July 27 Severe Weather Threat

[Dsnowx53]

I can't type too much due to badly spraining my wrist, but I did take a look at the threat for Sunday and it surely looks interesting, particularly on the 00z NAM.

A potent trough is entering the country, but most of the closed off trough should stay in Canada, with a piece of it coming down towards the Great Lakes. This gives us the necessary dynamics for a severe weather event, but prevents our 500mb winds from essentially being due south, which would have given us too much moisture and convective debris.

Relatively westerly flow aloft combined with potent shortwaves in a dynamically and thermodynamically favorable environment lead to plenty of severe weather potential -- particularly just to our south and west, who will be located just south of the strongest shortwave, leading to the most bulk shear (70 knots!), particularly during strong daytime heating.

Though timing may be a tad too slow for us (sigh), the NAM does show things getting quite interesting around 03 - 06z. Vortmax near our area increases dynamics, lowers surface pressures, and allows surface winds to back significantly -- while flow is still relatively westerly and strong aloft. This leads to plenty of bulk shear and helicity.

Additionally, the day 2 SPC outlook is ominous.

The GFS is not as interesting, but still shows a decent combination of bulk shear and instability.

[Animal]

Mt holly nws discussion from this morning is starting beat the war drum on a possible decent event.

[Weathergun]

6z nam backed off with it's convectively-enhanced low Sunday night. But tomorrow morning also has a isolated tornado threat with the warm front. Mlcape is 1k+ J/kg with winds veering more southerly to westerly with height over NE NJ/NYC/LI area.

[Superstorm93]

Upton 

 

 

 

THIS IS WHERE THE FORECAST GETS INTERESTING WITH THE FOCUS TURNING
TO A WEAKENING CUTOFF LOW DROPPING THROUGH THE UPPER MIDWEST
TONIGHT...THE GREAT LAKES SUN AND PIVOTING THROUGH NEW ENGLAND ON MON.
SOME OF THE MODEL GUIDANCE IS INDICATING A SECONDARY AREA OF LOW
PRES DEVELOPING OVER CENTRAL NJ SUN NIGHT...WHILE OTHERS KEEP THE
PARENT LOW IN CONTROL FURTHER N AND W. CONSIDERABLE SPREAD REMAINS
AMONGST THE GUIDANCE WITH REGARDS TO TIMING AND TRACK OF THE LOW.
THE NAM IS THE WORST CASE SCENARIO WITH THE LOW TRACKING NE FROM
CENTRAL NJ TO MA WITH 60+KT OF 0-6KM BULK SHEAR (~15KT 0-1KM
SHEAR)...APPROX 1K J/KG OF SBCAPE...400-500 M2/S2 OF SFC-1KM
HELICITY AND AN LCL BELOW 1K FT AROUND 06Z MON. THIS WOULD BE
SUFFICIENT FOR ROTATING STORMS. HOWEVER IF THIS SECONDARY LOW DOES
NOT DEVELOP THE MOST SEVERE STORMS SHOULD REMAIN FURTHER N AND W.
NEEDLESS TO SAY...STILL SOME FAIRLY BIG UNCERTAINTY IN HOW MUCH OF
AN IMPACT THIS WILL BE...BUT SINCE THERE IS THE THREAT FOR SVR
WX HAVE ADDED ENHANCED WORDING TO THE FORECAST SUN AFTN AND NIGHT.
PWATS INCREASING TO NEAR 2 INCHES ALSO INDICATE THE POTENTIAL FOR
HEAVY RAIN IN ANY THUNDERSTORMS.

[NycStormChaser]

[PB GFI]

The Euro has the first severe threat Sunday morning as the remnant EML crosses the

region. There could be a spin up with this early round of convection as the surface

flow will be SSE under a strong SW LLJ.

 

Screen shot 2014-07-26 at 8.13.03 AM.png

There looks to be 2 rounds one Sun AM and then again late at night . We will have to see how much instability will be left for the 2nd go around .

Sometimes round 2 just tends to be a heavy rain maker . 

[NJWxWatcher201]

Wish we could get this thread pinned or something. Would love to see more convo for a possible TOR threat tomorrow morning around this area.

[Dsnowx53]

12z NAM continues to look impressive for tomorrow morning.

[NJWxWatcher201]

12z NAM continues to look impressive for tomorrow morning.

