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June Obs and Daily Disco


H2O

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  lots of model agreement that multiple waves of rainfall will be moving through the Mid-Atlantic through the evening and overnight hours but still a lot of disagreement on the placement/timing of the heavier rain.   For those wanting good storms, one issue is that the NAM and HRRR both have very, very little progged instability unless you go well west or south of DC, even for parcels starting above the boundary layer.    It's possible that lightning may be quite limited, and it may just be soaking showers.

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  lots of model agreement that multiple waves of rainfall will be moving through the Mid-Atlantic through the evening and overnight hours but still a lot of disagreement on the placement/timing of the heavier rain.   For those wanting good storms, one issue is that the NAM and HRRR both have very, very little progged instability unless you go well west or south of DC, even for parcels starting above the boundary layer.    It's possible that lightning may be quite limited, and it may just be soaking showers.

 

Is that just for the regular NAM, or does that include the HI-RES one as well?  The 4KM NAM seems to like a band of what looks to be heavy storms in N VA around 11pm

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    I saw that - not sure what to make of it.   Both the NAM and NAM nest forecasts for 3z tonight have at best a few hundred j/kg of best (accounting for sfc-based and elevated parcels) cape.   The values are slightly higher further west where it has the storms at 3z (although seemingly still not sufficient for intense updrafts), but with the cape dropping off ahead of it, I would expect weakening if these forecasts are correct.  I still wonder if these good reflectivity signals are just indicating very heavy rain showers, consistent with the 2"+ precipitable water values that the NAM (and GFS) are showing.

 

 

Is that just for the regular NAM, or does that include the HI-RES one as well?  The 4KM NAM seems to like a band of what looks to be heavy storms in N VA around 11pm

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    I saw that - not sure what to make of it.   Both the NAM and NAM nest forecasts for 3z tonight have at best a few hundred j/kg of best (accounting for sfc-based and elevated parcels) cape.   The values are slightly higher further west where it has the storms at 3z (although seemingly still not sufficient for intense updrafts), but with the cape dropping off ahead of it, I would expect weakening if these forecasts are correct.  I still wonder if these good reflectivity signals are just indicating very heavy rain showers, consistent with the 2"+ precipitable water values that the NAM (and GFS) are showing.

That's a shame - but doesn't surprise me. Do you have any thoughts for the weekend with possible Bill remnants?

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FWIW, SPC has added the SW portion of the LWX CWA as having a SLGT risk for severe on their 1630 OTLK... as in down by CHO/Staunton/Harrisonburg... marginal gets close to EZF

 

ETA:  MD out -- http://www.spc.noaa.gov/products/md/md1047.html

 

Seems to include SW corner of LWX CWA since LWX is mentioned on the ATTN line

 

 


 ...MIDDLE OHIO VALLEY INTO CENTRAL APPALACHIANS...   A BELT OF 30-40 KT LOWER/MID TROPOSPHERIC FLOW...ASSOCIATED WITH AT   LEAST A COUPLE OF SUBTLE IMPULSES ROUNDING THE NORTHERN PERIPHERY OF   THE SUBTROPICAL RIDGE...COULD SUPPORT THE EVOLUTION OF ONE OR   MORE...GENERALLY SMALL BUT ORGANIZED...CONVECTIVE CLUSTERS LATE THIS   AFTERNOON AND EVENING.  POTENTIAL FOR INTENSIFICATION OF ONE   SUSTAINED CLUSTER OF STORMS...NOW ADVANCING ACROSS CENTRAL/SOUTHERN   WEST VIRGINIA...APPEARS TO EXIST AS IT PROGRESSES ACROSS AND EAST OF   THE CREST OF THE APPALACHIANS THIS AFTERNOON.  FORCING ALONG THE   AFOREMENTIONED STALLED FRONTAL ZONE MAY SUPPORT ANOTHER EVOLVING   CLUSTER BACK TO THE WEST...ACROSS THE MIDDLE OHIO VALLEY INTO   CENTRAL APPALACHIANS...LATER THIS AFTERNOON AND EVENING.  GIVEN THE   HIGH MOISTURE CONTENT...HEAVY PRECIPITATION LOADING AND THE DOWNWARD   TRANSFER OF MOMENTUM MAY CONTRIBUTE TO THE RISK FOR POTENTIALLY   DAMAGING WIND GUSTS.
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   The guidance seems to have shifted a bit south as what's left of Bill approaches us Sunday - it looked like the remnant center would go to our north, but it looks now like it may come closer.   But if you take the models verbatim, overall shear is weakening a lot, and the timing and strong forcing (it kinda merges with a nice shortwave) would make it more of a heavy rain event than a severe event.  That said, I guess it still bears some watching for severe concerns if it arrives later Sunday.

 

That's a shame - but doesn't surprise me. Do you have any thoughts for the weekend with possible Bill remnants?

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   The guidance seems to have shifted a bit south as what's left of Bill approaches us Sunday - it looked like the remnant center would go to our north, but it looks now like it may come closer.   But if you take the models verbatim, overall shear is weakening a lot, and the timing and strong forcing (it kinda merges with a nice shortwave) would make it more of a heavy rain event than a severe event.  That said, I guess it still bears some watching for severe concerns if it arrives later Sunday.

We just can't buy anything other than heat. 

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  some hi-res simulations teased us with impressive late afternoon / early evening convection, but the majority of the guidance has been showing the most organized lift moving into the area later tonight

 

 

Doesn't look that far off. Nothing heavy in the area attm.

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  some hi-res simulations teased us with impressive late afternoon / early evening convection, but the majority of the guidance has been showing the most organized lift moving into the area later tonight

 

18z NAM continues to insist on a complex of rain and some storms in W VA around 11pm, and coming through C VA around 2am

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   Those plots from TT start using the "exciting" colors at some fairly low values of reflectivity.

 

 

Its so interesting how different tropicaltidbits sim radar is from wxbells. 

 

wxbell doesn't look nearly as exciting as those, yoda. 

 

18z NAM continues to insist on a complex of rain and some storms in W VA around 11pm, and coming through C VA around 2am

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