centers were reproduced from the other WSOM Chapters.

a. To prevent misinterpretation by users, it is preferable that word contractions be avoided in narrative sections of discussions. Any use of word contractions shall conform with the latest issuance of Federal Aviation Administration Contractions Handbook 7340.1. Use of location identifiers and acronyms well known within the scientific community are acceptable. Word contractions and other abbreviations are appropriate in coded forecast sections and summaries of watch/warning/advisory information.

c. The watch/warning/advisory section of SFDs shall be introduced in the format ".XXX..." beginning at the left margin and one blank line below the last line of the text, where XXX is the three letter identifier of the issuing office.

d. Watches and warnings for hurricanes and tropical storms shall be included in the watch/warning/advisory section of the SFD. Only affected areas within the forecast office's area of responsibility need be described.

e. When unscheduled forecast changes prompt issuance of an unscheduled SFD, the forecaster should follow guidelines for content of scheduled SFDs, including any updated information for the watch/warning/advisory section.

f. Unscheduled SFDs may also be issued that focus on shortterm mesoscale meteorological trends, typically for 6 hours or less. Such updates may omit unchanged watch/warning/advisory sections except during the period following the scheduled SFD until 1 hour after the transmission of the scheduled public zone forecast. In these cases, the watch/warning/advisory section should be present to ensure receipt by the National Severe Storms Forecast Center, A.M. Weather, and other users.

g. A Weather Service Office (WSO) with a commissioned Doppler weather surveillance radar (WSR-88D) that prepares public and/or marine forecasts (beyond adaptation of the first 12-hour forecast period) should issue an Area Forecast Discussion (AFD) to the parent forecast office. Other WSOs with WSR-88Ds in operation may also issue an APD. Upon recommendation of the WSO and the parent forecast office, regional headquarters in coordination with the Office of Meteorology's Operations Division may authorize dissemination of the AFD.

h. The AFD serves a similar function as the SFD except that a separate watch/warning/advisory section is not included. Otherwise guidelines for the content of scheduled and unscheduled --AFDs are the same as those for SFDs.

Supersedes OML 8-88, filed with WSOM Chapter C-42, issued November 4, 1988, and other previous instructions on the SFD from the superseded WSOM Chapter C-42 (section 7, pages 22-23, Transmittal Issuance 83-19, dated November 9, 1983) that were' still used for guidance.

*In implementing this Chapter, negotiations between the NWS and the National Weather Service Employees Organization have been completed. The generic set of proposals for implementing WSOM issuances involving new or modified products and/or services apply. Please inform the steward assigned to your office about this new Chapter.

1. Purpose. This chapter contains guidelines for exchange of meteorological information among offices for effective forecast decision making. In addition, effective discussion products can facilitate exchange of scientific information throughout the meteorological community. Written instructions cannot cover every possible situation. Forecasters are expected to use initiative and professional judgment in conjunction with these guidelines.

The National Weather Service (NWS) is proceeding with the modernization and associated restructuring (MAR). Guidance outlined in this chapter will be valid through Stage 1 of the MAR. Stage 1 is characterized by the introduction of the Weather Surveillance Radar-1988 Doppler (WSR-88D), which was developed by the Next Generation Weather Radar (NEXRAD) Program, and the Automated Surface Observing System (ASOS).

2.1 Weather Service Headquarters (WSH). The overall management of the program for discussions and forecast coordination rests with the Assistant Administrator for Weather Services. Staff assistance is provided by the Director, Office of Meteorology (OM), and OM's Operations Division and the Director, Office of Hydrology (OH), and OH's Operations Division.

2.2 National Meteorological Center (NMC). Each center or division of the NMC listed below provide instructions for its messages and coordination based on the guidelines in this Weather Service Operations Manual (WSOM) chapter. This assures quality control for effective coordination within NMC and with field offices.

2.2.1 Climate Analysis Center (CAC). CAC issues prognostic discussions for their 6- to 10-Day Outlooks, 30-Day Outlooks, and 90-Day Outlooks. CAC may assist forecast offices that seek guidance for incorporating outlook information in local products.

2.2.2 Meteorological Operations Division (MOD). MOD issues prognostic and interpretative discussions and charts and administrative messages for guidance and coordination on a regional or national scale. Except for administrative messages, the emphasis is on the physical evolution of significant global, synoptic, and mesoscale meteorological events. MOD may coordinate directly with forecast offices and other National Centers to provide information useful in the issuance of watches, warnings, and advisories. MOD coordinates with the National Hurricane Center (NHC) and the forecast office in Honolulu when these offices issue high seas forecasts for their areas of responsibility.

2.2.3 National Severe Storms Forecast Center (NSSFC). NSSFC issues prognostic and interpretative discussions and charts for the contiguous United States focusing on meteorological processes that lead to convection and severe local storms. NSSFC coordinates with field forecast offices before issuing watches for tornadoes and severe thunderstorms in the contiguous United State. NSSFC coordinates with the NHC when issuing tornado watches associated with hurricanes or tropical storms. NSSFC also coordinates with MOD as necessary.

2.2.4 National Hurricane Center (NHC). NHC issues guidance discussions and prognostic charts for tropical weather in the North Atlantic, Caribbean, Gulf of Mexico, and eastern North Pacific east of 140E west longitude, including the development, movement, and intensification of tropical storms and hurricanes. NHC also coordinates with coastal forecast offices and MOD before the issuance of hurricane and tropical storm watches and warnings. NHC and MOD coordinate as necessary when issuing high seas forecasts for their areas of responsibility. NHC and NSSFC coordinate on NSSFC's issuance of tornado watches associated with hurricanes and tropical storms.

2.3 Central Pacific Hurricane Center (CPHC). CPHC, under the Director, Pacific Region, issues guidance discussions for the central North Pacific from 140E west to 180E west longitude regarding tropical weather, including the development, movement, and intensification of tropical storms and hurricanes. CPHC also coordinates with Pacific Region field offices before the issuance of hurricane and tropical storm watches and warnings.

2.4 Great Lakes Coordination Center. The Weather Service Forecast Office (WSFO) at Cleveland is recognized as the focal point for Great Lakes information and warning coordination with other field offices that have Great Lakes forecast responsibility.

2.5 Regional Headquarters. The regions provide instructions for field offices based on guidelines found in this WSOM chapter and submit them to WSH for approval before issuance. Regional Headquarters also ensure that the field office products are of high quality and adequately provide information for effective coordination.

2.6 Field Offices. Each WSFO and NEXRAD WSFO (NWSFO) prepares and issues discussions on factors affecting their forecast area of responsibility. NEXRAD Weather Service Offices (NWSO) and Weather Service Offices (WSO) with a precommissioned WSR-88D in operation may issue discussions for their county warning area of responsibility according to regional authorization. WSFO/NWSFOs are responsible for maintaining quality control for all discussions issued within their area of responsibility. WSFO/NWSFOs shall coordinate with adjacent WSFO/NWSFOs, WSO/NWSOs in their own area, and the National Centers.

3. Discussions and Coordination. Discussions facilitate a coordinated exchange of scientific information among NWS offices, emergency managers knowledgeable in the science, other government agencies, and sophisticated users in the private sector. They are a means to provide technical information to sophisticated users to assist in critical decision making and support users' understanding of the situation. Because of their technical nature, discussion products are not intended for the general public. However, they can be used by various users to enhance their knowledge and credibility when communicating with the general public.

The issuance of forecast discussions does not eliminate the need for coordination calls among offices, particularly during significant weather. Where possible, National Centers and field offices are encouraged to use the full capacity of telephone systems for convenient multiple party contacts without operator assistance. NHC coordinates with field offices and MOD via the hurricane hotline prior to issuing a hurricane watch or warning. Use of the hurricane hotline is also encouraged, where possible, for conference calling among field offices and National Centers for other major storms.

To prevent misinterpretation by users, it is preferable that word contractions be avoided in narrative sections of discussions. Any use of word contractions shall conform to the latest issuance of Federal Aviation Administration Handbook 7340.1. Use of location identifiers and acronyms well-known within the scientific community for numerical models and meteorological phenomenon are acceptable. Some examples of acceptable acronyms are NGM for the nested grid model and PVA/NVA for positive/negative vorticity advection. Word contractions and other abbreviations are appropriate for coded forecast sections and summaries of watch/warning/ advisory information.

Some discussions, particularly from the National Centers, are transmitted before forecast decisions are made and, thus, can help facilitate forecast coordination among field offices and the National Centers. Other messages, particularly from field offices, occur after decisions are made but may assist in coordination for succeeding forecast cycles and thus provide improved continuity of service to the public.

Certain discussion messages emphasize large-scale (global and synoptic) weather patterns. Other messages emphasize smaller scale (mesoscale) patterns. The presentation in this chapter goes approximately from largescale analysis (in space and time) to smaller scale analysis. The combination of these messages gives users a continuity of information to assist in forecast formulation and coordination.

3.1 Discussions and Coordination by CAC. CAC issues prognostic discussions that give the meteorological and climatological basis for its long-range outlooks. Field offices may want to coordinate with CAC when issuing any statements incorporating outlook information into field office products. This coordination could help in determining a confidence level when referring to the outlook. Further information on outlooks and related discussions is contained in WSOM Chapter C-12, 6- to 10-Day, 30-Day, and 90-Day Outlooks.

3.1.1 Prognostic Discussion for the 90-Day Outlook (PMD9OD. FXUSOS RWBC). This may include analysis of numerical and statistical models, meteorological and sea surface temperature patterns and trends, and confidence factors.

THE SEASONAL FORECAST FOR MARCH THROUGH MAY 1993 IS BASED ON SEVERAL TOOLS. LAG CORRELATIONS OF 700 MB HEIGHT ANOMALIES FROM LAST MONTH AS WELL AS FROM LAST SEASON SUGGEST CONTINUED NEGATIVE ANOMALIES AT 45N AND 145W...FROM HUDSON BAY NORTHEAST ACROSS GREENLAND INTO THE ARCTIC OCEAN...AND OVER SUCH OF THE SUBTROPICAL PACIFIC. POSITIVE HEIGHT ANOMALIES ARE LIKELY TO PERSIST OVER WEST CENTRAL CANADA.