It does indeed. Def appears to be good timing for the morning .

[Metsfan]

Tomorrow morning looks intriguing.

 

 

[REDMK6GLI]

I will say morning threat to me hold ALOT more merit than these threats that happen in the afternoon and evening that 99% of the time go poof

[SnoSki14]

Morning storms can often over perform under the right conditions.

[NJWxWatcher201]

Morning storms can often over perform under the right conditions.

Usually the case. Anyone who can recall severe morning storms, usually can always say the same.

[Mikehobbyst]

I think many will be startled off the toilet seat while reading their morning newspaper come tomorrow morning, when all of a sudden it goes crash outside, and looks like night at 7:30 in the morning.  Put on traffic and weather channel and see giant red blobs dotted over the area. I'd say close the potty, turn off the faucet, get out of the shower watch for tomorrow morning.

 

I'd say SVR risk is there for tomorrow morning: Warm front mini super cells riding NE from NJ and PA

 

15 % wind

10 % tor

5 % hail

 

-6 LI

2500 Cape

45 knt shear

 

WVA, SE OH and WMD look like super cell city tomorrow. MDT risk ???

 

Sunday night: Squall line possible from West. May miss to the south.

-5 LI

1500 Cape

35 knt shear

 

15% wind

5% tor

10% hail

[REDMK6GLI]

I think many will be startled off the toilet seat while reading their morning newspaper come tomorrow morning, when all of a sudden it goes crash outside, and looks like night at 7:30 in the morning. Put on traffic and weather channel and see giant red blobs dotted over the area. I'd say close the potty, turn off the faucet, get out of the shower watch for tomorrow morning.

Jeez i was looking forward to enjoying my morning doo doo to start off sunday.....well this sucks!

Tommorow morning looks promising thus far, afternoon evening storms im not counting on as ive learned my lesson in the past

[Snow_Miser]

12z RGEM has decent severe weather parameters for the NYC area tomorrow.

 

[Dsnowx53]

^ Love seeing the storm motion and 0-6km shear north of west for tomorrow morning.

[Snow_Miser]

Really decent parameters for portions of NJ tomorrow afternoon on the RGEM.

 

Isolated pockets of Helicity above 3, Lifted Index below -8, wind shear in the 35-40 kt. range, and CAPE above 3000 J/kg.

 

 

 

[NYC Weather Lover]

I think many will be startled off the toilet seat while reading their morning newspaper come tomorrow morning, when all of a sudden it goes crash outside, and looks like night at 7:30 in the morning.  Put on traffic and weather channel and see giant red blobs dotted over the area. I'd say close the potty, turn off the faucet, get out of the shower watch for tomorrow morning.

   Boy, do you like to go into detail!

[REDMK6GLI]

Boy, do you like to go into detail!

Give the man credit he swings for the fences and hangs himself out there to be trolled and verbally abused

[REDMK6GLI]

The 12z Euro has a LI-CT jackpot tomorrow morning with more convection across the

area in the afternoon.

12z-18z

ECMWF_MSLPThickQPF_ne_f30.png

18z-0z

ECMWF_MSLPThickQPF_ne_f36.png

I know this may very well be a two pronged event tommorow chris, but like paul pointed out after severe storms in the morning the atmosphere most of the time cannot recover or destabilize enough to bring severe weather to region. relegating us the heavy rain makes with pockets of stronger storms.

[Yanksfan]

I think many will be startled off the toilet seat while reading their morning newspaper come tomorrow morning, when all of a sudden it goes crash outside, and looks like night at 7:30 in the morning.  Put on traffic and weather channel and see giant red blobs dotted over the area. I'd say close the potty, turn off the faucet, get out of the shower watch for tomorrow morning.

 

 

Oh well, there goes my morning plans!

[REDMK6GLI]

Oh well, there goes my morning plans!

YUP! Stormaggedon is coming tommorow morning, batten down the hatches the rain drops cometh down on thee with great vengeance and fury

[Rtd208]

Mt.Holly:

 

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
THE GFS INITIALIZATION AT 500MB LOOKED BETTER THAN THE WRF-NMMB
WHILE THE WRF-NMMB LOOKED BETTER AT 850MB AND 925MB. OF NOTE THE GFS
HAS BEEN TRENDING DOWNWARD WITH ITS THERMAL MASS FIELDS THE LAST
COUPLE OF DAYS AS WE GET CLOSER TO F00.

