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EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1251 AM EST FRI MAR 07 2014

VALID 12Z MON MAR 10 2014 - 12Z FRI MAR 14 2014

...OVERVIEW AND MODEL PREFERENCES...

MEDIUM RANGE PERIOD WILL FEATURE THE RE-ESTABLISHMENT OF THE
ALL-TOO FAMILIAR RIDGE/TROUGH PATTERN OVER THE WESTERN/EASTERN
CONUS... RESPECTIVELY. NW ATLANTIC RIDGING IS ALSO FORECAST TO
RE-BUILD --AGAIN-- BY THE END OF THE PERIOD. WITH ENERGY INITIALLY
OVER MEXICO AND TEXAS AND THEN TRAILING/DIGGING ENERGY EXITING THE
PAC NW... THIS SPLIT-FLOW PATTERN SUGGESTS LOWER CONFIDENCE WITH
SPECIFIC TIMING/AMPLITUDE OF A PERHAPS PHASED OR SEMI-PHASED
SYSTEM TRACKING EASTWARD DURING THE MIDDLE OF THE WEEK NEXT
WEEK... BUT THERE REMAINS MUCH TO BE SORTED OUT. THE USUAL
SUSPECTS HAVE FALLEN IN LINE WITH THE HANDLING OF THIS FEATURE IN
THE CENTRAL/EASTERN STATES -- THE 12Z/18Z GFS RUNS WERE
QUICKER/WEAKER WITH THE DEVELOPING SFC SYSTEM WHILE THE 12Z ECMWF
WAS SLOWER/DEEPER. THE TRENDS OF THESE DETERMINISTIC MODELS ARE
ABOUT AS CLEAR AS MUD... EXCEPT FOR MAYBE AT THE LEAST SIGNALING
THE POTENTIAL FOR AN IMPACTFUL SYSTEM /WHICH IS EVIDENT SIMPLY
FROM THE GENERAL PATTERN/. THE GEFS/ECENS ENSEMBLES OFFER A MORE
CONSISTENT TREND OVER THE LAST 48 HRS TOWARD A SLOWER AND MORE
DEVELOPED SYSTEM AND THAT IS WHERE THE PREFERENCE LIES BY ABOUT
WED/D5 ONWARD. TO THE SOUTH... THE INITIAL SHORTWAVE OVER MEXICO
HAS BEEN HANDLED POORLY BY THE RECENT ECMWF RUNS WHILE THE GFS HAS
BEEN MORE CONSISTENT /BUT WILL IT BE RIGHT?/. IN LIGHT OF THE
INTERMEDIATE ENSEMBLES... BEST BET MAY BE TO SPLIT THE GFS/ECMWF
DIFFERENCE AT THIS POINT. IN-HOUSE CLUSTERING OF 12Z GEFS/ECENS
MEMBERS SHOW THE LARGEST CLUSTER OF 8 CAMPS /13 MEMBERS OUT OF 70/
FAVORING THIS INTERMEDIATE SOLUTION.

IN THE WEST... INITIAL SHORTWAVE ON MON/D3 WILL GIVE WAY TO HIGHER
HEIGHTS UNTIL MID-LATE WEEK NEXT WEEK. MODELS ARE UNSURE IF ENERGY
PASSING THROUGH 45N/145W WILL MOVE BODILY NORTHEASTWARD LIKE THE
12Z ECMWF OR SEPARATE AND REMAIN WEST OF 130W LIKE THE 18Z GFS...
OR PERHAPS A LITTLE OF BOTH. ENSEMBLE SPAGHETTI SHOWS THE ECMWF TO
BE ON THE STRONGEST/QUICKEST SIDE OF THE 90-MEMBER SUITE WHILE THE
CONSENSUS APPEARS TO TAKE A MUCH WEAKENED SHORTWAVE INTO BRITISH
COLUMBIA... MOSTLY MAINTAINING THE RIDGE. AGAIN... CONFIDENCE IS
LOW GIVEN THE POOR CONTINUITY AND CANNOT RULE OUT AT LEAST SOME
ENERGY COMING INTO WA/OR LATER NEXT WEEK.

...SENSIBLE WEATHER HIGHLIGHTS...

