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 Progs 0900 Z• Prelim PREEPD 0900 Z

• Medium Range Pressure/Fronts• Prelim Day 3-7 500 mb Progs 1130 Z• Updated Day 3-7 Frontal Progs 1315 Z• Updated PREEPD 1400 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 QPF 1200 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 QPF 2300 Z

Two Forecaster Team

Hours 1030-1930 Z

Operates 24/7

PRIMARY MEDIUM RANGE MODELS USED BY HPCMODEL RUN TIME RUN DURATION MIN HORIZONTAL MEMBERS (UTC) (DAYS) GRID SPACING (KM) PER DAY

DGEX 6,18 8 12 2

ECMWF 0,12 10 15 2

ECM ENS 12 10 30 51

GFS 0,6,12,18 16 35 4

CANADA 0,12 10/6 35 2

NOGAPS 0,12 6 55 2

UKMET 0,12 6 60 2

NGPS ENS 0 10 85 10

CAN ENS 0 10 90 17

GFS ENS 0,6,12,18 16 105 60

152 / 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 improvementsDay 7 = Day 3 from 1976 & Day 5 from 1996 Day 5 = day 3 from 1996

EMC

WINTER 2004-2005SUMMER

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 3-7 500mb 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

DAY 5 MAX TEMP

0

5

10

15

20

25

30

35

40

3 4 5 6 7

MINMAXPOPOVERALL 0

5

10

15

20

25

30

35

40

45

WEST CENTRAL SOUTH EAST

MINMAXPOP

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 – 0900z1200 – 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 STORMNWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD1000 PM EST THU FEB 1 2007

...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)

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 FFGDelineated 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 UTC 00 UTC to 00 UTC (24 hours) (Optional)

• 03 UTC 03 UTC to 00 UTC (21 hours)

• 06 UTC 06 UTC to 12 UTC (30 hours)

• 12 UTC 12 UTC to 12 UTC (24 hours) (Optional)

• 15 UTC 15 UTC to 12 UTC (21 hours)

• 18 UTC 18 UTC to 00 UTC (30 hours)

• 21 UTC 21 UTC to 00 UTC (27 hours) (Optional)

Questions ???

michael.eckert@noaa.gov

301-763-8201