Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Graphics & Text | 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 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FOUS30 KWBC 250100
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
859 PM EDT FRI JUL 24 2015

...VALID 01Z SAT JUL 25 2015 - 12Z SAT JUL 25 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 WSW OCF 15 ESE BKV 20 NW PGD 25 SSW SRQ 55 W PIE 95 WNW PIE
40 SW CTY 25 WSW OCF.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 SSW MQB 40 SW UIN 30 ENE MCI 10 WNW CNK 60 N GCK 35 S ITR
25 NNE ITR 25 SE ODX 15 S DNS 10 W MUT 20 SSW MQB.


01Z UPDATE...

CONVECTION CONTINUES TO FIRE ALONG THE OUTER PERIPHERY OF THE
UPPER RIDGE...ACROSS WESTERN KS AND ALONG/BEHIND THE LOW-LEVEL
BOUNDARY DRAPED FROM NORTHWEST KS ENE THROUGH SOUTH-CENTRAL AND
SOUTHEAST NE. THE NORTHERN CONVECTION IS GETTING A BOOST FROM THE
ENHANCED LOW-LEVEL ISENTROPIC ASCENT (SUFFICIENTLY DEEP TO THE
LFC) BEHIND THE SURFACE COLD FRONT...WITH THE SURFACE-BASED
COOLING AIDED BY THE CONVECTIVE OUTFLOWS. THE CONVECTION IN
WESTERN KS AND ALONG THE WESTERN OK PANHANDLE IS AIDED BY
SHORTWAVE ENERGY MOVING OUT OF EASTERN CO. BOTH OF THESE AREAS ARE
WEAKENING THE CAP A BIT...THOUGH NOT MUCH PER THE LATEST SPC
MESOANALYSIS (+12 TO +14C 700 MB TEMPS).

OVERNIGHT...AS THE STRONG/DEEP INSTABILITY BECOMES MORE
ELEVATED...EXPECT THE MORE ORGANIZED CONVECTION TO ALIGN MORE
DISTINCTLY  NORTH OF THE CAP...BASICALLY ACROSS NORTHERN
KS/MO...SOUTH-CENTRAL AND SOUTHEAST NE...SOUTHERN IA...AND INTO
WEST-CENTRAL IL. THIS IS WHERE NOT ONLY THE MOST FAVORABLE LOW
LEVEL MOISTURE TRANSPORT (STRENGTHENING LLJ) WILL CONVERGE INTO
THE LOW LEVEL FRONTAL ZONE...BUT ALSO WHERE ENHANCED RIGHT
ENTRANCE REGION UPPER JET STREAK SUPPORT (SYNOPTICALLY ENHANCED
UPPER DIVERGENCE) WILL SET UP AS THE JET STREAK PASSES W-E ACROSS
THE NORTHERN PLAINS AND UPPER MS VALLEY).

HURLEY


21Z UPDATE...

REFINED THE PREVIOUS EXCESSIVE RAINFALL OUTLOOK WHICH NOW
INCORPORATES A NARROW RIBBON FROM EASTERN/SOUTHEAST NE TO ALONG
THE IA/MO BORDER AND INTO WESTERN IL. THIS IS BASED ON THE LATEST
WPC DETERMINISTIC AND PROBABILISTIC QPF AS WELL AS THE TRENDS IN
THE GUIDANCE (PARTICULARLY WITH THE HIGH RES MODELS -- THOUGH AS
PER THE QPFPFD IT WOULD APPEAR THE 12Z NSSL-WRF IS TOO FAR SOUTH
WITH THE AXIS OF HEAVIER RAINFALL (FARTHER SOUTH INTO NORTHEAST KS
AND NORTHWEST MO) CONSIDERING THE STRONG MID LEVEL CAP OVER THAT
AREA (700 MB TEMPS +12 TO +14C). CERTAINLY COULD SEE CONVECTION
WORKING SOUTHWARD INTO THIS REGION... HOWEVER GIVEN THE CAP WOULD
EXPECT MUCH LESS ORGANIZATION (WEAKENING TREND). THEREFORE...HAVE
REMOVED THE EXCESSIVE RAINFALL OUTLOOK OUT OF THE TOPEKA...KANSAS
CITY...AND COLUMBIA AREAS.