AS FAR AS MODEL SHORT WAVE VERIFICATION BASED ON 24HR FCSTS ITS THE
ECMWF, THE GFS @ 18HRS, THEN CAN GGEM AND WRF-NMMB. THIS IS BOTH A
VOLATILE AND ANOMALOUS REGIME FOR LATE JULY AND WE ARE GOING TO RUN
WITH THE ASSUMPTION UNTIL THE TROF CLEARS THAT SHORT WAVES WILL
OUTPERFORM. 12Z UA ANALYSIS SHOWED A POCKET OF 19C DEW POINTS AT
850MB/925MB WEST OF CHICAGO. THIS CANT BE DENIED OVERNIGHT AND
CONVECTION IS FIRING OVER NORTHERN INDIANA.

MEANWHILE AFTER THE ALONG THE COAST SHORT WAVE CLEARS, WAA IS
FORECAST TO CONTINUE OVERNIGHT. TAKE THAT POCKET OF VERY HIGH
EQUIVALENT THETA E AND MATCH IT WITH A FAVORABLE JET REGIME AND WAA,
SEE NO REASON THAT THIS FEATURE CANT KEEP ON PRODUCING PCPN
OVERNIGHT. WHILE POPS HAVE BEEN DROPPED FROM THIS EVENING AS THE
FIRST SHORT WAVE PASSES OFF THE COAST. THEY ARE INCREASED AGAIN
OVERNIGHT WITH THE GREATEST EMPHASIS NORTH.

BIG DEW POINT DIFFERENCES ACROSS OUR CWA MAINLY BASED ON WHERE THE
RAIN HAS FALLEN MORE HEAVILY. WITH AN ATTENDANT SOUTHERLY FLOW
CONTINUING THRU THE NIGHT, WE BELIEVE THE HIGHER STAT GUIDANCE MINS
WILL VERIFY THE BEST, ESPECIALLY SOUTHEAST HALF OF CWA.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
SLIGHT RISK FOR SEVERE THUNDERSTORMS CONTINUES FOR SUNDAY AS OUR RUN
OF DRY WEEKEND WEATHER REALLY TAKES A HIT. NOW COMES THE FORECAST
PROBLEMS OF SHORT WAVE STRENGTH AND THEIR EFFECT ON THE SENSIBLE
WEATHER. HERE OUR CONFIDENCE IS LESS THAN AVERAGE BASED ON THIS
MORNING`S OUTCOME.

THE NEXT SHORT WAVE IS INITIATING AN MCS IN EASTERN NEBRASKA AS
WE TYPE. THIS IS THE ONE THAT THE GFS TAKES TO THE NTH DEGREE ON
SUNDAY MORNING AND MAKES FOLLOWING ITS MASS FIELDS FOR THE REST OF
SUNDAY IMPOSSIBLE. THE GENERAL IDEA APPEARS CORRECT. BUT DOES THIS
SHORT WAVE ARRIVE TOO SOON BEFORE INSTABILITY CAN INCREASE
ADEQUATELY FOR SEVERE AND STABILIZE US "SOMEWHAT"? DOES THE
CONVECTION MUDDY THE CONVECTIVE WATERS FOR THE REAL DEAL COMING
OUT OF EASTERN CANADA? DOES THE PREDECESSOR SHORT WAVE LINGER TOO
LONG DURING THE EARLY MORNING? THE FCST BULK SHEAR IS WELL WITHIN
RANGE OF SEVERE AT 30-40KTS. THE QUESTION BECOMES ABOUT AIR MASS
RECOVERY OR PURITY AROUND THESE SHORT WAVES. WE DONT HAVE THE
ANSWER YET. THE SUNNIER SUNDAY IS, THE TRULY STRONGER THE
CONVECTION WILL BECOME. REGARDLESS, A MORE THAN ADEQUATE WIND
FIELD IS IN PLACE (ANOMALOUSLY STRONG FOR LATE JULY) AND WE WILL
CONTINUE THE ENHANCED WORDING IN THE ZONES/GRIDS STARTING DURING
THE AFTERNOON. CAN GGEM AND UKMET TIMING WOULD GIVE OUR CWA A
HIGHER CHANCE FOR SEVERE. GFS/ECMWF TIMING AT LEAST THRU THE
DAYTIME HOURS WOULD BE LESS. POPS WERE LEFT AS LIKELY WITH AN
INCREASE FROM SOUTHWEST TO NORTHEAST AS THE AFTERNOON AND EARLY
EVENING PROGRESS. DONT WANT TO FORGO THE HEAVY RAIN THREAT, BUT
WITH A FASTER OVERALL WIND FIELD WOULD HAVE TO SEE TRAINING TO
HAVE ANY FLASH FLOOD THREAT.