RIDGE/TROUGH UPPER PATTERN WILL FAVOR... UNSURPRISINGLY...
WARMER/COLDER THAN AVERAGE TEMPERATURES OVER THE WEST/EAST...
RESPECTIVELY. THE EARLY PART OF THE PERIOD WILL AT LEAST YIELD
SOME MILDER AIR IN THE EAST AS THE TROUGH ORGANIZES IN THE CENTRAL
CONUS. PRECIPITATION SHOULD FOCUS IN THE PAC NW EARLY AND THEN
AROUND THE DEVELOPING SYSTEM IN THE CENTRAL/EASTERN STATES
MID-LATE WEEK. BATTLE OF THE AIRMASSES WILL SUPPORT WINTRY WEATHER
ON THE NORTH SIDE OF THE SYSTEM AND WET WEATHER ALONG AND TO THE
SOUTH OF THE BOUNDARY. TEMPERATURES SHOULD NOSEDIVE BY THE END OF
THE WEEK IN THE EAST IN THE WAKE OF THE COLD FRONT... WITH FREEZES
POSSIBLE DOWN TOWARD THE I-20 CORRIDOR.

FRACASSO

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Raging flizzard in Lenior City this morning on my way to work...I had a little bit of slush on the car roof top when I got up to leave this morning....exciting I know! Amazing winter though from breadth and depth....I had snow right around Thanksgiving to start this winter off!

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I still haven't given up on the Sunday/Monday storm yet. The Canadian gives Kentucky a good snow on the backside and turns us in NETN over to snow toward the end of the event. I think the GFS is trying to hold to much energy back in the Southwest. Just doesn't look right to me. Anyway this is probably winter's last stand. Picked up 1/4 of an inch last night which is more than I expected. Still have some snow left on the car.

 

http://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html

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The GFS took a cutoff all the way thru the Southeast but it is too far south for us and too warm as well. We didn't get much precip after it cutoff. I'm still not writing this one off completely. If we can get the cutoff more northwest and not over the Gulf Coast we would stand a better chance of some backside snows. But regardless this should be a very interesting system to watch.

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Euro echoes the GFS solution with a much slower back piece of energy. Precip still starts on Sunday. Southwest Virginia and the northwest NC mountains are still in play for snow. In the higher mountains a 546 thickness with 700mb below -2C gets it done with multi-layer clouds. Between waves if only low clouds it could be liquid drizzle. Colder back piece of energy would get mountains back to snow if these models are right. It is a sloppy setup but it is mid March too.

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6z NAM is further south with the 0c line. It actually is the furthest south I've seen modeled for this storm with wave #1. Take a look at the HI-Res NAM Hour 60:

yta7ymes.jpg

Mr. Bob or Jeff or anyone do you see any room left for this to shift and give KTRI some snow/sleet/zr? I know I'm grasping for straws this late in the season but I still haven't given up on this storm.

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NASHVILLE TN
505 AM CDT SAT MAR 15 2014

TNZ005>011-023>034-056>066-075-077>080-093>095-151815-
STEWART-MONTGOMERY-ROBERTSON-SUMNER-MACON-CLAY-PICKETT-HOUSTON-
HUMPHREYS-DICKSON-CHEATHAM-DAVIDSON-WILSON-TROUSDALE-SMITH-
JACKSON-PUTNAM-OVERTON-FENTRESS-PERRY-HICKMAN-LEWIS-WILLIAMSON-
MAURY-MARSHALL-RUTHERFORD-CANNON-DE KALB-WHITE-CUMBERLAND-BEDFORD-
COFFEE-WARREN-GRUNDY-VAN BUREN-WAYNE-LAWRENCE-GILES-
INCLUDING THE CITIES OF...DOVER...CLARKSVILLE...SPRINGFIELD...
GALLATIN...LAFAYETTE...CELINA...BYRDSTOWN...ERIN...WAVERLY...
DICKSON...ASHLAND CITY...NASHVILLE...LEBANON...MOUNT JULIET...
HARTSVILLE...CARTHAGE...GAINESBORO...COOKEVILLE...LIVINGSTON...
JAMESTOWN...LOBELVILLE...CENTERVILLE...HOHENWALD...FRANKLIN...
BRENTWOOD...COLUMBIA...LEWISBURG...MURFREESBORO...WOODBURY...
SMITHVILLE...SPARTA...CROSSVILLE...SHELBYVILLE...TULLAHOMA...
MANCHESTER...MCMINNVILLE...ALTAMONT...SPENCER...WAYNESBORO...
LAWRENCEBURG...PULASKI
505 AM CDT SAT MAR 15 2014

...FREEZING RAIN AND SLEET EXPECTED OVER NORTHERN MIDDLE TENNESSEE
SUNDAY NIGHT AND EARLY MONDAY MORNING...

RAIN IS FORECAST TO CHANGE TO FREEZING RAIN AND SLEET OVER THE EXTREME
NORTH LATE SUNDAY EVENING...BEFORE ENDING EARLY MONDAY MORNING.

