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RIC Airport

Richmond Metro/Hampton Roads Discussion

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Spring can go ahead and arrive now. I don't see us getting anymore snow the way this pattern is. Technically, RIC did get above average snowfall but almost all of it came back on the December event. Since then it's been cold rain. 

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Can't say I call it just yet the Next Weds- Monday time frame will be our best hope in awhile.. Nothing certain but Def still a chance.. ha

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12 hours ago, eaglesin2011 said:

Can't say I call it just yet the Next Weds- Monday time frame will be our best hope in awhile.. Nothing certain but Def still a chance.. ha

I'm calling it. We are done. Persistence this winter has been north and west. 12/9 was a fluke. On to 2019-20. 

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12 minutes ago, RIC Airport said:

I'm calling it. We are done. Persistence this winter has been north and west. 12/9 was a fluke. On to 2019-20. 

I’m calling it too even up here.  This event is the shovel of dirt in my 6ft hole.  19-20 will be rockin’

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3 minutes ago, wasnow215 said:

Any thoughts on tomorrow night’s/overnight into Monday severe threat?

LWX had a great write up in their evening AFD that I posted in the catchall severe thread... dunno what Wakefield is saying though

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April 17, 2019

this Wednesday afternoon

502 PM EDT

 * * * *  Severe Weather & Heavy Rainfall event for Eastern Virginia  * * * * 

 * * * *  Coming for Friday afternoon & Friday night, 4/19/2019  * * * *

 * * * *  Tornado Watches, warnings, & urban-small stream flood advisories likely * * * *

I.  Introduction.

So the way I see this upcoming Friday afternoon, 4/19, & night event playing out is this:  I see 2 rounds of inclement weather moving in to the Richmond, VA & Eastern Virginia region starting-up early Friday afternoon.  This 1st phase on Friday afternoon, I think will bring the attendant severe weather risk of a wind damage threat & some tornadoes, too.

The 2nd phase of this event I believe will evolve on Friday night, & take shape as a heavy rainfall event, through the late night hours.

II.  Friday afternoon Severe Weather.

I'm going to quantify the severe weather threat in a numbers sense, by touching on the calculated indices.

Here's a look at the severe weather parameters, advertised on Friday afternoon, CENTERED on Richmond, VA, at 2 PM Friday:

#1.)  SB-Cape:  2 PM-5 PM Friday -- Averaging about 1,000 J/kg, varying 750 J/kg from Gfs; 1250 J/kg Nam  This average amount of 1,000 J/kg will be sufficient to sustain convective severe storms on Friday afternoon, with no doubts.

#2.)  SWEAT index -- 2 PM Friday:  321 - 349.  This assesses the tornado risk.  I pay close attention when this value reaches 350+.   To get large tornadoes a high degree of instability with high wind shear gets involved.  I also watch for a BACKED surface wind, and arched hodographs.  Straight-lined hodographs are indicative of a squall line, or line echo wave patterns, lewps.  I don't see much directional shear here, with winds coming from a Southerly direction through the depth of the troposphere.  This value upwards to 349 is marginally close enough to continue the watch for a few or several tornado warnings, owing to the cape & shear values present.

#3.)  TT's:  of 46-48 for Friday afternoon.  This is a non-player for Friday afternoon & night, as this parameter is focused on assessing the hail threat, with its examination of the thermal profile comparisons aloft at different layers.  Values at and above 50 indicate severe storms, and in the mid 50's, scattered severe storms.  But values now are shown to be mid to upper 40's.  

#4.)  Calculated PEAK WIND GUSTS:  52 kts, Gfs; 54 kts, Nam between 11 AM to 5 PM Friday 52 kts = 60 mph; 54 kts = 62 mph.

