Quantitative Precipitation Forecast
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FOUS30 KWBC 140830
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
430 AM EDT FRI JUL 14 2017

...VALID 12Z FRI JUL 14 2017 - 12Z SAT JUL 15 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 N BIX 30 NE 7R3 LFT 45 SSE ESF HKS 25 NNE NMM 40 NNW GZH
25 N BIX.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
50 E FFA 10 NNE EDE 25 ESE FVX 25 NNW DAN 10 SE TNB 15 N MDQ
30 WSW UTA 30 NE TXK 10 NNW DEQ 20 ESE RKR 15 ENE FSM 15 S SLG
10 E GCM 15 SSW BVO 25 NW BVO 35 S EMP 10 S OJC 30 E TBN SDF
20 NE AGC 30 S CWQP CTAE CWVZ CWFQ 25 SSW ALB 15 NNW IJD
20 SSW MVY 60 SSW ACK.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
100 SW OLS 70 WSW TUS 55 SW SOW 15 S GUP 45 NE GUP 10 S MTJ
10 ENE EGE 10 NNW DEN 25 NNE GLD 55 N GCK 35 SSE GCK EHA
35 WNW CAO 35 N LVS 10 NE AEG 50 NNW TCS 15 NE DUG 90 SSE DUG
80 ENE MMHO.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
85 NE FFA 10 NE LFI LKU 10 WSW OKV 20 E AOO AVP 10 SSE FRG
100 SSE FOK.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 NNE MKL 15 E LRF 20 NW HOT 35 NNW RUE 25 SE JLN 30 ENE JLN
15 E SGF 35 E UNO 25 NNW BWG 20 N HTS 10 WSW MGW 25 SSE 2G4
20 ESE BKW 15 NNW TRI 10 WNW OQT 15 NW BNA 20 NNE MKL.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 W PUB 15 SE LIC 15 SSE GLD 30 WNW GCK 25 N EHA 25 E TAD
25 S VTP 25 NW VTP 15 W PUB.


...MID ATLANTIC AND NORTHEAST...

EXPECT AN ACTIVE DAY OF THUNDERSTORMS AND LOCALLY HEAVY RAINFALL
HERE WITH THE RISK OF FLASH FLOODING ESPECIALLY PRONOUNCD DURING
THE AFTERNOON HOURS OVER SOUTHERN NEW JERSEY...MUCH OF
DELAWARE...AND ADJACENT PARTS OF PA/MD.

A FEW CLUSTERS OF EARLY MORNING CONVECTION WERE ONGOING IN PA/NY
AT 08Z AND WILL LIKELY CONTINUE...FORCED BY THE APPROACH OF A
TROUGH OVER THE GREAT LAKES...AND INCREASINGLY CONVERGENT LOW
LEVEL FLOW BENEATH INCREASINGLY
DIVERGENT UPPER FLOW TO THE REAR OF A DEVELOPING 90 KNOT 250 MB
JET STREAK. THERE WILL BE SOME CONCERN FOR LOCAL HEAVY RAINFALL
EVEN DURING THE EARLY MORNING HOURS.

OUTFLOWS AND CLOUD COVER WILL CERTAINLY PLAY A ROLE IN THE SMALLER
SCALE LOCATION OF CONVECTION DURING THE DAYTIME...BUT THE SYNOPTIC
SQUEEZE PLAY BETWEEN THE APPROACHING GREAT LAKES WAVE...AND A
STALLED BACKDOOR SURFACE BOUNDARY STRETCHING FROM CENTRAL NJ TO
CENTRAL NY...SUGGESTS STORMS WILL EVENTUALLY HAVE A TENDENCY TO
LATCH ONTO THE
STALLED BOUNDARY AND RIDE DOWN THROUGH THE COASTAL MID ATLANTIC
FROM NEW JERSEY SOUTHWARD. THIS COULD LEAD TO A RELATIVE FOCUS FOR
HEAVY RAINFALL IN THE EASTERN PORTION OF THE WARM SECTOR...AND IS
STRONGLY SIGNALED IN THE HI-RES MODELS...MOST OF WHICH PRODUCE 1
TO 3 INCHES OF RAIN FANNING OUT FROM SOUTHEAST PA TOWARD THE SOUTH
AND EAST.

FARTHER SOUTH...WITH RESPECTABLE HEIGHT FALLS FOR SUMMER OCCURRING
DOWN TO THE LATITUDE OF SOUTHERN VIRGINIA...THERE SHOULD BE
SCATTERED TO NUMEROUS STORMS THROUGHOUT THE MID ATLANTIC...WITH A
TENDENCY FOR GREATER COVERAGE TO THE EAST OF I-95...EAST OF A
SUBTLE TROUGH DOWNSTREAM OF THE MOUNTAINS WITHIN WESTERLY FLOW
ALOFT. WITH PRECIPITABLE WATER RUNNING AROUND 2 INCHES AND
SUFFICIENTLY STEEP MID LEVEL LAPSE RATES...EXPECT POTENTIAL FOR
INTENSE SHORT
TERM RAIN RATES AND FLASH FLOODING THROUGHOUT THE REGION.


