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JULY 2012 Severe Weather /Convection Discussion


NEG NAO

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No other model? Where are you getting this stuff?

SREFS have nothing until afternoon, GFS has nothing until tommorow night, RAP has minimal precip in the area at the time...and sounds like the Euro and UKIE were mainly dry as well in the morning...what other model does show heavy rains in the morning?

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SREFS have nothing until afternoon, GFS has nothing until tommorow night, RAP has minimal precip in the area at the time...and sounds like the Euro and UKIE were mainly dry as well in the morning...what other model does show heavy rains in the morning?

I assumed you meant the evening rush hour referring to the "main show" second graphic that was posted.

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Latest Upton AFD : Today could be another active day but not as dramatic as yesterday :

NEAR TERM /UNTIL 6 PM THIS EVENING/

COVERAGE OF SHOWERS AND THUNDERSTORMS WILL INCREASE AS THE DAY

PROGRESSES. SFC FRONTAL BOUNDARY SLOWLY APPROACHES FROM THE

WEST...BUT MOVES LITTLE AS IT BECOMES NEARLY PARALLEL TO MID AND

UPPER LEVEL STEERING FLOW.

ATMOSPHERE REMAINS QUITE MOIST...ALTHOUGH NOT QUITE AS MOIST AS

YESTERDAY. WEAK VORTICITY ADVECTION ALOFT COULD AID IN ANY

CONVECTION...BUT DO NOT SEE MUCH OF A TRIGGER IN THE LOWER LEVELS OF

THE ATMOSPHERE. HOWEVER...WITH MARGINAL TO MODERATE INSTABILITY IN PLACE

(FORECAST MODEL CAPE VALUES) AND TOTAL TOTALS AROUND 50...WOULD

EXPECT SCATTERED SHOWERS AND TSTMS...SOME OF WHICH COULD PRODUCE

HEAVY DOWNPOURS.

I DO NOT SEE MUCH OF A SEVERE THREAT...BUT A FEW STRONG TO SEVERE

STORMS CANNOT BE RULED OUT AIDED BY JET PLACEMENT/DIVERGENCE

ALOFT AND AMPLE CAPE AS MENTIONED.

AS FOR TEMPS...USED A BLEND OF THE MAV/MET GUIDANCE...WHICH YIELDS

MID 80S TO AROUND 90...PERHAPS LOWER 90S IN AND AROUND METRO NJ.

CLOUDS MAY INHIBIT TEMPS SLIGHTLY...AND OVERALL WARMER AIRMASS

DOES SETTLE JUST SOUTH AS INDICATED BY H8 TEMPS/LAYER THICKNESS.

HOWEVER...WITH HIGH DEW POINTS IN THE UPPER 60S TO AROUND

70...APPARENT TEMPS WILL RISE INTO THE 90S ACROSS MUCH OF THE

AREA. I DO NOT BELIEVE WIDESPREAD MIDDLE 90S WILL OCCUR IN NYC TO

WARRANT HEAT ADVISORY (MID AND UPPER 90S OCCURRED YESTERDAY)...BUT

IT WILL BE CLOSE.

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SPC now has Central NJ, NYC, Western LI, in a slight risk today. 2% Tor, 15% Wind, 5% hail.

2% Tor extends a little further north:

day1probotlk_1300_torn.gif

...ERN SEABOARD...

WEAK HEIGHT FALLS SHOULD MAINTAIN BACKGROUND ASCENT ACROSS THE

REGION AMIDST ANOMALOUSLY MOIST AIRMASS WITH PW VALUES AROUND 2

INCHES. OVERTURNING YESTERDAY AND RESIDUAL CONVECTIVE DEBRIS WILL

PROBABLY LIMIT THE POTENTIAL FOR GREATER DESTABILIZATION TODAY.

HOWEVER...EVEN A COUPLE OF HOURS OF SUNSHINE WILL BOOST INSTABILITY

SUFFICIENTLY FOR AN INCREASE IN AFTERNOON AND EVENING CONVECTIVE

VIGOR. EXPECT STORMS TO BE MOST PREVALENT WITHIN LEE TROUGH AND

AHEAD OF A LEADING LOW AMPLITUDE SHORT WAVE TROUGH CURRENTLY MOVING

EAST FROM THE OH VALLEY. SURFACE TROUGH ALONG THE EAST COAST FROM

DELMARVA TO NYC MAY PROVIDE A FOCUS FOR WEAK SURFACE LOW/WAVE

DEVELOPMENT ESPECIALLY LATER TODAY AS THE STRONGER IMPULSE NOW OVER

WI/LAKE MI BEGINS TO ENHANCE LARGE SCALE ASCENT ACROSS THE EAST.

