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Undertakerson
Rank: F5 Superstorm
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Blue Mtn, N of Hbg - Elev 1000'
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Undertakerson

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12 Aug 2014
I decided to jump the gun and open this thread to discuss the potential warm up FINALLY (?) coming to most of the region.

I based my thoughts (see LR summer thread) on the pattern finally becoming less blocky which I had attributed, mainly, to the large scale amplification of the mean flow (as an aside, I recall posting last year - an article on Phys.Org about what would drive an increasingly amplified pattern), AND that the push off the NW Pac zone would translate the heat of seat to the east.

Part One - the blocking

For some reason the CPC site is not showing the D5-9 blocking pattern, so I had to rely on the MREF's and loop the images to see that the western block detaches from the ridge and seems to absorb northward. The eastern block also relaxes in the Atlantic and it may be fairer to say it translocates to a more standard SER configuration.

12z MREFS http://mp1.met.psu.edu/~fxg1/ENSHGTAVGNH_1...nsloopmref.html

This "backing in" of the SER should drive heat and humidity in the usual fashion. Especially this summer, it will likely get mighty uncomfortable for many who have seen a less than scorching summer.

As per the 12z GFS - it seems to show the 20c 850 zone very close by or directly over parts of the region during this period (follow link to MREFs - switch screen to Ewall Home and select GFS12z)


The relaxation of both blocks will favor a flooding of Pacific air to move along the N US border - shutting off the frequent visits from our friends in the Great White North, or at least, blunting their blows.

Of course, the increase in heat and humidity will drive afternoon T storms and we'll have to watch for added fire should any cool fronts be in the offing - such as around the 19th.

Here is what CTP had to say earlier.

QUOTE
FOR THE VERY EXTENDED THE ECMWF SHOWS A RARE...FOR THIS
SUMMER...SURGE IN THE WESTERN ATLANTIC SUBTROPICAL RIDGE WITH 500
MB HEIGHTS EXCEEDING 5900M ALL THE WAY INTO SOUTHERN NEW ENGLAND.
GIVEN THE TENDENCY FOR A TROUGH TO DOMINATE OUR WEATHER MUCH OF
THIS SUMMER...THIS SOLUTION HAS TO BE VIEWED DUBIOUSLY AT THIS
TIME...BUT MAY GIVE HOPE TO REAL SUMMER LOVERS THAT WE COULD HAVE
AT LEAST ONE TRUE HEAT WAVE IN STORE FOR US.


So - what say you all? Another bluff towards summer heat (wave?) or the only REAL threat we are to see?
1 Aug 2014
Thought I'd create a thread so any who care to can post rainfall tallies in their zones.

Someone could get mighty wet - looks like most at risk is the coastal plain, especially to the south. But it wouldn't take much of a shift for areas back towards the spine of the Apps to get in on the "action"

Attached Image


QUOTE
Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
314 AM EDT Fri Aug 1 2014

Valid 12Z Fri Aug 1 2014 - 12Z Sun Aug 3 2014

***Rainy conditions with stalled front near East Coast***

***Numerous showers and thunderstorms for the Rockies***


A return to warmer and more humid weather can be expected for the East
Coast states as the recent cool air mass lifts northward into Canada. The
frontal boundary near the Gulf coast is developing a wave of low pressure
along it that is expected to bring a warm front near the Mid-Atlantic
coast by Friday evening, and this will bring widespread rain and embedded
thunderstorms from the Carolinas to southern New England. Warm and humid
air over-riding cooler air inland will be the main forcing mechanism for
rain.

http://www.hpc.ncep.noaa.gov/discussions/h...php?disc=pmdspd
24 Jul 2014
OK - looks like its time for me to put a voodoo hex on the IMBY weather and open another thread. The next severe threat to challenge us is Sunday (p.m.?)/Monday (and may even go a bit beyond)

First, let's look at what SPC has to say about D3 which takes us to Sunday at 12z (7 a.m. here)

