The Weather Prediction Center’s “Meteorological Watch”

Providing situational awareness duringFlash floods

Patrick C. BurkeGregg Gallina, Andrew Orrison, Richard Otto, David Roth, Brendon Rubin-Oster

NCEP / Weather Prediction CenterCollege Park, MD

Blanco River Flash Flood, May 23/24 Texas

Product Lead TimeSlight Risk 72 hoursUpgraded to Moderate Risk

48 hours

Flash Flood Watch 33 hoursMPD #113: Upgrade to High Risk

12 hours

MPD #115: Emphatic message

6 hours

Flash Flood Warning 90 min?Flash Flood Emergency (0423 UTC)

30 min

…LIFE-THREATENING…4 TO 8 INCHES… HEAVIEST ACTIVITY FOCUSING JUST NORTH AND WEST OF A LINE FROM SAN ANTONIO TO AUSTIN TO WACO.

MPDsprovidedspecifictiming,magnitude

…COVERAGE OF HEAVY RAINFALL…EXPECTED TO INCREASE…2-5 PM…WITH IMPACTS POTENTIALLY INCREASING FURTHER DURING THE EVENING.

MPD #113 MPD #115

Mesoscale Precipitation Discussion• Fashioned after SPC product

• Transferred to WPC April 2013

• Operation of a desk whose core function is to anticipate flash flooding is unique in NWS history

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Metwatch Team

WPC traditionally known for synoptic scale…but this core Metwatch group has a passion for deep moist convection, mesoscale meteorology, observations, and short-fuse high-impact weather

Tropical Guru;Gulf Coast expertStorm

Chasers

Satellite / GOES-R Focal PointNorman connection;

strong in radar12 yrs NESDIS precipitation desk

What can we do?

Depends on predictability

10 hours in advance ofsignificant flash flooding

After onset of small scale, deadly flash flood…still provides expected end time,event totals

How do we do it?Focused MissionCONUS domain = repetition / calibrationDeep familiarity with hi-res model performanceAnalysis, ingredients and pattern recognition

What are the go-to datasets?Satellite; dual-pol 88D; SPC Mesoanalysis;Mesonet obs; NWS Chat; Hi-res & rapid update models; storm mode & motion tools

Subjective Verification

What is unique about WPC Metwatch?

Unparalleled access to mesoscale models

Hydrometeorological Testbed

GOES-RProving Ground

Boulder, CO, September 2013

“UNIQUE THREAT…AT RISK FOR SIGNIFICANT FLASH FLOODING…

SATURATED LOW LEVELS LEAVING LITTLE ROOM FOR COLD POOL PRODUCTION…

LONG DURATION PERIOD OF THIS TYPE OF ORGANIZED HEAVY RAIN…

WRF ARW…NSSL WRF…NAM CONEST…AND EXPERIMENTAL PREDICTING 3-4 INCH RAINFALL…

LACK OF LIGHTNING WILL MAKE THIS A DECEPTIVE RAINFALL…”

Islip, NY, state record rainfall, Aug 2014

“LOW LEVEL WIND PROFILES ARE QUITE FAVORABLE FOR STORM ORGANIZATION WITH 925-850 MB WINDS IN EXCESS OF 30-35 KNOTS BASED ON LOCAL VAD WIND PROFILES.

WARM RAIN PROCESSES HAVE DOMINATED AS WET BULB ZERO HEIGHTS ARE UP IN THE 14-15 KFT RANGE.

THE 12Z HRW-NMMB/00Z NAM CONEST/12Z SSEO MEAN/01Z HRRR MAINTAIN IMPACTS ACROSS THE EASTERN SIDE OF NJ AND UP INTO NYC AND WESTERN LONG ISLAND.”

Monsoon Event in 2013

“THE STORMS SHOULD BE EFFICIENT RAIN MAKERS, AS PRECIPITABLE WATER VALUES OF 1.75-2.50 INCHES LIE ACROSS THE REGION, WHICH IS WELL ABOVE NORMAL, BEYOND THE 90TH PERCENTILE FOR LATE AUGUST.

CORFIDI VECTORS ARE LIGHT, ON THE ORDER OF 5 KNOTS, WHICH COULD BE RELEVANT PER THE EXPECTATION OF ORGANIZED CONVECTION.

THE 12Z AFWA, 12Z EXREF MEAN, 06Z ARW, AND 06Z NMM SEEM TO HAVE THE BEST HANDLE OF THE CURRENT CONVECTIVE DEVELOPMENT. CONFIDENCE IN REGIONAL FLASH FLOODING IS HIGH. “

MPD during historically wet June 2014“MODEL AGREEMENT IS STRONG…GIVEN THAT CELLS WILL BE ROOTED ALOFT AS THEY LIFT NORTHWARD...UPSCALE GROWTH AND EASTWARD PROPAGATION MAY BE DELAYED...RESULTING IN A PROLONGED PERIOD OF TRAINING.

LOW LEVEL JET INCREASES TO 55 KT...YIELDING HIGHLY ANOMALOUS MOISTURE FLUX...5 STANDARD DEVIATIONS...PER THE GEFS STANDARD ANOMALIES.

MODELS PREDICT PW VALUES UP TO 1.75 INCHES...BUT THIS MAY FOLLOW THE CONVECTIVE OVERTURNING...WHILE INITIAL BACKGROUND VALUES ARE CLOSER TO 1.50 INCHES. WITH SOME HAIL INVOLVEMENT... EXPECT RAIN RATES UP TO 1.5 INCH/HR ON AVERAGE...BUT LOCAL ACCUMULATIONS EXCEEDING 3 AND MAYBE 4 INCHES.”

Relation to Flash Flood Guidance

“RAINFALL RATES OF 1-2 IN/HR ARE EXPECTED AND IS FORECAST BY RECENT RUNS OF THE RAP AND HRRR WHICH WILL TEST FFG OF 1.5 IN/HR…”

Coming November 16, 2015

NESDIS Satellite Precipitation Estimates(SPENES) and 12Planet chats are retired over the CONUS

Per Western Region request, WPC will issue MPDsfor atmopsheric river, longer duration heavy rainfall.

NESDIS desk (located 50 feet from Metwatch) stilla valuable source of input.

patrick.burke@noaa.gov@FerventDownpour

@NWSWPCwww.wpc.ncep.noaa.gov

WPC’s Metwatch…Force of the future