The 54-hr Nam forecast Skew-T sounding shows the presence of an inverted-V sounding at 2 PM Friday.  This along with the NOSE of an approaching jet max at 850 mb, 5K ft, level at speeds of 40 kts increase to 55 kts, will be sufficient to produce and enhance microbursts & downdrafts.  The leading edge of an accelerating jet max in the lower levels as this has well been known to de-stabilize the atmosphere by instigating the formation of warm-air advective showers & thunderstorms, at the gradient of the change, as it punches Northbound.  This will be in play on Friday afternoon over Eastern Virginia.  Watch for attendant severe weather in the form of wind damage by fast-racing showers & storms.

#5.)  0-6 km shear, (deep shear) -- Values appearing between 47 kts, Nam to 56 kts, Gfs for Friday afternoon in Richmond, VA.  Minimum threshold desired for severe weather is 40 kts; this is already forecast to be exceeded.  

#6.)  500 mb, ~18K-19K ft winds:  Forecast at 55 kts to 70 kts between 2 PM and 8 PM Friday afternoon.  I look for a minimum value of 40 kts to be reached for severe weather, so this amount forecasted well exceeds this for the promulgation of severe storms, at the mid-level altitudes.   At 250 mb, in the highest altitudes, ~35K ft, only 60 kts is forecast.  While not a particularly necessary condition, it's great when winds at this level exceed 100 kts, as a dynamic suction vacuum aloft, as it helps increase UVV's, as what transpired in your late Sunday night even.  But more importantly, the lower levels are where high winds are needed to produce the damaging wind gusts, which will be present at 850 mb.

#7.)  PW, preciptable water, moisture values escalate quickly between Friday morning to Friday afternoon, between 0.97" 8 AM Friday to 1.68" Friday at 2 PM, Nam; and 1.2" 8 AM Friday to 1.7" 2 PM Friday by Gfs.  All the right ingredients at all the right timing together should quickly inflate this event to severe levels on Friday.  Sudden increase in moisture; sudden increase in low & mid-level jets, sudden increase in SB-cape, and rising of instability with daytime heating, although will be preceded by cloud cover.  

III.  Heavy Rainfall Event, Friday night.

Whenever I spot this pattern of a closed upper 500 mb low, slowly approaching with a LENGTHY, fetch of meridional 500 mb flow from South-Southwest at all levels of the troposphere, at terrific speeds of 40-60 kts from boundary layer to mid-levels, then this *screams* th words heavy convective rainfall all over it, for Friday night.  Having been a long-time resident of New Orleans for 17 years of my life, I've come to recognize these pattern settings down South.

Of particuarly importance that I've also spotted is your 12Z Gfs rainfall grid that depicts what I call a RATHER SLOW progression of a thick, heavy rain band which only moves from Western Virginia at 2 PM Friday over to Eastern Virginia 12 hours later, at 2 AM Saturday.  Gang, that's a SLOW 12-hour progression, only going from Western Virginia to Eastern Virginia in a 12-hour span of time.  And this is coming from a model who's notoriously biased in being overly progressive in moving out rain quickly.  

Additionally, I see a sharp uprising in PW's from 1.20" 8 AM Friday up quickly to 1.70" 6 hours later, at 2 PM Friday afternoon, coincident with the nose of an 850 mb low-level jet increasing during peak heating time & instability time as well.

Whenever I see 3-hour rain rates of 3/4" to 1" being advertised 54-60 hours in advance over a progressive 12 hour period across the state of Virginia in the coarser grid domain of the GFS, I can only be thinking that once this hits the finer-mesh resolution grids of H-Rap & WRF, that these rainfall rates will be AMPLIFIED SO MUCH GREATER.  PLUS, I also have to be thinking there will be numerous heavy bands of 50+ dbz rates.  And when that happens amidst a strengthening powerful low-level & mid-level jet structures in the presence of modest, but ample levels of SB-Cape, then this spells both a severe risk & heavy rainfall potential that looks pretty certain to unfold on Friday afternoon & Friday night.  I think 1" to 3" of rainfall will be commonplace for rainfall totals between Friday afternoon & Friday night.  

