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April 28-30th Severe Threat and Flood event potential


mackerel_sky

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Even if the clouds hang on today, we still have to worry about tomorrow. Just trying to remember the last big outbreak we had in NC back in April 2011. What was it like that morning? I thought it was similar to today, cloudy and overcast for the most of the day, and then the sun came out some in the afternoon. It doesn't take much if the conditions are ripe enough. 

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Yeah..visible imagery shows the low cloud deck eroding SE of the Triangle from SE to NW. Will be interesting to see if we can break out of this low cloud deck in the Triangle by early afternoon.

 

The fog is starting to lift in downtown.  It's still foggy, but it's noticeably less so than a half hour ago.

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Even if the clouds hang on today, we still have to worry about tomorrow. Just trying to remember the last big outbreak we had in NC back in April 2011. What was it like that morning? I thought it was similar to today, cloudy and overcast for the most of the day, and then the sun came out some in the afternoon. It doesn't take much if the conditions are ripe enough. 

 

Yup, it was incredibly windy and cloudy.

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I just took a look at the national radar which shows a growing split between an area of precipitation in Alabama and Georgia near the gulf and another area just to the north of the North Carolina/Virginia border.  I'm wondering if today will turn out to be like yesterday for central NC with very little rain and overcast skies.  It's almost noon and the temperature outside is 56F.

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I don't think we are going to have much severe weather all our moisture is hanging by the gulf.. 81 with full sunshine here

 

PWATS are 1.3-1.5" over all of central and eastern NC thats above normal for this time of year.....plenty of moisture to work with....there will be storms firing along the boundry and all in the warm sector of NC later this afternoon.

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Last hour Raleigh was 57 while Goldsboro was 71...there's a boundary in there somewhere.

 

Finally got some stronger filtered sun here and temps are responding as are DP's going to be interesting to see if the storms can get going and how they do today might be a good indicator of how tomorrow will go......

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Finally got some stronger filtered sun here and temps are responding as are DP's going to be interesting to see if the storms can get going and how they do today might be a good indicator of how tomorrow will go......

 

The clouds continue to thin SE of the Triangle. Also, take note of the two cells that have developed near Greensboro in the last hour...that's interesting to me given the stable/cool air regime there. If storms are firing there I suspect there will be greater coverage this afternoon in the warm sector as better lift overspreads the region.

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looking at the visibile imagery, eastern NC and far east SC should see some decent heating today with a thin cloud layer.

 

 

Down here in SENC, had plenty of FOG Early this morning... Sunshine;(fuel) has broken through, It's MUGGY, Wind(s), West~ WSW around 10~15mph...

Temp(s) currently 77, dew of high 60's...

Looking for the SeaBreeze to Hopefully to fire today, though for severe Activity, T-storms, I'd be Looking more Inland around the **Piedmont trough** ... Fairly New overview of this; related to Weather here throughout the Coastal Plain & Central NC/SC/GA..

(As another poster opined about Fayettnam/ Elizabeth Town and sections of the CENTRAL Coastal Plain... Being a **Tornado Magnet**).... Great explanation; for those that haven't read up on this relative New Phenomena discovered here in the Coastal Plain(s)..

Hope I made a contribution to the thread...

LINK--> http://theweatherprediction.com/weatherpapers/026/index.html

 

In part---> QUOTE:  The piedmont trough is a relatively new discovery in the eastern part of North Carolina. The key effects of a piedmont trough are soil type and diurnal heating. The North Carolina Sandhills region of the Southeast is an elongated area of sandy soil that is located adjacent to regions of varying soil type. The Piedmont area in the eastern part of the state has soils that are mainly loam and clay-loam, while a variety of soil types exists in the Coastal Plain to the southeast. It is the differences in these soil types that create differential heating of the surface. Areas with sandy soil will more easily release their moisture to the area, allowing for a higher sensible heat flux than loam or clay-loam soils. This allows more energy to be used for heating the surface rather than evaporating moisture in the soil. Also, the heat capacity for sand is much less than that of clay or loam, so that given the same amount of energy, sandy soil would increase in temperature more than the loam or clay soils. End quote..

 

As per Disc's Sat Pic, I notice some Gravity Waves "incoming"...

Look closely at the Sat Pic..

 

post-2767-0-11114100-1398790357_thumb.jp

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DAY 1 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   1130 AM CDT TUE APR 29 2014

   VALID 291630Z - 301200Z

   ...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR SRN
   AND ERN MS INTO W CENTRAL/SW AL...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MS VALLEY TO THE
   GREAT LAKES AND NC/VA...

