Quantitative Precipitation Forecast
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FOUS30 KWBC 011829
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 PM EDT WED APR 01 2015

...VALID 18Z WED APR 01 2015 - 00Z FRI APR 03 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 E MCW 10 SSE AIO 20 SSW ICL 35 WNW CDJ 35 N SZL 20 W SZL
25 SW IXD 25 NNW UKL 15 S MHK 40 NNW MHK 10 NNW HJH JYR
15 ESE SUX FRM 15 E MCW.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 NW HTS 35 SE LEX 35 NW BWG 30 W HOP 10 NW DYR 15 W BYH
10 E SRC 20 WSW BVX 30 NW ARG 20 W CGI 15 SSW ENL OLY 35 WSW CVG
45 SE ILN 20 NW HTS.


...EASTERN NE/WESTERN IA/NORTHEAST KS/NORTHWEST MO...

THE MODELS HAVE TRENDED LATER IN INITIATING CONVECTION ACROSS THE
LOWER MO VALLEY THIS AFTERNOON AND EVENING...WITH THE HIRES
GUIDANCE SUGGESTING THAT CONVECTION WILL TAKE UNTIL CLOSE TO 00Z
TO BEGIN OVER EASTERN NE AND NORTHWEST IA. THE LARGER SCALE SET-UP
IS ESSENTIALLY UNCHANGED AS WE HAVE A ROBUST MID LEVEL TROUGH
EJECTING OUT OF THE WESTERN U.S. THAT WILL BE ADVANCING EAST
ACROSS THE CENTRAL/NORTHERN PLAINS AND INTO THE UPPER MIDWEST
TONIGHT AND THURS. THIS WILL DRIVE A COLD FRONT SOUTHEASTWARD
THROUGH THE PERIOD...AND IT IS THIS FRONT THAT SHOULD BE THE
PRIMARY SURFACE FOCUS FOR CONVECTION LATER TODAY. DIURNAL HEATING
AND A GRADUAL INCREASE IN BOUNDARY LAYER MOISTURE SHOULD PROVIDE
SUFFICIENT LEVELS OF INSTABILITY COUPLED WITH STEEPENING MID LEVEL
LAPSE RATES FOR A SW/NE ORIENTED AXIS OF CONVECTION TO EVOLVE THIS
EVENING AS HEIGHT FALLS ARRIVE FROM THE WEST. THE HEAVIER RAINFALL
AMOUNTS ARE LIKELY TO BE OVER ESPECIALLY PORTIONS OF SOUTHEAST
NE/FAR WESTERN IA AND NORTHEAST KS BASED ON THE 12Z NAM-CONEST AND
12Z ARW WHICH SUGGEST STRONGER 850 MB MOISTURE TRANSPORT ACROSS
THESE AREAS. STRONGER INFLOW ASSOCIATED WITH A STRENGTHENING LOW
LEVEL JET AND RELATIVELY HIGHER PWATS UP TO NEAR 1.25 INCHES WILL
HELP GENERATE HEAVIER RAINFALL RATES. DEEPER LAYER FLOW WILL BE
SOMEWHAT PARALLEL TO THE FRONT FOR A PERIOD OF TIME THIS
EVENING... AND SO THERE IS EXPECTED TO BE POTENTIAL FOR SOME
TRAINING AND BACK-BUILDING OF CONVECTION. CONSEQUENTLY...THERE
WILL BE CONCERNS FOR RUNOFF PROBLEMS AND SOME FLASH FLOODING. BY
06Z...THE CONVECTION SHOULD TEND TO BE MORE CONCENTRATED OVER
NORTHEAST KS AND ESPECIALLY NORTHWEST MO WITH AN MCS LIKELY
EVOLVING BY THAT TIME AND THIS SHOULD TEND TO INHIBIT STRONGER
MOISTURE/INSTABILITY FARTHER NORTH ALONG THE COLD FRONT ACROSS THE
UPPER MIDWEST. THIS ACTIVITY SHOULD WEAKEN TOWARD 12Z WITH THE
LOSS OF FAVORABLE INSTABILITY.


...FAR EASTERN OK/SOUTHWEST MO/AR...

A TRICKY FORECAST FOR THIS AFTERNOON AND EVENING ACROSS PORTIONS
OF THE MID AND LOWER MS VALLEY AS A WELL-DEFINED CONVECTIVE VORT
SEEN IN IR/WV IMAGERY LIFTS GRADUALLY NORTHEAST OUT OF NORTHEAST
OK/SOUTHEAST KS AND INTO SOUTHWEST MO. ALREADY SEEING A SMALL
CONCENTRATED CLUSTER OF CONVECTION THAT HAS REDEVELOPED NEAR THE
VORT CENTER ALONG THE OK/KS/MO TRI-STATE BORDER AREA. THE ENERGY
WILL SLOWLY LIFT NORTHEAST ACROSS THE MID MS VALLEY THIS AFTERNOON
AND EVENING AND WILL BE TAPPING INTO A THERMODYNAMICALLY MORE
FAVORABLE ENVIRONMENT FOR CONVECTION TO INCREASE IN COVERAGE AND
INTENSITY. PWATS INCREASING TO OVER 1.25 INCHES COUPLED WITH
STRONG DIURNAL HEATING SHOULD ENHANCE THE POTENTIAL...AND ALREADY
THE LATEST VIS IMAGERY IS INDICATING AN INCREASINGLY AGITATED CU
FIELD OVER CENTRAL/SOUTHERN AR. RELATIVELY SLOW-CELL MOTION AND
LOCALLY INTENSE RAINFALL RATES SHOULD FOSTER AT LEAST SOME
LOCALIZED CONCERNS FOR RUNOFF PROBLEMS THROUGH THE AFTERNOON AND
EVENING HOURS.


...OH RIVER VALLEY...

THE SAME VORT ENERGY THAT IS CURRENTLY CROSSING INTO THE LOWER/MID
MS VALLEY WILL GET CAUGHT UP AHEAD OF THE LARGER SCALE
TROUGH/HEIGHT FALLS ADVANCING EAST INTO THE MIDWEST ON THURS. THIS
LEAD ENERGY SHOULD TEND TO INTERCEPT A STRONGER LOW LEVEL
SOUTHWESTERLY FETCH OF MOISTURE AND INSTABILITY BY THURS AFTERNOON
LIFTING OUT OF THE LOWER MS AND TN VALLEYS...AND THE LATEST HIRES
MODELS SUGGEST AN AXIS OF STRONGER CONVECTION AND HEAVY RAINS
DEVELOPING AND OVERSPREADING PORTIONS OF THE OH RIVER VALLEY
THROUGH THE AFTERNOON. THE GLOBAL MODELS SUPPORT A LOW LEVEL JET
REACHING OVER 50 KTS AND INCREASINGLY DIFFLUENT FLOW ALOFT THROUGH
THE PERIOD...AND SO CONVECTION SHOULD TEND TO BE ORGANIZED AND
PERSISTENT THAT ADVANCES NORTHEASTWARD UP ALONG AND ADJACENT THE
OH RIVER. THE HIRES MODELS SUPPORT LOCALLY A COUPLE INCHES OF
RAINFALL POTENTIAL WITH ISOLATED HEAVIER AMOUNTS...AND THIS WILL
FOSTER SOME POTENTIAL FOR FLASH FLOODING.

ORRISON
$$





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