WPC Met Watch |
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Mesoscale Precipitation Discussion: #0495 (2018) |
(Issued at 902 PM EDT FRI JUL 20 2018
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MPD Selection |
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MESOSCALE PRECIPITATION DISCUSSION 0495...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
902 PM EDT FRI JUL 20 2018
CORRECTED FOR REMOVING EXTRA CODING FROM DIFFERENT MPD
AREAS AFFECTED...CENTRAL NV
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 210057Z - 210627Z
SUMMARY...THUNDERSTORMS WITH POTENTIALLY HEAVY RAIN APPEAR TO BE
DEVELOPING IN CENTRAL NV AND EAST-CENTRAL CA. HOURLY RAIN TOTALS
TO 1.5" SHOULD BE POSSIBLE HERE UNTIL ~06Z.
DISCUSSION...THUNDERSTORMS HAVE BEEN DEVELOPING ACROSS CENTRAL NV
AND EAST-CENTRAL CA SINCE ~20Z IN THE VICINITY OF A LOW-LEVEL
TROUGH AXIS SHOWING CONVERGENT WINDS AT THE 850 AND 700 HPA
LEVELS. SATELLITE IMAGERY SHOWS SOME OVERSHOOTING TOPS WITHIN THE
CONVECTION. THE STORMS APPEAR TO BE SHOWING LITTLE MOVEMENT IN NV
AND A NORTHWEST DRIFT IN CA. MU CAPE VALUES IN THEIR VICINITY IS
~2000 J/KG. PRECIPITABLE WATER VALUES OF 0.7-1" LIE IN THE AREA.
EFFECTIVE BULK SHEAR IS 25 KTS PER SPC MESOANALYSES.
RAP MASS FIELDS SUGGEST THAT LOW-LEVEL CONVERGENCE SHOULD PERSIST
UNTIL AROUND 06Z BEFORE FADING. AN APPROACHING VORTICITY
LOBE/SHORTWAVE ACROSS CENTRAL CA MAY ALLOW CONVECTIVE TO TAP SOME
INSTABILITY ALOFT (UTILIZING THE MU CAPE RATHER THAN MERELY ML
CAPE PRESENT) AND PERSIST UNTIL 05-06Z, WHICH IS ROUGHLY WHEN
CONVECTION FADED ACROSS SOUTHERN NV YESTERDAY. THE AVAILABLE
MOISTURE AND INSTABILITY ALLOWS FOR HOURLY RAIN TOTALS TO 1.5",
WHICH COULD BE PROBLEMATIC WITHIN THE ROUGHLY TOPOGRAPHY OF THE
AREA.
ROTH
ATTN...WFO...HNX...LKN...REV...STO...VEF...
ATTN...RFC...CNRFC...
LAT...LON 39531650 39431566 38731536 37961586 37151749
37471889 37981955 38771995 39111883
Last Updated: 902 PM EDT FRI JUL 20 2018
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