BECAUSE OF UNCERTAINTY AS TO CLOUD COVER AND A DOWNWARD TREND TO THE
GFS THERMAL FIELDS, WE TENDED TO LEAN TOWARD THE LOWER GFS MOS FOR
MAX TEMPS. PRETTY CLOSE TO CONTINUITY.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
A WET START TO THE LONG TERM, FOLLOWED BY A PROLONGED DRY PERIOD.

ON SUNDAY NIGHT, WE EXPECT AN INITIAL SURFACE TROUGH TO MOVE ACROSS
THE AREA DURING THE EVENING AND PUSH OFFSHORE OVERNIGHT AS AN AREA
OF SURFACE LOW PRESSURE MOVES THROUGH PENNSYLVANIAN INTO NEW YORK.
MEANWHILE, SEVERAL SHORT WAVE/VORTICITY IMPULSES WILL SLIDE ACROSS
THE AREA WITHIN THE SOUTHWEST FLOW ALOFT AS THE MID-LEVEL LOW MOVES
OUT OF THE GREAT LAKES AND INTO WESTERN PENNSYLVANIA. THIS WILL KEEP
A HIGH LIKELIHOOD OF SHOWERS AND THUNDERSTORMS ACROSS THE AREA. PW
VALUES ARE FORECAST TO BE CLOSE TO 1.5-1.75 INCHES EARLY IN THE
NIGHT, SO A PERIOD OF HEAVY RAIN IS POSSIBLE. HOWEVER, AS THE NIGHT
MOVES ON, THE PW VALUES DROP, SO HEAVY RAIN WILL BECOME LESS LIKELY.

 

Upton:

 

.NEAR TERM /THROUGH SUNDAY/...
SPRINKLE ACTIVITY SHOULD COME TO AND END ACROSS EASTERN SECTIONS
OVER THE NEXT HOUR OR TWO AS SHORTWAVE ENERGY SLIDES EAST. ANY
ISOLATED DIURNAL CONVECTION LATE TODAY/EARLY THIS EVENING...MAINLY
WEST OF HUDSON...SHOULD DISSIPATE WITH LOSS OF DAYTIME INSTABILITY.

THE NEXT FEATURE OF INTEREST IS A JET STREAK AND SHORTWAVE ENERGY
TRACKING ESE THROUGH THE GREAT LAKES THIS AFTERNOON/EVE AND TOWARDS
THE REGION OVERNIGHT. AT THE SURFACE...A RESULTANT SURFACE WAVE WILL
TRACK EAST THROUGH ONTARIO...WITH ACCOMPANYING WARM FRONT
APPROACHING THE REGION LATE TONIGHT AND TOWARDS DAYBREAK.

INCREASING THETA-E/INSTABILITY WITH A DEVELOPING LLJ AHEAD OF THE
WARM FRONT AND MID/UPPER FORCING WILL INCREASE THE CHANCE FOR
SHOWERS AND THUNDERSTORMS W TO E LATE TONIGHT INTO SUN MORNING FROM
THE NYC METRO AND PTS WEST...AND SUN MORNING INTO EARLY AFTERNOON
FOR LI/CT.