THE OVERALL TEMPERATURE FORECAST PATTERN REFLECTS THE ABOVE INDICATIONS. THUS...WE ARE CALLING FOR ABOVE NORMAL TEMPERATURES IN THE NORTHWEST AND BELOW NORMAL IN THE SOUTHEAST. THIS GENERAL PATTERN WAS AMENDED ONLY SLIGHTLY BY THE OTHER TOOLS...SUCH AS PERSISTENCE FROM LAST MONTH AND SEASON SURFACE TEMPERATURES...THE LONG LEAD TINE CANONICAL CORRELATION AND OBJECTIVE PREDICTIVE ANALOG SYSTEM...AS WELL AS DETAILED CONSIDERATION OF SEASON SURFACE TEMPERATURES ALONG THE WEST COAST AND PRECIPITATION VS TEMPERATURE CORRELATION.

AS USUAL...IT WAS HARDER TO SPECIFY PRECIPITATION FROM THE 4 OR 5 HEIGHT ANOMALY LOCATIONS. THE FINAL PRECIPITATION FORECAST REFLECTS THE CONSENSUS AMONG THE INDIVIDUAL FORECASTERS AND TO A LARGE EXTENT THE SPECIFICATION OF PRECIPITATION BY ANALOGS TO THE CONSENSUS TEMPERATURE FORECAST.

3.1.2 Prognostic Discussion for 30-Day Outlook (PMD30D, FXUS07 KWBC). This discussion gives the meteorological and climatological basis for the outlook. It is issued twice monthly, just before the beginning and just b fore the middle of the month, at around 3 p.m., eastern local time (around 2000 UTC or 2100 UTC).

Discussions may include analysis of numerical and statistical models, meteorological and sea surface temperature patterns and trends, and confidence factors. Discussions may also refer to the method of operational ensemble prediction at NMC (practical aspects), which is described in an article of the name by M. S. Tracton in Weather and Forecasting, volume 7, no. 3 (September 1993).

THE 30-DAY MEAN PROGNOSTIC 700MB HEIGHT ANOMALY MAP FOR MARCH 1993 IS BASED MOSTLY ON THE NUMERICAL PROGS THROUGH 10 DAYS FROM THE 14 MEMBER MRF ENSEMBLE MEAN AND ECMWF FORECAST PLUS MONTH TO MONTH CORRELATIONS OF = 700 MB HEIGHT ANOMALIES. MOST WEIGHT WENT TO THE MRF PRODUCT GIVEN THE CONSISTENCY AMONGST MEMBERS AND DISAGREEMENT OF ECMWF FROM THEM IN SOME IMPORTANT RESPECTS. THE FORECAST CALLS FOR AN ELONGATED EAST-WEST NEGATIVE ANOMALY CENTERED OVER THE NORTHERN GULF OF MEXICO AND A POSITIVE ANOMALY CENTERED OVER THE NORTHWEST TERRITORIES AND EXTENDING SOUTHWEST OFF THE CALIFORNIA COAST. CONFIDENCE IS RELATIVELY HIGH WITH THESE FEATURES BECAUSE OF THE FAIRLY CONSISTENT SIGNAL PROVIDED BY THE ENSEMBLE PREDICTIONS.

THE TEMPERATURE AND PRECIPITATION PROGS ARE BASED ON SPECIFICATION EQUATIONS FROM THE PROG HEIGHT ANOMALY. THE PROBABILITIES SHOWN ARE NOT AS HIGH AS THEY MIGHT BE BECAUSE PERSISTENCE FROM THE FIRST 10 DAYS THROUGH THE BALANCE OF THE MONTH IS NOT AS GREAT THIS TIME OF YEAR.

3.1.3 Prognostic Discussion for 6- to 10-Day Outlook (PMDMRD, FXUS06 RMBC).This discussion may include analysis of numerical and statistical models, meteorological circulation patterns and trends, and confidence factors. Reference is usually made to the manually produced 6- to 10-day Northern Hemisphere prognoses for mean 500 millibar heights (AFOS graphic NMCGPG96H) and mean 500 millibar height anomalies (AFOS graphic NMCGPH96C). Discussions may also refer to the method of operational ensemble prediction at NMC (practical aspects), which is described in an article of the same name by M. S. Tracton in Weather and Forecasting, volume 7, no. 3 (September 1993). It is issued 3 times a week and disseminated around 3 p.m., eastern local time (2000 UTC or 2100 UTC), Monday, Wednesday, and Friday, including holidays.

THE ECNWF AND MRF MODELS ARE IN GOOD AGREEMENT TODAY AND IN GOOD AGREEMENT WITH THEIR RECENT RUNS. TODAY'S SOLUTIONS OF BOTH MODELS TELECONNECT QUITE WELL AND HAVE REASONABLE CONTINUITY FROM THE FIRST 5 DAYS. THUS EXPECT OVERALL MEAN PATTERN TO REMAIN MOSTLY UNCHANGED... WITH POSITIVE HEIGHT DEPARTURES FROM NORMAL OVER CANADA AND THE NORTHERN UNITED STATES AND THE SUBTROPICAL JET IN THE SOUTHERN UNITED STATES. A TROUGH RUNS JUST OFF OF THE WEST COAST OF NORTH AMERICA WHICH SHOULD MAKE THE WEST COAST STORMY. THE MODIFIED 500 MB PROG IS A WEIGHTED BLEND OF ECNWF...MRF...MULTIPLE REGRESSION OF THE MRF AND ECMWF...AND THE MRF BAROTROPIC EXTENSION.

THE TEMPERATURE PROG IS A BLEND OF REGRESSION CORRECTED PERFECT PROG TEMPERATURES...OBJECTIVE TEMPERATURES BASED ON THE MODIFIED PROG...AND OBSERVED CASES WITH POSITIVE HEIGHT DEPARTURES FROM NORMAL NEAR 53N 90W...AND NEGATIVE HEIGHT DEPARTURES FROM NORMAL NEAR 30N 125W AND NEAR 3ON 70W. THE PRECIPITATION PROG IS BASED ON MRF GUIDANCE MODIFIED FOR RECENT OBSERVED CASES AND OBSERVED CASES WITH ABOVE DEPARTURES FROM NORMAL.

meteorological forecast coordination. Except for administrative messages, the emphasis is on the physical evolution of significant global, synoptic, and/or mesoscale meteorological events and meteorological analysis of the performance of various numerical models.

As many of these messages are available to field forecasters before forecast issuance time, they provide useful input into the forecast decision process and help to facilitate coordination among field offices and/or National Centers. These discussions may be useful to field offices in preparation of state/area forecast discussions, either to extract pertinent sections or to use as reference, particularly aspects dealing with variance from model guidance.

MOD may coordinate directly with WSFO/NWSFOs and other National Centers to exchange information for difficult forecast situations involving significant weather (including situations where watch/warning/advisory decisions are made), large deviation from computer guidance, and/or major changes from previous forecasts. NOD coordinates with NHC and the WSFO in Honolulu when issuing high seas forecasts (see section 3.6). MOD also coordinates with NHC on hurricane and tropical storm watches and warnings.

3.2.1 Administrative Messages (ADMNFD, ADMN9 RWRA). MOD is responsible for issuing routine and special administrative messages that provide information to the field and outside users. These messages contain the following information: (1) the current status of the model run cycles (e.g., any delays in model guidance)i (2) upper-air sounding data that were edited or deleted before their use by the models; (3) delays in the creation and/or distribution of MOD products; and (4) delays in the creation and/or distribution of data sets processed on NNC computers (e.g., plot files of surface data).

3.2.2 Prognostic Map Discussions (PMD). These products are intended primarily to offer expertise in model circulation interpretation, selection of the "model of the day," describe important model differences, and serve as a coordinating mechanism.

3.2.2.1 Hemispheric Map Discussion (PMDHMD, FXUS03 KWBC). This discussion is issued once a day around 1800 UTC and is primarily intended to provide insight into the hemispheric circulation patterns over the next 5 days. This includes a discussion of the 5-day mean circulation pattern. Comparisons, differences, and continuity among the numerical models are highlighted, and preferred solutions are proposed with an explanation of why a solution is preferred. This includes any reasons why the preferred solution differs from any model. In cases where certain models are not universally available, an attempt should be made to describe that model's solution to an extent that a reader can understand its important aspects. Although actual or forecast sensible surface weather conditions are not a focus of this discussion, some discussion may be made to correlate them to circulation patterns.

THE MEDIUM RANGE MODELS MEAN PATTERN ARE IN GOOD AGREEMENT TODAY...BUT THIS MORNINGS SHORT RANGE MODELS HAVE TOSSED SEVERAL QUESTIONS/DOUBTS INTO THE MEDIUM RANGE FORECAST. THE MEAN 500 MB PATTERN CONTINUES TO SHOW A STRONG POSITIVE HEIGHT ANOMALY NEAR SON 80W WITH A STRONG NEGATIVE ANOMALY OVER GREENLAND. FARTHER WEST...THE MODELS ARE FORECASTING A NEGATIVE HEIGHT ANOMALY QUITE FAR SOUTH...NEAR 25N 110W OVER W A. A LARGE AREA OF NEGATIVE HEIGHT ANOMALY IS FORECAST OVER THE PACIFIC IN FAST ZONAL FLOW.

