RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Wed Apr 23 12:50:01 UTC 2014.
No Mesoscale Discussions are in effect as of Wed Apr 23 12:50:02 UTC 2014.
SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0746 AM CDT WED APR 23 2014
VALID 231300Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL/SRN PLAINS...
...SUMMARY...
SEVERE THUNDERSTORMS ARE EXPECTED THIS AFTERNOON INTO TONIGHT ACROSS
THE CENTRAL AND SOUTHERN GREAT PLAINS. LARGE HAIL WILL BE THE
PRIMARY INITIAL HAZARD...WITH DAMAGING WINDS AND A FEW TORNADOES
POSSIBLE.
...SYNOPSIS...
PROGRESSIVE UPPER-AIR PATTERN IS FCST ACROSS CONUS THIS
PERIOD...MAIN INFLUENCING FEATURE ALOFT FOR SVR RISK BEING
SYNOPTIC-SCALE TROUGH NOW LOCATED FROM BC TO NRN ROCKIES...UT AND
LOWER CO RIVER VALLEY. SERIES OF NRN-STREAM VORTICITY MAXIMA WILL
TRAVERSE THAT PORTION OF THIS TROUGH LOCATED OVER NRN ROCKIES AND
NRN PLAINS...LEADING TO ITS NET EWD MOVEMENT TO SK...WRN DAKOTAS AND
WRN NEB BY END OF PERIOD. MEANWHILE...BASAL VORTICITY LOBE NOW OVER
SRN SIERRAS IS EXPECTED TO SHIFT ESEWD AND INTENSIFY
TODAY...EXTENDING FROM SWRN CO TO AZ/NM BORDER BY 00Z. BY 12Z THIS
PERTURBATION SHOULD REACH SWRN KS AND TX PANHANDLE...WITH ASSOCIATED
DCVA PLUME SPREADING OVER CENTRAL KS...CENTRAL/WRN K AND NW TX.
AT SFC...COLD FRONT ANALYZED AT 11Z OVER ERN WY WILL MOVE EWD AND
SEWD ACROSS CENTRAL HIGH PLAINS TODAY...WHILE SFC LOW DEVELOPS ALONG
ITS INTERSECTION WITH LEE TROUGH OVER ERN CO/EXTREME WRN KS. BY
00Z...FRONT SHOULD ARC FROM NWRN ND ACROSS CENTRAL NEB AND NWRN KS.
INITIALLY DIFFUSE DRYLINE SHOULD BECOME BETTER-DEFINED BY 00Z FROM
NRN COAHUILA NNEWD OVER ERN TX PANHANDLE THEN NWD ACROSS E-CENTRAL
KS. COLD FRONT WILL OVERTAKE DRYLINE FROM N-S TONIGHT WHILE SFC
CYCLONE MOVES RAPIDLY NEWD TO IA. BY 12Z...FRONT SHOULD EXTEND FROM
IA LOW SWWD ACROSS ERN KS...SWRN KS AND SERN CORNER OF NM.
...SLGT RISK AREA...CENTRAL/SRN PLAINS...
SCATTERED TSTMS ARE EXPECTED TO DEVELOP THIS AFTN ALONG COLD
FRONT...SOME OF WHICH MAY ATTAIN SUPERCELL STRUCTURES BEFORE
AGGREGATING INTO QUASI-LINEAR/FRONTALLY FORCED MODE. THIS
CONVECTION SHOULD BE RATHER HIGH-BASED AND MAY BE PRONE TO
EARLY-STAGE OUTFLOW-DOMINANCE. STILL...BAND OF STG-SVR TSTMS SHOULD
OFFER RISK FOR SVR GUSTS AND HAIL INTO EVENING ACROSS NRN PORTIONS
OUTLOOK AREA...BEFORE MOVING EWD AND DIMINISHING. AIR MASS N OF
ABOUT I-70 IS LIKELY TO STABILIZE DIABATICALLY FASTER THAN THAT
INFLUENCE CAN BE OFFSET BY THETAE ADVECTION.
