Quantitative Precipitation Forecast
Issued by NWS

Home | Current Version | Previous Version | Text Only | 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
000
FOUS30 KWBC 301506
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1105 AM EDT FRI SEP 30 2016

...VALID 15Z FRI SEP 30 2016 - 12Z SAT OCT 01 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
100 SSE SUT 30 S SUT 10 NNE JNX 15 ESE MKJ 25 W UNI 25 WNW WMO
35 N BWG 20 N HOP 15 SSE HSB MTO 20 E IKK LWA 25 NNW GRR
15 NE MOP 25 WSW CWGD 10 WNW CXDI 15 W ERI 20 N BTP 20 W DUJ
10 S ELZ 10 E ELM 15 SSW PSF 10 WNW LWM 70 ENE PVC 130 E CQX.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 S RMY 20 WNW FPK 10 S HYX 25 NNW PHN 20 SSE PHN TTF 10 S RMY.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 SSW EKN 20 SE CBE 10 SSE MRB CHO 15 NE LYH 20 ENE MTV
15 WNW MTV 10 W PSK 15 W BKW 25 ESE CRW 20 SSW EKN.


...GREAT LAKES/CENTRAL APPALACHIANS/MID ATLANTIC REGION...

15z UPDATE:

NOT MUCH CHANGE FROM THE PREVIOUS THINKING DESCRIBED BELOW. THE
MAIN THREAT THIS MORNING APPEARS TO BE FOCUSED ACROSS WESTERN VA
WHERE CONVECTION IS REGENERATING ALONG A LOW LEVEL CONVERGENCE
BOUNDARY. IT REMAINS VERY DIFFLUENT ALOFT OVER THIS REGION AS WELL
IN THE RIGHT ENTRANCE REGION OF AN UPPER JET...LIKELY HELPING
INCREASE CONVECTIVE COVERAGE AND PERSISTENCE. THIS AREA OF
CONVECTION SHOULD SLOWLY PROGRESS NORTHWARD ACROSS WESTERN VA
THROUGH THE AFTERNOON HOURS. IN GENERAL LOOKING FOR AMOUNTS IN THE
1-2" RANGE...ALTHOUGH GIVEN THE ANTECEDENT RAINFALL AND THE
POTENTIAL FOR TRAINING RESULTING IN LOCALIZED HEAVIER
AMOUNTS...WILL MAINTAIN THE SLIGHT RISK FOR EXCESSIVE RAINFALL.

THE OTHER AREAS OF FOCUS ARE OVER COASTAL NC WHERE SOME
BACKBUILDING CONVECTION IN A HIGH PRECIPITABLE WATER ENVIRONMENT
IS RESULTING IN LOCALIZED HEAVY RATES. IN GENERAL EXPECT THE WAVE
RESPONSIBLE FOR THIS CONVECTION TO BE PROGRESSIVE ENOUGH TO THE
NORTHEAST TO PRECLUDE A MORE WIDESPREAD FLASH FLOOD
THREAT...ESPECIALLY GIVEN THE HIGH FLASH FLOOD GUIDANCE. THUS WILL
MAINTAIN JUST THE MARGINAL RISK TO COVER THE ISOLATED FLASH FLOOD
RISK INTO EARLY AFTERNOON.

CLOSER TO THE UPPER LOW SHOULD SEE THE POTENTIAL FOR 1-3" OVER
PORTIONS OF CENTRAL IN AND OH...ALTHOUGH THE LACK OF ANOMALOUS
MOISTURE SHOULD KEEP ANY FLASH FLOOD RISK PRETTY ISOLATED AND THE
MARGINAL RISK SHOULD COVER THINGS. DID KEEP THE SLIGHT RISK ACROSS
FAR SOUTHEAST MI WHERE RECENT HEAVY RAINFALL HAS LOWERED FLASH
FLOOD GUIDANCE. SO EVEN THOUGH A GENERAL LACK OF INSTABILITY
SHOULD KEEP RATES AND AMOUNTS LOW...AN INCREASE IN SHOWER ACTIVITY
THIS AFTERNOON STILL MAY CAUSE SOME ISSUES.

DID CUT BACK THE MARGINAL RISK ACROSS PORTIONS OF THE MID
ATLANTIC...WITH THE BETTER FORCING AND MOISTURE TRANSPORT
SPLITTING THIS AREA. ALSO THE LACK OF INSTABILITY SHOULD PRECLUDE
MUCH OF A FLASH FLOOD RISK. DID MAINTAIN THE MARGINAL OVER
PORTIONS OF SOUTHERN NEW ENGLAND...WHERE PERSISTENT SHOWERS MAY
EVENTUALLY LEAD TO A FEW ISOLATED FLOOD ISSUES...ESPECIALLY IF
SOME MARGINAL ELEVATED INSTABILITY IS ABLE TO WORK NORTH INTO
PORTIONS OF COASTAL SOUTHERN NEW ENGLAND.

PREVIOUS DISCUSSION...

OVERALL THE 00 UTC GUIDANCE WAS IN GOOD AGREEMENT WITH THE
ANOMALOUSLY DEEP LOW THAT HAS NOW SETTLED INTO THE LOWER OH VALLEY
AND IS FORECAST TO RETURN SLOWLY TO THE NORTH...NEARING THE UPPER
GREAT LAKES BY EARLY SAT.  THROUGH THE REMAINDER OF THE OVERNIGHT
HOURS INTO EARLY FRI...DEEP SOUTHEASTERLY FLOW EAST OF THE CENTER
WILL CONTINUE TO CHANNEL MOIST AND UNSTABLE AIR FROM THE MID
ATLANTIC INTO THE CENTRAL APPALACHIANS AND OH VALLEY.  THIS
MOISTURE INTERACTING WITH THE LARGE SCALE FORCING AFFORDED BY THE
LOW WILL SUPPORT ADDITIONAL HEAVY RAINS AND POTENTIAL FLASH
FLOODING...ESPECIALLY IN THE UPSLOPE REGIONS OF THE CENTRAL
APPALACHIANS.  FLASH FLOOD GUIDANCE VALUES ARE QUITE LOW ACROSS
MUCH OF WESTERN VA...SUGGESTING ADDITIONAL RAINS MAY BE
PROBLEMATIC.  EXPECT GENERALLY LIGHTER AMOUNTS WEST OF THE
MOUNTAINS...HOWEVER THE OVERNIGHT GUIDANCE DOES CONTINUE TO SHOW
AREAS OF LOCALLY HEAVY AMOUNTS...AFFORDED IN PART BY STRONG UPPER
FORCING...ESPECIALLY ACROSS LOWER MI WHERE STRONG DIVERGENCE ALONG
THE LEFT-EXIT REGION OF THE UPPER JET IS EXPECTED TO INTERACT WITH
MOIST DEEP LAYER SOUTHEASTERLY TO EASTERLY INFLOW.  THIS ALONG
WITH INCREASING INSTABILITY MAY PRODUCE SOME LOCALLY HEAVY
RAINFALL RATES AND ACCUMULATIONS ON FRI.  LOW FLASH FLOOD GUIDANCE
VALUES ACROSS SOUTHEASTERN LOWER MI...SUGGESTING ANY HEAVY AMOUNTS
THAT DO OCCUR MAY RESULT IN RUNOFF CONCERNS.

PEREIRA
$$





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