Sat, 11 Feb 2012 05:57:10 +0000 SPC MD 115 MD 0115 CONCERNING HEAVY SNOW FOR NWRN IND...FAR SWRN LOWER MI
MESOSCALE DISCUSSION 0115
NWS STORM PREDICTION CENTER NORMAN OK
1150 PM CST FRI FEB 10 2012
AREAS AFFECTED...NWRN IND...FAR SWRN LOWER MI
CONCERNING...HEAVY SNOW
VALID 110550Z - 110945Z
A PERSISTENT AND WELL-DEFINED LAKE EFFECT SNOW BAND CONTINUES TO
PRODUCE HEAVY SNOWFALL OVER LAKE AND PORTER COUNTIES IND /PER 0545Z
RADAR REFLECTIVITY IMAGE/. VWP DATA FROM LOT/IWX SHOW NEARLY
UNIDIRECTIONAL NLY FLOW EXTENDING THROUGH AT LEAST 2 KM AGL. WITH
TIME...SLIGHT BACKING OF LOW-LEVEL FLOW OVER SRN LAKE MICHIGAN IS
FORECAST TO OCCUR /AS SUPPORTED BY 00Z WRF-NMM AND 03Z
WRF-HRRR/...WHICH WILL RESULT IN A GRADUAL EWD SHIFT OF THE LAKE
EFFECT BAND...EVENTUALLY REACHING PORTIONS OF FAR SWRN LOWER MI AND
AREAS E OF VPZ IN NWRN IND /LIKELY BY 10Z/.
THERMODYNAMIC PROFILES OVER SRN LAKE MICHIGAN CONTINUE TO REMAIN
FAVORABLE FOR GENERATION OF HEAVY SNOWFALL GIVEN THE PRESENCE OF A
COLD ARCTIC AIR MASS...WITH RUC/NAM POINT FORECAST SOUNDINGS SHOWING
STEEP LAPSE RATES EXTENDING UP TO 2.5 KM AGL...AND EL TEMPERATURES
BELOW -20C. THESE CONDITIONS WILL CONTINUE TO SUPPORT SNOWFALL RATES
OF 1-2 INCH/HR...WITH LOCALLY HIGHER AMOUNTS OCCASIONALLY OBSERVED.
ADDITIONALLY...SUSTAINED SFC WINDS OF 20-25 MPH COULD RESULT IN
LOCALLY REDUCED VISIBILITIES.
..ROGERS.. 02/11/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...IWX...LOT...
LAT...LON 41608734 41218732 41078715 41008685 41278641 41608630
42018631 42098644 42028653 41848670 41698696 41608734
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 PM CST FRI FEB 10 2012
VALID 121200Z - 131200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS STILL INDICATE THAT A WESTERN CANADIAN UPPER HIGH CENTER WILL
CONTINUE TO BECOME LESS PROMINENT DURING THIS FORECAST PERIOD.
HOWEVER...THE UPPER PATTERN IS EXPECTED TO REMAIN CHARACTERIZED BY
AT LEAST A COUPLE OF DISTINCT BELTS OF STRONGER FLOW THAT EXTEND
EASTWARD OUT OF THE EASTERN PACIFIC THROUGH MUCH OF WESTERN AND
CENTRAL NORTH AMERICA...BEFORE CONVERGING INTO BROAD UPPER TROUGHING
NEAR/EAST OF THE ATLANTIC SEABOARD. WHILE A CLOSED LOW MAY CONTINUE
TO DEEPEN WITHIN THE EASTERN TROUGH...ACROSS PARTS OF NORTHERN NEW
ENGLAND AND THE CANADIAN MARITIMES...THE SOUTHERN PORTION OF THE
TROUGH APPEARS LIKELY TO PIVOT AWAY FROM SOUTHEAST COASTAL AREAS.
AS THIS OCCURS...SUPPORT FOR THE COLD SURFACE RIDGE EAST OF THE
ROCKIES SHOULD DIMINISH...AND THE ASSOCIATED HIGH CENTER IS PROGGED
TO WEAKEN WHILE RETREATING FROM THE OZARK PLATEAU INTO THE
CUMBERLAND PLATEAU/SOUTHERN APPALACHIANS REGION. AT THE SAME
TIME...SOUTHERLY LOW-LEVEL FLOW IS EXPECTED TO DEVELOP AND
STRENGTHEN ACROSS THE SOUTHERN AND CENTRAL PLAINS...BUT MOISTURE
RETURN FROM THE GULF OF MEXICO WILL REMAIN QUITE LIMITED IN THE WAKE
OF THE ONGOING COLD INTRUSION.