FARTHER S...COVERAGE SHOULD BE MORE WIDELY SCATTERED IN FIRST 2-3
HOURS FOR DRYLINE-INITIATED CELLS FROM WRN KS TO NW TX...WITH
DISCRETE SUPERCELLS PROBABLE. CHANCE FOR DISCRETE SUPERCELLS WITH
ENOUGH MOISTURE CONTENT FOR SIGNIFICANT/DAMAGING HAIL APPEARS
LARGEST IN ERN TX PANHANDLE...WRN OK AND NW TX. SOME INITIALLY
DRYLINE-FIRED CONVECTION MAY AGGREGATE INTO CLUSTERS THIS EVENING
AND MOVE EWD ACROSS PORTIONS OK OR N TX WITH POTENTIAL FOR BOWS AND
EMBEDDED SUPERCELLS. WHERE ANY DISCRETE SUPERCELLS LAST INTO
EVENING...THEY WILL ENCOUNTER RAPIDLY ENLARGING HODOGRAPHS DUE TO
STRENGTHENING LLJ...CONCURRENT WITH LOSS OF DIURNAL MIXING AND
RESULTANT ADVECTION-RELATED BOOST IN INFLOW-LAYER MOISTURE THAT
LOWERS LCL. TIME WINDOW NEAR SUNSET AND INTO TWILIGHT THEREFORE MAY
POSE SOME TORNADO RISK...WHERE TSTM MODES STILL ARE SUITABLE...AND
BEFORE NOCTURNAL COOLING PROHIBITIVELY STRENGTHENS SBCINH.
SUFFICIENT DIURNAL HEATING WILL OCCUR ON BOTH SIDE OF
DRYLINE...AIDING IN AFTN DEVELOPMENT...DESPITE PERSISTENT/ANTECEDENT
HIGH CLOUDS. MEANWHILE...CORRIDOR OF RETURN-FLOW MOISTURE ADVECTION
WILL BE OFFSET BY AFTN VERTICAL MIXING SUCH THAT SFC DEW POINTS MAY
NOT RISE MUCH ABOVE CURRENT VALUES OVER MUCH OF NW TX...OK AND KS.
HOWEVER...AROUND 00Z AND INTO EVENING...60S F DEW POINTS MAY REACH
RED RIVER REGION WITH 50S INTO KS. EFFECTIVE SHEAR MAGNITUDES MAY
REACH 40-50 KT ACROSS PRE-DRYLINE/PREFRONTAL CORRIDOR BY 00Z.
...W-CENTRAL/SW TX...
ISOLATED TSTMS ARE POSSIBLE OVER THIS CORRIDOR...INITIATED BOTH
INVOF DRYLINE AND OVER HIGHER TERRAIN OF NRN COAHUILA. LATTER
CONVECTION MAY REACH ADJOINING PORTIONS TX RIO GRANDE VALLEY BEFORE
DISSIPATING. ANY OF THIS ACTIVITY MAY DEVELOP SOME SUPERCELL
CHARACTERISTICS WITH LARGE HAIL AND DAMAGING GUSTS BEING MAIN
CONCERNS...THOUGH POTENTIAL COVERAGE/DURATION APPEAR MORE LIMITED
THAN FARTHER N. GREATEST POTENTIAL LONGEVITY MAY BE FOR CONVECTION
MOVING OFF SERRANIAS DEL BURRO RANGE AND FOOTHILLS...GIVEN
RELATIVELY MAXIMIZED BOUNDARY-LAYER MOISTURE CONTENT OVER THIS AREA.
..EDWARDS/ROGERS.. 04/23/2014
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Day 4-8 Outlook
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0351 AM CDT WED APR 23 2014
VALID 261200Z - 011200Z
...DISCUSSION...
..SIGNIFICANT MULTI-DAY SEVERE EVENT EXPECTED ACROSS PORTIONS OF THE
CENTRAL AND SOUTHERN PLAINS SATURDAY AND SUNDAY AND ACROSS THE MS
VALLEY AND MID SOUTH ON MONDAY...STRONG TORNADOES ARE POSSIBLE...
MEDIUM RANGE FORECAST CONTINUES TO BE HEAVILY WEIGHTED TOWARD THE
ECMWF DUE TO RUN-TO-RUN CONSISTENCY REGARDING THE 500MB EVOLUTION OF
WRN U.S. TROUGH. CONCERNS REGARDING POLAR FRONT UNDERCUTTING STRONG
SWLY FLOW ALOFT HAVE ABATED THIS MORNING. LATEST GUIDANCE DEEPENS
LEE CYCLONE OVER SERN CO SATURDAY AFTERNOON WITH SUBSEQUENT MOVEMENT
INTO WRN KS ON SUNDAY. INTENSE 500MB SPEED MAX APPROACHING 90KT
SHOULD ROUND THE BASE OF THE TROUGH ALONG THE AZ/MEXICAN BORDER THEN
EJECT INTO SWRN KS EARLY SUNDAY. AS A RESULT SFC LOW IS NOT
EXPECTED TO ADVANCE APPRECIABLY EWD UNTIL LATER MONDAY AS SECONDARY
MID-LEVEL SPEED MAX DEVELOPS FROM NORTH TX INTO THE LOWER OH RIVER
VALLEY.