Attached Image


QUOTE
CNTRL PLAINS TO OH VALLEY/LOWER GREAT LAKES...
S OF THE QUASI-STATIONARY FRONT...A STRONG TO EXTREMELY UNSTABLE AIR
MASS SHOULD BE PRESENT FROM PARTS OF THE CNTRL PLAINS TO MIDWEST AS
THE PLAINS EML PLUME IS ADVECTED E TOWARDS THE NRN APPALACHIANS
.
WAA-DRIVEN ELEVATED TSTM CLUSTERS SHOULD BE ONGOING AT 12Z/SAT OVER
PARTS OF THE MIDWEST. IN THE WAKE OF THIS ACTIVITY...CAPPING SHOULD
LARGELY INHIBIT SURFACE-BASED TSTM DEVELOPMENT UNTIL LATE DAY. THE
DEGREE OF INHIBITION SHOULD GENERALLY BE LESS COMPARED TO D2...OWING
TO MINOR HEIGHT FALLS AND COOLER 700 MB TEMPERATURES /ESPECIALLY E
OF THE MS RIVER/.

SCATTERED CLUSTERS OF STORMS SHOULD FORM BY EVENING WITHIN THE
FRONTAL ZONE. GIVEN THE DEGREE OF INSTABILITY...ALONG WITH
STRENGTHENING DEEP-LAYER SHEAR...AN ORGANIZED MCS OR TWO MAY
DEVELOP. LARGE HAIL WILL BE MOST PROBABLE DURING THE LATE AFTERNOON
AND EVENING...WITH POTENTIAL FOR ONE OR MORE
SWATHS OF DAMAGING
WINDS DURING THE EVENING INTO SAT NIGHT. IF SHORTER-TERM MESOSCALE
PREDICTABILITY INCREASES...CORRIDORS OF HIGHER SEVERE PROBABILITIES
MAY BECOME EVIDENT IN LATER OUTLOOKS.

http://www.spc.noaa.gov/products/outlook/day3otlk.html

Looks very well aligned to translate east from this position and give us plenty to worry about.

Next, the 0z GFS 4 panel (with mark up)

Attached Image


As you can see, the upper left panel represents the picture at H5 (500 mb), I have circled the two distinct areas of enhanced vort max, one already into PA and a second, more vigorous one dropping out of the lakes and driving the front to the south and the east.

Upper right panel is the surface - upper level picture 1000mb-500mb (I use this to discern where the surface feature main drivers are) - we see some return flow from the Atl ridge, but it's a bit weak. Still the preceding day should put down at least some low level warm moist air - just not a lot.

Lower Left is the H7 or 700mb Rh - or mid level moisture. As you can see, there is a decent slug of it present. So two elements necessary for severe storms are on the field - mid level moist and high level spin.

Lower right is the H8.5 picture and is a good indicator of temperatures. Among other things, I use this image to demonstrate when the corridor between warm air and cold air is narrow, This is a decent picture of where the front or boundary layers may be and the sharpness of that boundary. We see here that the corridor looks relatively tight and the best heat is to the south of the Mason Dixon with the cooler air still over the lakes. Puts the region directly in "no man's land" where, any military person would tell you - the most danger lay.

OK UTS - but what about the other models? Well, surprisingly enough the Euro images support the GFS. Mind now, the Euro does not have an Hr90 interval such that I've shown with the GFS, but when you compare you see the same elements in locations very close to the GFS depiction of 6 hours earlier

Attached Image


So FWIW, I think we'll be in for some more severe storm tracking as we wind up the weekend.
25 Jun 2014
OK - I thought I'd put up some early pro thoughts for this time period. If you've been following along in the preceding thread (6/25-26) you will know I've been watching this time period for a while now and see better than average chance of this threat unfolding. Let's hope things don't fold like some more recent events.