TELECONNECTIONS FOCUSING ON THE POSITIVE HEIGHT ANOMALY OVER THE EASTERN NORTH AMERICA RIDGE AGREE REMARKABLY WELL WITH THE REST OF THE UPPER PATTERN OVER THE WESTERN HEMISPHERE. THE NEGATIVE HEIGHT ANOMALY OVER GREENLAND AND OVER BAJA IS WELL SUPPORTED. AT FIRST WE HAD SOME, QUESTIONS ABOUT THE NEGATIVE ANOMALY OVER BAJA BEING SO FAR SOUTH FOR THIS TIME OF YEAR...BUT ALL THREE MEDIUM RANGE MODELS ARE FORECASTING A CUTOFF TO DEVELOP AND THE TELECONNECTIONS SUPPORT THIS.

IN THE DAILY FORECASTS...IT LOOKS LIKE WE'RE GOING TO HAVE TO DEAL WITH MODEL DIFFERENCES IN TIMING AND STRENGTH OF SYSTEMS MOVING INTO THE WESTERN U.S. THIS FORECAST PERIOD. THE MEDIUM RANGE MODELS BRING THE SHORT WAVE THAT IS CRASHING THE PACIFIC NORTHWEST TODAY DUE EAST AND INTO WYOMING BY DAY 3. THEN THIS SHORT WAVE WEAKENS AND LIFTS NORTHEAST INTO CANADA...WHILE THE NEXT SHORT WAVE DIGS INTO THE WESTERN U.S. AND EVENTUALLY BECOMES A CUTOFF LOW OVER BAJA BY DAY 5. THIS FORECAST SEEMED OKAY EARLIER THIS MORNING...BUT AFTER SEEING THE SHORT RANGE MODELS AND THIS MORNINGS UPPER AIR DATA WE HAVE A LOT OF QUESTIONS THAT NEED TO BE ANSWERED.

THE NEW SHORT RANGE MODELS...ETA/RGL/AVN DAY 2 FORECAST SHOWS A MUCH STRONGER SYSTEM WITH ETA/AVN NEAR THE FOUR CORNERS AREA AND THE RGL OVER SE WYOMING. THIS MORNINGS UPPER AIR DATA SHOWS DRAMATIC HEIGHT FALLS OF 100-200 METERS AT ALL THE MANDATORY LEVELS TELLS US THAT THE SYSTEM IS VERY STRONG. WITH PLENTY OF JET STILL REMAINING ON THE BACKSIDE...THE SYSTEM SHOULD DIG FARTHER SOUTH INTO THE CENTRAL/SOUTHERN ROCKIES BEFORE LIFTING NORTHEAST IN RESPONSE TO THE NEXT POWERFUL SHORT WAVE THAT IS LOCATED OVER THE CENTRAL PACIFIC NEAR 47N 165W THIS MORNING. BASICALLY WE'VE ALLOWED THE SYSTEM NOW MOVING ONTO THE PACIFIC COAST TO DIG FARTHER SOUTH LIKE THE SHORT RANGE MODELS AND THEN KEEP IT FARTHER SOUTH AND

OVER EASTERN NORTH AMERICA...RIDGING WILL REMAIN IN THE PLAINS WITH THE SHORT WAVES LIFTING FROM THE PLAINS TO THE GREAT LAKES AND WEAKENING IN THE FAST CONFLUENT FLOW...THEN STRENGTHENING AS THEY MOVE INTO THE MEAN TROUGH OVER GREENLAND. THE SHORT WAVE OVER THE CENTRAL PLAINS TODAY WILL LIFT NORTHEAST AND CROSS THE GREAT LAKES ON DAY 3...THEN INTENSIFY ON DAYS 4 AND 5. THIS ALLOWS A RATHER STRONG SURFACE HIGH TO BUILD SOUTH INTO SOUTHEAST CANADA/NORTHEAST U.S. WITH PLENTY OF COOL AIR...AND POSSIBLY SOME EARLY MAY FROST/FREEZE TEMPERATURES THE MORNING OF DAY 5 AS THE SURFACE GRADIENT RELAXES.

OVER HAWAII...MODERATE PRECIPITATION IS EXPECTED ON WINDWARD AREAS AND LIGHT ON LEEWARD AREAS DUE TO SLIGHTLY STRONGER THAN NORMAL TRADES. CENTRAL ALASKA WILL ENJOY ABOVE NORMAL TEMPERATURES...WITH IN EXTREME SOUTH AND PARTS OF THE NORTH TO HAVE NORMAL TEMPERATURES. THE EXTREME NORTHERN COASTAL AREA WILL HAVE BELOW NORMAL TEMPERATURES THIS PERIOD. PRECIPITATION SHOULD BE LIGHT OVER WESTERN SECTIONS AND HEAVY IN THE EASTERN SECTION.

IN THE SHORT RANGE...THE MODELS ARE HANDLING THE STRONG PACIFIC NORTHWEST SYSTEM DIFFERENTLY AS WE MOVE TOWARD 48 HOURS. THE RGL IS THE FARTHEST NORTH...WITH THE AVN/ETA SOUTHWEST OF THE RGL POSITION. THE CONSENSUS HERE IS TO DISCOUNT THE RGL CONSIDERING ITS BIAS IS TO KEEP THE SYSTEM TOO FAR NORTH. THE AVN/ETA SOLUTION BY 48 HOURS ARE VERY CLOSE AT 500 MB WITH THE AVN SHOWING A VERY REASONABLE SURFACE SOLUTION...SIMILAR TO WHAT THE SHORT RANGE FORECASTER WAS GOING WITH. IN THE EAST...THE CLOSED LOW OVER OK/AR THIS MORNING WILL SLOWLY FILL AND LIFT NORTHEAST INTO THE GREAT LAKES. LOW LEVEL FLOW WILL REMAIN OFF THE GULF OF MEXICO AND ATLANTIC SO PLENTY OF MOISTURE WILL BE AVAILABLE FOR THIS SYSTEM AS IT DIES A SLOW DEATH OVER IN OHIO VALLEY/GREAT LAKES STATES.

3.2.2.2 Extended Forecast Discussion (PNDEPD, FXUS02 KWBC). This discussion is issued once a day around 1900 UTC and is primarily intended to provide insight into the guidance forecasts for the 3- to 5-day forecast period. Where's the PMDHMD is hemispheric in scope, the geographic focus of this discussion is on the United States (including Alaska and Hawaii). Although portions of this narrative will parallel the PMDHMD, a much greater effort is made to routinely relate the model forecasts and necessary modifications to weather forecasts, mainly in terms of temperature and precipitation. Other significant parameters, such as wind, may be discussed when deemed reliably predictable. This discussion and the corresponding graphical output listed below are the primary guidance to the WSFO/NWSFOs for the extended forecast section of the state forecasts. See WSOM Chapter C-10, State Forecasts.

Graphical output for extended forecasts:
93P (Day 3 temperature and precipitation forecast)
94P (Day 4 temperature and precipitation forecast)
95P (Day 5 temperature and precipitation forecast)
9JH (Day 3 surface prog, valid 1200 UTC)
9KH (Day 4 surface prog, valid 1200 UTC)
9LH (Day 5 surface prog, valid 1200 UTC)
95A (5-day mean maximum temperature anomaly forecast)
95B (5-day mean minimum temperature anomaly forecast)
95E (5-day total precipitation forecast)

DESPITE SEVERAL DIFFERENCES IN THE TRACK AND SPEED OF A STRONG SHORT WAVE ROUNDING THE BASE OF THE MEAN TROUGH CENTERED ALONG 90-100W OVER THE CENTRAL PART OF THE NATION...ALL MEDIUM RANGE MODELS ARE FORECASTING A MAJOR STORM FOR THE EASTERN HALF OF THE NATION. THE TRENDS STARTED YESTERDAY IN THE EASTERN PACIFIC...WITH A WESTWARD SHIFT OF THE TROUGH AND RIDGE POSITIONS ACROSS THIS REGION CONTINUING TODAY. THIS WESTWARD SHIFT...WHICH KEEPS THE MEAN RIDGE POSITION ALONG 130W...CONTINUES TO ALLOW AMPLIFICATION OF SHORT WAVE ENERGY DRIVING SOUTHEAST INTO THE MEAN TROUGH POSITION OVER THE CENTRAL U.S.

THE MRF MODEL HAS BACKED OFF SOMEWHAT WITH THE STRENGTH OF THIS DIGGING VORTICITY AND IS FASTER THAN YESTERDAYS RUN WITH THE EAST MOVEMENT THRU THE BASE OF THE CENTRAL U.S. TROUGH. HOWEVER...THIS IS STILL NEARLY 12 TO 18 HOURS SLOWER THAN THE ECMWF AND THE 1200 UTC MARCH 8 UKMET RUN. THE LAmanual 0000 UTC MARCH 9 UKMET APPEARS TO BE FAVORING THE SLOWER MOVEMENT OF THE MRF AND WE HAVE FOLLOWED THIS SPEED IN THE MANUAL PROGS TODAY.

THERE IS STILL SOME DOUBT OF THE FINAL TRACK OF THIS LOW AS IT MOVES NORTHEAST OUT OF THE WESTERN GULF OF MEXICO INTO THE SOUTHEAST U.S. ALL BUT THE 0000 UTC UKMET KEEP THE LOW OFFSHORE...POSING THE THREAT OF LATE WINTER HEAVY SNOWFALL FROM THE SOUTHERN APPALACHIANS/EASTERN TENNESSEE VALLEY NORTHEAST THROUGH THE MAJOR METRO AREAS FROM D.C. TO BOSTON. WE HAVE FOLLOWED THE OFFSHORE SOLUTION...NOT WANTING TO PIN OUR FORECAST TRACK ON ONE RUN OF THE UKMET. EITHER TRACK WILL PRODUCE ABUNDANT WINTER WEATHER...AT LEAST INITIALLY...AS THE UPPER CONFLUENT AXIS CENTERED OVER SOUTHEAST CANADA SHOULD MAINTAIN AN ABUNDANT SUPPLY OF COLD AIR.