MODERATE TO EXTREME INSTABILITY SHOULD DEVELOP EAST OF THE DRYLINE
SATURDAY AFTERNOON ALONG ERN PLUME OF STEEP LAPSE RATES. STRONGLY
DIFLUENT FLOW ALOFT SHOULD ENCOURAGE VIGOROUS SUPERCELL DEVELOPMENT
FROM PORTIONS OF WCNTRL TX...NWD INTO KS. VERY LARGE HAIL AND
TORNADOES CAN BE EXPECTED WITH THIS ACTIVITY.
IT/S NOT ENTIRELY CLEAR HOW FAR EAST THE DRYLINE WILL MIX SUNDAY AS
LOWEST PRESSURES WILL REMAIN FOCUSED ACROSS THE HIGH PLAINS OF WRN
KS. MODELS MIX DRYLINE EAST OF I-35 CORRIDOR ACROSS OK BY 18Z
SUNDAY BUT THE DAY5 FORECAST WILL ACCOUNT FOR DRYLINE NOT MIXING
ACROSS THE PLAINS AS FAST AS MODELS CURRENTLY DEPICT. AS A
RESULT...SUBSTANTIAL MID-LEVEL FLOW SHOULD OVERSPREAD THE
MOIST/BUOYANT WARM SECTOR AND ANOTHER DIURNALLY-INITIATED ROUND OF
POTENTIALLY TORNADIC SUPERCELLS COULD EVOLVE.
LATER MONDAY IT APPEARS THE SFC FRONT/DRYLINE SHOULD ADVANCE INTO
THE MS VALLEY. SCATTERED-NUMEROUS SUPERCELLS SHOULD EVOLVE AHEAD OF
THE FRONT FROM LA...NWD INTO MO AND POSSIBLY AS FAR EAST AS MIDDLE
TN. TORNADOES AND LARGE HAIL REMAIN POSSIBLE WITH WARM-SECTOR
CONVECTION.
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SPC Day 1 Fire Weather Outlook
DAY 1 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0332 AM CDT WED APR 23 2014
VALID 231200Z - 241200Z
...CRITICAL FIRE WEATHER AREA FOR ERN AZ...MUCH OF NM...SRN/CNTRL
HIGH PLAINS...
...SYNOPSIS...
AN UPPER TROUGH WILL SHIFT OFFSHORE THE ATLANTIC COAST EARLY IN THE
PERIOD...BUT A TRAILING BELT OF ENHANCED MIDLEVEL FLOW WILL EXTEND
FROM THE UPPER GREAT LAKES INTO THE MID-ATLANTIC. FARTHER W...A
PROGRESSIVE SHORTWAVE UPPER TROUGH WILL SHIFT FROM THE
INTER-MOUNTAIN WEST/ROCKIES INTO THE GREAT PLAINS. AT THE SFC...A
LEE LOW WILL DEEPEN NEAR THE CO/KS BORDER...WITH AN ATTENDANT LEE
TROUGH AND DRYLINE EXTENDING SWD ACROSS THE HIGH PLAINS OF W TX. A
COLD FRONT WILL PROGRESS SWD LATE AFTERNOON AND EVENING ACROSS
SRN/CNTRL HIGH PLAINS.
...ERN AZ...MUCH OF NM...SRN/CNTRL HIGH PLAINS...
LOW-MIDLEVEL FLOW WILL STRENGTHEN THROUGHOUT THE MORNING SURROUNDING
THE BASE OF AN APPROACHING UPPER TROUGH. THE COMBINATION OF DEEP
BOUNDARY-LAYER MIXING /ENHANCED VIA DOWNSLOPE EFFECTS OVER THE HIGH
PLAINS/ AND A TIGHTENING SFC PRESSURE GRADIENT WILL SUPPORT
SUSTAINED WIND SPEEDS OF 20-30 MPH /HIGHER GUSTS/. RH VALUES AS LOW
AS THE SINGLE DIGITS ARE LIKELY OVER ERN NM...WHILE GENERALLY
RANGING FROM 10-15 PERCENT ELSEWHERE. THE CRITICAL FIRE WEATHER
THREAT WILL BE DELINEATED TO THE E BY A DRYLINE/LEE SFC TROUGH
BECOMING ESTABLISHED OVER THE ERN TX/OK PANHANDLES. MEANWHILE...A
COLD FRONT WILL ENTER NERN CO BY EARLY EVENING...AND RESULT IN AN
ABRUPT WIND SHIFT OUT OF THE N.
...HIGH PLAINS OF SERN WY...WRN NEB...NERN CO...NWRN KS...
STRONG POST-FRONTAL WLY-NWLY WINDS /25-35 MPH/ WILL OVERSPREAD ERN
WY AND WRN NEB...AND EVENTUALLY NERN CO/NWRN KS BY LATE AFTERNOON.