Any stalling of this heavy rain banding that sets up meridionally, from South to North will accentuate rainfall totals beyond 4" for any temporal stalling of this heavy rainfall in areas as it slowly crawls Eastbound.

Last Sunday night's event escaped everyone's attention because of the inopportune timing of 1 AM and 4 AM, while nearly most were sleeping.  Not this time.  This time many of you will be up to watch it on radar & feel the experience for yourselves.  

 

--  cyclogenesis 

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April 19, 2019

this Pre-Dawn Friday morning

115 AM EDT

 

* * *  Still a good chance for severe storms & HEAVY RAINFALL for the Richmond, VA area, Friday afternoon & Friday night, 4/19  * * *

* * *  Tornado watches likely to be issued by early Friday afternoon, for Richmond & Eastern Virginia * * *

* * *  Predominant threat still looks to be spots of wind damage & heavy rainfall, ponding of water * * * 

* * *  3 distinct rounds of storms coming  * * * 

 

I.  Timing for Richmond, VA.

 

I'm seeing 3 distinct time periods for showers & storms for Richmond, VA on Friday.  The first wave comes betweeen 3 PM and 4 PM.  The 2nd more serious severe round of weather comes in the evening hours between 5 PM and 7 PM, and then after 8 PM, comes the 3rd round which I think will be the heavy rain period spanning from 7 PM onward to 11 PM.

Viewing late this Thursday night, at timing progressions, appears this weather event will present itself starting as soon as early Friday afternoon, in the form of detached showers randomly racing Northward through the area.  Shower activity will first start out WEST of us and SOUTHWEST of us in the late morning hours.  Then, about the timing in the early afternoon, between 12 PM and 2 PM, I think the 1st tornado watch will be issued close for Richmond.  Storm warnings for detached multi-cellular activity should come between 1 PM and 5 PM.  Interestingly enough, WRF's animation shows NO pockets or LINES of 40+ or 50+ 10 meter surface wind gusts in its 1-hour grids, as I step through its 00Z, 4/19 output.  Non-important, low-ranking moisture advection showers will begin racing Northbound late Friday morning in our area, with SB-Cape increasing during the 11 AM to 2 PM time frame. 

II.  More details. 

Discrete & unattached multi-cellular showers & a few storms should develop across the area between 11 AM and 2 PM, well ahead of the parent line, since a strong morning capping inversion at 8 AM, shown at 12Z/8AM on Nam's 12 hr depiction btwn 800 mb - 750 mb withers away completely by 2 PM, with 0 CINH, (convective inhibition) remaining by 2 PM.   

It's appearing there'll be a revised 750 J/kg, to at most 1,000 J/kg of SB-Cape available for Friday afternoon's storms in the Richmond area. 

While severe weather parameters such as SWEAT, Cape, helicity, Total-totals have all de-escalated since I last wrote you, and numbers have come down a bit, it cannot be ignored that a stout 45kt-55 kt low-level 850 mb jet and 55-60 kt 500 mb jet will be overhead during peak afternoon hours, concurrent with rising Cape levels, although still a bit on the low side of 750 - 1000 J/kg.  While neither speed shear nor directional shear for long-lived supercellular storms are present, the overall wind momentum throughout the depth from boundary layer to mid-levels is impressive enough to be able to transport some of this high wind momentum downward in the heaviest rain shafts produced of the multi-cellular & linear squall line modes.  You generally see a greater occurrence of wind damage with a veered WESTERLY component, but in this case we're dealing with a SOUTHERLY direction, and a fetch of deeper moisture, which is why I believe the heavy rain & flooding threat is kept alive for Friday night across Virginia.  So, not the most idyllic directional consideration for production of severe winds, the speeds are still great enough to produce instances of wind damage.

