Wednesday, January 30, 2013

Macon County Weather for 01-30-2013
High Wind Warning and Flood Watch in Effect

Simulated RADAR per the NAM Computer Model
Today's post is a long one because there is a lot that will be going on today. The graphic above is the simulated RADAR as forecast by the NAM Computer Model  for 1pm today. This means that the line of severe weather could be at that location in this time frame. As with all computer models, this SHOULD NOT be taken as the gospel truth. Just use it as a guideline for what could happen. We are currently (as of 4am) under both a High Wind Warning and a Flood Watch until midnight tonight. The area will be experiencing high winds ahead of this storm system and we may see some minor flooding after we get up to 2 to 2.5 inches dropped on us today, with the bulk of it falling when the squall line passes.

 Here is the weather outlook and the texts of the warning and watch that the National Weather Service has issued for Macon County:

A strong cold will move across Macon County today. Drier high pressure will follow, with another cold front passing through on Saturday.

Today: Showers, with thunderstorms also possible after 11am. Some of the storms could produce heavy rainfall. High near 66. Windy, with a south wind 17 to 22 mph increasing to 23 to 28 mph in the afternoon. Winds could gust as high as 47 mph. Chance of precipitation is 100%. New rainfall amounts between 2 and 3 inches possible.

 Hazardous Weather Outlook: A HIGH WIND WARNING and a FLOOD WATCH are in effect for Macon County all day today.

 A strong cold front will sweep across Macon County this afternoon, with isolated severe thunderstorms and damaging winds.

 Severe Weather is expected in Macon County today. Please listen to NOAA Weather Radio or go to http://www.weather.gov/gsp on the Internet or your favorite local TV, radio station or news website for more information and up to date information on these hazards. Please take heed to any warnings that are issued.

Tonight: Showers and thunderstorms likely before 11pm, then a slight chance of showers between 11pm and midnight. Some of the storms could produce heavy rainfall. Mostly cloudy, with a low around 30. Breezy, with a west wind 16 to 22 mph, with gusts as high as 33 mph. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.

Thursday: Mostly sunny, with a high near 42. West wind around 16 mph.

Thursday Night: A chance of snow showers, mainly after 3am. Increasing clouds, with a low around 25. West wind 8 to 13 mph. Chance of precipitation is 30%.

 WARNINGS and WATCHES for today:

***HIGH WIND WARNING***

URGENT -
WEATHER MESSAGE NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
353 AM EST WED JAN 30 2013

 ...STRONG TO DAMAGING WINDS TODAY ACROSS THE WESTERN CAROLINAS AND NORTHEAST GEORGIA... .STRONG SOUTH TO SOUTHWEST WINDS WILL SET UP ACROSS THE REGION TODAY IN ADVANCE OF AN APPROACHING COLD FRONT. THE STRONGEST WINDS WILL OCCUR ACROSS THE HIGHER ELEVATIONS OF THE SOUTHERN APPALACHIANS...BUT RAIN SHOWERS DEVELOPING ACROSS THE REGION COULD CHANNEL STRONG TO DAMAGING WINDS INTO THE LOWER ELEVATIONS AS WELL. IN ADDITION...SHOWERS AND THUNDERSTORMS ALONG THE APPROACHING FRONT WILL PRODUCE HEAVY RAINFALL ACROSS THE AREA. THE RESULTANT WET SOIL CONDITIONS WILL MAKE IT EASIER FOR THE WINDS TO TOPPLE TREES AND PRODUCE POWER OUTAGES. THE WINDS WILL TURN SHARPLY WEST BEHIND THE COLD FRONT LATE TODAY...BUT WITH VERY WINDY CONDITIONS LIKELY LASTING WELL INTO THE NIGHT. ...HIGH WIND WARNING REMAINS IN EFFECT UNTIL MIDNIGHT EST TONIGHT... * LOCATIONS...THE NORTH CAROLINA MOUNTAINS AS WELL AS RABUN COUNTY IN NORTHEAST GEORGIA.