...LOWER MISSISSIPPI VALLEY TO THE APPALACHIANS...

THE SLOWLY SAGGING FRONTAL ZONE IN THE MIDDLE OF THE NATION HAD
BEEN VERY PRODUCTIVE ON CONSECUTIVE DAYS. LOW LEVEL INFLOW WAS
LACKING...BUT STRONG SUMMERTIME HEATING OF AIR CHARACTERIZED BY
1.75 AND GREATER PRECIPITABLE WATER...HAD LED TO PSUEDO-ORGANIZED
AND SLOW MOVING CONVECTIVE CLUSTERS / SYSTEMS DURING THE LATE DAY
AND OVERNIGHT HOURS. A SIMILAR CYCLE IS EXPECTED AGAIN FRIDAY. THE
FRONTAL ZONE WILL CONTINUE TO SLOWLY PUSH SOUTHWARD TO NEAR
NORTHERN ARKANSAS TO WEST VIRGINIA. FURTHER HEAVY RAINS WILL NOT
LIKELY OVERLAP WITH SATURATED SOIL...BUT WE WERE MORE EXPANSIVE
WITH THE INITIAL SLIGHT RISK AREA BASED ON THE MOISTURE QUALITY
AND PREDICTED VERY SLOW CELL MOTIONS. RAIN RATES AT LEAST 2 INCHES
IN AN HOUR IN THIS ENVIRONMENT WILL BE SUFFICIENT TO MEET FLASH
FLOOD GUIDANCE VALUES.


...SOUTHWEST / COLORADO...

A MID LEVEL SHEAR AXIS OVER COLORADO AND KANSAS HAD FORMED ALONG
AND NORTH OF THE FRONTAL BOUNDARY SLIDING THROUGH THE CENTRAL HIGH
PLAINS. THIS WILL LEND SOME ORGANIZATION TO THE DIURNAL CONVECTION
EXPECTED AGAIN TODAY IN THE MOUNTAINS OF CENTRAL AND SOUTHERN
COLORADO...EXTENDING OUT WITHIN THE MOIST AND DEEPLY MIXED
POST-FRONTAL REGIME OUT ON THE EASTERN PLAINS. PREDICTED CELL
MOTIONS ARE VERY SLOW WITH MEAN 0-6 KM WINDS ZERO TO FIVE KNOTS
TOWARD THE EAST...OFFSET BY ENHANCED SOUTHEASTERLY LOW LEVEL
INFLOW LATE IN THE DAY. THESE WIND PROFILES ALONG WITH ABOVE
AVERAGE PRECIPITABLE WATER VALUES...WILL LIKELY LEAD TO AREAS OF
RAINFALL EXCEEDING FLASH FLOOD GUIDANCE...ESPECIALLY GIVEN LOWER
FFG VALUES IN EASTERN CO / WESTERN KS.

ELSWHERE SCATTERED MONSOON CONVECTION IS EXPECTED AGAIN IN WESTERN
NEW MEXICO AND SOUTHERN ARIZONA. AREAL COVERAGE AND INTENSITY MAY
BE REDUCED SOMEWHAT COMPARED TO THURSDAY...AS THE CORE OF THE
PRECIPITABLE WATER PLUME WILL MOVE OUT OVER THE DESERTS AHEAD OF
AN EASTERLY WAVE COMING THROUGH MEXICO. STILL...THE CONVECTION
THAT DOES FORM HERE WILL BE CAPABLE OF PRODUCING ISOLATED FLASH
FLOODING.


...CENTRAL GULF COAST...

A WEAK EASTERLY WAVE...WHAT REMAINS OF OLD ATLANTIC T.D.
FOUR...WILL WASH ASHORE INTO LOUSIANA AND MISSISSIPPI IN THE FORM
OF INVERTED LOW LEVEL TROUGHING AND SOMEWHAT ENHANCED CONVERGENCE.
ALTHOUGH DEEP LAYER LIFT WILL NOT BE VERY STRONG...RICH MOISTURE
AND ADEQUATE INSTABILITY WILL COMBINE WITH VERY SLOW CELL
MOTIONS...NEAR 5 KNOTS...TO BRING ABOUT THE POSSIBILITY OF
ISOLATED VERY HEAVY RAIN AMOUNTS AND RAINFALL EXCEEDING FLASH
FLOOD GUIDANCE.

BURKE
$$





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