MODELS ARE IN GOOD AGREEMENT WITH STRONG DEEP LAYER SHEAR AND AT
LEAST MODERATE LOW-LEVEL SHEAR FIELDS ALONG/AHEAD OF WARM FRONT LATE
TONIGHT INTO SUNDAY MORNING. THE INSTABILITY ENVIRONMENT IS A BIT IN
QUESTION THOUGH FOR LATE TONIGHT INTO SUNDAY MORNING...AS MODELS ARE
HANDLING ADVECTION OF STEEP MID-LEVEL LAPSE RATES FROM
MID-MISSISSIPPI RIVER VALLEY A BIT DIFFERENTLY. BUT IF STEEP LAPSE
RATES ARE MAINTAINED...AN ELEVATED MODERATELY UNSTABLE ENVIRONMENT
WOULD BE REALIZED...WHICH WOULD BE FAVORABLE FOR SOME STRONG TO
SEVERE CONVECTION IF LOW-LEVEL INVERSION CAN BE OVERCOME. MODERATE
INSTABILITY WITH STRONG SHEAR LEVELS WOULD INCLUDE POTENTIAL FOR
ORGANIZED STORMS AND POTENTIALLY ROTATING. WILL ADDRESS THIS
POTENTIAL IN HWO.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH 6 PM SUNDAY/...
SHORTWAVE AND WARM FRONT SHOULD PUSH NE OF THE REGION SUNDAY
AFTERNOON WITH ASSOCIATED EARLY CONVECTION EXPECTED TO BE PUSHING
EAST. ACROSS THE NYC METRO AND POINTS WEST...POTENTIAL EXISTS FOR
PARTIAL CLEARING WHICH SHOULD ALLOW TEMPS TO RISE WELL INTO 80S...TO
AROUND 90 DEGREES NYC/NJ METRO. A SIGNIFICANT INCREASE IN HUMIDITY
LEVEL WILL BE FELT IN THE WAKE OF THE WARM FRONT.

IN TERMS OF CONVECTION POTENTIAL SUNDAY AFTERNOON...MODERATE
INSTABILITY LEVELS ARE LIKELY FROM NYC METRO AND POINTS WEST...WITH
POTENTIAL FOR POCKETS OF HIGH INSTABILITY ACROSS NE NJ/LOWER HUDSON
VALLEY DEPENDING, THIS WILL DEPEND OF THE PERSISTENCE OF THE STEEPER
MID-LEVEL LAPSE RATES AND WITH ANY BREAKS OF SUN. THE QUESTION
APPEARS TO BE TRIGGER IN AFT...AS REGION COULD BE IN SOME WEAK
SUBSIDENCE IN WAKE OF THE MORNING/EARLY AFT SHORTWAVE. AT THE
SURFACE...A THERMAL TROUGH IS LIKELY IN THE VICINITY OF NJ/LOWER
HUDSON VALLEY WHICH COULD BE A FOCUS. INTERESTINGLY...THE NAM HOLDS
THE WARM FRONT ACROSS THE REGION DURING THE DAY...WHICH WOULD BE A
FOCUS FOR ROTATING STORMS AND TRAINING THUNDERSTORMS/FLASH FLOODING.
THIS IS A LOW PROB SOLUTION.

FOR NOW...WILL HANDLE WITH GRADUALLY INCREASING CHANCE POPS IN THE
AFTERNOON INTO THE EVENING FROM NYC AND POINTS N&W AS POTETNIAL FOR
APPROACHING SHORTWAVE/JET ENERGY INCREASES. IF CONVECTION IS
TRIGGERED...POTENTIAL IS THERE FOR ORGANIZED LINE SEGMENTS TO SEVERE
LEVELS BASED ON INSTABILITY...AND MODEST UNIDIRECTIONAL SHEAR
LEVELS.