THE AMPLIFYING UPPER TROUGH OVER THE CENTRAL U.S. WILL CONTINUE BELOW TO MUCH BELOW NORMAL TEMPERATURES FROM THE CENTRAL AND SOUTHERN PLAINS... WHICH WILL SPREAD EAST BEHIND THE EASTERN U.S. STORM. THICKNESS ANOMALIES ARE FORECAST TO BE AS LARGE AS 350 TO 400 METERS BELOW NORMAL FROM THE SOUTHERN PLAINS EAST ACROSS THE LOWER MISSISSIPPI VALLEY AND INTO THE SOUTHEAST U.S.

OVER NORTHWEST NORTH AMERICA...THE MEDIUM RANGE MODELS ARE STRONGER THIS RUN WITH A SHORT WAVE DIVING SOUTHEAST THROUGH NORTHWEST CANADA. THE MODELS ARE ATTEMPTING TO FORM A CLOSED LOW WITH THIS FEATURE OFF THE B.C. CANADA COAST ON DAY 4. THIS FLATTENS THE UPPER RIDGE THAT HAD BEEN FORECAST TO DOMINATE YESTERDAY ACROSS THIS REGION WITH MORE WESTERLY LOW LEVEL FLOW INTO THE PACIFIC NORTHWEST. THIS SHOULD BRING LIGHT TO MODERATE PRECIPITATION INTO THE PACIFIC NORTHWEST BEYOND DAY 4.

3.2.2.3 12- to 48-Hour Prognostic Discussion (PMDSPD, FXUS01 KWBC). This discussion is issued around 0700 UTC and 1900 UTC and is intended to provide insight into the guidance forecasts for the 1- to 2-day period. This discussion explains the basis for the manual surface prognostic charts listed below for the contiguous United States. Focusing mainly on precipitation forecasts, this discussion notes numerical model differences and explains preferences or deviations that went into the preparation of the forecast products.

92F (12-hour or 18-hour pressure/frontal surface prog)
94F (24-hour or 30-hour pressure/frontal surface prog)
96F (36-hour pressure/frontal surface prog)
98F (48-hour pressure/frontal surface prog)
L2P (12-hour or 18-hour instantaneous precipitation prog)
L4P (24-hour or 30-hour instantaneous precipitation prog)
L6P (36-hour instantaneous clouds/precipitation prog)
L8P (48-hour instantaneous clouds/precipitation prog)

THE MODELS CONTINUE TO FORECAST SLOW PROGRESSION OF SHORT WAVES FROM THE NORTHWEST STATES INTO THE NORTH CENTRAL STATES...WHILE A STRONG UPPER HIGH BUILDS NORTHEAST FROM THE NORTH CENTRAL U.S. TO THE NEW ENGLAND COAST BY THE END OF THE PERIOD. MODELS CONTINUE TO FLIP-FLOP WITH HANDLING OF MAIN UPPER TROUGH WHICH IS FORECAST TO LIFT EAST INTO THE NORTHERN HIGH PLAINS BY 48 HOURS. WHILE LAST NIGHTS RUN SHOWED THE ETA STANDING ALONE AS BRINGING OUT A MORE SIGNIFICANTLY INTACT UPPER TROUGH WHILE BACKING OFF SOMEWHAT DURING THE DAY RUN...TONIGHTS RUN IS AGAIN THE STRONGEST WITH A NEUTRALLY TILTED UPPER TROUGH AND FAIRLY STRONG PVA ACROSS THE NORTHERN PLAINS BY 48 HOURS.

PART OF THE PROBLEM IS THAT SEVERAL STREAMS OF FLOW ARE INVOLVED ACROSS THIS REGION AND SOUTHERN CANADA AND THE ETA MAY BE TRYING TO PHASE THE TWO STREAMS. STILL THINK THIS IS UNLIKELY AND THAT A MORE POSITIVE/ SHEARED UPPER TROUGH WILL LIFT EAST TOWARD THE NORTHERN PLAINS OVER THE NEXT TWO DAYS...SIMILAR TO THE NGM. EVEN THOUGH THE NGM HAS A DEEPER SURFACE LOW BY 48 HOURS IT HAS A SIGNIFICANTLY FLATTER WAVE STRUCTURE COMPARED TO THE ETA. CONVECTION ALONG AND SOMEWHAT POST FRONTAL WILL INCREASE THROUGH THE NORTHERN PLAINS UNDER FAVORABLE UPPER LEVEL JET POSITION AND 850 MB SPEED CONVERGENCE AND CONTINUE TO SPREAD SLOWLY EAST TOWARD THE UPPER MISSISSIPPI VALLEY ON DAY 2 AS THE UPPER TROUGH KICKS EAST.

ELSEWHERE ACROSS THE U.S. THERE WILL BE AN ABSENCE OF FRONTS TO HELP FOCUS RAINS AS THE BROAD UPPER RIDGE COVERS THE SOUTHERN TIER OF STATES THROUGH NEW ENGLAND. SEVERAL WEAK UPPER LEVEL DISTURBANCES ROTATING AROUND THE PERIPHERY OF THE RIDGES WILL TEND TO ENHANCE DAYTIME CONVECTION. ONE WILL BE A WEAR AXIS DROPPING SOUTH THROUGH THE MID ATLANTIC STATES ON DAY 1 AND THEN RETURNING NORTH ON DAY 2. ANOTHER IS OVER CENTRAL TEXAS WHICH WILL GRADUALLY WORK WEST TOWARD WESTERN SECTIONS OF THE STATE. SCATTERED DIURNAL SHOWERS SHOULD CONTINUE THROUGH FLORIDA AND MUCH OF THE REMAINDER OF THE GULF COAST REGION AS WEST EASTERLY WAVES MOVE THROUGH.

TROPICAL STORM HILLARY OFF THE SOUTHWEST COAST OF BAJA IS FORECAST TO MOVE SLOWLY NORTHWEST ALONG THE COAST IN THE NEXT 48 HOURS AND SLOWLY WEAKEN. HOWEVER THE ANTICYCLONIC OUTFLOW PATTERN ASSOCIATED WITH THE STORM MAY ENHANCE UPPER DIVERGENCE OVER PARTS OF SOUTHERN CALIFORNIA AND ARIZONA WHERE SOME DECENT LOW AND MID LEVEL MOISTURE WORKED NORTH INTO THE REGION.

3.2.3. Quantitative Precipitation Forecasts (QPF) Discussions. These products are issued primarily to facilitate coordination of winter storm and flood/flash flood forecasting among WSFO/NWSFOs, River Forecast Centers, and MOD. See WSOM Chapter E-20, Flood/Flash Flood Watch and Warning Program, for further details. Each QPF discussion has a corresponding QPF graphic(s). Also, there are three 6-hour QPF graphics (91E, 92E, and 93E) without a specific discussion accompanying them but may be referred to in QPF discussions.

3.2.3.1 QPF Discussion (OPFPFD, FXUS4 KWBC). This forecast discussion is directed completely to explaining manual forecasts of areas in the contiguous 48 states expected to receive 1/4 inch or more of precipitation during a 24-hour period. The manual forecasts are explained in terms of initial conditions and differences and/or similarities in the numerical model forecasts. The QPFPFD is issued 3 times a day as described below. General confidence in the manual forecast is expressed where appropriate, and possible alternatives may be offered.

UPDATED QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NATIONAL METEOROLOGICAL CENTER
NATIONAL WEATHER SERVICE WASHINGTON DC
600 AM EST SAT MAR 13 1993
DAY 1 QPF VALID MAR 13/1200 UTC TO MAR 14/1200 UTC
DAY 2 QPF VALID MAR 14/1200 UTC TO MAR 15/1200 UTC

ALL OF THE LAmanual MODEL RUNS CONTINUE TO PROG WHAT WOULD BE THE DEEPEST STORM EVER TO MOVE THROUGH THE MID ATLANTIC AND NEW ENGLAND REGIONS (OUTSIDE OF TROPICAL SYSTEMS IN NEW ENGLAND) AND CURRENT OBSERVATIONS ALONG THE GULF COAST AND SOUTHEAST STATES SIGNAL DEEPENING PROCESS IS WELL UNDERWAY. ALREADY AT 0900 UTC...THE SURFACE LOW WAS RAPIDLY INTENSIFYING IN VICINITY OF THE FLORIDA PANHANDLE...WITH PRESSURE FALLS APPROACHING 14 MB IN 3 HOURS OVER GEORGIA AND INTO SOUTH CAROLINA. THE TRACK OF THE LOW TO THE GEORGIA/SOUTH CAROLINA BORDER AT 1200 UTC AND THEN TO VICINITY OF THE CHESAPEAKE BAY BY 14/0000 UTC SEEMS QUITE GOOD. THE AVIATION MODEL HAS BEEN REMARKABLY CONSISTENT WITH POSITION AND DEPTH OF THE SURFACE LOW FOR 4 CONSECUTIVE RUNS...AND WAS THE MODEL OF CHOICE AGAIN TONIGHT. OTHER MODEL RUNS HAVE NOW COME INTO VERY CLOSE AGREEMENT WITH THE AVN...WHICH ONLY ADDS CONFIDENCE TO THE FORECAST.