   ...SUMMARY...
   SCATTERED TO NUMEROUS SEVERE THUNDERSTORMS WILL AFFECT PORTIONS OF
   THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS INTO CENTRAL AND EASTERN
   GULF STATES THIS AFTERNOON INTO TONIGHT. SEVERAL TORNADOES...A FEW
   OF WHICH COULD BE STRONG...VERY LARGE HAIL AND STRAIGHT LINE
   DAMAGING WINDS APPEAR LIKELY.

   ...MS/AL AND VICINITY THROUGH TONIGHT...
   A 90-120 KT MID-UPPER JET STREAK WILL TRANSLATE QUICKLY NEWD FROM TX
   TO THE OH VALLEY TODAY...WITH ASCENT ACCOMPANYING THE JET STREAK
   MANIFESTED AS THE MID CLOUD BAND FROM TXK-JBR.  IN RESPONSE TO THIS
   JET STREAK...A WEAK SURFACE WAVE IS FORECAST TO DEVELOP NEWD FROM LA
   TO THE TN VALLEY...BEGINNING AT THE INTERSECTION OF THE SYNOPTIC
   COLD FRONT A REMNANT OUTFLOW BOUNDARY IN CENTRAL LA. IN THE WAKE OF
   A LARGE OVERNIGHT MCS...RAPID RECOVERY IS ENSUING FROM LA TO SRN MS
   AS SURFACE HEATING OCCURS AND THE MARITIME TROPICAL AIR SPREADS
   NEWD.  THE PLUME OF STEEPER MIDLEVEL LAPSE RATES HAS BEEN CONFINED
   TO THE NW GULF COAST...WITH WEAKER LAPSE RATES WHERE WIDESPREAD
   CONVECTIVE OVERTURNING OCCURRED OVERNIGHT.

   THE LOWER 70S BOUNDARY LAYER DEWPOINTS AND SURFACE TEMPERATURES
   WARMING INTO THE LOW 80S WILL RESULT IN MLCAPE OF 2500-3500 J/KG
   ACROSS LA BY MIDDAY...WHILE LESSER BUOYANCY WILL DEVELOP NEWD INTO
   AL.  STRONG DEEP-LAYER VERTICAL SHEAR WILL SUPPORT SUPERCELL
   DEVELOPMENT IN THE ZONE OF RAPID DESTABILIZATION...AND A COMBINATION
   OF DISCRETE CELLS AND CLUSTERS WILL SUBSEQUENTLY SPREAD NEWD ACROSS
   MS/AL DURING THE AFTERNOON.  LARGE HAIL /SOME SIGNIFICANT/ AND
   DAMAGING WINDS CAN BE EXPECTED WITH THESE STORMS...WITH THE
   POTENTIAL FOR ANOTHER MCS TO EVOLVE BY THIS EVENING ACROSS CENTRAL
   AL.  EFFECTIVE BULK SHEAR AOA 70 KT AND EFFECTIVE SRH OF 150-200
   M2/S2 IN A MOISTENING ENVIRONMENT WILL SUPPORT THE RISK FOR
   TORNADOES...AND POSSIBLY A COUPLE STRONG TORNADOES WITH THE MORE
   DISCRETE STORMS LATER THIS AFTERNOON.

   ...NC THIS AFTERNOON...
   SURFACE HEATING ALONG A WARM FRONT WILL EVENTUALLY RESULT IN
   SUFFICIENT DESTABILIZATION FOR THUNDERSTORM DEVELOPMENT THIS
   AFTERNOON.  THOUGH LAPSE RATES ARE NOT PARTICULARLY STEEP...MODERATE
   BUOYANCY IS STILL EXPECTED WITH THE INCREASING LOW-LEVEL MOISTURE.
   ALSO...VERTICAL SHEAR PROFILES ALONG THE FRONT WILL BE FAVORABLE FOR
   SUPERCELLS...WITH AN ATTENDANT RISK FOR A COUPLE TORNADOES IN
   ADDITION TO LARGE HAIL AND DAMAGING WINDS.

 

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If there was just a little more moisture being transported overhead, I'd like my chances at a good old fashioned thunderboomer   :lol: Looks like I have that nice little complex of storms in Florida to thank for that   :(    

 

You sitting on a powder keg and the shear is flexing in from the west on the latest SPC meso products, the thing hurting you guys is something to set off the powder keg.

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Crazy, DEW just shot up from 67 to NOW,,  ---> 77 in since My last post...

Temp 77

Heat Index 78 °F Dew Point 77 °F Humidity

100%

 

 

Updated Local AFD for the SENC area(s)... 

Area forecast discussion
National Weather Service Wilmington NC
1159 am EDT Tuesday Apr 29 2014

Synopsis...
the risk for severe weather will increase today and peak Wednesday
and Wednesday night. Severe weather may still be possible on
Thursday. A cold front will move across the area late week. High
pressure will bring dry weather for the weekend...although a front
may approach the area from the north early next week.

