MESOSCALE DISCUSSION 0112
NWS STORM PREDICTION CENTER NORMAN OK
0342 AM CST SAT FEB 04 2012

AREAS AFFECTED...PORTIONS S-CENTRAL/SE TX.

CONCERNING...HEAVY RAINFALL 

VALID 040942Z - 041245Z

INITIALLY WIDELY SCATTERED AREAS OF 1-3 INCH/HOUR RAIN RATES MAY
BECOME MORE WIDESPREAD AS BAND OF TSTMS OVER S-CENTRAL THROUGH
E-CENTRAL TX BECOMES BETTER-DEFINED BY FRONTAL INTRUSION/ASCENT. 
PEAK OF HEAVY RAIN THREAT...INCLUDING SUSTAINED RAINFALL WITH
SLOW-MOVING/MERGING/TRAINING CELLS...WILL BE THROUGH 12Z.

09Z SFC MESOANALYSIS SHOWED COLD FRONT...EXTENDING SWWD FROM WEAK
LOW OVER WRN AR TO JUST SE OF TXK-GGG-HDO LINE.  FRONT HAS CAUGHT UP
TO PRE-EXISTING CONVECTIVE BAND FROM ABOUT I-45 SWWD...AND SHOULD DO
SO OVER REMAINDER E TX SEGMENT DURING NEXT 2 HOURS.  COLD FRONT HAS
UNDERCUT TSTM LINE OVER SAT AREA...THOUGH CONVECTION IS PERSISTING
AND MAY EVEN BACKBUILD AS FRONTAL ASCENT ACTS ON FAVORABLE
MOISTURE/BUOYANCY IN ELEVATED LOW-LEVEL AIR MASS.  ENHANCED LIFT
FROM FRONTAL FORCING ALL ALONG THIS BAND...AND STORM-RELATIVE INFLOW
AIDED BY BROAD/20-30 KT LLJ...WILL ACT TO CONCENTRATE/ENHANCE PRECIP
FIELDS.  INFLOW SECTOR WILL REMAIN CHARACTERIZED BY UPPER 60S TO LOW
70S SFC DEW POINTS...LAYER RH AOA 90%...AND PW REACHING 1.5-1.75
INCH RANGE.  PRECIP LOADING ALSO MAY CONTRIBUTE TO THREAT FOR
ISOLATED/LOCALIZED DAMAGING GUSTS...HOWEVER SVR HAZARD APPEARS TOO
DISORGANIZED FOR WW AND IS SECONDARY TO THREAT FROM HEAVY RAIN.  AS
FRONT CONTINUES TO CROSS S AND SE TX...ESPECIALLY AFTER ABOUT
12Z...NET SEWD MOTION OF TSTM BAND SHOULD ACCELERATE...REDUCING
AMOUNT OF TIME THAT HEAVIEST RAIN RATES ARE LIKELY TO REMAIN OVER
MOST SPOTS.

..EDWARDS.. 02/04/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...LCH...SHV...HGX...CRP...EWX...

LAT...LON   29369925 29569821 30569620 31559472 31589382 30919374
            29709549 28909760 28559894 28829946 29369925 

MESOSCALE DISCUSSION 0111
NWS STORM PREDICTION CENTER NORMAN OK
0327 AM CST SAT FEB 04 2012

AREAS AFFECTED...ERN NEB/WRN IA

CONCERNING...HEAVY SNOW 

VALID 040927Z - 041330Z

INCH AN HOUR SNOWFALL RATES /GREATER IN THUNDERSNOW/ WILL GRADUALLY
TAPER OFF LATER THIS MORNING. CESSATION OF HEAVIER RATES IS ALREADY
ONGOING ACROSS CNTRL NEB.

HEAVY SNOWFALL HAS DEVELOPED IN THE FAVORED LEFT EXIT REGION OF A
MID-UPPER LEVEL JET...NOW QUICKLY PROGRESSING NEWD. WITH THE
LESSENING OF MORE SUPPORTIVE VERTICAL MOTION...RATES SHOULD
GRADUALLY BEGIN TO TAPER OFF THIS MORNING. UNTIL THEN...WEAK MID
LEVEL INSTABILITY /ROOTED AT 600-450 MB/ HAS SUPPORTED THE
OCCASIONAL LIGHTNING STRIKE ACROSS SRN NEB. THIS AREA OF ENHANCED
CONVECTIVE SNOWFALL POTENTIAL WILL SHIFT INTO SRN IA OVER THE NEXT
FEW HOURS. BRIEF BURSTS OF HEAVIER SNOW REMAIN POSSIBLE IN
THUNDERSNOW.

..HURLBUT.. 02/04/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DMX...EAX...OAX...TOP...GID...