Also, on account of the TIMING of day, during the afternoon hours, helicity is shown to run upwards to 300 m2/s2 by WRF's modeling scenario, while NAM shows a spiked pocket of 350 to 500 m2/s2 helicity at 5 PM very near the Richmond area.  WRF's maximized CAPE timing is shown to come about 6 PM to the RVA area, right along the SAME TIMING of an approaching squall line to Richmond in the LATE afternoon hours between 5 PM and 7 PM.  

This timing of late afternoon & early evening 5 PM to 7 PM looks to correlate to the highest amount of Cape nearest to Richmond, at a timing when a squall line should be traversing the scene, along with the helicity, so tornado threat & SEVERE WIND THREAT look to be MAXIMIZED, I believe, at this timing of late afternoon & early evening for Richmond. 

Beyond 7 PM, it's a matter of how much RAIN & STORMS LINGER stagnate behind the parent line, as this is where I see the heavy rainfall event unfolding from Friday evening in to Friday night, from 7 PM to 11 PM.  This is the timing for a few flood warnings to be issued.  A higher BAND of PW's, precipitable waters, (1.6" to 1.85"), arrives our area between 11 AM to 2 PM, and REMAINS this HIGH, onward to 11 PM, Friday night.  Virginia Beach & the Hamptons looks to get their heaviest rain threat later in the night, 11 PM to 2 AM.  All of this mess scoots out the area by sunrise, Saturday.

 

-- cyclogenesis    

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Getting pretty warm in RVA. Cloud cover has increased. Had peaks of sun this morning for a few hours.

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Think this little rain storm here in my area (Glen Alen) may of decreased  the tornado chances for this specific area.

The more south definitely the higher chance of tornadoes & straight line winds. .. The main storms will be out of most of the area by 9pm

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April 26, 2019

this early Pre-Dawn Friday morning

149 AM EDT

 

* * *   Risk of Severe Storms across Eastern Virginia today on Friday, April 26, 2019  * * * 

* * *   Few severe T-storm warnings, with a watch box quite possible around late morning through the late afternoon * * * 

* * *  High wind gusts & hail to be the main perils starting late morning through late afternoon * * *

I.  Introduction.

It's appearing that the best timing, in Richmond, VA, for a few severe storms will run between 10 AM and 6 PM, with the peak in the early afternoon to mid-afternoon.  The appearance on radar should be multiple clusters of cellular activing both before a thin-banded squall line and shortly afterwards.  A pre-frontal trough is scheduled to sweep through the Richmond, VA area by late Friday afternoon about 5 PM, with wind shift to the West.  Then the cold front should pour in colder air to Richmond, later Friday night starting 10 PM to 11 PM.  

II.  Upper levels.

An upper level trough extending from Eastern Michigan South through Central Kentucky & Tennessee at 11 AM on Friday morning will dig Southeastward to a position extending from Western Pennsylvania to Western Virginia & Central North Carolina / South Carolina by 5 PM Friday.  

During this time of late morning through afternoon, a SW 850 mb ~5K ft low-level jet will be in place across Virginia, at speeds of 35-45 kts.  This, atop, a mid-level jet at 500 mb, ~19K ft, 45kts - 55 kts will work together to create 0-6 km shear between 40-50 kts, with a surface wind from the South-Southwest at 15-20 kts, just prior to the pre-frontal surface trough passage in the late afternoon.  Surface dewpoints will rise to the upper 50's during the early afternoon, with a high temp. in Richmond reaching 77°.   Precipitable water, PW, amounts increase upwards to 1.4" by early afternoon, with the best pooling of moisture at that time, before falling backward by later afternoon, with the pre-frontal trough wind shift to the West.

III.  Severe Indices.

Most of these indices do not look that impressive on areal forecast Skew-T soundings.  Helicity looks low & flat, generally 200 - 250 m2/s2 on account of the straight-lined hodographs overhead Richmond at peak timing of severe.  With uni-directional wind profiles from late morning to mid-afternoon, coming from the Southwest, this suggests a better threat for a few damaging straight-line thunderstorm wind gusts, vice a smaller tornado threat.  

