Hydrometeorological Prediction Center (HPC) Forecast Operations Branch Michael Eckert Senior Branch Forecaster

Who/What is HPC? NOT headquarters Part of NCEP & co-located with EMC, CPC, NCO, OPC, and NESDIS Access to tremendous amounts of model data (too much?) Work on a national scale Resource to field forecasts, partners & customers Forecast Operations Branch 30 Meteorologists, 2 Met Techs Development & Training Branch 6 Meteorologists/programmers (includes the SOO)

Partners & Customers NWS Field offices – WFOs, RFCs & CWSUs Other NCEP centers – OPC, TPC, AWC, SPC, EMC, NCO & CPC Federal Agencies - DHS/FEMA, COE, FAA, NTSB, DoD, EPA, White House State Agencies – EMA, water resources, flood management & DOT Media – TV, Radio, Internet, newspapers, wire services (AP/UPI) Private Sector – data vendors, forecast services, utilities, forensics, retailers, researchers Aviation – General aviation, AWC Academia – Universities & colleges International – MET services, media, travelers General Public – Analysis/forecast products

NWS OPERATIONAL FORECAST OFFICES (CWSUs not depicted) WFOs RFCs

Collaboration (increasingly more important past 2-3 years) Several combination of players WFO – WFO WFO – RFC RFC – HPC WFO – HPC HPC – TPC WFO – SPC HPC - SPC hpc_LEAD hpc_QPF1 hpc_QPF2 hpc_MEDR hpc_bawx hpc_SFC hpc_wwd hpc_MDLDIAG HPC IDs

Products HPC Issues QPF 6 hourly through D3 48 hr QPF D4-5 QPFPFD Flood Products Excessive Rainfall (94e) QPFERD River Flood Outlook Winter Weather (9/15 - 5/15) Snow/ZR Probability Snow/ZR accumulation thru D3 QPFHSD Winter Storm Summaries Low Track 3 hourly Surface Analyses Short Range (D 1-2) Fronts/Pressures Instantaneous Pcpn & Pcpn Type Medium Range (D3-7) 24 hr Front/Pressures Max/Min/12 hr PoPs PREEPD and PMDEPD Hawaii Narrative Model Diagnostics 500mb prog for West/E Pac PMDHMD PMDEPD NDFD Chat Coordination Tropical Weather (6/1 – 11/30) Backup/guidance for TPC Public Advisories for inland tropical systems South Amer. & Caribbean text products Selected Cities/Travelers Daily Weather Map Air Quality Narrative (summer)

HPC MEDIUM RANGE PRODUCTS Model Diagnostics Desk Prelim Day 3-7 Frontal Progs0900 Z Prelim PREEPD0900 Z Medium Range Pressure/Fronts Prelim Day mb Progs1130 Z Updated Day 3-7 Frontal Progs1315 Z Updated PREEPD1400 Z Targeted Observations (seasonal)1430 Z Tropical Hotline Call (seasonal) Noon ET Final Day 3-7 Fronts/500mb Progs 1900 Z PMDEPD (Final) 1930 Z Medium Range Temps/PoPs/QPF Hawaiian 1-7 Day Discussion 1130 Z Morning Day 4/5 and 1-5 QPF1200 Z Prelim Day 3-7 Min/Max/PoPs 1400 Z Prelim Medium Range Grids 500 Z Final Day 3-7 Min/Max/PoPs 1900 Z Final Medium Range Grids 2000 Z Afternoon Day 4/5 and 1-5 QPF2300 Z Two Forecaster Team Hours Z Operates 24/7

PRIMARY MEDIUM RANGE MODELS USED BY HPC MODEL RUN TIME RUN DURATION MIN HORIZONTAL MEMBERS (UTC) (DAYS) GRID SPACING (KM) PER DAY DGEX 6, ECMWF 0, ECM ENS GFS 0,6,12, CANADA 0,12 10/ NOGAPS 0, UKMET 0, NGPS ENS CAN ENS GFS ENS 0,6,12, / DAY!

