Alert archive / North Carolina / Special Weather Statements in 2012

Special Weather Statement, NWS Raleigh, NC

October 18, 2012Forsyth County, North Carolina

NWS Raleigh, NC issued this special weather statement at Oct 18, 2012, 8:19 PM EDT for Forsyth County, North Carolina. It was in force for 56 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Oct 18, 2012, 8:19 PM EDT (00:19 UTC)
Expired: Oct 18, 2012, 9:15 PM EDT
In force: 56 min
Issued by: NWS Raleigh, NC

County Forsyth County, NC

The radar

The Roanoke radar (KFCX), 116 km from the middle of the area, began a volume at 00:20 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Greensboro/Hi Pt, NC (KGSO), launched 00:00Z, 0.3 hours before the alert went out and 46 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 744 J/kg
Mixed-layer CIN: -11 J/kg
Mixed-layer LCL: 810 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: 121 m²/s²
0-3 km storm-relative helicity: 166 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 2.5

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Raleigh, NC wrote its last area forecast discussion before this special weather statement went out at Oct 18, 8:05 PM EDT, 14 minutes earlier.

Area forecast discussion, Oct 18, 8:05 PM EDT, 14 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
805 PM EDT THU OCT 18 2012

.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION LATE TONIGHT INTO EARLY FRIDAY.
HIGH PRESSURE WILL BUILD INTO THE CAROLINAS AND SOUTHERN VIRGINIA IN
THE WAKE OF THE FRONT AND LINGER OVER THE AREA THROUGH SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 305 PM THURSDAY...

CLOUDS WILL INCREASE IN COVERAGE FROM WEST TO EAST THIS EVENING
AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. AS OF THE 12Z UPPER
AIR ANALYSIS...UPPER LEVEL LOW PRESSURE WAS LOCATED OVER SRN MN/NRN
IA WITH THE TROUGH EXTENDING SOUTH INTO THE LOWER MS RIVER VALLEY.
BEST HEIGHT FALLS ARE STILL WELL TO THE NW...WITH A 140KT JET AT 250
MB OVER AR EXPECTED TO MOVE EASTWARD OVER THE APPALACHIANS LATER
TODAY. 16Z SURFACE ANALYSIS PLACES THE LOW OVER WI AND THE FRONT
EXTENDING EAST AND THEN SOUTH THROUGH THE OH AND TN VALLEYS. AS THIS
FRONT MIGRATES EASTWARD TODAY...WILL SEE INCREASING LOW-LEVEL
MOISTURE AND CLOUDS. AS FOR THE CONVECTION...THE 12Z NCEP WRF NMM
DEVELOPS A LINE OF SHOWERS OVER THE WESTERN PORTIONS OF THE AREA
BETWEEN 21Z AND 00Z...MAKING IT TO APPROX THE TRIANGLE AREA BEFORE
LIFTING NE AND DISSIPATING. THE 00Z NSSL WRF ARW SHOWS A SIMILAR
SCENARIO. GIVEN THE CURRENT SPC ANALYSES SHOWING INCREASING
LOW-LEVEL LAPSE RATES AHEAD OF THE DEVELOPING LINE OF SHOWERS AND
EFFECTIVE BULK SHEAR VALUES 45-50 KTS OVER THE MTS...CURRENTLY ABOUT
20 KTS OVER CENTRAL NC. ALSO...MUCAPE VALUES ARE AROUND 500 J/KG...
MAINLY ACROSS THE SOUTH. RUC ANALYSIS SHOWS BULK SHEAR VALUES
OVER CENTRAL NC INCREASING TO 50-60 KTS...WITH CAPE OF 500-1000
J/KG...MAINLY ACROSS THE WEST. THIS SUPPORTS THE POTENTIAL FOR
THUNDERSTORMS TO DEVELOP ACROSS THE WESTERN HALF OF THE AREA
TONIGHT...WITH AN ISOLATED STRONG TO SEVERE STORM POSSIBLE. MAIN
THREAT WOULD BE DAMAGING WINDS. SHOWERS AND ISOLATED STORMS ARE ALSO
POSSIBLE ALONG THE COASTAL PLAIN AHEAD OF THE MAIN LINE OF SHOWERS
AND STORMS THIS EVENING. HOW QUICKLY THE SHOWERS AND CLOUDS MOVE OUT
OF THE AREA WILL IMPACT THE LOW TEMPS FOR TONIGHT...BUT GENERALLY
LOOKING AT NEAR 50 DEGREES NW TO LOW 60S SE.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
AS OF 240 PM THURSDAY...