...CENTRAL/SOUTHERN GREAT BASIN INTO THE SOUTHERN PLAINS...
A COLD MID-LEVEL TROUGH WITHIN THE SOUTHERN BRANCH OF THE SPLIT FLOW
IS FORECAST TO PIVOT IN NEGATIVELY TILTED FASHION ACROSS EASTERN
PORTIONS OF THE SOUTHERN PLATEAU REGION INTO THE CENTRAL AND
SOUTHERN ROCKIES DURING THE PEAK AFTERNOON HEATING SUNDAY.
ASSOCIATED STEEPENING OF LAPSE RATES PROBABLY WILL BE SUFFICIENT FOR
THE DEVELOPMENT OF SCATTERED WEAK THUNDERSTORM ACTIVITY... AIDED BY
OROGRAPHIC AND SYNOPTIC SCALE FORCING FOR ASCENT.
LIFT ASSOCIATED WITH LOWER/MID TROPOSPHERIC WARM ADVECTION
DOWNSTREAM...COUPLED WITH WEAK MOISTURE RETURN...PROBABLY WILL BE
SUFFICIENT TO SATURATE PROFILES AND SUPPORT AT LEAST LIGHT
PRECIPITATION SPREADING NORTHEASTWARD FROM THE SOUTHERN HIGH PLAINS
SUNDAY INTO SUNDAY NIGHT. HOWEVER...EVAPORATIVE COOLING WITHIN A
RESIDUAL POTENTIALLY COLD AIR MASS BELOW SHOULD CONTRIBUTE TO THE
MAINTENANCE OF GENERALLY STABLE CONDITIONS. EVEN WITH SOME
STEEPENING OF LAPSE RATES ABOVE 700 MB PROGGED FROM WEST TO EAST
ACROSS THE SOUTHERN HIGH PLAINS LATE SUNDAY NIGHT...AS THE SHORT
WAVE TROUGH EMERGES FROM THE INTERMOUNTAIN WEST...THE POTENTIAL FOR
THUNDERSTORM ACTIVITY REMAINS UNCLEAR. THE RISK FOR SCATTERED WEAK
THUNDERSTORMS MAY NOT BE COMPLETELY NEGLIGIBLE...PARTICULARLY ACROSS
PARTS OF THE TEXAS SOUTH PLAINS INTO THE RED RIVER VALLEY...BUT
PROBABILITIES APPEAR LOWER THAN THE CURRENT 10 PERCENT MINIMUM
THRESHOLD FOR A CATEGORICAL THUNDER OUTLOOK AT THE PRESENT TIME.
..KERR.. 02/11/2012
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1116 PM CST FRI FEB 10 2012
VALID 111200Z - 121200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
LARGE TROUGH OVER THE ERN U.S. WILL DOMINATE THE SYNOPTIC PATTERN
SATURDAY...BUT THIS FEATURE WILL SHIFT EWD AND OFF THE ATLANTIC
SEABOARD BY THE END OF THE PERIOD. FARTHER UPSTREAM A SHORTWAVE
TROUGH NOW APPROACHING THE CA COAST WILL CONTINUE INLAND THROUGH THE
SWRN U.S. AND GREAT BASIN AREA. OFFSHORE FLOW ACCOMPANYING A LARGE
AREA OF SEWD ADVANCING POLAR HIGH PRESSURE WILL PREVAIL OVER THE ERN
HALF OF THE COUNTRY...KEEPING THUNDERSTORMS PROSPECTS LIMITED.
...GREAT BASIN AREA...