&&

Near term /through tonight/...
as of 1140 am Tuesday...a front lies just to the north of a line
from Watha to Elizabethtown to Lumberton. This front will likely
become the focus for showers and thunderstorms through the afternoon
and evening. This front will try to lift further to the north
through tonight...but if a large number of storms do indeed
develop...the front may have a difficult time making any significant
northward advancement as in this scenario...a significant cool pool
would develop. The highest risk for damaging winds and large hail
will be west of the seabreeze. Although a tornado can not be ruled out
anywhere along and west of the seabreeze...the highest risk for a
tornado will be along the frontal boundary draped along and north of the
forecast area where converging winds and shear will be strongest and
most persistent.

Isolated to scattered showers or thunderstorms are expected along a
pronounced seabreeze boundary. Finally...other showers and
thunderstorms may develop anywhere across the forecast area or move
into the area from the west and SW as we will remain in the warm and
unstable sector ahead of an upper level disturbance.

P/west values will be near 1.50 inches and so the risk for heavy rain
is high. Any convection that redevelops in the same general area or
trains will have the potential to produce significant ponding.

Temperatures will remain above average through the period...with
highs in the lower to middle 80s...middle and upper 70s at the immediate
coast...and lows in the muggy upper 60s and lower 70s.

&&

Short term /Wednesday through Thursday night/...
as of 300 am Tuesday...expect a rather unsettled couple of days as a
slow moving middle level system moves across the Midwest. I have
incrementally increased probability of precipitation across the board. The highest values
occur between 0000 and 0600 UTC Thursday when the best forcing...middle
and upper level divergence and moisture...the atmospheric river now
moving across the middle south are coupled. Storm Prediction Center continues to highlight
the area in a slight risk for Wednesday. No changes to the
temperature forecast which will be highly dependent on the coverage
and timing of convection.

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mcd0476.gif

MESOSCALE DISCUSSION 0476
   NWS STORM PREDICTION CENTER NORMAN OK
   1226 PM CDT TUE APR 29 2014

   AREAS AFFECTED...FAR NRN SC...NC...FAR SRN VA

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

   VALID 291726Z - 291900Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT

   SUMMARY...A SEVERE THREAT IS EXPECTED TO DEVELOP THIS AFTERNOON. AS
   CELLS INCREASE IN INTENSITY...A FEW TORNADOES MAY OCCUR WITH THE
   MORE DOMINANT ROTATING STORMS. THE STRONGER CELLS WILL ALSO BE
   CAPABLE OF PRODUCING HAIL AND DAMAGING WIND GUSTS. WW ISSUANCE MAY
   BECOME NECESSARY ACROSS NC LATER THIS AFTERNOON.

   DISCUSSION...THE LATEST SFC ANALYSIS SHOWS A SHARPLY-DEFINED WARM
   FRONT EXTENDING EWD ACROSS CNTRL AND ERN NC. THUNDERSTORMS ARE
   DEVELOPING NORTH OF THE BOUNDARY IN A WEAKLY UNSTABLE AIRMASS. THIS
   ACTIVITY COULD CONTAIN A HAIL THREAT. FURTHER TO THE SOUTH ACROSS
   SCNTRL NC AND NRN SC...MODERATE INSTABILITY IS IN PLACE WITH MLCAPE
   ESTIMATED IN THE 1000 TO 2000 J/KG RANGE. THE WRF-HRRR AND 12Z NAM
   ARE INITIATING SCATTERED CONVECTION OVER THE NEXT FEW HOURS ON THE
   NRN EDGE OF MODERATE INSTABILITY EXTENDING NWD TO NEAR AND JUST
   NORTH OF THE WARM FRONT. DUE TO CONTINUED DESTABILIZATION AND
   MODERATE DEEP LAYER SHEAR ASSOCIATED WITH A 50 TO 60 KT LOW TO
   MID-LEVEL JET...CELLS SHOULD BECOME ORGANIZED AS CELLS INCREASE IN
   COVERAGE THIS AFTERNOON. IN ADDITION...0-3 KM STORM RELATIVE
   HELICITIES AROUND 400 M2/S2 EVIDENT ON THE RALEIGH NC WSR-88D VWP
   SHOULD SUPPORT SUPERCELL DEVELOPMENT AND A POTENTIAL FOR TORNADOES.
   A WIND DAMAGE THREAT SHOULD ALSO DEVELOP AS LOW-LEVEL LAPSE RATES
   STEEPEN. ISOLATED LARGE HAIL MAY ALSO OCCUR WITH THE MORE INTENSE
   CORES.

   ..BROYLES/THOMPSON.. 04/29/2014
 

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