SPC 1730Z Day 2 Outlook
DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1230 PM CDT SUN JUL 26 2015 VALID 271200Z - 281200Z ...THERE IS AN ENH RISK OF SVR TSTMS MONDAY AFTERNOON AND EVENING ACROSS PARTS OF THE WESTERN AND CENTRAL DAKOTAS... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SURROUNDING AREAS OF THE NORTHERN INTO CENTRAL PLAINS... ...THERE IS A MRGL RISK OF SVR TSTMS AS FAR SOUTH AS THE FRONT RANGE OF THE ROCKIES INTO ADJACENT AREAS OF THE CENTRAL HIGH PLAINS...AND AS FAR EAST AS PORTIONS OF THE MIDDLE MISSOURI AND UPPER MISSISSIPPI VALLEYS... ...SUMMARY... SEVERE THUNDERSTORMS CAPABLE OF PRODUCING LARGE HAIL...POTENTIALLY DAMAGING WIND GUSTS...AND PERHAPS A COUPLE OF TORNADOES ARE EXPECTED MONDAY INTO MONDAY NIGHT ACROSS THE NORTHERN INTO CENTRAL PLAINS. ...SYNOPSIS.. A MID-LEVEL CLOSED LOW...WITHIN A SEASONABLY STRONG UPPER TROUGH PROGRESSING INLAND ACROSS THE BRITISH COLUMBIA/PACIFIC NORTHWEST COAST...APPEARS LIKELY TO DIG AS FAR SOUTH AS THE NORTHERN U.S. ROCKIES BY MIDDAY MONDAY. THIS FEATURE IS THEN EXPECTED TO TURN EAST NORTHEASTWARD TOWARD THE CENTRAL CANADIAN/U.S. BORDER AREA THROUGH THE REMAINDER OF THE PERIOD...AS SUBTROPICAL RIDGING ACROSS THE SOUTH CENTRAL U.S. REMAINS FAIRLY PROMINENT. THE CENTER OF THE RIDGE PROBABLY WILL SHIFT FROM THE SOUTH CENTRAL HIGH PLAINS INTO THE OZARK PLATEAU REGION...WITH AT LEAST SOME SUPPRESSION OF THE RIDGE AS FAR SOUTH AS THE CENTRAL ROCKIES INTO NORTH CENTRAL PLAINS...WHILE A RIDGE AXIS TO THE NORTH GRADUALLY SHIFTS EASTWARD ACROSS ONTARIO AND THE GREAT LAKES REGION. AS THIS OCCURS...DOWNSTREAM TROUGHING IS EXPECTED TO ADVANCE SOUTHEAST OF THE MID ATLANTIC COAST...BUT WEAK TO MODEST CYCLONIC MID-LEVEL FLOW PROBABLY WILL PERSIST ACROSS PARTS OF NEW ENGLAND. IN LOWER-LEVELS...MODELS CONTINUE TO EXHIBIT VARIABILITY CONCERNING SURFACE CYCLOGENESIS ACROSS THE NORTHERN HIGH PLAINS...THE MOST PROMINENT FEATURE OF INTEREST. BUT THE SURFACE LOW CENTER GENERALLY APPEARS LIKELY TO AT LEAST GRADUALLY DEEPEN BELOW 1000 MB WHILE MIGRATING NORTHWARD NEAR THE NORTH DAKOTA/MONTANA BORDER AREA DURING THE DAY...BEFORE MORE RAPID DEEPENING TAKES PLACE MONDAY NIGHT NEAR THE INTERNATIONAL BORDER AREA INTO SOUTHERN SASKATCHEWAN/MANITOBA. AS THIS OCCURS...A COLD FRONT SHOULD SURGE EASTWARD THROUGH MUCH OF THE NORTHERN PLAINS. ALTHOUGH HIGHEST MOISTURE CONTENT AIR IS EXPECTED TO REMAIN WITHIN A REMNANT FRONTAL BAND ACROSS THE SOUTHWEST ATLANTIC INTO FLORIDA PENINSULA...SEASONABLY MOIST CONDITIONS SHOULD PERSIST ACROSS MOST AREAS EAST OF THE ROCKIES...WITH A CONTINUING NORTHWARD SURGE OF HIGHER MOISTURE CONTENT AIR INTO PORTIONS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY REGION. ...NORTHERN PLAINS... BOUNDARY LAYER MOISTENING AND SURFACE HEATING...BENEATH VERY WARM ELEVATED MIXED LAYER AIR ENCOMPASSING MUCH OF THE PLAINS/MISSISSIPPI VALLEY REGION...IS EXPECTED TO CONTRIBUTE TO MODERATE TO STRONG POTENTIAL INSTABILITY IN THE WARM SECTOR OF THE CYCLONE BY LATE MONDAY AFTERNOON. AT LEAST WEAK MID-LEVEL COOLING ABOVE THE ELEVATED MIXED LAYER IS EXPECTED TO CONTRIBUTE TO A NARROW PLUME OF VERY STEEP MID-LEVEL LAPSE RATES NORTH NORTHEAST OF THE FRONT RANGE OF THE ROCKIES THROUGH THE HIGHER PLAINS OF THE DAKOTAS...WHERE MIXED LAYER CAPE OF 2000-4000+ J/KG IS EXPECTED. ALTHOUGH THE MID-LEVEL COLD CORE...AND STRONGER MID-LEVEL JET...MAY LAG TO THE WEST OF THE WARM SECTOR THROUGH THE PERIOD...THE FORECAST THERMODYNAMIC PROFILES...COUPLED WITH MOMENTUM/SHEAR ASSOCIATED WITH 20-40 KT SOUTHERLY LOWER/MID TROPOSPHERIC FLOW...SHOULD PROVE MORE THAN SUPPORTIVE OF SEVERE STORM DEVELOPMENT. AIDED BY LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION ASSOCIATED WITH THE APPROACHING UPPER IMPULSE... CONSIDERABLE THUNDERSTORM DEVELOPMENT SEEMS PROBABLE ALONG THE PRE-FRONTAL SURFACE TROUGH BY 28/00Z...IF NOT BEFORE. ISOLATED SUPERCELLS MAY NOT BE OUT OF THE QUESTION INITIALLY... PARTICULARLY IN THE VICINITY OF THE WARM FRONT NEAR THE NORTH DAKOTA/SASKATCHEWAN BORDER. HOWEVER...THE UPSCALE GROWTH OF SEVERAL STORM CLUSTERS...WHICH COULD GRADUALLY ATTEMPT TO CONSOLIDATE THROUGH MID TO LATE EVENING APPEARS MOST PROBABLE... PRIMARILY ACCOMPANIED BY A SEVERE WIND/HAIL THREAT. ..KERR.. 07/26/2015
from SPC Convective Outlooks http://1.usa.gov/1VHlHBD
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