A LOW PRESSURE SYSTEM IS FORECAST TO TRACK FROM SOUTHERN ARKANSAS
SUNDAY MORNING...TO NORTHWESTERN GEORGIA BY MONDAY MORNING. A WARM
FRONT WILL EXTEND FROM THE LOW UP ACROSS SOUTHERN MIDDLE TENNESSEE
ON SUNDAY...WHERE AFTERNOON TEMPERATURES ARE EXPECTED TO HIT THE
LOWER 60S. MEANWHILE...NORTH OF THE WARM FRONT...ACROSS NORTHERN
PARTS OF THE MID STATE...COLDER AIR WILL WORK IN FROM THE NORTH.
TEMPERATURES ACROSS THE NORTH WILL ACTUALLY FALL DURING THE DAY ON
SUNDAY...AND BY MID AFTERNOON...WHILE LAWRENCEBURG IS ENJOYING A
VERY MILD 62 DEGREES NEAR THE ALABAMA BORDER...CLARKSVILLE WILL BE
SHIVERING AT 41.

TEMPERATURES WILL CONTINUE TO FALL SUNDAY NIGHT OVER NORTHERN
PARTS OF THE MID STATE...WITH RAIN LIKELY TO CHANGE TO FREEZING
RAIN AND SLEET OVER THE EXTREME NORTH. AT SUNRISE MONDAY...THE
FREEZING LINE WILL PROBABLY EXTEND FROM NEAR WAVERLY... TO
DICKSON...JOELTON...AND LAFAYETTE. THEREFORE...THE AREAS MOST
VULNERABLE TO GETTING THE FREEZING RAIN AND SLEET WILL BE ALONG
THE HIGHLAND RIM...NORTH OF NASHVILLE...AND OVER THE
NORTHWEST...AROUND CLARKSVILLE AND DOVER.

RIGHT NOW...IT LOOKS LIKE THE FREEZING LINE WILL STRETCH ACROSS
EXTREME NORTHERN DAVIDSON COUNTY...JUST NORTH OF THE NASHVILLE
METRO AREA EARLY MONDAY MORNING. HOWEVER...IF THE COLD AIR PUSHES
FURTHER SOUTH THAN CURRENTLY EXPECTED...SOME SLICK SPOTS COULD
EVEN DEVELOP IN NASHVILLE FOR THE EARLY MORNING RUSH HOUR ON
MONDAY.

ALTHOUGH ICE AMOUNTS OVER THE NORTH ARE EXPECTED TO BE LIGHT...YOU
SHOULD REMEMBER THAT IT ONLY TAKES A SINGLE PATCH OF ICE TO CAUSE
AN ACCIDENT.

IF YOU PLAN ON DRIVING ACROSS NORTHERN MIDDLE TENNESSEE SUNDAY
NIGHT AND EARLY MONDAY...STAY ABREAST OF THE LATEST FORECAST SO
YOU CAN KNOW THE TYPE OF WEATHER YOU WILL ENCOUNTER ALONG THE WAY.

$$

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  • 2 weeks later...

WE THEN TURN OUR ATTENTION TO THURSDAY/FRIDAY/FRIDAY NIGHT. AS
WEDNESDAY`S SURFACE HIGH PUSHES EASTWARD...A SURFACE LOW WILL
DEVELOP AND MOVE ACROSS THE MIDWEST STATES. IN RESPONSE TO THE
LOW...A SOUTHWESTERLY LOW-LEVEL JET WILL DEVELOP. THIS JET WILL BE
RESPONSIBLE FOR THE POTENTIALLY STRONG WIND GUSTS THURSDAY...AND A
SLOW MOISTURE BUILDUP WILL BEGIN AS WELL. THURSDAY`S LOW WILL PASS
WELL TO OUR NORTH WITHOUT MUCH FANFARE. MAYBE A FEW SHOWERS...BUT
WE LOOK TO HAVE A WEAK CAP OVER THE AREA AND THIS WILL PROBABLY
LIMIT MOST DEVELOPMENT. WE`RE NOT DONE THOUGH. LATEST GUIDANCE IS
COMING INTO AGREEMENT WITH THE DEVELOPMENT OF A SECOND SURFACE LOW
THURSDAY NIGHT/FRIDAY MORNING OVER ARKLATEX. CYCLOGENESIS WITH
THIS LOW IS MUCH FARTHER TO THE SOUTH THAN THE FIRST AND IT WILL
LIKELY CAUSE A SPIKE IN SURFACE INSTABILITY FRIDAY ON THE ORDER
OF 800-1200 J/KG ACROSS A GOOD PORTION OF MIDDLE TENNESSEE. AS IT
PASSES JUST NORTH OF THE STATE IT WILL BE FILLING...SO THE
HELICITIES ARE NOT AS HIGH AS I WOULD LIKE TO SEE THEM FOR THE
DEVELOPMENT OF SEVERE WEATHER...BUT IT`S PASSAGE MAY BE CLOSE
ENOUGH TO MIDDLE TENNESSEE TO WARRANT A MARGINAL SEVERE WEATHER
THREAT. THE BIGGEST QUESTION WILL BE WHAT TIME THE FRONT DECIDES
TO PASS THROUGH THE AREA. THE GFS HAS A FRIDAY EVENING PASSAGE...
AND THE EURO IS A LITTLE SLOWER...PUSHING THE FRONT THROUGH AROUND
DAYBREAK SATURDAY. THIS WILL LIKELY BE A PLAYER IN STORM INTENSITY
AS WELL. BECAUSE THIS SECOND LOW IS A VERY RECENT CHANGE IN
GUIDANCE I AM GOING TO REFRAIN FROM ADDING THIS TO THE HAZARDOUS
WEATHER OUTLOOK...BUT PLEASE MONITOR THURSDAY AND FRIDAY`S
FORECAST CLOSELY OVER THE NEXT COUPLE OF DAYS.