MODELS IN GOOD AGREEMENT WITH LEAD SHORTWAVE ENERGY SWINGING THROUGH
THE REGION MON NIGHT...AHEAD OF A WEAKENING APPROACHING UPPER LOW
APPROACHES. AT THE SURFACE...ASSOCIATED LOW PRESSURE TRACKS THROUGH
THE EASTERN GREAT LAKES INTO CENTRAL NY SUN NIGHT...WITH A STRONG
COLD FRONT APPROACHING THE REGION. UNCERTAINTY STILL EXISTS IN TERMS
OF CONVECTIVE COVERAGE WITH THIS FEATURE OVERNIGHT. MOST WIDESPREAD
ACTIVITY WOULD BE WITH SURFACE LOW AND WARM FRONT ACROSS CENTRAL
NY/NEW ENGLAND. ALSO...SOME OF THE MODEL GUIDANCE INDICATES A
SECONDARY LOW/TRIPLE POINT...POSSIBLY MCS RELATED...WORKING THROUGH
MID-ATLANTIC INTO SOUTHERN NJ SUN NIGHT. TO THE SOUTH OF THE AREA WOULD
BE THE MOST FAVORABLE MCS TRACK BASED ON WIND FIELDS/THETA-E
GRADIENT. THE PRESENCE OF THIS TYPE OF FEATURE OVER OUR AREAS WOULD
BRING POTENTIAL FOR ROTATING STORMS AND FLASH FLOODING INTO THE
OVERNIGHT. CURRENTLY THAT LOOKS TO BE A LOW POTENTIAL. WITH ALL THAT
SAID...THE REGION COULD END UP BEING IN THE MIDDLE OF FAVORABLE
REGIONS. BUT WITH STRONG FORCING/SHEAR...INCLUDING AN UNSEASONABLY
STRONG LLJ...AND STRONG COLD FRONT INTERACTING WITH A MARGINAL TO
MODERATELY UNSTABLE ENVIRONMENT WOULD EXPECT ANY STRONG TO SEVERE
LATE DAY/EVE CONVECTION TO ONLY SLOWLY LOOSE INTENSITY AS IT WORKS
EASTWARD. SO WILL CONTINUE WITH LIKELY POPS FOR SHRA AND SCATTERED
STRONG TSTMS OVERNIGHT...TAPERING FROM W TO E LATE SUN NIGHT.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
UPPER LVL CLOSED LOW POSITIONED OVER SOUTHERN CANADA DIGS TO THE
SOUTH MONDAY AND WILL REMAIN POSITIONED OVER THE NORTHEAST THROUGH
MOST OF THE COMING WEEK. MEANWHILE...12Z MODEL SUITE CONTINUING WITH
THE DEVELOPMENT OF A SECONDARY LOW OVER THE EASTERN GREAT LAKES
SUNDAY NIGHT...WITH THE MOVEMENT OF THE LOW PUSHING IT THROUGH NEW
ENGLAND MONDAY. AS THE LOW LIFTS NORTH OF THE AREA...ITS ASSOCIATED
COLD FRONT WILL BE DRAGGED THROUGH. THE FRONT SHOULD CLEAR THE
EASTERN AREAS BY MON NIGHT...BUT STALLING TO THE EAST WITH LITTLE
MOVEMENT ALOFT ALLOWING IT TO PROGRESS FURTHER EAST TILL WED.
EVENTUALLY HIGH PRESSURE WILL BEGIN TO BUILD IN WED AND SHOULD TAKE
HOLD OF THE AREA THROUGH THE END OF THE WEEK. MODEL DISCREPANCIES IN
THE HANDLING OF THE NEXT LOW PRESSURE SYSTEM BUT SOME FORM OF LOW
PRESSURE WILL BEGIN TO APPROACH BY NEXT WEEKEND...THOUGH COULD HOLD
OFF ANY IMPACTFUL WEATHER TILL THE WORK WEEK.

 

Also just caught Dr. Greg Forbes on TWC, he is very concerned for a severe weather outbreak tomorrow in the Mid-atlantic & Northeast. Obviously there is still plenty of uncertainty on what affects us in the morning and what negative effects if any it may have on convection during the late afternoon and evening hours.

[WE GOT HIM]

SPC going big for today. You south shore guys could get in on the action.

[WE GOT HIM]

Still seems to be a lot of uncertainty

...SUMMARY...

SEVERE THUNDERSTORMS ARE EXPECTED TODAY INTO TONIGHT ACROSS MUCH OF

THE OHIO VALLEY AND MID ATLANTIC COAST REGION INTO PORTIONS OF

SOUTHERN NEW ENGLAND. SWATHS OF POTENTIALLY DAMAGING WIND GUSTS AND

LARGE HAIL ARE POSSIBLE...PARTICULARLY ACROSS PORTIONS OF THE MID

OHIO VALLEY INTO CENTRAL APPALACHIANS...WHERE A COUPLE OF TORNADOES

MAY ALSO NOT BE OUT OF THE QUESTION.

...SYNOPSIS...