 * HAZARDS...DAMAGING WIND GUSTS.

* TIMING...WINDS WILL INCREASE SHARPLY THROUGH THE EARLY MORNING HOURS AND REMAIN STRONG TO DAMAGING THROUGH THE DAY BEFORE SLOWLY DIMINISHING TONIGHT.

* WINDS...SOUTH 25 TO 35 MPH WITH GUSTS UP TO 65 MPH.

* IMPACTS...THE STRONG WINDS MAY BLOW DOWN TREES AND POWER LINES. LOOSE AND UNSECURED OBJECTS WILL BE BLOWN ABOUT BY THE WIND. TRAVEL WILL BE TREACHEROUS FOR HIGH PROFILE VEHICLES. PRECAUTIONARY/PREPAREDNESS ACTIONS...

A HIGH WIND WARNING MEANS A HAZARDOUS HIGH WIND EVENT IS EXPECTED OR OCCURRING. SUSTAINED WIND SPEEDS OF AT LEAST 40 MPH OR GUSTS OF 58 MPH OR MORE CAN LEAD TO PROPERTY DAMAGE. PLEASE REPORT DAMAGING WINDS TO THE NATIONAL WEATHER SERVICE BY CALLING TOLL FREE...1...800...2 6 7...8 1 0 1. LEAVE A MESSAGE WITH YOUR OBSERVATION AND THE ADDRESS WHERE IT OCCURRED.

***FLOOD WATCH*** 

NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
336 AM EST WED JAN 30 2013

 ...PERIODS OF HEAVY RAIN EXPECTED OVER THE SOUTHERN APPALACHIANS TODAY... .A STRONG COLD FRONT WILL CROSS THE SOUTHERN APPALACHIANS FROM THE WEST LATE TODAY. ABUNDANT MOISTURE FROM THE GULF OF MEXICO WILL STREAM INTO THE AREA AHEAD OF THE COLD FRONT...PRODUCING PERIODS OF HEAVY RAINFALL THROUGH THE DAY. SOUTHERLY FLOW INTO THE MOUNTAINS WILL ENHANCE THE RAINFALL TOTALS OVER THE EXTREME SOUTHERN MOUNTAINS THIS MORNING...AND THEN HEAVY SHOWERS AND STRONG THUNDERSTORMS JUST AHEAD OF THE COLD FRONT WILL PRODUCE ADDITIONAL HEAVY RAINFALL THIS AFTERNOON. THE RUNOFF FROM THIS HEAVY RAINFALL MAY BE EXCESSIVE...CAUSING FLOODING OF STREAMS AND RIVERS ACROSS THE MOUNTAINS OF EXTREME NORTHEAST GEORGIA...AS WELL AS FROM FRANKLIN TO BREVARD TO HENDERSONVILLE IN THE NORTH CAROLINA MOUNTAINS. ...FLOOD WATCH REMAINS IN EFFECT THROUGH THIS EVENING...

THE FLOOD WATCH CONTINUES FOR

 * PORTIONS OF NORTHEAST GEORGIA AND WESTERN NORTH CAROLINA... INCLUDING THE FOLLOWING AREAS...IN NORTHEAST GEORGIA...RABUN. IN WESTERN NORTH CAROLINA...HENDERSON...MACON...JACKSON...AND TRANSYLVANIA.

* THROUGH THIS EVENING.

* MOIST...SOUTHERLY...UPSLOPE FLOW WILL STRENGTHEN ACROSS THE SOUTHEAST FACING SLOPES OF THE SOUTHERN APPALACHIANS TODAY. THE COVERAGE AND INTENSITY OF THE RAIN SHOWERS WILL STEADILY INCREASE ACROSS RABUN COUNTY GEORGIA...AND FROM FRANKLIN TO BREVARD TO HENDERSONVILLE IN NORTH CAROLINA...THROUGH THE MORNING HOURS. A LINE OF INTENSE SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT APPROACHING FROM THE WEST WILL THEN CROSS THE SOUTHERN APPALACHIANS LATER THIS AFTERNOON.