PROGRESSIVE IMPULSE CURRENTLY APPROACHING THE CA COAST WILL BEGIN TO
AFFECT THE GREAT BASIN AREA LATER SATURDAY. INCREASING FORCING FOR
ASCENT...COLD AIR ALOFT AND STEEP LAPSE RATES ACCOMPANYING THIS
FEATURE WILL CONTRIBUTE TO A THREAT OF THUNDERSTORMS...MAINLY FROM
PORTIONS OF NV INTO UT SATURDAY AFTERNOON INTO THE EVENING. LIMITED
MOISTURE AND INSTABILITY SUGGEST COVERAGE WILL PROBABLY REMAIN
ISOLATED.
..DIAL.. 02/11/2012
Sat, 11 Feb 2012 05:21:08 +0000 SPC MD 114 MD 0114 CONCERNING HEAVY SNOW FOR NWRN IND
MESOSCALE DISCUSSION 0114
NWS STORM PREDICTION CENTER NORMAN OK
0753 PM CST FRI FEB 10 2012
AREAS AFFECTED...NWRN IND
CONCERNING...HEAVY SNOW
VALID 110153Z - 110600Z
SNOWFALL RATES OF 1-2 INCHES PER HR /WITH LOCALLY HIGHER RATES/ ARE
FORECAST TO DEVELOP WITHIN A LAKE EFFECT BAND OVER FAR NWRN IND THIS
EVENING AND INTO EARLY SAT MORNING. SUSTAINED SFC WINDS OF 20-30 MPH
COULD ALSO RESULT IN LOCALLY REDUCED VISIBILITIES.
WATER VAPOR LOOP SHOWS A SHARP POSITIVE TILT UPPER TROUGH TRAVERSING
EWD ACROSS THE UPPER GREAT LAKES/MID-MS RIVER VALLEY THIS EVENING.
LOW-LEVEL COLD FRONT HAS MOVED THROUGH PORTIONS OF NRN IND/IL...WITH
POST-FRONTAL NLY WINDS /20-30 KTS IN THE 0-2 KM AGL LAYER PER LOT
VWP DATA/ BECOMING ESTABLISHED IN IT/S WAKE. FAVORABLE N-S
ORIENTATION OF LOW-LEVEL FLOW WILL CREATE A LONG FETCH OFF LAKE
MICHIGAN...WHILE OBSERVATIONS FROM SRN LAKE MICHIGAN INDICATE WATER
TEMPERATURES GENERALLY RANGE FROM 3-4 DEG C...SUPPORTING A NARROW
LAKE EFFECT SNOW BAND ALONG/DOWNWIND OF THE SRN SHORE OF LAKE
MICHIGAN. 0145Z RADAR REFLECTIVITY LOOP SHOWS WEAK BANDED STRUCTURES
ALREADY DEVELOPING OFF SRN LAKE MICHIGAN. RUC/WRF-HRRR POINT
FORECAST SOUNDINGS INDICATE STRONG LOW/MIDLEVEL COLD ADVECTION WILL
CONTINUE THROUGH THE NEXT SEVERAL HRS...AND WILL RESULT IN
STEEPENING LOW-LEVEL LAPSE RATES AND INCREASING UPRIGHT INSTABILITY.
SNOWFALL RATES OF 1-2 IN/HR APPEAR PROBABLE TO DEVELOP WITHIN THIS
BAND...ALTHOUGH ISOLATED LOCATIONS MAY APPROACH 3 IN/HR AT TIMES.
MODEL GUIDANCE SUGGESTS HEAVIEST SNOWFALL WILL SHIFT EWD AFTER 06Z
AS LOW-LEVEL FLOW BACKS SLIGHTLY TOWARDS THE NNW AS THE MID/UPPER
TROUGH MOVES E OF THE REGION.
..ROGERS.. 02/11/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...IWX...LOT...
LAT...LON 40888708 40948744 41298748 41638747 41598729 41688697
41748678 41698659 41348658 40998673 40888708
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Mon
Tue
Wed
60% Morning
30% Late
43
54
55
25
30
36
FORECAST DISCUSSION
Rain/Snow Mix Friday Morning
Thursday February 9, 2012
Cold air aloft causing some snow to fall over Oklahoma this evening. Rain is now moving into Northwest Arkansas as of late Thursday evening. Because of the cold air aloft, some of the rain could be mixed with snow early Friday morning. I am staying with the possibility of a mix due to some warmer air at the ground levels. Cold on Saturday!!! Snow likely on Monday! But it will melt fast as we warm up into the 50s Tuesday.