EMC MODEL SCORES CAN VARY SIGNIFICANTLY ON A DAILY BASIS. IT’S OFTEN DIFFICULT TO IDENTIFY IN ADVANCE MODELS THAT ARE HAVING A BAD DAY Bad Day Model verification

Skill improvements Day 7 = Day 3 from 1976 & Day 5 from 1996 Day 5 = day 3 from 1996

EMC WINTER SUMMER 2005 NCEP AND ECMWF ENSEMBLE MEANS (SOLID LINES) MAINTAIN SKILL LONGER THAN THE GLOBAL MODELS IN THE WARM SEASON THE ECMWF AND ECMWF ENSEMBLE MEAN SCORE VERY WELL IN THE COLD SEASON THRU THE MEDIUM RANGE NORTHERN HEMISPHERE 500 MB A.C. SCORES

HPC HAS LIMITED INTERNET ACCESS TO ECMWF ENSEMBLES THRU DAY 9 HPC MASTERBLENDER (PMSL/500 MB/QPF ETC.)

Days 3-7 Surface Progs

Day mb progs

Day 1-5 QPF Issued twice daily 00z & 12z Day 4-5 QPF Issued twice daily 00z & 12z

HPC 5 KM GRIDDED MEDIUM RANGE FORECASTS MIN TEMPS MAX TEMPS WINDS 12 HOUR POPS DEWPOINTS CLOUD COVER WEATHER TYPE This is what is fed to the NDFD

DAY 5 MAX TEMP BIG HPC CHANGES TO GFS MOS 2004 BIGGER HPC IMPROVEMENT OVER GFS MOS BECOMES EVIDENT AT A MORE REGIONAL LEVEL

HPC SHORT RANGE PRODUCTS Surface progs Lows & Highs Fronts Isobars Precipitation coverage/intensity Valid Times 12, 18, 24, 30, 36 & 48 Hours (from model initialization time) Low Tracks (thru 72 hours) One Forecaster 0000 – 0900z 1200 – 2100z Two shifts per day Used heavily by: AWC Private Weather companies TV stations

12 Hour Surface Prog

Low Tracks Forecast (winter only)

Low track verification ( GFS-NAM mix is best )

Surface Analysis Every 3 hours Collaboration with OPC & TPC HPC Coverage is North America National Forecast Chart Quick look at US Weather Once per day (10Z) Storm summaries Inland Tropical Systems Well organized Winter storms Up to 4 times each day 02z, 08z, 14z & 22z

Surface Analysis

National Forecast Chart

STORM SUMMARY NUMBER 3 FOR SOUTHEASTERN U.S. WINTER STORM NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 1000 PM EST THU FEB PRECIPITATION ENDING ACROSS THE SOUTHEAST... ALL WINTER STORM WARNINGS HAVE NOW EXPIRED. WINTER WEATHER ADVISORIES ARE CURRENTLY IN EFFECT FOR EASTERN MARYLAND...DELAWARE...SOUTHEASTERN PENNSYLVANIA...AND MUCH OF NEW JERSEY. SNOW ADVISORIES ARE CURRENTLY IN EFFECT FOR EASTERN KENTUCKY. FREEZING RAIN ADVISORIES ARE CURRENTLY IN EFFECT FOR PORTIONS OF SOUTHWESTERN VIRGINIA AND NORTHWESTERN NORTH CAROLINA. ONE FLOOD WARNING REMAINS IN EFFECT FOR MARTIN COUNTY IN NORTH CAROLINA. AT 10 PM EST...A WEAK STORM SYSTEM MOVING ACROSS THE SOUTHEASTERN U.S. WAS PRODUCING AN AREA OF PRECIPITATION ACROSS SOUTHEASTERN VIRGINIA...THE CAROLINAS...GEORGIA...AND INTO FLORIDA. THIS AREA OF PRECIPITATION WAS DECREASING IN INTENSITY AND MOVING RAPIDLY NORTHEASTWARD. NEARLY ALL OBSERVATIONS WERE REPORTING JUST LIGHT RAIN...WITH ONLY A FEW REPORTS OF LIGHT SNOW OR SLEET....SELECTED STORM SNOW TOTALS IN INCHES AS OF 9 PM EST THURSDAY... Storm Summary