DESPITE COOLER TEMPERATURES...SUBSTANTIAL BOUNDARY-LAYER MIXING
ENHANCED BY DOWNSLOPE EFFECTS WILL YIELD RH VALUES IN THE TEENS AS
TEMPERATURES REACH THE 60S-70S F. THESE CONDITIONS WILL SUPPORT AN
ELEVATED FIRE WEATHER THREAT.
...VA...NRN NC...
A BELT OF NWLY DEEP-LAYER FLOW WILL TRANSPORT A VERY DRY AIR MASS
INTO THE MID-ATLANTIC...CHARACTERIZED BY PW VALUES AOB 0.4 INCH.
MUCH OF VA/NRN NC WILL BE POSITIONED ALONG THE SRN PERIPHERY OF
STRONG LOW-LEVEL WINDS SURROUNDING LOW PRESSURE CENTERED NEAR
COASTAL MAINE. TEMPERATURES WILL WARM INTO THE 60S/70S F WITHIN A
DOWNSLOPE REGIME E OF THE APPALACHIANS...YIELDING RH VALUES RANGING
FROM THE MID-20S TO LOW-30S.
..ROGERS.. 04/23/2014
...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...
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SPC Day 2 Fire Weather Outlook
DAY 2 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0338 AM CDT WED APR 23 2014
VALID 241200Z - 251200Z
...SYNOPSIS...
THE LARGE-SCALE PATTERN WILL REMAIN PROGRESSIVE...AS A SHORTWAVE
UPPER TROUGH BEGINS TO DEAMPLIFY AS IT APPROACHES THE UPPER GREAT
LAKES AND OH VALLEY. AN ASSOCIATED ELONGATED SFC TROUGH WILL EXTEND
FROM ND SEWD INTO THE UPPER-MS VALLEY...TO THE INTERFACE OF AN
ATTENDANT DRYLINE ORIENTED NE-SW TO THE TX RIO GRANDE VALLEY.
FARTHER E...A VERY DRY AIR MASS WILL BE MAINTAINED BY A BELT OF NWLY
FLOW IN THE WAKE OF A DEEP-LAYER CLOSED LOW POSITIONED OVER THE WRN
ATLANTIC. MEANWHILE...ANOTHER SHORTWAVE UPPER TROUGH WILL BEGIN TO
AMPLIFY WHILE APPROACHING THE PACIFIC COAST.
...CNTRL HIGH PLAINS...S-CNTRL SD AND N-CNTRL NEB...
WLY LOW-LEVEL WINDS WILL STRENGTHEN ACROSS THE CNTRL/NRN PLAINS...W
OF A SFC TROUGH SHIFTING EWD THROUGHOUT THE DAY. STEEPENING
LOW-LEVEL LAPSE RATES BENEATH 25-30 KT FLOW IN THE 0-3 KM AGL LAYER
WILL SUPPORT SUSTAINED SFC WINDS OF 20-30 MPH /HIGHER GUSTS/. THE
DOWNSLOPE REGIME WILL PROMOTE ANOTHER DAY OF WARM/DRY BOUNDARY-LAYER
CONDITIONS...WITH RH VALUES PROBABLY RANGING FROM 15-20 PERCENT BY
AFTERNOON. THE ELEVATED RISK AREA REFLECTS THE HIGHEST CONFIDENCE IN
LITTLE TO NO RAINFALL OCCURRING ON WED/D1...WITH HIGHER TOTALS
POSSIBLE INTO NRN/ERN PORTIONS OF SD.
...NRN DELMARVA PENINSULA NEWD INTO SRN NEW ENGLAND...
A DRY AIR MASS WILL BE TRANSPORTED INTO THE NORTHEAST AS A BELT OF
STRONG NWLY FLOW SHIFTS NWD IN CONJUNCTION WITH AN OFFSHORE LOW.
DESPITE DAYTIME TEMPERATURES ONLY FORECAST TO RANGE FROM THE
UPPER-50S N TO MID-60S S...THE EXCEPTIONAL DRYNESS OF THIS AIR MASS
/PW VALUES RANGING FROM 0.2-0.3 INCH/ WILL SUPPORT MIN RH VALUES OF
15-25 PERCENT. COMBINED WITH SUSTAINED WIND SPEEDS OF 15-20 MPH
/MUCH HIGHER GUSTS/...AN ELEVATED TO NEAR-CRITICAL FIRE WEATHER
THREAT IS LIKELY TO MATERIALIZE.
AN ELEVATED FIRE WEATHER RISK MAY ALSO EXTEND NWD INTO ADDITIONAL
PORTIONS OF WRN NY AND SRN NEW ENGLAND. HOWEVER...UNCERTAINTY EXISTS
ABOUT PRECIPITATION FORECAST TO OCCUR ON WED/D1...BUT THIS AREA WILL
CONTINUE TO BE MONITORED FOR INCLUSION IN FUTURE UPDATES.
..ROGERS.. 04/23/2014
...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...
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