Convective Hazards - National USData: Map Discussion: Day 1 Day 2 Day 3 Day 4-8

000
ACUS01 KWNS 170051
SWODY1
SPC AC 170049

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0749 PM CDT WED MAY 16 2012

VALID 170100Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS EVE ACROSS PARTS OF
CNTRL/NERN MASSACHUSETTS AND SERN NEW HAMPSHIRE INTO SWRN MAINE...

...CNTRL MASSACHUSETTS INTO SERN NEW HAMPSHIRE/SWRN MAINE...
LATEST RAPID REFRESH INDICATES THAT BOUNDARY LAYER CAPE REMAINS
MODERATELY LARGE ALONG A LINGERING PRE-FRONTAL AXIS OF STRONGER
DAYTIME HEATING.  PERHAPS AIDED BY LARGE-SCALE FORCING FOR UPWARD
VERTICAL MOTION ASSOCIATED WITH A SIGNIFICANT SHORT WAVE TROUGH...
THE SOUTHERN PORTION OF WHICH IS SHIFTING EAST OF THE GREAT LAKES
REGION...VIGOROUS CONVECTIVE DEVELOPMENT WITH LARGE HAIL/DAMAGING
WIND POTENTIAL MAY PERSIST INTO THE 02-03Z TIME FRAME...BEFORE
CONDITIONS STABILIZE WITH FRONTAL PASSAGE/LOSS OF SURFACE HEATING.

...INTERMOUNTAIN WEST/ROCKIES/PLAINS...
MUCH OF ONGOING THUNDERSTORM ACTIVITY IS EXPECTED TO DIMINISH BY THE
03-05Z TIME FRAME AS BOUNDARY LAYER STABILIZATION TAKES PLACE WITH
THE LOSS OF DAYTIME HEATING.  EVEN THOUGH MOISTURE LEVELS ARE RATHER
LOW ACROSS THE NORTHERN PLAINS...MODELS SUGGEST THAT SOME ADDITIONAL
THUNDERSTORM DEVELOPMENT IS STILL POSSIBLE LATER TONIGHT...IN
ASSOCIATION WITH STRENGTHENING LOWER/MID TROPOSPHERIC WARM
ADVECTION.  GIVEN THE PLUME OF VERY WARM ELEVATED MIXED LAYER AIR
ADVECTING EAST NORTHEAST THE NORTH CENTRAL ROCKIES INTO THE EASTERN
DAKOTAS...THE BEST CHANCE FOR THIS MAY BE ACROSS PARTS OF
NORTHEASTERN SOUTH DAKOTA INTO PARTS OF CENTRAL/SOUTHERN NORTH
MINNESOTA TOWARD 08-12Z...AS A VEERING LOW-LEVEL JET FINALLY BEGINS
TO FOCUS LIFT EAST OF STRONGER MID-LEVEL CAPPING.

...SOUTHEAST...
WITH WEAK UPPER TROUGHING CONTRIBUTING TO CONVECTIVE POTENTIAL...
SCATTERED VIGOROUS THUNDERSTORM ACTIVITY CONTINUES ACROSS THE SOUTH
ATLANTIC COAST STATES.  HOWEVER...GIVEN THE GENERALLY WEAK WIND
FIELDS AND VERTICAL SHEAR...SEVERE POTENTIAL STILL SEEMS
LOW...PARTICULARLY WITH CONTINUING GRADUAL BOUNDARY LAYER
STABILIZATION ANTICIPATED THIS EVENING.

..KERR.. 05/17/2012

000
ACUS02 KWNS 161724
SWODY2
SPC AC 161723

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1223 PM CDT WED MAY 16 2012

VALID 171200Z - 181200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A WEAK UPPER TROUGH IS FORECAST TO CROSS THE SOUTHEAST U.S./GULF OF
MEXICO DURING THE DAY 2 PERIOD...WITH AN ASSOCIATED BAND OF ENHANCED
MID-LEVEL WSWLYS EXPECTED ACROSS THE ERN GULF AND INTO FL.

FARTHER W...A WEAK SHORT-WAVE TROUGH MOVING INTO THE PLAINS SHOULD
WEAKEN WITH TIME...AS THE LARGER-SCALE RIDGE EXPANDS AHEAD OF A
STRONGER/SHARPER TROUGH MOVING INTO THE WRN CONUS.  

AT THE SURFACE...A BROAD/WEAK AREA OF LOW PRESSURE IS FORECAST OVER
THE SOUTHEAST U.S./ERN GULF IN CONJUNCTION WITH THE UPPER
SYSTEM...WHILE HIGH PRESSURE PREVAILS ACROSS MOST OF THE REST OF THE
ERN HALF OF THE CONUS.

FARTHER W...LEE TROUGHING IS FORECAST TO PERSIST ACROSS THE HIGH
PLAINS...WHILE A COLD FRONT PROGRESSES EWD ACROSS THE INTERMOUNTAIN
WEST AHEAD OF THE STRONGER WRN UPPER TROUGH.