FRIDAY...
LARGE UPPER LOW OVER THE UPPER MIDWEST WILL MIGRATE EAST OVER THE
GREAT LAKES ON FRIDAY.  THE COLD FRONT TO SLOWLY CROSS CENTRAL NC
TONIGHT IS FORECAST TO MOVE FROM ROUGHLY US HWY 1 AT 12Z TO WELL
EAST OF I-95 BY 18Z.   EARLY IN THE DAY...FORCING FOR ACCENT WILL
MAINLY BE LIMITED TO UPPER DIVERGENCE IN THE RIGHT ENTRANCE OF THE
DEPARTING 120KT UPPER JET...WITH ONLY 30M HEIGHT FALLS AND
INCREASINGLY STABLE AND DRY AIR ALOFT.  ANY REDEVELOPMENT OF SHOWERS
DURING THE FIRST HALF OF THE DAY WILL BE TIED TO WEAK FRONTAL
CONVERGENCE OVER THE COASTAL PLAIN...BUT EVEN THAT IS FORECAST TO
WEAKEN AS THE FLOW BECOMES MORE UNIDIRECTIONAL AND SOUTHWESTERLY.
WITH CLEARING SKIES AND A MODEST HEIGHT GRADIENT BEHIND THE
FRONT...FORECAST SOUNDINGS SHOW BOUNDARY LAYER MIXING...GREATEST IN
THE WEST...LEADING TO SOUTHWESTERLY WIND GUSTS OF UP TO 20-25KT
DURING THE AFTERNOON.  A LOW LEVEL TRAJECTORY OUT OF THE SOUTHWEST
BEHIND THE FRONT WILL NOT LEAD TO A LARGE COOL DOWN BASED ON THE
UPSTREAM AIRMASS...WITH MOST GUIDANCE SHOWING HIGHS OF 70-78
NORTHWEST TO SOUTHEAST.

FRIDAY NIGHT...
OTHER THAN THE POTENTIAL FOR MID CLOUDS PASSING THROUGH THE BASE OF
THE UPPER LEVEL LOW...WHICH WILL BEGIN TO OPEN UP BY SATURDAY
MORNING...SKIES SHOULD BE MOSTLY CLEAR.  AGAIN THERE IS NO REAL
STRONG COLD ADVECTION SATURDAY NIGHT AND LOWS SHOULD SETTLE JUST
BELOW NORMAL INTO THE MID TO UPPER 40S FOR MOST AREAS.

SATURDAY THROUGH SUNDAY......
THE MEAN TROUGH AXIS IS FORECAST TO CROSS THE APPALACHIANS AS
THE UPPER LOW OPENS AND LIFTS NORTHEASTWARD ON SATURDAY.  THE
COMBINATION OF UPSTREAM MOISTURE AND THE COLDEST AIR ALOFT PASSING
OVERHEAD SHOULD LEAD TO ENHANCED STRATOCU IN THE LEE OF THE
MOUNTAINS DURING THE AFTERNOON.  1000-850MB THICKNESSES HOVER IN THE
1360S DURING THE DAY WITH A WEAK DOWNSLOPE FLOW POTENTIALLY
OFFSETTING WEAK COLD ADVECTION.  THUS...WILL KEEP HIGHS WITHIN A
COUPLE DEGREES OF THOSE BASED ON THICKNESSES...66-73 NORTHWEST TO
SOUTHEAST.  LOWS SATURDAY NIGHT IN THE LOW TO MID 40S UNDER MOSTLY
CLEAR SKIES...ALTHOUGH FORECAST SOUNDINGS SUGGEST CONDITIONS COULD
BE FAVORABLE FOR SOME OROGRAPHIC CIRRUS. HIGH PRESSURE WILL BEGIN TO
BUILD INTO THE AREA FROM THE SOUTHWEST SUNDAY WITH MOSTLY SUNNY
SKIES AND HIGHS AROUND 70S.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 250 PM THURSDAY...