NEEDLESS TO SAY...INCREDIBLE INTENSITY OF THE SURFACE LOW WILL PRODUCE WINDS NEAR OR ABOVE HURRICANE FORCE IN MID ATLANTIC REGION INTO NEW ENGLAND. SAME INCREDIBLY STRONG WINDS WILL ALSO BRING COPIOUS MOISTURE INLAND FROM THE ATLANTIC...WHICH WILL SUPPORT VERY HEAVY PRECIPITATION AMOUNTS IN THE MID ATLANTIC STATES INTO SOUTHERN NEW ENGLAND. WATER EQUIVALENTS APPROACHING 3 INCHES WILL ALLOW FOR 2-3 FOOT SNOWS IN PARTS OF WESTERN Virginia/EASTERN WEST VIRGINIA NORTHEAST THROUGH WESTERN MARYLAND INTO CENTRAL AND NORTHEAST PENNSYLVANIA...AND EASTERN NEW YORK/WESTERN MASSACHUSETTS/SOUTHERN VERMONT/NEW HAMPSHIRE BY SUNDAY MORNING...WITH BLIZZARD CONDITIONS LIKELY FROM MID ATLANTIC STATES INTO NEW ENGLAND. WITH SURFACE LOW TAXING AN INLAND TRACK..EXPECT SNOWS TO EVENTUALLY CHANGE TO RAIN IN THE MAJOR METROPOLITAN AREAS FROM 3.C. TO BOSTON...BUT NOT BEFORE HEAVY SNOWS ACCUMULATE IN EACH OF THE CITIES. HAVE BASED RAIN/SNOW LINE ON THE PROG OF AVN 850 MB THERMAL GUIDANCE. THOSE HEAVIEST PRECIPITATION AMOUNTS FROM THE MID-ATLANTIC INTO SOUTHERN NEW ENGLAND REGION ARE ALSO BASED ON THE FACT THAT GREAmanual SURFACE DEEPENING WILL OCCUR FROM SOUTHEAST STATES INTO MID-ATLANTIC REGION TODAY...WITH LITTLE ADDITIONAL DEEPENING EXPECTED THROUGH NEW ENGLAND SATURDAY NIGHT.

THERE WILL BE PLENTY OF WIND LEFT THROUGHOUT NEW ENGLAND AND MID-ATLANTIC STATES ON SUNDAY BEHIND RAPIDLY DEPARTING SUPER-STORM...BUT EXPECT GENERALLY ONLY LIGHT AMOUNTS OF SNOW IN WRAP-AROUND FROM UPSTATE NEW YORK INTO MAINE. LAKE EFFECT SHOULD ALSO KICK IN BIG TIME IN THE LEE OF LAKES ERIE AND ONTARIO...AS EXTREMELY COLD LOW LEVEL AIR STREAMS ACROSS THE LAKES.

PRECIPITATION EMPHASIS WILL THEN SHIFT TO THE WEST COAST...WHERE MODELS ARE PROGGING CLOSED LOW IN THE EASTERN PACIFIC TO COME ASHORE. CLOSED LOW WILL BE SQUEEZED INTO WASHINGTON/ OREGON/NORTHERN CALIFORNIA ON SUNDAY UNDERNEATH SYSTEM DROPPING SOUTHEAST THROUGH B.C. SYSTEM CERTAINLY LOOKS "COLD" ENOUGH ON SATELLITE IMAGERY TO SUPPORT AT LEAST MODERATE TO LOCALLY HEAVY PRECIPITATION IN MUCH OF WESTERN WASHINGTON/OREGON AND NORTHERN PORTIONS OF CALIFORNIA. PRECIPITATION AMOUNTS MAY BE FURTHER ENHANCED IN WASHINGTON SUNDAY NIGHT BY B.C. SYSTEM ITSELF...WHICH DROPS INTO WASHINGTON BY MONDAY MORNING.

24HR QP VT 14/12Z DAY 1
0.25    305795 312796 322798 328802 333809 334818 333829 332840 333851
            340859 354861 373857 391849 405838 425819 442799 458778 470752
            482726 490697 496672 499650 501630
0.25    452265 455254 451242 444236 436234 429233 423226 420216 412208 401206               391205 387212 389221 384228 378234 374242 374249
(continues with additional forecast isoyets as needed)

24HR QP VT 15/12Z DAY 2
0.25    409098 406094 400102 393106 381107 372116 372126 379128 391122 403118             412116 417110 416107 409098
0.25    481649 468663 453687 442709 434731 429750 424768 417790 414802 415811             416812 424799 435779 447756 459740 473726 487709 497692 501683
0.25    519177 505162 494156 481150 470142 459136 450136 442142 439149 443156             446163 448172 457173 469173 481179 485184 485188 480192 465197 454200              439202 426202 412202 401203 389200 381196 376199 381209 386219 379224              372230 370238 370246
(continues with additional forecast isoyets as needed)

3.2.3.2 Excessive Rainfall Discussion (OPFERD, FOUS30 KWBC). This message discusses the potential for excessive rainfall in the contiguous United States until 1200 UTC the next day. This includes mentioning areas where rainfall is forecast to be locally heavy, approach or exceed flash flood guidance, or exceed 5 inches. This product includes evaluation of initial conditions and short-term numerical model forecasts and analysis of radar and satellite data.

Unscheduled special updates (QPFSRD, FOUS31 KW8C) may be issued as needed, particularly around 0200 UTC, following careful and detailed analysis and evaluation of the 0000 UTC upper air data. This forecast would generally be valid for the period from 0300 UTC to 1200 UTC. In addition, the QPFSRD may be used to support other QPF-related requirements from field offices.

RAINFALL IS EXPECTED TO EXCEED FLASH FLOOD GUIDANCE VALUES TO THE RIGHT OF A LINE 40SW PSX-60NW SAT-ACT-TYR-MCB-BVE. WITHIN THIS AREA RAINFALL AMOUNTS MAY EXCEED 5 INCHES TO THE RIGHT OF A LINE PSX-20NW HOU-30N LCHBTR-MSY-29N 90W.

A SYNOPTIC TYPE HEAVY RAINFALL EVENT SEEMS TO BE SHAPING UP FOR LOUISIANA AND TEXAS FOR THIS FORECAST PERIOD. A STRONG LOW LEVEL JET HAS DEVELOPED ACROSS TEXAS AHEAD OF THE FRONT. BOTH ARE FORECAST TO SHIFT SLOWLY EAST OVER THE NEXT 24 HOURS. THE LAmanual 500 MB PLOT SHOWS ANOTHER SHORT WAVE SWINGING AROUND THE WEST SIDE OF THE TROUGH WHICH SHOULD HELP TO SLOW THE FRONT LATER TODAY.

LAST NIGHT'S GRIDDED MODEL OUTPUT WAS SHOWING STRONG MOISTURE FLUX AIMED AT LOUISIANA. THIS RAPID INCREASE IN LOW LEVEL MOISTURE SHOULD LEAD PLENTY OF INSTABILITY AND CONVECTION. LI'S ACROSS EAST TEXAS ARE FORECAST TO BE IN THE MINUS 4 TO 8 RANGE LATER THIS EVENING. STRONG UPPER LEVEL Divergence IS FORECAST ACROSS LOUISIANA IN THE AREA BETWEEN THE POLAR AND SUBTROPICAL JET STREAMS. THE MODELS ARE ALSO FORECASTING STRONG LOW LEVEL CONVERGENCE OVER THE SANE REGION. FIVE INCHES OF RAINFALL PROBABLY WILL FALL DURING THE NIGHT.

THE ONE FLY IN THE OINTMENT IS IF A MAJOR MESOSCALE CONVECTIVE COMPLEX WORKS OFF THE GULF COAST AND STAYS OVER THE GULF TONIGHT. SUCH A SYSTEM MIGHT TEND TO BLOCK THE BEST MOISTURE INFLOW FROM LOUISIANA. HOWEVER... THE CURRENT TRACK OF THE BEST CONVECTION SUGGESTS THAT IT WILL TRACK ACROSS LOUISIANA SO THE POTENTIAL FOR 5 INCH OR HIGHER AMOUNTS IS FAIRLY HIGH.

LOCALLY HEAVY RAINFALL IS EXPECTED ACROSS CENTRAL AND EASTERN NEBRASKA IN THE ZONE OF STRONG OVERRUNNING IN THE VICINITY OF THE INVERTED TROUGH EXTENDING NORTH FROM THE MAIN SURFACE LOW. SATELLITE IMAGERY SHOWS THAT A PRETTY DECENT COMMA HEAD HAS FORMED. MAXIMUM RAINFALL IS EXPECTED TO BE IN THE 1 TO 1.5 INCH RANGE.

3.2.3.3 Heavy Snow Discussion (OPFHSD, FOUSll RWBC). This message discusses the potential for heavy snowfall in the contiguous United States. The threshold value in this product for heavy snow is 4 inches or more in a 12-hour period. However, this product discusses all potential snowstorms, including those not expected to attain the threshold. Although the focus is on the meteorological reasoning for the forecast, the impact of numerical model forecasts and model differences are also explained.

This narrative is a three-part product. The first part is a synopsis and short-term forecast for the few hours before the main 12-hour forecast period. The second part includes the 12-hour forecast and the accompanying meteorological reasoning. The third part is a meteorological discussion of the outlook period that extends 12 hours beyond the forecast period. There is an accompanying graphic for each forecast under the AFOS identifier 93S. The QPFHSD is issued 4 times a day from September 15 to May 15 and other times as needed as described below. A revised or amended QPFHSD may be issued as necessary. Routine issuances are as follows.

THE LAmanual MODELS ALL FORECASTING AN EXTREMELY POWERFUL STORM TO MOVE UP THE EAST COAST...WITH CENTRAL PRESSURES DROPPING TO THE 960S OR 950S. THE LAmanual AVN IS VERY CONSISTENT AT 36 HOURS WITH ITS PREVIOUS RUNS... PUTTING THE CENTER OF ITS SURFACE LOW IN VICINITY OF DELMARVA/CHESAPEAKE BAY. THE ETA IS NOT TOO DIFFERENT FROM ITS PREVIOUS RUN...MAYBE SLIGHTLY TO THE EAST. THE ODD MAN OUT IS THE NGM...WHICH IS GOING FARTHER TO THE WEST THAN IN PREVIOUS RUN...AND FARTHER IN THAT DIRECTION THAN ANY OF THE OTHER MODELS. IT MAY BE RESPONDING TO ITS FASTER PACE OF RAPID DEEPENING IN THIS RUN. HOWEVER...THIS MODEL DOES HAVE SOME HISTORY OF DEEPENING ITS STRONG LOWS TOO FAR NORTHWEST INTO THE COLD AIR.