 

 

http://forecast.weather.gov/product.php?site=NWS&issuedby=OHX&product=AFD&format=CI&version=1&glossary=1

 

.LONG TERM...FRIDAY THROUGH EARLY NEXT WEEK...
MODEL GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT THAT A LOW
PRESSURE SYSTEM WILL MOVE ACROSS THE GREAT LAKES REGION AND AN
ASSOCIATED COLD FRONT WILL SWING THROUGH THE MID-SOUTH FRIDAY
MORNING. AHEAD OF THIS FRONT...A STRONG DYNAMIC WIND FIELD AND
SUFFICIENT INSTABILITY WILL RESULT IN A CHANCE OF THUNDERSTORMS
ACROSS THE MAJORITY OF THE REGION. BEHIND THE FRONT...
INSTABILITY WILL INCREASE DURING THE DAY ON FRIDAY AS WARM AIR
MOVES IN ALOFT AND EFFECTIVELY CAPS THE ENVIRONMENT. SBCAPE VALUES
APPROACHING 1500 J/KG...LI/S AROUND -5...AND 700 TO 500MB LAPSE
RATES APPROACHING 8 C/KM WILL BE FOUND ACROSS A LARGE PART OF THE
MID-SOUTH. A SECONDARY NEUTRAL TO SLIGHTLY NEGATIVELY TILTED
TROUGH WILL MOVE ACROSS THE MID-SOUTH BY LATE FRIDAY AFTERNOON.
AS A RESULT...A FEW STRONG TO SEVERE THUNDERSTORMS MAY OCCUR...MAINLY
SOUTH OF THE I-40 CORRIDOR. WILL CONTINUE TO MONITOR THE THREAT IN
UPCOMING FORECASTS AS THE MODELS MAY BE OVERDOING THIS. FOR
NOW...JUST A MENTION APPEARS SUFFICIENT BEING 4 DAYS OUT.

 

http://forecast.weather.gov/product.php?site=NWS&issuedby=MEG&product=AFD&format=CI&version=1&glossary=1

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day3otlk_0730.gif

 

DAY 3 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   0230 AM CDT WED MAR 26 2014

   VALID 281200Z - 291200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FRIDAY INTO FRIDAY NIGHT ACROSS
   PARTS OF THE OZARK PLATEAU INTO THE TENNESSEE VALLEY AND ADJACENT
   PORTIONS OF THE GULF STATES...

   ...SYNOPSIS...
   MODELS INDICATE THAT A SIGNIFICANT BUT WEAKENING SURFACE CYCLONE
   WILL CONTINUE TO RAPIDLY DEVELOP NORTHEASTWARD WITH ITS ASSOCIATED
   MID-LEVEL IMPULSE...ACROSS THE LOWER GREAT LAKES...NEW ENGLAND AND
   THE CANADIAN MARITIMES DURING THIS PERIOD.  AS THIS OCCURS...THE
   BELT OF STRONGER DEEP LAYER MEAN FLOW SHOULD ALSO SHIFT OUT OF THE
   UPPER OHIO VALLEY...AND EVENTUALLY NORTHEAST OF NORTHERN ATLANTIC
   COASTAL AREAS.  AT THE SAME TIME...THOUGH...A SEASONABLY MODEST
   MOISTURE RETURN LIKELY WILL CONTINUE ON LIGHT SOUTHERLY LOW-LEVEL
   FLOW OFF THE GULF OF MEXICO INTO PARTS OF THE SOUTHERN PLAINS AND
   LOWER MISSISSIPPI VALLEY...AHEAD OF THE FRONTAL ZONE TRAILING FROM
   THE CYCLONE.

