MESO: Nws Weather Prediction Center College Park Md

AWUS01 KWNH 161346
FFGMPD
GAZ000-FLZ000-ALZ000-MSZ000-LAZ000-161945-

MESOSCALE PRECIPITATION DISCUSSION 0004
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
946 AM EDT SUN MAR 16 2014

AREAS AFFECTED...CENTRAL GULF COAST

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 161345Z - 161945Z

SUMMARY...HEAVY RAINFALL RATES WITHIN A QUASI-STATIONARY BAND OF
CONVECTION NEAR THE CENTRAL GULF COAST COULD LEAD TO REGIONAL
FLASH FLOODING OVER THE NEXT SEVERAL HOURS.

DISCUSSION...AN CONVECTIVELY-INDUCED OUTFLOW BOUNDARY HAS ALIGNED
WITH THE LOW- TO MID-LEVEL FLOW NEAR THE CENTRAL GULF COAST, PER
13Z SURFACE OBSERVATIONS, RADAR IMAGERY, AND MODEL DATA. THERE
HAS BEEN RECENT CLOUD TOP COOLING PER SATELLITE IMAGERY, IMPLYING
THE CONTINUED DEVELOPMENT OF TALL/DEEP CONVECTION ACROSS THE
REGION. RADAR IMAGERY INDICATES RAINFALL RATES OF AROUND 3"/HR IN
THE BAND ACROSS SOUTHERN MS, WITH LOCAL TOTALS EXCEEDING 5" SO
FAR. THE MOST RECENT MESOSCALE GUIDANCE IS UNANIMOUS THAT 4"+ OF
RAINFALL IS EXPECTED THROUGH 18Z. THIS IS BEING DRIVEN BY
PRECIPITABLE WATER VALUES OF 1.50-1.75", NEAR THE 95TH PERCENTILE
(OR AROUND TWO STANDARD DEVIATIONS ABOVE NORMAL) FOR MID-MARCH FOR
SLIDELL LA AND VALPARAISO, FL. DIVERGENCE IS GOOD ACROSS THE
REGION, AHEAD OF A DEEP CYCLONE MOVING ACROSS AR. CORFIDI VECTORS
ARE RELATIVELY LIGHT ACROSS THE AREA, GENERALLY UNDER 10 KNOTS,
AND ARE ALIGNED WITH THE 850-400 HPA FLOW, ENHANCING THE RISK OF
CELL TRAINING.

THE 00Z ARW INDICATES CAPE VALUES IN THE NEIGHBORHOOD OF 1000-1500
J/KG, AND 0-3 KM SHEAR OF AROUND 45 KTS, WHICH SUPPORTS CONTINUED
DEVELOPMENT WET MULTI-CELLULAR CLUSTERS. AS THE BEST 850 HPA
INFLOW SHIFTS SLOWLY EASTWARD, SO SHOULD THE CONVECTIVE BAND.
HOWEVER, THE BACK EDGE OF CLOUDINESS PER SATELLITE IMAGERY HAS NOT
BEEN MOVING RECENTLY, INDICATING THE POSSIBILITY THAT THE SOUTHERN
PORTION OF THE BAND STANDS THE BEST CHANCE TO REMAIN STATIONARY
ACROSS SOUTHEAST LA WHILE THE NORTHERN PORTION OF THE BAND SAGS
SOUTHEASTWARD. AS FLASH FLOOD GUIDANCE VALUES ARE 3-4"/3 HRS IN
THIS REGION, AND RAINFALL RATES SHOULD BE ROUGHLY 2"/HR THROUGH
THE PERIOD PER SOME EAST TO SOUTHEAST MOVEMENT TO THE BAND,
REGIONAL FLASH FLOODING IS CONSIDERED POSSIBLE OVER THE NEXT
SEVERAL HOURS. THE 11Z RAP AND 00Z ARW INDICATE THAT LOW-LEVEL
VERTICAL WIND SHEAR/INFLOW SHOULD BEGIN TO DECREASE AROUND 18Z
ONCE THE COLD FRONT BEGINS TO CATCH UP TO THIS THUNDERSTORM BAND
AND OUTFLOW BOUNDARY...THOUGH THE PARAMETERS FOR WET MULTICELL
CLUSTERS SHOULD CONTINUE THROUGH AT LEAST 19Z. THIS LED TO A SIX
HOUR TIME HORIZON FOR THE MPD.

ROTH

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FFC...TAE...BMX...MOB...LIX...

ATTN...RFC...LMRFC...SERFC...

LAT...LON 29649076 30768924 31688730 32098570 31988478 31258447
30418578 30028811 29188897 28918982 29079095 29599080
29649076

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.