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October 19 Severe Obs/Disc


Ellinwood

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MESOSCALE DISCUSSION 2267

NWS STORM PREDICTION CENTER NORMAN OK

0526 PM CDT WED OCT 19 2011

AREAS AFFECTED...ERN NC...SERN VA...SERN MD/DE

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 192226Z - 200030Z

A FEW STRONG THUNDERSTORMS CAPABLE OF GUSTY WINDS WILL AFFECT THE

REGION THROUGH EVENING. HOWEVER...THE OVERALL TORNADO THREAT

CONTINUES TO BE LOW.

A LINE OF BROKEN CONVECTION CONTINUES TO MOVE RAPIDLY NEWD ACROSS

CNTRL INTO SRN NC...ON THE LEADING EDGE OF THE DRY SLOT ALOFT. THESE

STORMS HAVE SHOWN SOME LOW TO MID LEVEL ROTATION AT TIMES...DRIVEN

BY THE COMBINATION OF STRONG FORCING AND AMPLE SHEAR IN THE LOWEST 3

KM.

OTHER STORMS WERE BEGINNING TO FORM OVER NERN NC...DEEPER INTO THE

SURFACE MOIST AXIS. HERE...LOW LEVEL SHEAR IS EVEN BETTER THAN

FARTHER SW.

THE MAIN PROBLEM WITH THE ENVIRONMENT IS THERMODYNAMIC IN

NATURE...WITH VERY POOR LOW TO MID LAPSE RATE PROFILES DUE TO LITTLE

SURFACE HEATING AND WARM AND DRY AIR ALOFT. INDEED...NONE OF THE

ONGOING CONVECTION EVEN HAS LIGHTNING...SUGGESTING UPDRAFT STRENGTH

IS WEAK AS WELL.

ALTHOUGH INSTABILITY IS QUITE WEAK...AND UPWARD

ACCELERATION/STRETCHING POTENTIAL APPEARS LIMITED...SOME OF THE

DEEPER STORMS MAY AT LEAST BE CAPABLE OF STRONG TO LOCALLY DAMAGING

WINDS GIVEN THE STRONG FORCING ASSOCIATED WITH THIS SYSTEM. A

WEAK/BRIEF TORNADO STILL MAY OCCUR...ESPECIALLY WITH THE DRYLINE

STORMS AS THEY CONTINUE NEWD INTO A SLIGHTLY MORE MOIST ENVIRONMENT.

HOWEVER...LOSS OF HEATING AS WELL AS WARMING ALOFT WILL WORK AGAINST

TORNADO POTENTIAL.

AS SUCH...A WATCH IS NOT ANTICIPATED.

..JEWELL.. 10/19/2011

ATTN...WFO...AKQ...MHX...LWX...RAH...ILM...

LAT...LON 34147883 34937899 35527912 36097879 37027798 37677720

38357669 38437574 38017515 37057581 36227562 35567541

35167546 34467662 34217744 34147883

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That's somewhat emberassing, never thought it worked like that.

And I can't be sure that was the problem, but there is definitely a chance. It would almost never be a problem in Bethesda since LWX is only 19 miles away, but the cloud bases were ridiculously low yesterday. At the 0.5° scan, the center of the beam would be 1154' above sea level over Bethesda (875' if I remember high school trig, plus the 279' elevation of the radar). If the ceiling was indeed 600' at DCA (near sea level), you can see where the problem lies.

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And I can't be sure that was the problem, but there is definitely a chance. It would almost never be a problem in Bethesda since LWX is only 19 miles away, but the cloud bases were ridiculously low yesterday. At the 0.5° scan, the center of the beam would be 1154' above sea level over Bethesda (875' if I remember high school trig, plus the 279' elevation of the radar). If the ceiling was indeed 600' at DCA (near sea level), you can see where the problem lies.

Ah thanks makes sense. I knew nothing about how satellite radar operates. Theres another one for the book of BB screwups.

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have been getting a steady, drenching rain for the past hour and nothing on radar, not sure why that is. 0.09" in the past hr, 0.61" for the event total.

Also the DP is 65 degrees, temp is 66 degrees. Nastiness

We have that a lot up in eastern areas of SNE. Many times when we have warm moist air override the cooler air at the surface and a ne wind..we get this low top, but very efficient rain process. Droplet size is small, but it adds up. That happens a lot with a very warm and most airmass if you don't have strong updrafts and the cloud is warm (below 32F)...but collision and coalescence allows many small droplets to form.

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We have that a lot up in eastern areas of SNE. Many times when we have warm moist air override the cooler air at the surface and a ne wind..we get this low top, but very efficient rain process. Droplet size is small, but it adds up. That happens a lot with a very warm and most airmass if you don't have strong updrafts and the cloud is warm (below 32F)...but collision and coalescence allows many small droplets to form.

Thanks a bunch for the knowledge, makes sense now. Reminds me of my years in Seattle though not sure if it's the same process?

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