PREFER TO GO WITH THE CONSISTENCY OF THE AVN AND WITH THE SIMILARITY OF TRACKS OF THE AVN AND OTHER MODELS. CONSIDERING THE HUGE AMOUNTS OF MOISTURE AND DYNAMICS INVOLVED...THIS WILL PRODUCE MAXIMUM SNOWS OF 12 TO 24 INCHES DURING THIS FORECAST PERIOD...WITH BEST AMOUNTS ALONG THE EAST SLOPES OF THE SOUTHERN/CENTRAL APPALACHIANS...ESPECIALLY IN SOUTHWEST VIRGINIA. FOUR INCH OR MORE AMOUNTS CAN BE EXPECTED FROM NORTHERN GEORGIA MOUNTAINS ACROSS WESTERN NORTH CAROLINA AND EASTERN SECTIONS OF TENNESSEE THROUGH MOST OF VIRGINIA AND SOUTHEAST WEST VIRGINIA INTO SECTIONS OF THE D.C. METRO AREA. BLIZZARD CONDITIONS CAN BE EXPECTED IN MANY PORTIONS OF THE SNOWFALL AREA.

ACCORDING TO TRACK DESCRIBED ABOVE...WOULD EXPECT 12 TO 24 INCH AMOUNTS TO OCCUR FROM NORTHWEST VIRGINIA AND THE EASTERN PANHANDLE OF WEST VIRGINIA NORTHEAST ACROSS WEST CENTRAL MARYLAND AND MUCH OF EASTERN PENNSYLVANIA TO THE WEST OF PHILADELPHIA. FOUR INCH OR MORE AMOUNTS CAN BE EXPECTED DURING THIS TIME FROM WESTERN NORTH CAROLINA NORTHEAST ACROSS MOST OF PENNSYLVANIA AND NEW JERSEY TO SOUTHERN NEW ENGLAND. SOME SNOW ACTIVITY WILL BE IN THE FORM OF WRAP AROUND BEHIND THE LOW. BLIZZARD CONDITIONS WILL CONTINUE TO EXIST IN MANY PORTIONS OF THE SNOWFALL AREA. NAME/BRANCH

3.3 Discussions and Coordination by NHC and CPHC. In addition to tropical weather discussions, NHC is responsible for issuing tropical storm and hurricane watches and warnings for the North Atlantic, Caribbean, Gulf of Mexico, and eastern North Pacific. CPHC has the same responsibility for the central North Pacific in addition to its discussion messages. NHC coordinates with selected field offices and MOD via the hurricane coordination hotline prior to issuing a watch or warning. Selected field offices may initiate

hotline coordination calls with the NHC when particular items were missed during the normal hotline coordination or when the situation warrants. CPHC coordinates with Pacific Region field offices by telephone before the issuance of watches and warnings. See WSOM Chapter C-41, Hurricane Warnings, for further details on NHC's and CPHC's coordination activities and discussions. See section 3.6 of this chapter on NHC's coordination with MOD on high seas forecasts.

3.3.1 Tropical Weather Discussion (TWD, AX). These messages are issued 4 times a day by NHC at around 0000 UTC, 0600 UTC, 1200 UTC, and 1800 UTC to describe significant synoptic weather features in the tropics. One message (MIATWDAT, AXNT20 KMIA) covers the Gulf of Mexico, the Caribbean, and the North Atlantic between the equator and 32E north latitude. A second message (MIATWDEP, AXPZ20 RMIA) covers the eastern North Pacific between the equator and 32E north latitude and east of 140E west longitude.

SURFACE SYNOPTIC ANALYSIS 07/1200 UTC... ...A TROUGH WAS LOCATED ALONG 30N60W 25N70W...MOVING WEST AT 10 KNOTS. ...A TROUGH WAS LOCATED ALONG 3ON55W 2lN61W...MOVING WEST AT 10 KNOTS. ...EASTERN ATLANTIC COLD FRONT EXTENDED THROUGH 32N12W TO 29N18W...MOVING EAST-SOUTHEAST AT 15 TO 20 KNOTS. ...A RIDGE EXTENDED ALONG 32N70W ACROSS SOUTH/CENTRAL FLORIDA TO 23N88W. ...HIGH PRESSURE DOMINATED THE ATLANTIC NORTH OF 2ON BETWEEN 20W-50W. ...A WEAK 1011 MB LOW WAS CENTERED NEAR lN45W. ...TROPICAL WAVES WERE LOCATED SOUTH OF 20N ALONG 41W...56W/57W... 67W/68W...79W/80W AND 93W...MOVING WEST AT 10 TO 15 KNOTS.

GULF OF MEXICO...MESOSCALE FEATURES... BROKEN/OVERCAST MULTILAYERED CLOUDS WITH PATCHES OF RAIN/FOG AND WIDELY SCATTERED SHOWERS WERE OBSERVED NORTH OF A LINE FROM NORTHEAST MEXICO NEAR 2SN98W TO TALLAHASSEE FLORIDA. SCATTERED LOW CLOUDS PREVAILED ELSEWHERE.

CARIBBEAN SEA... SCATTERED MODERATE/STRONG THUNDERSTORMS WERE OCCURRING ALONG THE COAST OF CENTRAL PANAMA BETWEEN 78W-81W. MAXIMUM TOPS TO 50000 FEET WERE INDICATED NEAR 10N79W. WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WERE OBSERVED FROM 13N-14N BETWEEN 76W-79W. ISOLATED SHOWERS DOTTED THE REMAINDER OF THE CARIBBEAN.

SUBTROPICAL ATLANTIC... OVERCAST MULTILAYERED CLOUDS WITH NUMEROUS SHOWERS AND A FEW MODERATE THUNDERSTORMS WERE OBSERVED NORTH OF 3lN WEST OF 76W...AND WERE SPREADING EAST AT 15 KNOTS. WIDELY SCATTERED MODERATE/STRONG THUNDERSTORMS WERE NOTED WITHIN 1 DEGREE EITHER SIDE OF A LINE ALONG 32NSlW 24N56W... ASSOCIATED WITH A TROUGH. WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WERE NOTED WITHIN 1 DEGREE OF 27N66W. SIMILAR CONVECTION WAS INDICATED ALONG THE AFRICAN COAST FROM 21N TO THE CANARY ISLANDS.

TROPICAL ATLANTIC... THE AXIS OF THE ITCZ-RELATED CLOUDS/CONVECTION WAS CENTERED ALONG 7N12W SN34W 12N47W 9N61W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION WAS LOCATED 2-3 DEGREES EITHER SIDE OF THE AXIS BETWEEN 18W-34W AND WITHIN 1-2 DEGREES OF THE AXIS BETWEEN 44W-51W. WIDELY SCATTERED MODERATE AND ISOLATED STRONG CONVECTION WAS NOTED WITHIN 2 DEGREES OF THE AXIS OF 51W. ISOLATED MODERATE CONVECTION EXISTED ELSEWHERE SOUTH OF 11N EAST OF 48W.

One NHC message (MIATCDAT [1-5], WTNT[41-45]) is for tropical cyclones in the Gulf of Mexico, the Caribbean, and the North Atlantic between the equator and 32E north latitude. A second NHC message (MIATCDEP[1-5], ATPZ[41-45] KMIA) is prepared for tropical cyclones in the eastern North Pacific between the equator and 32E north latitude and east of 140E west longitude.

a. Format and Content. These discussions normally include prognostic reasoning; objective techniques employed; NHC/CPHC and NMC guidance used; coordinated 12-, 24-, 36-, 48-, and 72-hour tropical cyclone forecast points (unless the tropical cyclone is forecast to dissipate, move inland, or become extratropical, in which case points will be given only to that moment in time); maximum wind speed forecasts for each forecast point; other meteorological decisions; and plans for watches and warnings. The Saffir/Simpson Hurricane Scale may be given when a storm is within 72 hours of the United States coast.

b. Issuance Times. Tropical cyclone discussions shall be issued in conjunction with all scheduled public/marine advisories. Also, unscheduled TCDs should be issued when special public/marine advisories are issued. NHC's scheduled TCDs should be issued at 0300 UTC, 0900 UTC, 1500 UTC, and 2100 UTC. CPHC's scheduled TCDs should be issued no later than 0330 UTC and 1530 UTC.

SATELLITE ANALYSTS AT BOTH SAB AND NHC HAVE BEEN CLASSIFYING THE TROPICAL WAVE OVER THE MID ATLANTIC FOR THE PAST COUPLE OF DAYS. THE DVORAK CI NUMBER HAS BEEN 2.0 FOR THE PAST 12 HOURS. METEOSAT IMAGES CONTINUE TO SHOW A BANDING TYPE PATTERN AND DEEP CONVECTION HAS INCREASED CLOSE TO THE CLOUD SYSTEM CENTER...ENOUGH TO WARRANT ISSUING DEPRESSION ADVISORIES.

THE AVN MODEL INDICATES THAT THE SYSTEM SHOULD REMAIN EMBEDDED WITHIN THE DEEP EASTERLIES...AND ALL TRACK MODELS ARE IN GENERAL AGREEMENT. INITIAL NOTION IS 280/18 AND THIS SAME GENERAL MOTION SHOULD CONTINUE THROUGHOUT THIS FORECAST PERIOD.

3.4 Discussions and Coordination by NSSFC. NSSFC's Severe Local Storms Unit (SELS) has the responsibility for issuing severe thunderstorm and tornado watches for the contiguous United States. Coordination of the watch release occurs among NSSFC and affected field offices prior to watch release. NSSFC also coordinates on tornado watches with NHC if they are related to hurricanes or tropical storms. Status reports are issued by NSSFC to provide guidance on significant events occurring within ongoing watches and any planned changes. NSSFC's discussions should be used as a tool for field forecasters to have "coordinated" forecasts across office county warning areas. See WSOM Chapter C-40, Severe Local Storm Watches, Warnings, and Statements, for further details on coordination among NSSFC, field offices, and other National Centers.