LAT...LON   41719543 41339465 40749509 39989670 39829767 40239849
            41049753 41439676 41719543 

DAY 3 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0120 AM CST SAT FEB 04 2012

VALID 061200Z - 071200Z

...SYNOPSIS...
A QUASI-SPLIT FLOW REGIME WILL PERSIST ACROSS THE CNTRL/ERN CONUS
INTO THE FIRST PART OF THE WEEK AS A STRONG NRN STREAM TROUGH MOVES
OUT OF CANADA TO THE GREAT LAKES AND MEETS WITH MORE ZONAL WSWLY
FLOW ALOFT ASSOCIATED WITH THE NRN EDGE OF THE SUBTROPICAL JET
STREAM. A HIGH AMPLITUDE RIDGE AXIS WILL BE THE DOMINANT FEATURE
ACROSS MUCH OF WRN NORTH AMERICA. WITH A MUCH COLDER AIRMASS
SPREADING ACROSS THE NRN STATES...AND GENERALLY MARGINAL TO WEAK
FORCING FOR ASCENT ELSEWHERE...THE POTENTIAL FOR TSTM DEVELOPMENT
APPEARS QUITE LOW AT THIS TIME.

..CARBIN.. 02/04/2012

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1237 AM CST SAT FEB 04 2012

VALID 051200Z - 061200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A LARGE AND ELONGATED DEEP-LAYER CYCLONE FROM THE FOUR-CORNERS TO
THE CENTRAL PLAINS WILL CONTINUE TO UNDERGO AN UNUSUAL
TRANSFORMATION THIS WEEKEND. ONE PIECE OF SHORT WAVE ENERGY
ASSOCIATED WITH THIS SYSTEM WILL SPREAD EAST TOWARD A REGION OF
STRONG DOWNSTREAM CONFLUENCE...EVENTUALLY BECOMING ABSORBED BY A
STRONGER TROUGH MOVING SEWD FROM THE GREAT LAKES TO THE MID ATLANTIC
COAST ON SUNDAY. WHAT REMAINS OF THE MID/UPPER LEVEL LOW WILL
PERSIST AS A WEST-TO-EAST TROUGH FROM THE GREAT BASIN TO THE MID MS
VALLEY. WEAK MID LEVEL ELY FLOW WILL RESIDE NORTH OF THE AXIS FROM
MO/IA TO THE INTERIOR NORTHWEST...WHILE SOMEWHAT STRONGER ZONAL/WLY
FLOW EXISTS OVER THE SRN TIER OF STATES FROM AZ/NM TO THE SOUTHEAST
COAST.

GIVEN THE EVENTUAL DEMISE OF THE CNTRL/SRN U.S. SYSTEM AS IT IS
STRETCHED APART IN THE MID AND UPPER LEVELS...ASSOCIATED DEEP-LAYER
FRONTAL ZONE WILL SUBSEQUENTLY STALL AND REMAIN IN A RELATIVELY
WEAKENED STATE FROM THE LOWER RIO GRANDE VALLEY/NRN MEXICO EAST
ALONG OR JUST OFFSHORE OF THE NRN GULF COAST...AND THEN ENEWD TO THE
SOUTHEAST.

...SOUTHEAST...
CURRENT GUIDANCE SUGGESTS A NARROW WINDOW OF OPPORTUNITY FOR
INSTABILITY AND FORCING TO COINCIDE AND PROMOTE SCATTERED TSTM
DEVELOPMENT OVER GA/SC ON SUNDAY AFTERNOON. THIS DEVELOPMENT SHOULD
OCCUR AS LIFT ALONG AN ADVANCING FRONTAL SEGMENT IS ENHANCED BY
HEIGHT FALLS WITH THE UPPER TROUGH SPREADING ACROSS THE
NORTHEAST/MID ATLANTIC...AND SLOPED ASCENT WITHIN RIGHT ENTRANCE
REGION OF MID/UPPER JET. GENERALLY WEAK INSTABILITY BUT MODEST/FLOW
SHEAR ACROSS THE REGION SUGGEST THE POTENTIAL FOR A COUPLE OF
STRONGER STORMS WITH GUSTY WINDS AND/OR SMALL HAIL DURING THE
AFTERNOON.

...S TX...
WEAK ISENTROPIC LIFT MAY BE SUPPLEMENTED BY THE PASSAGE OF A SUBTLE
LOWER LATITUDE SHORT WAVE TROUGH TO SUPPORT TSTM DEVELOPMENT ATOP
PRONOUNCED FRONTAL INVERSION ACROSS THE LOWER RIO GRANDE
VALLEY...ESPECIALLY EARLY SUNDAY. HOWEVER...SEVERE TSTMS DO NOT
APPEAR LIKELY.