QUOTE
WITH SUMMERTIME RIDGING MAKING ITS PRESENCE FELT ACROSS MUCH OF
THE LOWER 48...THE PRIMARY STORM TRACK...IN TURN...WILL BE LIFTED
NWD ALONG THE US/CANADIAN BORDER - WHICH IS VERY TYPICAL HEADING
INTO JULY. THE LATEST DETERMINISTIC MODEL AND ENSEMBLE DATA
ADVERTISE A SHORTWAVE TROUGH/CLOSED LOW MOVING ACROSS SOUTH-
CENTRAL CANADA /MANITOBA INTO WRN ONTARIO/ BY NEXT TUE-WED
. PCPN
WILL BE FOCUSED ALONG SERIES OF ATTENDANT COLD FRONTS PUSHING EWD
THRU THE PLAINS/MIDWEST INTO THE GREAT LAKES/OH VLY. WPC SFC
PROGS SHOW A LEAD BOUNDARY REACHING THE UPPER OH VLY ON 30 JUNE

FOLLOWED BY A MORE WELL-DEFINED COLD FRONT APPROACHING THE REGION
BY 1-2 JULY
. USING PWATS AS A GENERAL GUIDE...THE HIGHEST POPS
ARE LKLY IN THE SUN-WED TIMEFRAME WHEN MSTR AVAILABILITY WILL BE
+1SD ABOVE NORMAL. CONFIDENCE IS ABOVE AVG IN SEEING TEMPERATURES
NEAR TO ABOVE NORMAL.

&&


So we see the heat and its been pretty well advertised, we have moist air mass and a defined CF coming in.

GFS for this time period shows some H5 spin, (but little H7 moisture feed - which may be OK given the ambient moisture present in the columns)

Attached Image


WPC D7 map - concensus map (for now)
Attached Image


Edge of the ring of fire, cold front, some shear possible from the developing short wave along the front. Most of the checklist is accounted for (again, for now)
10 May 2014
I thought I would go ahead and start watching next weekend for potential severe weather in the region. I had mentioned in the 12-14th thread that this time period could turn out to be the best most recent threat (which is not saying much, granted)

Anyway SPC is starting to also turn their heads in that direction

QUOTE
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 100825
SPC AC 100825

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0325 AM CDT SAT MAY 10 2014

VALID 131200Z - 181200Z

...DISCUSSION...
CONSENSUS OF GUIDANCE SUGGESTS A BROAD UPPER-LEVEL TROUGH WILL BE
PRESENT FROM S-CNTRL CANADA TO NM AT 12Z/TUE. POOR PREDICTABILITY
PERSISTS WITH THE EVOLUTION OF THIS TROUGH...ESPECIALLY WITH THE
POTENTIAL AMPLIFICATION OF AN EMBEDDED SRN-STREAM SHORTWAVE IMPULSE
.
THE 00Z ECMWF/UKMET ARE MOST PRONOUNCED WITH THIS SCENARIO EVOLVING
ACROSS THE LOWER MS VALLEY TO SOUTHEAST ON D6/THU. THIS COULD INDUCE
STRENGTHENING WIND PROFILES ACROSS A RESIDUAL WARM SECTOR OVER PARTS
OF THE ERN CONUS.
BUT WITH MERIDIONAL WIND PROFILES AND EXTENSIVE
CONVECTIVE OVERTURNING THROUGH AT LEAST D2-3 OVER THE CNTRL
STATES...MID-LEVEL LAPSE RATES SHOULD BE LIMITED
. EVEN SO...GIVEN
THE POTENTIAL ROBUSTNESS OF WIND PROFILES...AT LEAST A MARGINAL
SEVERE RISK COULD DEVELOP.

..GRAMS.. 05/10/2014

CLICK TO GET WUUS48 PTSD48 PRODUCT


http://www.spc.noaa.gov/products/exper/day4-8/

The 0z Euro - decent spin profile and enough Rh and 850 moisture to work with.

Attached Image

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/ecmwfloop.html

0z GFS looks similar
Attached Image
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