Model Diagnostics Discussion Two discussions each day (no graphics) 0530z & 1730z Resolve differences between models and ensemble solutions Model initialization… Model trends... Model differences and preferences… Summer Air quality discussion (conference call as needed) CARCAH (Chief, Aerial Reconnaissance Coordination, All Hurricanes) USAF Reserve Flying squadron Winter storm reconnaissance for Gulf/East Coast winter storms Midnight shift also produces preliminary medium range forecasts Fronts & Pressures Preliminary EPD

Winter Weather Snow and ice accumulations Days 1, 2 & 3 Probabilistic Accumulations Low, Moderate & High Risk 4”, 8”, 12” snow and 0.25” ice Impact Graphics Based solely on SREF members Eta, WRF & RSM Surface Visibility Snow rate Duration

Probabilistic Snow Forecast

Impact Graphics Snowfall Rate >1” per hour

Internal Snow Collaboration amounts

Internal Ice Collaboration amounts

Tropical Weather Backup to TPC Second opinion for TPC Track forecast for west of 60W E of 60W handled by OPC HPC forecast based on non-tropical models 03, 09, 15 & 21z Rainfall statement for public advisories Public advisories After system is below TS status While heavy rain threat exists US & Mexico

International Forecast Desk Training visitors in the use of NWP Central, South American & Caribbean Assist HPC forecaster with QPF related to tropical cyclones

Miscellaneous Duties Selected cities (twice each day) Travelers (twice each day) Daily Weather map Significant River Flood Outlook

QPF Six hour QPF through Day 3 Day 1 & 2 – 06, 10, 18 & 22z Day 3 – 10 & 22z 24 hour QPF through Day 3 Day 1 & 2 – 06, 10, 18 & 22z Day 3 – 10 & 22z CONUS, Columbia & Rio Grande Rivers Fuel for RFC hydrologic models Fuel for NDFD (future) Work closely with SAB Satellite Briefings

QPF

QPF (verification)

Excessive Rainfall

Little or no threat Rainfall not expected to exceed FFG No excessive rainfall is expected during the forecast time period SEE TEXT < 5% chance of rainfall exceeding FFG Slight Risk of rainfall exceeding FFG 5% - 10% chance of rainfall exceeding FFG Delineated by a green arrow/line encompassing an area Slight Risk

Moderate & High Risk Moderate Risk of rainfall exceeding FFG 10% - 15% chance of rainfall exceeding FFG Delineated by a blue arrow/line encompassing an area High Risk of rainfall exceeding FFG > 15% chance of rainfall exceeding FFG Delineated by a red arrow/line encompassing an area Moderate Risk High Risk

Total Rainfall > 5 inches Threat of 5 or more inches of rain during the forecast period Used mostly for: Well organized MCS Tropical systems Persistent overrunning events 5 Inch

? What is the Flash Flood Guidance? Defined as a specific rainfall amount, in a specific time period, that will result in flash flooding One, three, six and twelve hour FFG values are provided daily by RFCs At HPC we focus on the one and three hour FFG 6 & 12 hour FFG values represent time periods too long to accurately define a flash flood

1 or 3 hour FFG? Very difficult question to answer Different answer for each event & day One hour FFG generally used for convective rainfall Three hour FFG generally used for convective/stratiform rainfall

FFG Can be misleading at times Based on county average 5km values are run experimentally once per day RFCs don’t have an agreed upon method for computing FFG FFG in steep terrain & urban areas is not very useful FFG is constantly changing, especially during periods of heavy rainfall High FFG does not necessarily mean a low excessive rainfall threat

Issue/Valid Times 00 UTC00 UTC to 00 UTC (24 hours) (Optional) 03 UTC03 UTC to 00 UTC (21 hours) 06 UTC06 UTC to 12 UTC (30 hours) 12 UTC12 UTC to 12 UTC (24 hours) (Optional) 15 UTC15 UTC to 12 UTC (21 hours) 18 UTC18 UTC to 00 UTC (30 hours) 21 UTC21 UTC to 00 UTC (27 hours) (Optional)

Questions ???