Quantitative Precipitation Forecast
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000
FOUS30 KWBC 210700
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 AM EDT THU AUG 21 2014

...VALID 06Z THU AUG 21 2014 - 12Z FRI AUG 22 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
DUH 10 NW BJJ 20 E PHD AFJ 15 NE MGW 25 SSW 2G4 10 SSE EKN
30 NNE LWB 20 NNE BKW 20 NNW I16 25 SE HTS 35 WNW HTS 15 SW DAY
20 W GUS 20 SSW DKB 25 WSW MRJ 10 SSW DEH 15 SSW AEL 10 WSW FRM
MJQ 10 NNW OTG 10 E PQN 15 SE BKX 30 W BKX HON 35 WNW HON
55 WNW HON 55 NE PIR 45 W ABR 35 NW ABR 15 W K2D5 20 NNE K2D5
30 NNE KGWR 15 ESE JKJ 20 SE DTL SAZ 20 ESE LXL OEO 10 NNE LUM
25 SW MDZ CWA CLI 10 ENE MTW 25 NNE MKG 10 ESE FPK 15 NE ADG DUH.

A COUPLE OF STREAMS OF H5 S/WV ENERGY MOVING THRU THIS REGION IN A
GRADUALLY RISING HEIGHT REGIME..A WARM FRONT LIFTING SLOWLY
NORTHWARD WITH VERY HIGH
PWS POOLED VICINITY OF THIS FRONT..AND A BROAD AND MODEST
SOUTHWESTERLY TO WESTERLY LOW LEVEL JET WILL ALL COMBINE TO
PRODUCE AN AXIS OF ORGANIZED CONVECTION WITH MODERATE TO HEAVY AND
EVEN ISOLATED EXCESSIVE RAINFALL AMOUNTS WITHIN THIS AXIS FROM
PARTS OF THE UPPER MS VALLEY SOUTHEASTWARD INTO THE CENTRAL
APPALACHIANS THIS PERIOD.  ONGOING CONVECTION FROM PARTS OF THE
EASTERN DAKOTAS INTO WESTERN MN SHOULD BECOME BETTER ORGANIZED THE
REMAINDER OF THE NIGHT INTO EARLY THURSDAY MORNING AS THE
SOUTHWESTERLY LOW LEVEL JET STRENGTHENS A BIT..WITH THIS ACTIVITY
TENDING TO WEAKEN A LITTLE DURING THURSDAY BEFORE ENHANCING AGAIN
THURSDAY NIGHT UNDER WHAT WILL AGAIN BE AN INCREASING WESTERLY LOW
LEVEL JET THRU THE OH VALLEY AT THIS TIME.  OVERALL..THERE
CONTINUES TO BE GOOD AGREEMENT AMONGST THE MODELS FOR AN ORGANIZED
AND SIGNIFICANT CONVECTIVE/RAINFALL EVENT..BUT WITH SOME
DIFFERENCES IN THE LATITUDE OF WHERE THE HEAVIER RAINS WILL OCCUR.
 THE HIRES ARW SEEMED TO BE A BIT OF A SOUTH OUTLIER..SO STAYED
CLOSER TO SOME OF THE OTHER HIRES GUIDANCE WHICH HAD A SLIGHTLY
FARTHER NORTH AXIS..INCLUDING THE NMMB..NAM CONEST AND THE ECMWF
AND GEM REGIONAL HIRES QPFS.  EXPECT AREAL AVERAGE 1-3 INCH RAINS
ESPECIALLY ACROSS THE LOWER GREAT LAKES..AND INTO THE CENTRAL
APPALACHIANS WHERE THE WESTERLY FLOW WILL ENHANCE AMOUNTS ON
THURSDAY NGHT..WITH ISOLATED HEAVIER TOTALS CERTAINLY
POSSIBLE..WHICH COULD CAUSE SOME ISOLATED FLOODING CONCERNS.


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 ENE DDH 10 SSW PSF 10 N POU 10 W MGJ 20 SW MSV 35 NNE AVP
25 SE BGM 20 NE BGM UCA 20 NE GTB 15 ENE OGS MSS CWBZ 15 NE PLB
15 NE BTV 10 W MPV RUT 10 ENE DDH.


TEMPORARY REX BLOCK WILL REMAIN IN PLACE FROM EASTERN CANADA
SOUTHWARD INTO THE NORTHERN MID ATLANTIC STATES THIS PERIOD..WITH
THE CLOSED H5 LOW COMPRISING THE SOUTHERN PORTION OF THIS BLOCK
MOVING ONLY VERY SLOWLY FROM THE EASTERN GREAT LAKES INTO
SOUTHEASTERN NY STATES DURING THE PERIOD.  AHEAD OF THIS CLOSED H5
LOW..AN AXIS OF HIGHER PWS WILL PERSIST FROM PARTS OF PA AND NJ
NORTHWARD THRU NY STATE AND INTO WESTERN NEW ENGLAND ON A
RELATIVELY WEAK BUT PERSISTENT SOUTHERLY LOW LEVEL JET.  THIS
SHOULD SUPPORT ENHANCED BANDS OF RAINFALL DURING MUCH OF THIS
PERIOD..WITH THE DURATION OF THE EVENT SUPPORTING AT LEAST SOME
0.50-1.00+ INCH AREAL AVERAGE RAINFALL AMOUNTS..BUT WITH WITH
ISOLATED AMOUNTS OF 2+ INCHES POSSIBLE WHERE SOME BANDS MAY REPEAT.

TERRY
$$





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