...S FL...
AS THE WEAK UPPER TROUGH CROSSES FL...INDUCING SUBTLE SURFACE
RESPONSE...SHOWERS AND SCATTERED THUNDERSTORMS SHOULD DIURNALLY
DEVELOP ACROSS THE SRN 2/3 OF FL.  WEAK LAPSE RATES -- AND THUS
MODEST CAPE -- IS EXPECTED...WHICH SHOULD LIMIT STORM INTENSITY. 
HOWEVER...WITH ENHANCED WSWLY MID-LEVEL FLOW ASSOCIATED WITH THE
UPPER SYSTEM EXPECTED ACROSS THE REGION...THIS MAY OFFSET THE LACK
OF INSTABILITY TO ALLOW A FEW ORGANIZED/MARGINALLY SEVERE STORMS TO
EVOLVE DURING THE AFTERNOON.

..GOSS.. 05/16/2012

000
ACUS03 KWNS 160731
SWODY3
SPC AC 160730

DAY 3 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT WED MAY 16 2012

VALID 181200Z - 191200Z

...SYNOPSIS...
MODEL GUIDANCE IS HIGHLY CONSISTENT THAT A SHORT WAVE IMPULSE
EMBEDDED WITHIN AN AMPLIFIED UPPER-LEVEL TROUGH SHOULD TRACK FROM
THE SOUTHWEST TO THE SRN ROCKIES ON D3. A LEE SURFACE TROUGH WILL
PERSIST FROM THE BLACK HILLS TO THE SRN HIGH PLAINS...INTERSECTING A
COLD FRONT THAT SHOULD ACCELERATE SEWD ACROSS THE NRN INTO THE CNTRL
HIGH PLAINS BY EARLY SAT.

...NRN TO SRN HIGH PLAINS...
ALTHOUGH THIS WILL BE THE THIRD DAY OF POLEWARD TRANSPORT OF A
MARGINALLY MOIST AIR MASS FROM THE SRN PLAINS...RETURN FLOW OFF THE
WRN GULF SHOULD REMAIN MODEST AFTER NOT COMMENCING UNTIL LATE D2.
SURFACE DEW POINTS /ALTHOUGH INCREASING/ WILL BE MARGINAL FOR A
TYPICAL PLAINS WARM SECTOR...LARGELY EXPECTED TO BE IN THE 30S/40S
ALONG THE LEE TROUGH IN THE HIGH PLAINS TO PERHAPS LOWER 50S OVER
THE NRN PLAINS ALONG THE COLD FRONT. STRENGTHENING CONVERGENCE ALONG
THESE BOUNDARIES AND STRONG HEATING SHOULD GENERALLY RESULT IN WEAK
BUOYANCY AND AT LEAST ISOLATED TSTMS FORMING DURING THE LATE
AFTERNOON TO EARLY EVENING.

DEEP-LAYER FLOW WILL GRADUALLY INCREASE WITH APPROACH OF THE WRN
CONUS TROUGH...BUT SHOULD REMAIN LARGELY MODERATE AND LIKELY
STRONGER WITH NRN EXTENT. THIS MAY SUPPORT A FEW HIGH-BASED
SUPERCELL STRUCTURES CAPABLE OF ISOLATED SEVERE WIND/HAIL.
STILL...WITH MID-LEVEL S/SWLYS ROUGHLY PARALLELING THE SURFACE COLD
FRONT AND ANAFRONTAL CHARACTERISTICS OF THIS BOUNDARY...PROSPECTS
FOR SUSTAINED ORGANIZED STORMS APPEAR TOO MARGINAL TO WARRANT A
SLIGHT RISK DELINEATION ATTM.

..GRAMS.. 05/16/2012

ACUS48 KWNS 160842
SWOD48
SPC AC 160842
DAY 4-8 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0342 AM CDT WED MAY 16 2012
VALID 191200Z - 241200Z
...DISCUSSION...
ISOLATED SEVERE POTENTIAL SHOULD EXIST ON SAT/D4 FROM THE UPPER MS
VALLEY TO THE CNTRL PLAINS...WITH INCREASINGLY LIMITED PROSPECTS
THEREAFTER. ABOVE-AVERAGE CONFIDENCE PERSISTS WITH HIGH CONTINUITY
AMONG THE 00Z ECMWF/GFS AND GEFS MEAN WITH THE DEPICTION OF A
DAMPENING SHORT WAVE TROUGH EJECTING FROM THE SRN ROCKIES INTO THE
CNTRL PLAINS ON D4. AT THE SURFACE...A COLD FRONT WILL ADVANCE
E/SEWD...LIKELY REACHING THE UPPER MS VALLEY TO CNTRL PLAINS BY SAT
AFTERNOON. CONCERNS OVER WARM SECTOR MOISTURE RETURN DESCRIBED IN
THE D2/3 OUTLOOKS SUGGEST GFS/GEFS MEAN SURFACE DEW POINTS CONTINUE
TO DISPLAY A HIGH BIAS. GFSX MOS AND THE ECMWF APPEAR MORE
REASONABLE WITH GENERALLY 50S SURFACE DEW POINTS. GIVEN THE
DAMPENING NATURE OF THE SHORT WAVE TROUGH...MID-LEVEL FLOW NEARLY
PARALLELING THE SURFACE FRONT AND LIKELY ONLY MODERATE
BUOYANCY...SETUP DOES NOT RENDER SEVERE PROBABILITIES AOA 30 PERCENT
ATTM.
..GRAMS.. 05/16/2012