HURLEY


PREVIOUS DISCUSSION BELOW...


...EASTERN NE EASTWARD THROUGH SOUTHERN IA/NORTHERN MO AND
WEST-CENTRAL ILLINOIS...

A SLIGHT RISK AREA WAS ADDED OVER PORTIONS OF THE CENTRAL PLAINS
INTO THE LOWER MO VALLEY ALONG AND TO THE SOUTH OF THE WEST TO
EAST ORIENTED FRONTAL BOUNDARY.  CONVECTION MAY BECOME MORE
ORGANIZED ALONG AND SOUTH OF THIS FRONT AS SHORTWAVE ENERGY MOVES
EASTWARD ALONG THE SOUTHERN EDGE OF THE WESTERLIES---ENHANCING
UVVS IN AN AXIS OF HI CAPE VALUES EXTENDING WEST TO EAST ALONG THE
FRONT AND SOUTHWARD ACROSS EASTERN KS INTO WESTERN MO.  THE HI RES
RUNS FROM 0000 UTC ARE EMPHASIZING HEAVY RAINFALL POTENTIAL IN A
NORTH SOUTH AXIS FROM IN THE VICINITY OF CENTRAL IA INTO WESTERN
TO CENTRAL MO---WHILE THE REMAINING GUIDANCE IS MORE EMPHATIC
ABOUT CONVECTION IN A WEST TO EAST AXIS CLOSER TO THE FRONT.
CONFIDENCE IS NOT GREAT WITH DETAILS GIVEN THE LARGE SPREAD.
WITH POTENTIAL FOR ORGANIZED CONVECTION IN BOTH THE WEST TO EAST
AXIS AND NORTH TO SOUTH AXIS---THERE MAY BE ISOLATED RUNOFF ISSUES
WHERE CONVECTION DOES BECOME ORGANIZED.


...NORTHWEST TO NORTH FL INTO COASTAL GA AND COASTAL SC...

PW VALUES WILL REMAIN MUCH ABOVE AVERAGE ALONG AND TO THE SOUTH OF
THE SLOW MOVING FRONTAL BOUNDARY CURRENTLY EXTENDING EAST TO WEST
ACROSS NORTHERN SC INTO THE SOUTHERN APPALACHIANS---WITH VALUES 2+
STANDARD DEVIATIONS ABOVE THE MEAN FROM THE COASTAL SECTIONS OF
SC/GA INTO NORTHERN FL.  THERE IS A WELL DEFINED HEAVY RAINFALL
SIGNAL IN THE LATEST GUIDANCE--ESPECIALLY THE HI RES RUNS---IN
THIS ABOVE AVERAGE PW AXIS.  THE MOST WIDESPREAD HEAVY TOTALS
LIKELY OVER PORTIONS OF NW FLORIDA WHERE MOIST WEST NORTHWESTERLY
FLOW WILL FOCUS FOR A MAJORITY OF THIS PERIOD.   FARTHER TO THE
NORTH AND NORTHEAST---HEAVY RAINS MAY ALSO FOCUS DURING THE FIRST
HALF OF THIS PERIOD ALONG THE IMMEDIATE GA/SC COASTS AHEAD OF THE
SLOW SOUTHWARD MOVING FRONTAL BOUNDARY.  THERE IS FAIRLY GOOD
AGREEMENT HERE IN THE LATEST MODEL SUITE FOR THE HEAVY RAIN AXIS
TO EXTEND NORTHEASTWARD INTO COASTAL GA AND SC.  WHILE FFG VALUES
ARE HIGH ACROSS THESE AREAS---INTENSE RAINFALL RATES IN THE ABOVE
AVERAGE PW AXIS MAY LEAD TO ISOLATED RUNOFF ISSUES.

ORAVEC/TERRY
$$




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