OVERALL...THIS PERIOD WILL BE DOMINATED BY HIGH PRESSURE BOTH AT THE
SURFACE AND ALOFT. SURFACE HIGH PRESSURE WILL SETTLE RIGHT OVER THE
REGION...WHILE A MID LEVEL RIDGE WILL BUILD IN FROM THE GULF COAST
AREA. THIS WILL RESULT IN A PROLONGED PERIOD OF DRY CONDITIONS. AS
HEIGHTS GRADUALLY INCREASE THROUGHOUT THE PERIOD...TEMPS WILL SLOWLY
MODERATE...WITH HIGHS TRENDING TO ABOVE NORMAL. HOWEVER...WITH
FAIRLY DRY AIR IN PLACE AND MOSTLY CLEAR SKIES...OUR DIURNAL RANGE
SHOULD BE LARGE...WITH OVERNIGHT LOWS ABLE TO DROP OFF INTO THE 40S.
A BACK DOOR FRONT MAY APPROACH THE REGION LATE IN THE PERIOD...BUT
AS OF NOW MODELS SHOW LITTLE IMPACT TO THE AREA.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 802 PM THURSDAY...
SHOWERS WEST OF KINT AND KGSO WILL MOVE INTO THE AREA OVER THE NEXT
HOUR AND WILL AFFECT THE AREA THROUGH APPROXIMATELY 03Z... WITH KRDU
AND KFAY EXPERIENCING SHOWERS BETWEEN 03 AND 06Z. SOUTHERLY FLOW AND
INCREASED MOISTURE IN ADVANCE OF THE FRONT WILL BRING LOWERED
CEILINGS TO ALL TERMINALS BETWEEN 06 AND 12Z... BEFORE DRIER AIR
BEGINS TO MOVE IN TO THE AREA FROM THE WEST LATE FRIDAY MORNING
BEHIND THE FRONT. GUSTY WINDS OF 15 TO 20 KTS ARE POSSIBLE FRIDAY
AFTERNOON. HIGH PRESSURE WILL BUILD IN TO THE AREA THROUGH
MIDWEEK... BRINGING GENERALLY VFR CONDITIONS.

&&

.FIRE WEATHER...
A COLD FRONT WILL CROSS CENTRAL NC LATE TONIGHT AND EARLY FRIDAY.
BEHIND THE FRONT...DEWPOINTS ARE FORECAST TO MIX OUT INTO THE LOW
TO MID 30S...WHILE TEMPS WILL BE RELATIVELY WARM FOR A POST-FRONTAL
AIRMASS. THIS WILL CAUSE RH VALUES TO DROP BELOW 30 PERCENT OVER
MUCH OF THE WESTERN PIEDMONT. CONCURRENTLY...SOUTHWESTERLY WIND
GUSTS WILL LIKELY REACH THE 20-25MPH RANGE FRIDAY AFTERNOON.
DESPITE THESE CONDITIONS...THE NCFS REPORTS RELATIVELY HIGH FUEL
MOISTURE AT THIS TIME...AND THUS NO STATEMENTS REGARDING FIRE
WEATHER WILL BE ISSUED FOR FRIDAY.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

SYNOPSIS...BLS
NEAR TERM...KC
SHORT TERM...BLS
LONG TERM...KRR
AVIATION...SEC
FIRE WEATHER...BLS

Hazardous weather outlook, Oct 18, 4:10 PM EDT, 4 hours 9 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RALEIGH NC
410 PM EDT THU OCT 18 2012

NCZ007>011-021>028-038>043-073>078-083>086-088-089-190930-
PERSON-GRANVILLE-VANCE-WARREN-HALIFAX-FORSYTH-GUILFORD-ALAMANCE-
ORANGE-DURHAM-FRANKLIN-NASH-EDGECOMBE-DAVIDSON-RANDOLPH-CHATHAM-WAKE-
JOHNSTON-WILSON-STANLY-MONTGOMERY-MOORE-LEE-HARNETT-WAYNE-ANSON-
RICHMOND-SCOTLAND-HOKE-CUMBERLAND-SAMPSON-
410 PM EDT THU OCT 18 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NORTH CAROLINA.

.DAY ONE...TODAY AND TONIGHT.