MUCH AS HAS BEEN INDICATE BY THE MODELS...AMPLIFICATION APPEARS

UNDERWAY WITHIN THE LARGE-SCALE UPPER FLOW PATTERN. AS SUBTROPICAL

RIDGING BUILDS NORTHWARD THROUGH THE NORTHERN INTERMOUNTAIN REGION

AND ROCKIES...A CLOSED LOW...WHICH HAS BEEN UNDERCUTTING THE

BLOCKING HIGH OVER NORTHERN CANADA...IS CURRENTLY TURNING SOUTHEAST

OF THE INTERNATIONAL BORDER AREA INTO THE UPPER MIDWEST. THIS

FEATURE IS FORECAST TO CONTINUE DIGGING ACROSS SOUTHWESTERN PORTIONS

OF THE GREAT LAKES REGION TODAY...BEFORE TURNING EASTWARD TOWARD THE

NORTHERN MID ATLANTIC COAST AND SOUTHERN NEW ENGLAND TONIGHT...TO

THE SOUTH OF THE PERSISTENT EASTERN CANADIAN VORTEX. AS THIS

OCCURS...SEASONABLY STRONG /50-70 KT/ CYCLONIC MID-LEVEL FLOW

/700-500 MB/ IS EXPECTED TO NOSE SOUTHEASTWARD ACROSS THE OHIO

VALLEY TOWARD THE MID ATLANTIC COAST REGION. AND AN INITIAL

SIGNIFICANT COLD FRONT LIKELY WILL SURGE SOUTHEASTWARD THROUGH MUCH

OF THE MIDDLE MISSISSIPPI AND OHIO/TENNESSEE VALLEYS BY 12Z MONDAY.

WITH MOISTURE SEASONABLY HIGH BENEATH THE REMNANTS OF ELEVATED MIXED

LAYER AIR STILL PRESENT ACROSS THE MIDDLE MISSISSIPPI VALLEY THROUGH

A LARGE PORTION OF THE OHIO VALLEY...SUFFICIENT POTENTIAL

INSTABILITY EXISTS TO SUPPORT WIDESPREAD THUNDERSTORM ACTIVITY

TODAY. THIS WILL INCLUDE THE RISK FOR SEVERE STORMS...IN THE

PRESENCE OF ANOMALOUSLY STRONG DEEP LAYER FLOW FIELDS AND SHEAR.

OTHERWISE...LINGERING MONSOONAL MOISTURE ACROSS THE SOUTHERN

PLATEAU/GREAT BASIN INTO THE CENTRAL AND SOUTHERN ROCKIES...AND

EASTWARD ALONG A FRONTAL ZONE ADVANCING INTO THE SOUTH CENTRAL

PLAINS...IS EXPECTED TO CONTRIBUTE TO CONSIDERABLE THUNDERSTORM

ACTIVITY TODAY. ADDITIONAL SCATTERED THUNDERSTORM ACTIVITY IS

PROBABLE IN THE CONTINUING PRESENCE OF HIGH MOISTURE CONTENT AIR

NEAR CENTRAL AND SOUTHERN FLORIDA PENINSULA ATLANTIC COASTAL AREAS.

...OHIO VALLEY INTO MID ATLANTIC COAST/SOUTHERN NEW ENGLAND...

CONVECTIVE DEVELOPMENT NOW SPREADING ACROSS THE CENTRAL APPALACHIANS

REGION...AS WELL AS ADDITIONAL CONVECTIVE DEVELOPMENT WHICH STILL

MAY OCCUR UPSTREAM OVER THE MIDDLE MISSISSIPPI VALLEY PRIOR TO

DAYBREAK...PROVIDE UNCERTAINTY CONCERNING THE EXTENT AND MODE OF THE

SEVERE WEATHER POTENTIAL FOR TODAY. THE WEAKENING LEAD CONVECTION

APPEARS TO BE ASSOCIATED WITH AN IMPULSE THAT EMERGED FROM THE

SOUTHWESTERN U.S. MONSOONAL REGIME. THIS FEATURE IS FORECAST TO

SHIFT EAST OF THE CENTRAL APPALACHIANS INTO MID ATLANTIC COASTAL

AREAS BY MIDDAY...WHERE ASSOCIATED FORCING MAY SUPPORT RENEWED

STRONG/SEVERE STORM DEVELOPMENT IN THE PRESENCE OF A DESTABILIZING

BOUNDARY LAYER.

