Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
444
FOUS30 KWBC 191934
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
333 PM EDT FRI MAY 19 2017

...VALID 1933Z FRI MAY 19 2017 - 12Z SAT MAY 20 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
105 ENE FFA 45 NE FFA 15 WNW EDE 10 W TDF 15 NNE MRN 20 NE 1A5
15 S OQT 30 SE MQY 35 WNW MSL 25 ESE UTA LLQ 10 ESE TXK 25 W TYR
15 WSW GTU 15 E UVA 50 WSW MMPG 60 SSE 6R6 50 W E29 40 N DYS
15 S CSM 30 WSW PTT 40 WSW MCK 30 NE OGA 35 NE ANW 20 NE FRM
15 SW EFT 10 SW SBN 25 ESE DFI 20 SE LPR 10 SSE YNG 10 SW IDI
10 S HGR 10 S WWD 75 SE OXB 105 ENE FFA.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
05F 25 WSW 6R9 25 NNW JCT 45 ENE SJT 40 ENE ABI 10 NNW SPS
15 S OUN 15 W OKM GCM 25 ESE CFV 20 ENE CNU 10 N UKL 30 NW EMP
15 SW SLN 40 E HLC 30 E MCK 25 NNW LXN 30 NW ODX 20 SE YKN
10 WNW SLB 10 ESE ADU 30 WSW LWD 25 N CDJ 10 E IRK 10 WNW MQB
15 ESE BMI 15 ENE HUF 25 ESE GEZ SGH 25 SW HLG 30 W CKB
25 WNW HTS 15 NNE LEX 30 SSE FTK 35 SSW OWB 35 SE PAH 15 SSE DYR
30 S JBR 15 N PBF 20 WNW OSA 20 E INJ 05F.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 W DEQ 10 S PRX 10 SE DAL 15 WNW F18 10 SSW MWL 20 N 1F9
30 WSW 1F0 ADH 10 SSW MKO 15 S SLG 15 WSW HRO 30 SSW FLP
20 E RUE MWT 10 W DEQ.


1930Z UPDATE...

...PLAINS/MS VALLEY...GULF COAST STATES...OH/TN
VALLEYS...MID-ATLANTIC...

SOME SIGNIFICANT CHANGES TO THE EXCESSIVE RAINFALL OUTLOOK ARE
NECESSITATED AT THIS TIME GIVEN THE LATEST CONVECTIVE TRENDS ALONG
WITH HIRES MODEL SIGNALS.

THE STRONG CLOSED MID TO UPPER LOW CURRENTLY CROSSING THE CENTRAL
ROCKIES WILL EJECT EAST OUT ACROSS THE CENTRAL HIGH PLAINS
OVERNIGHT AND THIS WILL DRIVE SURFACE LOW PRESSURE FROM THE
SOUTHERN HIGH PLAINS NORTHEAST UP THROUGH THE LOWER MO VALLEY BY
12Z SAT. A VIGOROUS TRAILING COLD FRONT THAT WILL EJECT EAST
ACROSS THE SOUTHERN PLAINS FROM SOUTHERN KS DOWN ACROSS CENTRAL
TX. THIS STRONG SYNOPTIC SCALE SYSTEM WITH AN IMPRESSIVE ARRAY OF
JET FORCING/DYNAMICS WILL BE INTERACTING WITH PLENTY OF DEEPER
LAYER MOISTURE/INSTABILITY TRANSPORT FOR WIDESPREAD SHOWERS AND
THUNDERSTORMS WHICH WILL BE FOCUSED ALONG AND AHEAD OF THE COLD
FRONT. ONE OF THE MAJOR CHALLENGES TO THE FORECAST...ESPECIALLY
FOR OVERNIGHT...IS THE PRESENCE OF A PRE-FRONTAL DIFFERENTIAL
HEATING/OUTFLOW BOUNDARY OVER NORTHERN TX AND SOUTHEAST OK
INCLUDING THE RED RIVER VALLEY AREA. THIS BOUNDARY WILL BECOME AN
EFFECTIVE FRONT THIS AFTERNOON AND EVENING THAT IS EXPECTED TO
INTERCEPT SOME OF STRONGER SOUTHERLY LOW LEVEL FLOW AND ASSOCIATED
MOISTURE TRANSPORT WHILE ALSO REPRESENTING A NEW WELL-DEFINED
INSTABILITY GRADIENT FOR CONVECTION TO FOCUS ALONG. MEANWHILE...AN
UPSTREAM JET MAX EJECTING OUT OF THE SOUTHERN ROCKIES WILL PIVOT
THROUGH THE SOUTHERN HIGH PLAINS AND PLACE THE RED RIVER VALLEY
AREA IN A FAVORABLE REGION FOR STRONGER JET ASCENT/FORCING WHICH
SHOULD AID CONVECTION. WHILE THERE WILL STILL LIKELY BE CONVECTION
FARTHER NORTH ALONG THE COLD FRONT...IT IS EXPECTED THAT THE MORE
ORGANIZED CONVECTION WILL BE FARTHER SOUTH CLOSER TO THE RED RIVER
VALLEY OVERNIGHT AND THROUGH EARLY SAT...WITH A CONVECTIVE AXIS
THAT EXTENDS NORTHEAST UP ACROSS CENTRAL/EASTERN AR AND MUCH OF
EASTERN MO BEFORE THEN GRADUALLY ADVANCING EAST INTO THE OH VALLEY
DOWNSTREAM. PWATS OF 1 TO 2 STANDARD DEVIATIONS ABOVE NORMAL AND A
GOOD SET-UP FOR TRAINING/BACK-BUILDING CELLS WILL PROMOTE AS MUCH
AS 2 TO 4 INCH RAINFALL TOTALS...WITH ISOLATED 5+ INCH AMOUNTS NOT
OUT OF THE QUESTION. THE HEAVIEST TOTALS ARE LIKELY TO BE IN THE
NEW MODERATE RISK AREA WHICH INCLUDES NORTHERN TX AND SOUTHEAST
OK. THIS IS WHERE THE GREATEST FLASH FLOOD THREAT IS AT THIS TIME.
AN OTHERWISE LARGE AREA OF 1 TO 2 INCH AMOUNTS ARE STILL EXPECTED
ELSEWHERE INCLUDING MUCH OF THE MID MS AND OH VALLEY AREA WHERE
MULTIPLE ROUNDS/CLUSTERS OF THUNDERSTORMS THIS EVENING AND
OVERNIGHT WILL RESULT IN SOME ELEVATED CONCERNS FOR FLASH
FLOODING...AND THIS AN EXPANSIVE SLIGHT RISK AREA IS MAINTAINED TO
ACCOMMODATE THIS THREAT. FARTHER EAST WITH THIS UPDATE...WE HAVE
INCLUDED THE GREATER MID-ATLANTIC REGION IN A MARGINAL RISK GIVEN
THE HIGHER PWAT ENVIRONMENT AND EXPECTATION OF THUNDERSTORMS
ADVANCING EAST OF THE APPALACHIANS THIS EVENING AND OVERNIGHT.
THESE LATEST CHANGES ARE WITH RESPECT TO THE LAST SEVERAL RUNS OF
THE HRRR/HRRRX AND THE 12Z WRF-ARW AND NSSL-WRF SOLUTIONS...WHICH
IN PARTICULAR SUPPORT THE AFOREMENTIONED ADJUSTMENTS OVER THE
CENTRAL/SOUTHERN PLAINS AND MID MS VALLEY.

ORRISON
$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.