CLOUD-BEARING SHEAR VALUES WILL BE IN THE RANGE OF 30-40KT FROM NRN

VA TO SRN NEW ENGLAND WITH THE HIGHER MAGNITUDES LIKELY NORTH AND

OFFSET FROM THE GREATER POTENTIAL INSTABILITY. NONETHELESS...STORMS

DEVELOPING IN THIS REGIME COULD ORGANIZE INTO SHORT LINE SEGMENTS

WITH WIND DAMAGE POSSIBLE. A SUPERCELL OR TWO CANNOT BE RULED OUT

AND LOCALLY STRONGER LOW LEVEL SHEAR AND LOW LFC/HIGH BOUNDARY LAYER

RH NEAR ANY WEAK SURFACE LOWS COULD SUPPORT A WEAK BRIEF TORNADO.

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Dont know how many times you are going to post about this.

Models can be used for placement of fronts, ULLs and other factors, which determine position of the likely convection area. I trust the euro far and beyond over any model with regards to placement of fronts, vorts, etc., despite it being affected by feedback yesterday.

Sometimes models suffer from convective feedback (clearly the euro did yesterday) but they are useful tools as a whole.

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radars becoming active iin PA moving east

http://www.intellica...cation=USDC0001

latest Upton AFD

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE NEW YORK NY

119 PM EDT FRI JUL 27 2012

NEAR TERM /UNTIL 6 PM THIS EVENING/

JUST MINOR CHANGES TO TEMPS TO REFLECT LATEST OBSERVATIONS. SHOWERS

DEVELOPING JUST NORTH OF THE CWA WILL MOVE SOUTHEAST ACROSS THE

AREA THROUGH THIS AFTERNOON. STORMS WILL INCREASE IN COVERAGE AS

THE DAY PROGRESSES.

SFC FRONTAL BOUNDARY SLOWLY APPROACHES FROM THE WEST...BUT MOVES

LITTLE AS IT BECOMES NEARLY PARALLEL TO MID AND UPPER LEVEL

STEERING FLOW.

ATMOSPHERE REMAINS QUITE MOIST...ALTHOUGH NOT QUITE AS MOIST AS

YESTERDAY. WEAK VORTICITY ADVECTION ALOFT COULD AID IN ANY

CONVECTION...BUT DO NOT SEE MUCH OF A TRIGGER IN THE LOWER LEVELS OF

THE ATMOSPHERE. HOWEVER...WITH MARGINAL TO MODERATE INSTABILITY IN PLACE

(FORECAST MODEL CAPE VALUES) AND TOTAL TOTALS AROUND 50...WOULD

EXPECT SCATTERED SHOWERS AND TSTMS...SOME OF WHICH COULD PRODUCE

HEAVY DOWNPOURS.

I DO NOT SEE MUCH OF A SEVERE THREAT...BUT A FEW STRONG TO SEVERE

STORMS CANNOT BE RULED OUT AIDED BY JET PLACEMENT/DIVERGENCE

ALOFT AND AMPLE CAPE AS MENTIONED.

AS FOR TEMPS...USED A BLEND OF THE MAV/MET GUIDANCE...WHICH YIELDS

MID 80S TO AROUND 90...PERHAPS LOWER 90S IN AND AROUND METRO NJ.

CLOUDS MAY INHIBIT TEMPS SLIGHTLY...AND OVERALL WARMER AIRMASS

DOES SETTLE JUST SOUTH AS INDICATED BY H8 TEMPS/LAYER THICKNESS.

HOWEVER...WITH HIGH DEW POINTS IN THE UPPER 60S TO AROUND

70...APPARENT TEMPS WILL RISE INTO THE 90S ACROSS MUCH OF THE

AREA. I DO NOT BELIEVE WIDESPREAD MIDDLE 90S WILL OCCUR IN NYC TO

WARRANT HEAT ADVISORY (MID AND UPPER 90S OCCURRED YESTERDAY)...BUT

IT WILL BE CLOSE.

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Slight risk today. Seems warranted with good s/w trof moving in. I wouldn't be surprised if today out performs the 26th. Forcing is better. We'll see how it goes by midday.

Let us get out the scales of justice to analyze this threat:

Pro's

Slight 500 mb height falls throughout the day

Warm, moist lower atmosphere

Some directional and speed shear

Con's

Weak winds aloft

High wet bulb zero height

Poor 700 mb - 500 mb lapse rates

Don't know if we can get to the 1.00" severe hail criteria, perhaps a wet microburst to meet severe criteria.

RAP forecast sounding for KEWR at 21Z today.

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Slight risk today. Seems warranted with good s/w trof moving in. I wouldn't be surprised if today out performs the 26th. Forcing is better. We'll see how it goes by midday.

Given that you nailed the 9/16/2010 tornado/microburst event for our area 24 hours in advance with not even a slight risk that day, I give your insight a lot of credence!

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