..CARBIN.. 02/04/2012

DAY 4-8 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0153 AM CST SAT FEB 04 2012

VALID 071200Z - 121200Z

...DISCUSSION...
HIGHLY AMPLIFIED FLOW IS HANDLED IN A SIMILAR FASHION BY BOTH THE
EURO AND GFS MODELS INTO THE MEDIUM RANGE. EXTENSIVE RIDGE AXIS WILL
PREVAIL ACROSS WRN NORTH AMERICA THROUGH AT LEAST THE END OF THE
WEEK. DEEP-LAYER NLY FLOW BETWEEN ERN FLANK OF THE RIDGE AXIS AND
WRN SEMI-CIRCLE OF POLAR VORTEX OVER NRN CANADA WILL ENSURE THE
EFFICIENT DELIVERY OF ARCTIC AIR TO MUCH OF THE NRN AND CNTRL U.S.
THROUGH MIDWEEK...MODELS ALSO DEPICT THE EVOLUTION OF A BAJA LOW BY
DAY 6/THURSDAY. HOWEVER...THIS LOW IS FORECAST TO BE SHUNTED WELL
SOUTH INTO MEXICO THROUGH THE END OF THE WEEK AS THE BLOCKING UPPER
RIDGE SHOWS LITTLE INDICATION OF WEAKENING. GIVEN THE COLD AND
GENERALLY DRY CONDITIONS...AND LACK OF STRONG ASCENT AND DEARTH OF
INSTABILITY DEPICTED IN MODEL GUIDANCE...SEVERE STORM DEVELOPMENT
APPEARS UNLIKELY DURING THIS PERIOD.

DAY 1 FIRE WEATHER OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0205 AM CST SAT FEB 04 2012

VALID 041200Z - 051200Z

...SYNOPSIS...
A RELATIVELY STAGNANT UPPER PATTERN WILL OCCUR...WITH A BROAD UPPER
TROUGH PERSISTING OVER THE NORTHEAST...THOUGH A STRONGER EMBEDDED
WAVE WILL PROGRESS THROUGH THE GREAT LAKES REGION INTO THE NORTHEAST
OVERNIGHT. MEANWHILE...A CNTRL PLAINS UPPER LOW WILL DRIFT INTO
MO...WHILE A LOW CONTINUES TO LINGER OVER THE FOUR CORNERS REGION.
THE BLOCKING PATTERN WILL MAINTAIN AN UPPER RIDGE ALONG THE PACIFIC
COASTAL STATES INTO THE WRN CANADIAN PROVINCES.

AT THE SURFACE...AN AREA OF LOW PRESSURE WILL PROGRESS TO THE RIDGE
OF THE APPALACHIANS...EXTENDING SWWD TO SRN TX OVERNIGHT. HIGH
PRESSURE CENTERED OVER THE CNTRL STATES WILL MAINTAIN WEAK OFFSHORE
FLOW ACROSS SRN CA.

...SRN CA...
00Z SAN DIEGO SOUNDING SHOWS LITTLE CHANGE IN THE ANTECEDENT AIR
MASS...WITH DRY CONDITIONS CONTINUING ACROSS SRN CA. POOR RELATIVE
HUMIDITY RECOVERY WILL BE ONGOING AT THE START OF THE FORECAST
PERIOD...AND WITH HIGH TEMPERATURES ONCE AGAIN WARMING INTO THE
LOWER 70S...EXPECT MINIMUM RELATIVE HUMIDITY VALUES TO BE SIMILAR TO
YESTERDAY...GENERALLY IN THE TEENS AND 20S. GIVEN A WEAK OFFSHORE
COMPONENT...LOCALIZED AREAS OF GUSTY WINDS REMAIN POSSIBLE IN
FAVORED CANYONS AND PASSES...LEADING TO SHORT-DURATIONS OF ENHANCED
FIRE THREAT.

..HURLBUT.. 02/04/2012

...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...

DAY 2 FIRE WEATHER OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0234 AM CST SAT FEB 04 2012

VALID 051200Z - 061200Z

...SYNOPSIS...
AN UPPER TROUGH IN THE NORTHEAST WILL QUICKLY EJECT OFFSHORE...WHILE
THE NEXT ONE DIVES SWD THROUGH THE CNTRL CANADIAN PROVINCES
OVERNIGHT. THE COMPACT UPPER LOW CENTERED ROUGHLY OVER MO WILL
FINALLY BEGIN TO PROGRESS TO KY/TN. MEANWHILE...THE STAGNANT LOW
OVER THE ERN GREAT BASIN WILL BLOCK PROGRESSION OF THE UPPER PATTERN
IN THE WEST...MAINTAINING AN UPPER RIDGE ALONG THE PACIFIC COASTAL
STATES.

...SRN CA...
WEAK OFFSHORE FLOW WILL BE ONGOING AT THE START OF THE FORECAST
PERIOD...WITH POOR RELATIVE HUMIDITY RECOVERY EXPECTED. GIVEN VERY
LITTLE CHANGE IN THE AIR MASS AND SIMILAR HIGH TEMPERATURES AS
SATURDAY...MINIMUM RELATIVE HUMIDITY VALUES IN THE TEENS AND 20S ARE
LIKELY. GUSTY WINDS REMAIN POSSIBLE THROUGH FAVORED CANYONS AND
PASSES...PARTICULARLY CLOSER TO THE L.A. AREA. OVERNIGHT...A PATTERN
CHANGE WILL SLOWLY BEGIN TO OCCUR AS ONSHORE FLOW ENSUES...BECOMING
MORE PREDOMINANT INTO THE D3/MON PERIOD.

..HURLBUT.. 02/04/2012

...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...