3.4.1 Convective Outlook (SWODYl[DY2], ACUS1[2] KMXC). This outlook discussion delineates areas forecast to have thunderstorm activity. The text gives the meteorological reasoning that supports the forecast and, to the extent possible, provides information concerning the timing of the most active severe weather during the forecast period.

The "Day 1" Outlook (SWODY1, ACUS1 KMKC) delineates areas of slight, moderate, or high risk of severe thunderstorms; areas where thunderstorms may approach severe limits; and areas where general thunderstorms are forecast. It is issued daily at 0700 UTC and is valid for a 24-hour period from 1200 UTC to 1200 UTC the next day. This product is updated at 1500 UTC and covers the period 1500 UTC to 1200 UTC the next day. At 1930 UTC, a second update is issued for the period 2000 UTC to 1200 UTC the next day. Amendments areissued as required.

The "Day 2" Outlook (SWODY2, ACUS2 KMKC) only delineates areas of severe thunderstorms (without risk category) and areas where thunderstorms may approach severe limits. It is issued daily at 0800 UTC and covers the 24-hour period beginning at 1200 UTC the following day. This product is updated at 1800 UTC.

The convective outlook serves as guidance to NWS field offices for use in the preparation of local forecast products; to advise the public, media, and other interests of the possibility of severe weather; and to assist with preliminary planning for additional staffing should severe weather be anticipated.

WE HAVE DECIDED TO TRIM DOWN SLIGHT RISK OUTLOOK IN PLAINS. THE BEST RISk AREA WOULD APPEAR TO BE AHEAD OF A COLD FRONT CURRENTLY PUSHING SOUTHEAST ACROSS MINNESOTA. WATER VAPOR LOOP AND NEW ERL SUPPORT CONTINUED DIGGING OF A SHORT WAVE TROUGH AS IT APPROACHES UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES. DO NOT THINK AIRMASS HAS HAD SUFFICIENT TIME TO RECOVER ADEQUATE LOW LEVEL MOISTURE TO SUPPORT OTHER THAN VERY ISOLATED STRONG/SEVERE THUNDERSTORMS. THUS...HAVE REDUCED AREA OUTLOOKED. SECONDARY BAND OF 30 KNOT MID-LEVEL WINDS ACROSS COLORADO INTO CENTRAL HIGH PLAINS IS STRONGER THAN PROGGED. DECENT DIRECTIONAL SHEAR ALONG WESTERN EDGE OF CLOUDINESS CURRENTLY OVER SOUTHERN PLAINS AGAIN MAY BE SUFFICIENT TO SUPPORT ISOLATED SEVERE THUNDERSTORMS IN MARGINAL TO MODERATELY UNSTABLE AIRMASS.

HAVE ADDED SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE SOUTHEAST UNITED STATES. WE ARE CONCERNED ABOUT LINGERING LOW LEVEL MOISTURE OVER NORTHEAST ALABAMA AND GEORGIA. WATER VAPOR IMAGERY AND 700 MB ANALYSIS INDICATE PRONOUNCED MID LEVEL DRYING WHILE VISUAL IMAGERY SUGGESTS SOME BREAKS IN LOWER CLOUDS MAY DEVELOP...THUS ALLOWING Pockets OF SURFACE HEATING. SURFACED BASED LI'S ALREADY ABOUT MINUS 5 AND WITH SURFACE TEMPERATURES INTO THE LOWER 80S...LI'S COULD REACH MINUS 8 RANGE. ALSO THINK SHORT WAVE TROUGH DIGGING INTO UPPER MISSISSIPPI VALLEY MAY TEND TO NUDGE QUASI-STATIONARY UPPER TROUGH OVER SOUTHEASTERN UNITED STATES NORTHEASTWARD...PROVIDING ADDITIONAL UPWARD VERTICAL VELOCITIES.

MID/UPPER LEVEL TROUGH EXPECTED TO CONTINUE SOUTHEAST INTO THE GREAT LARES REGION AS MID-LEVEL RIDGING CONTINUES TO DOMINATE THE INTERMOUNTAIN REGION. COLD FRONTAL BOUNDARY WILL MOVE SOUTHEAST ACROSS THE GREAT LAKES REGION...AND SLOWLY SOUTH ACROSS THE CENTRAL PLAINS AND MIDMISSISSIPPI VALLEY. THE UPPER LEVEL JET OF 70/80 KNOTS IS FORECAST TO BE ON BACKSIDE OF UPPER LEVEL TROUGH MOVING SOUTH ACROSS WISCONSIN. THIS WILL BRING COLDER MID-LEVEL TEMPERATURES OVER THE CENTRAL/EASTERN GREAT LAKES...DESTABILIZING THE AIRMASS DURING THE PERIOD OF MAXIMUM HEATING. STRONG THUNDERSTORMS COULD DEVELOP DURING THE AFTERNOON AND EARLY EVENING HOURS ACROSS PORTIONS OF LOWER MICHIGAN...NORTHERN INDIANA...AND NORTHERN OHIO AS UPPER LEVEL DIFFLUENCE AND THE MID-LEVEL DRY INTRUSION ENHANCES UPWARD VERTICAL VELOCITIES. BUT...RELATIVELY WEAR FLOW AND ONLY MARGINAL INSTABILITY SHOULD INHIBIT SEVERE THUNDERSTORM DEVELOPMENT.

QUASI-STATIONARY FRONTAL BOUNDARY WILL STILL BE HANGING AROUND THE EASTERN COASTAL SECTIONS AND AIRMASS IS EXPECTED TO BE UNSTABLE WITH LI'S AROUND -4. LACK OF SUFFICIENT LOW LEVEL FLOW WILL INHIBIT SEVERE THUNDERSTORM DEVELOPMENT.

3.4.2 Status Reports (WWAMRC, WWUS8 RNRC). NSSFC should issue a watch status report at least 1 hour prior to watch expiration. The status report should describe current thoughts on the severe weather situation and whether the watch will expire or be reissued. A status report may not be issued if a cancellation or replacement watch has been issued at least 1 hour prior to the expiration time of the original watch. The status report may also include information on where the severe weather threat has ended within the watch.

THERE IS LITTLE CHANGE IN RADAR AND SATELLITE IMAGERY IN THE PAST HOUR THROUGH THE WATCH AREA...AND WITH SOME DECREASE EXPECTED THROUGH 1930 UTC...PRESENT INDICATIONS ARE THAT WEATHER WATCH 183 WILL NOT BE EXTENDED. WW NUMBER 182 IS NO LONGER IN EFFECT WEST OF A LINE FROM OMA TO ICT.

3.4.3 Mesoscale Discussion (SWOMCD, ACUS3 KMRC). A mesoscale discussion is issued as a routine/daily but non-scheduled, short-term (0-6 hours) product to communicate the current thoughts of SELS to the user community. It also providing guidance on other short-term mesoscale phenomena that may be of significance (e.g., heavy rain or snow potential, formation, or dissipation of dense fog, etc.).

A LINE OF THUNDERSTORMS HAS BEEN STEADILY INTENSIFYING SINCE 0800 UTC ALONG/JUST AHEAD OF A SURFACE COLD FRONT FROM EAST CENTRAL NORTH DAKOTA INTO NORTH CENTRAL MINNESOTA. STRONGEST THUNDERSTORMS ARE SOUTH OF GFR AND SOUTHEAST OF TVF. THE AIRMASS IN VICINITY AND AHEAD OF THE THUNDERSTORM LINE IS ONLY MARGINALLY UNSTABLE WITH SURFACE LI'S AROUND ZERO. HOWEVER...A FAVORABLE MOISTURE CONVERGENCE PATTERN AND INCREASING UPWARD VERTICAL VELOCITY FROM THE SHORT WAVE TROUGH CROSSING MANITOBA AT THIS MOMENT ARE PROVIDING FAVORABLE DYNAMIC SUPPORT FOR THUNDERSTORM ACTIVITY. PRESSURE FALLS AHEAD OF THE FRONT ACROSS MINNESOTA/SOUTHEAST NORTH DAKOTA SUGGEST LOW LEVEL SUPPORT WILL CONTINUE FAVORABLE FOR THUNDERSTORMS TO CONTINUE PROPAGATING EAST AND EAST SOUTHEAST THROUGH SOUTHEAST NORTH DAKOTA/NORTH CENTRAL AND WEST CENTRAL MINNESOTA OVER THE NEXT 2 TO 4 HOURS. EXPECT THUNDERSTORMS TO REMAIN BELOW SEVERE LEVELS DUE TO LACK OF INSTABILITY AND RATHER WEAR LOW LEVEL INFLOW.

3.5 Discussions and Coordination by Field Offices. Coordination between adjacent WSFO/NWSFOs is especially important in difficult forecast situations involving significant weather (including situations where watch/warning/advisory decisions are made), large deviations from computer guidance, and/or major changes from previous forecasts. Coordination in these situations is also important between WSFO/NWSFOs and their WSO/NWSOs. The sending of draft work files of statements, forecasts, and discussions among field offices for review via AFOS can facilitate coordination as well as save telephone time. WSFO/NWSFOs should also coordinate with the National Centers to exchange information useful for difficult forecast situations. particularly when there is disagreement with discussion products issued by NSSFC and MOD.

a. Purpose. WSFO/NWSFOs prepare the SFD. It is primarily used as a means to explain the technical and scientific basis for forecast decisions and accounts for coordination among adjacent field offices (including WSO/NWSOs) and National Centers. By serving as a briefing tool, the information in these messages also can facilitate coordination for succeeding forecasts. In addition, the SFD is a good forum to provide technical information (e.g., satellite, radar, Profiler, etc.) to WSO/NWSOs, other Federal agencies, and outside users. Coordination calls prior to the release of the SFDs should be made for the difficult forecast situations mentioned above.

c. Content of scheduled SFDs. The scheduled SFD consists of two sections: (1) a narrative description of forecast reasoning and (2) a summary of public and marine watch/warning/advisory issuances. Since forecaster adjustments to model guidance are usually more common in the near periods, the discussions normally should emphasize the first 24 hours of the forecast, unless watches and warnings are issued beyond this time frame.