A COLD FRONT WILL MOVE ACROSS CENTRAL NORTH CAROLINA TONIGHT AND
THEN OFFSHORE ON FRIDAY. SCATTERED SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO MOVE ACROSS THE AREA THROUGH LATE TONIGHT. A FEW OF
THUNDERSTORMS COULD BE STRONG TO POSSIBLY SEVERE WITH A PRIMARY
HAZARD OF DAMAGING WINDS. THE RISK OF SEVERE STORMS WILL BE HIGHEST
THROUGH AROUND MIDNIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION MAY BE NEEDED TONIGHT. SPOTTERS SHOULD
KEEP INFORMED OF THE LATEST FORECASTS AND STATEMENTS THROUGHOUT THE
DAY.

In the hours before

Special weather statement, Oct 18, 5:44 PM EDT, 2 hours 35 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RALEIGH NC
544 PM EDT THU OCT 18 2012

NCZ007-008-025-182245-
DURHAM-GRANVILLE-PERSON-
544 PM EDT THU OCT 18 2012

...A STRONG THUNDERSTORM WILL MOVE ACROSS PERSON...GRANVILLE AND
DURHAM COUNTIES THROUGH 645 PM EDT...

AT 544 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER
BAHAMA...OR ABOUT 10 MILES NORTH OF DURHAM...MOVING NORTH AT 30 MPH.

SOME LOCATIONS AFFECTED BY THIS STORM INCLUDE...ROUGEMONT...MORIAH...
SURL...BEREA.

HAZARDS INCLUDE...
GUSTY WINDS OF 30 TO 40 MPH.

THIS INCLUDES INTERSTATE 85 BETWEEN EXITS 189 AND 191.

SEEK SHELTER IN A NEARBY BUILDING OR VEHICLE. STRONG WINDS ARE
CAPABLE OF KNOCKING DOWN SMALL TREES AND BLOWING AROUND TRASH CANS...
POTTED PLANTS...LAWN FURNITURE AND OTHER LIGHT OUTDOOR OBJECTS.

&&

LAT...LON 3642 7858 3610 7874 3610 7898 3624 7895
      3624 7896 3642 7893
TIME...MOT...LOC 2144Z 194DEG 24KT 3615 7887

SEC

Special weather statement, Oct 18, 8:19 PM EDT, 0 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RALEIGH NC
819 PM EDT THU OCT 18 2012

NCZ021-038-190115-
DAVIDSON-FORSYTH-
819 PM EDT THU OCT 18 2012

...A STRONG THUNDERSTORM WILL MOVE ACROSS FORSYTH AND DAVIDSON
COUNTIES THROUGH 915 PM EDT...

AT 819 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM 16
MILES WEST OF LEXINGTON...OR ABOUT 6 MILES SOUTH OF MOCKSVILLE...
MOVING NORTHEAST AT 40 MPH.

SOME LOCATIONS AFFECTED BY THIS STORM INCLUDE...ARCADIA...AND...
WELCOME...MIDWAY...SEDGE GARDEN...KERNERSVILLE.

HAZARDS INCLUDE...
GUSTY WINDS OF 30 TO 40 MPH.

DEADLY CLOUD TO GROUND LIGHTNING.

THIS INCLUDES INTERSTATE 40 BETWEEN EXITS 182 AND 203.

THIS INCLUDES INTERSTATE 85 BETWEEN EXITS 87 AND 102.

SEEK SHELTER IN A NEARBY BUILDING OR VEHICLE. STRONG WINDS ARE
CAPABLE OF KNOCKING DOWN SMALL TREES AND BLOWING AROUND TRASH CANS...
POTTED PLANTS...LAWN FURNITURE AND OTHER LIGHT OUTDOOR OBJECTS.

&&

LAT...LON 3612 8050 3614 8044 3626 8046 3625 8003
      3587 8005 3573 8045 3584 8049 3584 8043
      3586 8042 3585 8039 3589 8042 3589 8037
      3596 8038 3599 8043 3602 8042 3606 8047
      3604 8050 3609 8052
TIME...MOT...LOC 0019Z 232DEG 37KT 3582 8052

SEC

The office that day

Everything else NWS Raleigh, NC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 18, 8:30 PM EDT	Severe Thunderstorm Warning	RAH	Davidson, Forsyth	45 min
Oct 18, 8:59 PM EDT	Severe Thunderstorm Warning	RAH	Davidson, Forsyth, Guilford, Randolph	63 min
Oct 19, 2:17 AM EDT	Special Weather Statement	RAH	Alamance, Anson, Chatham, Montgomery, Moore, Randolph and 2 more	88 min

Nearby

Special Weather Statements in North Carolina, 2012 Every special weather statement in 2012

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.