   THE FRONT IS EXPECTED TO INITIALLY STALL ACROSS THE OHIO VALLEY AND
   OZARK PLATEAU INTO THE SOUTH CENTRAL PLAINS...IN ADVANCE OF ANOTHER
   COUPLE OF SHORT WAVE IMPULSES PROGRESSING EAST OF THE ROCKIES.
   GUIDANCE INDICATES THAT SOME CONSOLIDATION OF THESE FEATURES IS
   POSSIBLE...AS UPSTREAM FLOW AMPLIFIES SOMEWHAT ACROSS THE EASTERN
   PACIFIC INTO THE INTERMOUNTAIN WEST AND ROCKIES.  AND ASSOCIATED
   FORCING MAY CONTRIBUTE TO SECONDARY FRONTAL WAVE DEVELOPMENT ACROSS
   THE OZARK PLATEAU INTO THE LOWER OHIO/TENNESSEE VALLEY REGION BY
   LATE FRIDAY NIGHT.

   ...OZARK PLATEAU/TN VALLEY AND PORTIONS OF ADJACENT GULF STATES...
   ALTHOUGH SURFACE DEW POINTS AND PRECIPITABLE WATER CONTENT WILL
   PROBABLY NOT BE ESPECIALLY HIGH FOR THE TIME OF YEAR...STEEP LAPSE
   RATES BENEATH A SEASONABLY COOL MID-LEVEL AIR MASS MAY CONTRIBUTE TO
   SIZABLE BOUNDARY LAYER CAPE BY LATE FRIDAY AFTERNOON.  SOME
   UNCERTAINTY LINGERS CONCERNING TIMING OF DEVELOPMENT.  BUT...WITH
   THE ONSET OF INCREASING LARGE-SCALE FORCING FOR UPWARD VERTICAL
   MOTION...STORMS ARE EXPECTED TO INITIATE BY THE EVENING HOURS...IF
   NOT BEFORE...ACROSS ARKANSAS.  LARGE HAIL SHOULD BE THE PRIMARY
   SEVERE THREAT INITIALLY...BUT UPSCALE GROWTH INTO A FORWARD
   PROPAGATING MESOSCALE CONVECTIVE SYSTEM SEEMS A DISTINCT POSSIBILITY
   AS ACTIVITY SPREADS EASTWARD TOWARD THE TENNESSEE VALLEY FRIDAY
   NIGHT.  THIS MAY BE AIDED BY A 40-50+ KT LOWER/MID TROPOSPHERIC
   SPEED MAXIMUM...WHICH WILL CONTRIBUTE TO THE RISK FOR SEVERE WIND
   GUSTS.

 

 

 

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Thursday and Friday would be a beautiful setup in late April or May. Too early to wish for a slow/stalled front and multiple shortwaves upstairs. Can we save this setup in a drawer; then, take it out and put it in the Plains in May? Late March in the South this setup includes lots of other rain destroying odds of seeing anything. Just as well I got basketball to watch. Cheers!

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mcd0218.gif

 

MESOSCALE DISCUSSION 0218
   NWS STORM PREDICTION CENTER NORMAN OK
   0543 PM CDT FRI MAR 28 2014

   AREAS AFFECTED...SWRN TN...NRN MS

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

   VALID 282243Z - 290045Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT

   SUMMARY...A FEW STRONG TO SEVERE STORMS ARE EXPECTED TO PERSIST E OF
   WW 37...WITH A WIND OR HAIL THREAT. A SMALL WATCH COULD BE REQUIRED.

   DISCUSSION...A CLUSTER OF STORMS PERSIST ACROSS ERN AR NEAR THE
   SURFACE FRONT...AND CONTINUE TO GRADUALLY MOVE EWD NEAR THE MS
   RIVER. FAVORABLE FORCING WITH THE UPPER TROUGH WILL PERSIST AS SWLY
   LOW-LEVEL FLOW HELPS TO BRING UNSTABLE AIR NEWD INTO FAR SWRN TN AND
   NRN MS. A 21Z SOUNDING NEAR SHAW MS SHOWED STEEP LAPSE RATES THROUGH
   A DEEP LAYER WHICH WILL AID IN UPDRAFT STRENGTH. LONG HODOGRAPHS AND
   SUFFICIENT INSTABILITY SHOULD AID THE EXISTING STORMS...WITH A
   SEVERE THREAT POSSIBLY SPREADING E OF WW 37.

 

 

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