(1) Narrative Discussion. The narrative discussion should contain a concise explanation of forecast reasoning. Use of data sources, such as the WSR-88D, ASOS, Profiler, satellite, local and national models, and local and national analysis are encouraged. The discussion should emphasize the following significant aspects concerning the forecast:

A MAJOR WINTER STORM IS MOVING INTO NORTHERN CALIFORNIA AND CURRENT WARNINGS LOOK GOOD. COLD FRONT AT 1900 UTC EXTENDS FROM NEAR SFO TO RDD. THERE ARE SEVERAL BANDS OF PRECIPITATION MERGING AND IT WILL BE HARD TO TELL WHERE ONE ENDS AND THE NEXT BEGINS. WITH 980 MB SURFACE LOW LINGERING OFF THE OREGON COAST...ANY WIND SHIFTS WILL BE BRIEF AND WINDS WILL SWITCH BACK TO THE SOUTHEAST. PRECIPITATION SHOULD SPREAD OVER ENTIRE AREA WITH SHOWERS CONTINUING INTO AT LEAST WEDNESDAY. AVN AND NGM MODELS ARE REASONABLY IN SYNC...AS CONFIRMED BY SATELLITE IMAGERY... THOUGH RH FIELDS ARE INITIALIZED TOO DRY. COULD SEE A FEW THUNDERSTORMS WITH COLD AND UNSTABLE AIR MASS. SNOW LEVELS HAVE RISEN SLIGHTLY IN THE LAST FEW HOURS...BUT WILL PLUMMET AS POST-FRONTAL COLD AIR SPREADS OVER AREA.

PRECIPITATION IS STARTING TO CHANGE TO SNOW OVER PART OF SOUTHWEST KANSAS IN MORE INTENSE AREAS OF PRECIPITATION. CHANGEOVER WILL LIKELY Continue AS COLD UPPER SYSTEM APPROACHES THIS AFTERNOON. UPPER AIR ANALYSIS SHOWS STRONG Divergence OVER MOST OF THE REGION. THE AXIS OF HIGHEST DIVERGENCE EXTENDS FROM TOP TO DDC. Q-VECTOR CONVERGENCE IS CONCENTRATED FROM SOUTHEAST COLORADO TO SOUTHWEST OF DDC AND INTO OKLAHOMA WHERE WARM ADVECTION IS GREAmanual. EXPECT PRECIPITATION TO SPREAD NORTH AND EAST THIS AFTERNOON THROUGH KANSAS. WILL DROP MENTION OF THUNDERSTORMS OVER NORTH AS SOUNDINGS INDICATE TOO MUCH STABILITY. TEMPERATURES LOOK GOOD FOR THE MOST PART. WILL CONTINUE FOG ADVISORY IN THE NORTHWEST THIS AFTERNOON.

d. Content of unscheduled SFDs. When unscheduled forecast changes prompt issuance of an unscheduled SFD, the forecasted should follow guidelines for content of scheduled SFDs, including any updated information for the watch/warning/advisory section.

Offices may also issue unscheduled SFDs that focus on short-term mesoscale meteorological trends, typically for 6 hours or less. This type of unscheduled SFD may supply information on modes of operation of equipment (such as the WSR-88D, ASOS, Profiler, satellite, etc.), technical aspects of mesoscale events, and for coordinating with the electronic media and emergency managers during active weather. Such updates may omit unchanged watch/ warning/advisory information except during the period following the scheduled SFD until 1 hour after the transmission of the scheduled public zone forecast. In these cases, the watch/warning/advisory section should be present to ensure receipt by NSSFC, A.M. Weather, and other users.

THE DOPPLER WEATHER RAD M IN STERLING IS INDICATING WIDESPREAD THUNDERSTORMS SOUTHEAST AND NORTHWEST OF THE WASHINGTON DC METROPOLITAN AREA. THE WARNINGS WHICH HAVE BEEN ISSUED HAVE BEEN BASED PRIMARILY ON THE VERTICAL INTEGRATED LIQUID (VIL). VIL VALUES IN THE 30 TO 40 KILOGRAM (RG) PER METER SQUARED RANGE HAVE PRODUCED HAIL OF 1/4 TO 1/2 INCH IN DIAMETER. WARNINGS HAVE BEEN ISSUED WHEN THE VIL EQUALS OR EXCEEDS A VALUE OF 45 RG PER METER SQUARED. THE STORM TRACKING PRODUCTS ARE EXCELLENT AND ARE BEING USED FOR STORM MOVEMENT.

THE VAD WIND PROFILES INDICATE STRONG SPEED SHEAR WHICH SHOWS UP IN THE REFLECTIVITY PRODUCTS AS LIGHT PRECIPITATION EXTENDING OUT AHEAD OF STORM. THE ABSENCE OF DIRECTIONAL SHEAR WOULD INDICATE THAT THE POTENTIAL FOR STORM ROTATION IS LOW.

CELL NEAR MORENCI LOOKS LIKE IT HAS JUST BROKEN OFF THE MAIN LINE OF THUNDERSTORMS. IF THIS STORM MOVES TO THE RIGHT OF THE MEAN STORM MOTION...IT COULD BECOME TORNADIC. LAmanual ADAP AT 2200 UTC SHOWS MOISTURE POOLING ACROSS NORTHWEST OHIO AND NORTHEAST INDIANA. WITH SOUTHEAST WINDS...INCREASED MOISTURE WILL LIKELY FEED UP INTO LENAWEE COUNTY FUELING THIS STORM THERE.

3.5.2 Area Forecast Discussion (AFD, FPUS3). An NWSO preparing public and/or marine forecasts (beyond adaptation of the first 12-hour forecast period) should issue an AFD to the parent WSFO/NWSFO. Other NWSOs or WSOs with a WSR-88D in operation may also issue an AFD. Upon recommendation of the WSO/NWSO and the parent WSFO/NWSFO, regional headquarters in coordination with OM's Operations Division may authorize external dissemination of the AFD.

The AFD serves a similar function as the SFD except that a separate watch/warning/advisory section is not included. Otherwise, guidelines for the content of scheduled and unscheduled AFDs are the same as those for SFDs in section 3.5.1.

If WSOs/NWSOs routinely prepare AFDs before scheduled forecast releases, they should be issued early enough to that the parent WSFO/NWSFO can determine accuracy of forecast reasoning and, if necessary, contact the WSO/NWSO to further coordinate any forecast decisions.

Note: For certain offices with responsibilities for both public (and/or marine) forecasts and related long-fuse warnings, the AFD is an operationally required product that serves in place of the SFD. Those offices should follow all instructions in section 3.5.1 when issuing AFDs for their area of responsibility, including watch/warning/advisory information.

THE LOW WHICH FORMED ON THE WARM FRONT OFF CRP HAS PUSHED THE FRONT TO THE UPPER TEXAS COAST. THIS HAS CAUSED THE TEMPERATURES TO BE IN THE UPPER 60S OVER MANY SECTIONS WITH 69F AT HGX BY 1500 UTC. THEREFORE I WILL RAISE THE INLAND HIGHS TO THE MID 70S. THE WSR-88D WIND PROFILE AT 1330 UTC INDICATED A 35 TO 40 KNOT WIND MAXIMUM FROM 160 DEGREES AT 2000 FEET. WIND INFORMATION WAS LACKING ABOVE 2000 FEET DUE TO LACK OF SCATTERERS. A LINE OF SHOWERS IS OCCURRING ALONG A MOISTURE CONVERGENCE GRADIENT FROM 50 MILES SOUTHEAST OF PSX TO JUST SOUTH OF CLL. SO I WILL RAISE THE POP TO 30 PERCENT FOR INLAND ZONES. THE ONLY OTHER CHANGE IS TO MENTION THE FOG ALONG THE COAST IMPROVING SOMEWHAT BY EARLY AFTERNOON.

3.6 High Seas Forecast Coordination. MOD and NHC coordinate to issue high seas forecasts for the Atlantic Ocean (HSFAT1, FZNT01 RWBC) and eastern Pacific Ocean (HSFEP1, FZPN01 RWBC). WSFO Honolulu and MOD coordinate to issue high seas forecasts for the central Pacific Ocean (HNLHSFNP, FZPN10 PHNL). In turn, these forecasts are intended to coordinate offshore forecasts among the Centers and coastal offices; Certain forecast situations in the

3.7 Great Lakes Marine Forecast Coordination. WSOM Chapter D-52, Marine Services for the Great Lakes, has information on products issued by WSFO Cleveland facilitating forecast coordination, such as the Great Lakes Marine Synopsis (GLSCLE, FZUS71 RCLE), Storm Outlooks (GLOCLE, FZUS70 RCLE), and Storm Summaries (GLFGLS, FZUS66 RCLE).

When other forecast offices expect to issue storm warnings, they should notify WSFO Cleveland 90 staffing can be arranged to issue the GLFGLS. When storm conditions are possible beyond the time frame of routine open lake forecasts, WSFO Cleveland should contact the forecast office responsible for those lakes to coordinate the issuance of the GLOCLE. WSOM Chapter D-52 has further details of the role of WSFO Cleveland in coordinating Great Lakes forecasts and warnings.

3.8 Satellite Interpretation Discussions. NHC, NSSFC, CPHC, and WSFO Honolulu all issue products that include information interpreting satellite information and may prove useful in forecast coordination among offices. See WSOM Chapter B-55, Distribution and Use of GOES Pictures, for further details on all satellite messages.