Category Archives: Mesoscale Discussion

Mesoscale Discussion… for Flooding…

This particular mesoscale discussion is courtesy of the Weather Prediction Center…

mcd0022

MESOSCALE PRECIPITATION DISCUSSION 0022
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
759 AM EDT SUN APR 28 2013

AREAS AFFECTED……NORTHEASTERN AL/NORTHERN GA/EASTERN TN

CONCERNING…HEAVY RAINFALL…FLASH FLOODING POSSIBLE

VALID 281159Z – 281429Z

SUMMARY…STRONG CONVECTION MAINTAINED FROM OVERNIGHT ACTIVITY
WILL BRING A THREAT FOR FLASH FLOODING OVER AREAS OF NORTHERN
GEORGIA THIS MORNING.

DISCUSSION…A NOCTURNAL COMPLEX OF SHOWERS AND THUNDERSTORMS
APPEARS TO HAVE MAINTAINED ITS INTENSITY PER IR SATELLITE TRENDS
AND LIGHTNING DATA. THERE IS LITTLE REASON TO BELIEVE THIS AXIS OF
CONVECTION WILL WEAKEN DURING THE NEXT FEW HOURS AS THE
PRECIPITATION MOVES ACROSS AN AREA OF DIMINISHED 3-HOUR FFG
VALUES. IT APPEARS THIS THREAT SHOULD MOVE JUST TO THE NORTH OF
THE ATLANTA METRO AREA. THE 850-MB FLOW IS FORECAST TO PUMP SOME
OF THE HIGHER MOISTURE CONTENT OUT OF THE GULF OF MEXICO INTO THE
LOWER TENNESSEE VALLEY. ADDITIONALLY…MOST OF THE HIGH-RESOLUTION
GUIDANCE SUGGESTS THIS AREA WILL BE IMPACTED BY 1 TO 2 INCH
RAINFALL TOTALS IN 6 HOURS WITH LOCALIZED HIGHER AMOUNTS. THIS
SUPPORT INCLUDES THE 00Z SPC WRF/00Z HIGH-RES WRF-NMM ALONG WITH
DETERMINISTIC RUNS FROM THE 06Z NAM/GFS.

RUBIN-OSTER
ATTN…WFO…GSP…MRX…FFC…BMX…HUN…

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Mesoscale Discussion 1951 (Alabama, Georgia, Tennessee)

MESOSCALE DISCUSSION 1951
NWS STORM PREDICTION CENTER NORMAN OK
0353 PM CDT MON SEP 17 2012

AREAS AFFECTED…SE TN…NE AL…NW GA

CONCERNING…SEVERE POTENTIAL…WATCH POSSIBLE

VALID 172053Z – 172230Z

PROBABILITY OF WATCH ISSUANCE…40 PERCENT

SUMMARY…A TORNADO THREAT MAY DEVELOP ACROSS NE AL…NW GA AND SE
TN LATE THIS AFTERNOON AND THIS EVENING. WW ISSUANCE CAN NOT BE
RULED ACROSS THE REGION.

DISCUSSION…NUMEROUS THUNDERSTORMS ARE ONGOING ACROSS THE TN VALLEY
WHERE THE AIRMASS IS WEAKLY UNSTABLE. IN SPITE OF THIS…SOME CELLS
ARE SHOWING SIGNS OF ROTATION MAINLY DUE TO THE MODERATELY SHEARED
ENVIRONMENT. THE LATEST WSR-88D VWP AT HUNTSVILLE AL SHOWS SOME
DIRECTIONAL SHEAR IN THE BOUNDARY LAYER WITH AN ESTIMATED 0-1 KM
SHEAR OF 25 KT. THIS COMBINED WITH LOW LCL HEIGHTS…SFC DEWPOINTS
APPROACHING 70 F AND BACKED SFC WINDS MAY BE SUPPORTIVE OF AN
ISOLATED TORNADO THREAT THIS AFTERNOON. THE ACTIVITY WILL CONTINUE
TO BE MONITORED IN CASE WW ISSUANCE BECOMES NECESSARY.

..BROYLES/MEAD.. 09/17/2012

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