Quantitative Precipitation Forecast
Issued by NWS

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QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
802 PM EDT SAT JUL 26 2014

...VALID 00Z SUN JUL 27 2014 - 00Z MON JUL 28 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 W SPD 15 W CAO 45 NW TCC 35 SSE LVS 30 ESE SAF 20 S SKX
35 SE ALS 30 NW VTP 25 ESE MYP 35 ESE CCU 25 SW APA 10 SW AFF
PUB 20 ESE PUB LHX 15 W SPD.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 WSW I16 20 NNE LOZ 10 SSE HNB 10 ENE 1H2 20 SE DNV DAY
35 NE PKB 10 NE CKB EKN 30 N HSP 10 ENE LWB 15 SW LWB 20 WSW I16.


...OHIO VALLEY AND CENTRAL APPALACHIANS...

ORGANIZED HEAVY RAINFALL...AT LEAST ON SMALL SCALES...APPEARS MOST
LIKELY TO OCCUR LATE TONIGHT WITH THE DEVELOPMENT OF A SECOND MCS
NEAR THE PATH OF THE FIRST...AND SUNDAY AFTERNOON WHEN DEEP LAYER
ASCENT WILL PROMOTE BRIEF PERIODS OF TRAINING ALONG THE OUTFLOWS
OF SUPERCELLS AND SHORT LINE SEGMENTS IN THE EASTERN PORTION OF
THE SLIGHT RISK AREA.

OVERNIGHT...A WEST TO EAST ORIENTED ZONE OF FAVORABLE INSTABILITY
AND UPGLIDE IS FORECAST TO STRADDLE THE OHIO RIVER. FOCUSED 850 MB
MOISTURE TRANSPORT BENEATH THE ARRIVAL OF MID LEVEL HEIGHT FALLS
IS LIKELY TO INITIATE ANOTHER MCS NEAR SOUTHERN INDIANA AS SEEN IN
THE 12Z WRF ARW AND MULTIPLE RECENT HRRR RUNS. FOR THIS REASON WE
EXPANDED THE SLIGHT RISK OF EXCESSIVE RAINFALL SOUTH TO CATCH MORE
OF NORTHERN KENTUCKY...ALTHOUGH THE NORTHERN BOUNDARY OF THE RISK
WAS ONLY SHAVED AWAY MINIMALLY GIVEN THE UNCERTAINTY IN THE
NORTH/SOUTH POSITION OF THE HEAVIEST RAINFALL IN THIS SCENARIO.

LITTLE CHANGE WAS MADE TO THE EASTERN PORTION OF THE RISK
AREA...WHERE IT APPEARS THAT CONVECTIVE CLUSTERS MAY EFFECTIVELY
LIMIT THE NORTHWARD ADVANCEMENT OF MOISTURE AND INSTABILITY INTO
WESTERN PA UNTIL LATER SUNDAY...AT WHICH TIME SHEAR AND CELL
MOTIONS WILL INCREASE SUCH THAT A FOCUSED FLASH FLOOD THREAT IS
NOT AS LIKELY ON MORE THAN A VERY LOCAL SCALE. THE WRF ARW DOES
SUGGEST SOME TRAINING MAY BE POSSIBLE FARTHER SOUTH INTO WEST
VIRGINIA...OWING TO CLOSER PROXIMITY TO MODERATELY UNSTABLE INFLOW
AND SLIGHTLY SLOWER CELL MOTIONS.

GIVEN SUFFICIENT PRECIPITABLE WATER VALUES OF AT LEAST 1.5 INCHES
IN THE PRE-CONVECTIVE ENVIRONMENT...SOME INTENSE SHORT TERM
RAINFALL RATES APPROACHING 2 INCHES IN AN HOUR COULD LEAD TO FLASH
FLOODING TONIGHT AND SUNDAY.


...EASTERN COLORADO AND EASTERN NEW MEXICO...

ACRS CO...THERE IS MODEL AGREEMENT IN SHOWING ENHANCED EASTERLY
UPSLOPE FLOW BEHIND A SOUTHWARD MOVING COLD FRONT INTO THE ERN
SLOPES OF THE CNTL/SRN CO MTNS ON SUN WITH PWS INCREASING TO OVER
1.5 INCHES OVER SE CO SUN AFTN. THE PERIOD OF FOCUSED UPSLOPE MAY
ONLY PERSIST FOR 2-3 HOURS AT A GIVEN LOCATION AS THE FRONT DIVES
INTO NEW MEXICO...BUT THE UPSLOPE IS FAVORABLY TIMED NEAR PEAK
HEATING. TSTM ACTIVITY COULD RAPIDLY ORGANIZE DURING UNDER AN
ANTICYCLONIC SHEAR ZONE NEAR NE SIDE OF THE UPR HIGH OVER PARTS OF
SE CO/NE NM...WHILE SLOWLY PROPAGATING SEWD INTO THE LL JET/DEEPER
INSTABILITY.  AS A RESULT...SOME ELEVATED RISK OF EXCESSIVE RAINS
CAN BE EXPECTED HERE.


...MICHIGAN...

UPR DYNAMICS WILL BE MORE IMPRESSIVE BUT A BIT MORE REMOVED FROM
THE DEEPER MSTR. SHORT TERM...ISOLD HEAVIER CONVECTIVE RAINS WILL
BE PSBL FROM PARTS OF THE GREAT LAKES EWD INTO NEW ENGLAND. SLOWER
MOVING AREAS OF MODERATE RAIN WITH EMBEDDED CONVECTION ARE LIKELY
NEAR A DEVELOPING COMMA HEAD OVER LOWER MI/WI WHICH COULD LEAD TO
ISOLD RUNOFF ISSUES.

BURKE/SULLIVAN
$$




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