Conventional forecast soundings from both models show a peak wind gust from Gfs to be 48 kts and from Nam to be 51 kts with storms between late morning through late afternoon.  Amidst other models, WRF higher resolution model doesn't indicate any peak wind gusts even to 40 kts during its one-hour peak wind gusts through the convective period.

One area that did catch my eye was the forecast temperatures at 700 mb & 500 mb running between 1°C at 700 mb at 2 PM and about -14 to -15°C  at 500 mb at 2 PM.  These 500 mb temps cool further to -20 to -21C by 8 PM.  With this cold-air advection spreading in ALOFT in the upper levels during the afternoon, this could help promote a HAIL threat with SB-Cape running between 750 J/kg to about 1,200 J/kg at the height of the event.  Wet-bulb zero heights by both forecasting models reach the favorable 8000-9000 ft level for hail production.  The trickiest part about forecasting hail is that the thermal profile aloft comes typically most favorable *after* the best upper level ascent, (upward dynamic forcing), has already passed.   

While CVA / PVA is evident at 500 mb, this supports the lightning-thunder threat as cyclonic vorticity advection promotes this aspect, the trouble I'm seeing is that H-Rap doesn't show much lightning density strikes showing up, even though spotty convective cellular activity reaches 50 dbz in spots across Eastern Virginia.  Watch to see if later hourly updates includes some increase.  Hail storms are typically associated with plenty of lightning occuring within the cumulonimbus cloud.

I reviewed 250 mb upper divergence dynamics, and don't see anything heralding; Gfs 700 mb strongest UVV's, (Upward Vertical Velocities), come in to the RVA area around 2 PM, and it appears most models are anticipating a broken line of storms that comes together as it advances in through Eastern Virginia, perhaps firming-up the strongest once passing EAST of Richmond.

IV.  Rainfall Amounts.

-- Centered on Richmond, VA --

A.)  Gfs -->>  0.49" between 8 AM and 8 PM Friday

B.)  Nam -->> 0.35" between 8 AM and 8 PM Friday

C.) ECMWF -->> 0.81 , 8 AM - 8 PM Friday

D.)  UKM -->>  0.32" , 8 AM - 8 PM Friday

E.)  WRF -->>  ~~ 0.50", approx. 8 AM - 8 PM Friday

Other non-decorated, non-celebrated showers will occur prior to 8 AM Friday morning, and this is already light rain showers appearing on radar at 145 AM as I write this.

V.)  Conclusion

While I don't see this shower & thunderstorm event being as grand as the previous 2 events, in the preceding 1-2 weeks prior, there is enough instability & speed shear present on Friday which should sustain several waves / clusters of showers and a few thunderstorms, throughout the day, with a few storms having the eligbility to reach severe levels, (high winds/hail), as the approaching upper short-wave trough sharpens & approaches the Mid-Atlantic states by early this evening.  

-- cyclogenesis

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June 17, 2019

this Monday night

1115 PM EDT

 

Hey Gang,

 

Those of yous guys in the Eastern Virginia region, I think it continues to look interesting for severe storms coming up...especially on Thursday evening, June 20.  Also, I'm getting some subtle clues that tomorrow evening on Tuesday evening & Tuesday night, this may be a more widespread & lingering heavy thunderstorm event that unfolds across Southeast - Eastern Virginia, the way the Precip. Water mappings show a persistent plume of higher moisture feed that hangs in the same area during the evening & overnight hours.  Simulated rainfall also suggests it on a couple of the forecast models.  

 

As for Thursday evening, LOTS of high wind momentum gathers quickly with a great amount of instability & moisture all pooling together for this event.  Lifted indices quite low at -7°C.  SI at -6°C & K-index in upper 30's all highly supportive of T-storms.  SW fcst to be 409-487 & TT's at 53.  This all spells a good likelihood for SEVERE STORMS in this area come Thursday evening.

 

-- cyclogenesis  

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