IN ITS WAKE...DEPENDING ON THE EVOLUTION OF UPSTREAM CONVECTION...IT

APPEARS POSSIBLE THAT A TRAILING LOW-LEVEL BAROCLINIC ZONE ACROSS

THE CENTRAL APPALACHIANS INTO THE MIDDLE OHIO VALLEY COULD BECOME A

FOCUS FOR DISCRETE STORM DEVELOPMENT...AS THE MAIN UPSTREAM IMPULSE

CONTINUES TO DIG ACROSS THE GREAT LAKES. IF THIS OCCURS...MOST

GUIDANCE SUGGESTS THAT STRENGTHENING DEEP LAYER FLOW FIELDS AND

SHEAR...INCLUDING SIZABLE CLOCKWISE CURVED LOW-LEVEL

HODOGRAPHS...WILL BE SUPPORTIVE OF SUPERCELLS CAPABLE OF PRODUCING

STRONG TORNADOES. CONFIDENCE REMAINS RELATIVELY LOW AT THE PRESENT

TIME...BUT THE BOUNDARY WOULD SEEM TO FOCUS THE HIGHEST TORNADO

PROBABILITIES ACROSS PARTS OF EASTERN KENTUCKY INTO WEST VIRGINIA.

THE EVOLUTION OF A SIGNIFICANT PRE-FRONTAL SQUALL LINE ALSO DOES NOT

APPEAR OUT OF THE QUESTION...AS STRONGEST MID/UPPER FORCING FOR

UPWARD VERTICAL MOTION DEVELOPS SOUTHEASTWARD ACROSS THE MIDDLE OHIO

VALLEY INTO THE CENTRAL APPALACHIANS BY EARLY THIS EVENING...BEFORE

CONTINUING TOWARD THE MID ATLANTIC COAST OVERNIGHT. AGAIN THIS

LARGELY DEPENDS ON THE CONVECTIVE EVOLUTION PRIOR TO MID

AFTERNOON...WHICH STILL REMAINS UNCLEAR AT THE PRESENT TIME.

[tmagan]

Showers developing near Allentown, PA.

[NEG NAO]

I think many will be startled off the toilet seat while reading their morning newspaper come tomorrow morning, when all of a sudden it goes crash outside, and looks like night at 7:30 in the morning.  Put on traffic and weather channel and see giant red blobs dotted over the area. I'd say close the potty, turn off the faucet, get out of the shower watch for tomorrow morning.

 

I'd say SVR risk is there for tomorrow morning: Warm front mini super cells riding NE from NJ and PA

 

15 % wind

10 % tor

5 % hail

 

-6 LI

2500 Cape

45 knt shear

 

WVA, SE OH and WMD look like super cell city tomorrow. MDT risk ???

 

Sunday night: Squall line possible from West. May miss to the south.

-5 LI

1500 Cape

35 knt shear

 

15% wind

5% tor

10% hail

Looks like this mornings severe potential is the one that will be going in the crapper - and the key is how unstable we get and the amount of daytime heating will determine the severe potential and outcome later today and this evening. This is going to be another nowcasting event IMO meaning don't rely on the models that much as they have let us down in recent severe events just watch this satellite to see if there will be any clearing  and radar trends

 

http://climate.cod.edu/flanis/satellite/1km/index.php?type=LongIsland-vis-12

 

http://www.wunderground.com/radar/radblast.asp?zoommode=pan&prevzoom=zoomν

[rcad1]

Looks like this morning is in the crapper cause the warm frontal passage was delayed. Hopefully we can get some sun today or this afternoon and evening might be in the crapper as well...

[REDMK6GLI]

Looks like this mornings severe potential is the one that will be going in the crapper - and the key to how unstable we get and the amount of daytime heating will determine the severe potential and outcome later today and this evening. This is going to be another nowcasting event IMO meaning don't rely on the models that much as they have let us down in recent severe events just watch this satellite to see if there will be any clearing and radar trends

http://climate.cod.edu/flanis/satellite/1km/index.php?type=LongIsland-vis-12

http://www.wunderground.com/radar/radblast.asp?zoommode=pan&prevzoom=zoomν

I woke up this morning to a radar that was very far from impressive and not what i wanted to see on a day that was forecasted to have some great morning severe potential. Who knows may still change, but as of right now it looks like just heavy rain with some thunder/lightning......that said going fishing when i get off at 1 today from captree