RAINFALL TOTALS ARE EXPECTED TO REACH 2 TO 3 INCHES IN THE WATCH AREA BY LATE DAY...WITH ISOLATED TOTALS UP TO 4 INCHES. THE HEAVY RAINFALL WILL PRODUCE RAPID RISES ON SMALL STREAMS AND CREEKS...AS WELL AS THE HEADWATERS OF THE FRENCH BROAD RIVER...WITH FLOODING INCREASINGLY POSSIBLE THIS AFTERNOON. THE PRECIPITATION WILL END FROM THE WEST THIS EVENING AS THE COLD FRONT SWEEPS EAST THROUGH THE PIEDMONT.

* RIVER FLOODING IS MOST LIKELY ALONG THE FRENCH BROAD RIVER AT BLANTYRE THIS EVENING. MANY STREAMS AND CREEKS WILL LIKELY APPROACH OR EXCEED BANKFULL THIS AFTERNOON...AND FLOODING OF LOW LYING OR POOR DRAINAGE AREAS IS LIKELY. PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLOOD WATCH MEANS THERE IS A POTENTIAL FOR FLOODING BASED ON CURRENT FORECASTS. YOU SHOULD MONITOR THE LATEST FORECASTS AND BE ALERT FOR POSSIBLE FLOOD OR FLASH FLOOD WARNINGS. THOSE LIVING IN AREAS PRONE TO FLOODING SHOULD BE PREPARED TO SEEK HIGHER GROUND IF FLOODING DEVELOPS.

Here are the graphics issued by the Storm Prediction center for today, followed by the text of the discussion for today's convective weather outlook...
Categorical Graphic
Probabilistic Tornado Graphic
Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Probabilistic Damaging Wind Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probabilistic Large Hail Graphic
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.




  SPC AC 300609
   
   DAY 1 CONVECTIVE OUTLOOK RESENT 1
   NWS STORM PREDICTION CENTER NORMAN OK
   1209 AM CST WED JAN 30 2013
   
   VALID 301200Z - 311200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL GULF
   COAST STATES...ERN GULF COAST STATES...CAROLINAS...SRN APPALACHIAN
   MTNS...CNTRL APPALACHIAN MTNS AND MID-ATLANTIC...
   
   ...GULF COAST STATES/SRN APPALACHIAN MTNS/CAROLINAS...
   AN UPPER-LEVEL TROUGH WILL APPROACH THE MS VALLEY TODAY AS AN
   INTENSE 100 TO 125 KT MID-LEVEL JET TRANSLATES EWD ACROSS THE OH AND
   TN VALLEYS. ON THE ERN EDGE OF THE MID-LEVEL JET...A NEARLY
   CONTINUOUS SQUALL-LINE WILL LIKELY BE ONGOING AT DAYBREAK. THE
   SQUALL-LINE IS EXPECTED TO MOVE EWD ACROSS THE SRN APPALACHIAN MTNS
   AND ECNTRL GULF COAST STATES THIS MORNING AND INTO THE CAROLINAS
   THIS AFTERNOON. A GRADUAL INTENSIFICATION OF THE LINE MAY OCCUR THIS
   MORNING AS SFC TEMPS WARM AND DESTABILIZATION OCCURS AHEAD OF THE
   LINE. MODEL FORECASTS SUGGEST THE LINE WILL BE MAINTAINED EWD ACROSS
   GA AND THE WRN CAROLINAS THIS AFTERNOON WITH THE LINE MOVING ACROSS
   THE ATLANTIC COASTAL PLAINS THIS EVENING.
   
   FORECAST SOUNDINGS JUST AHEAD OF THE LINE AT MIDDAY FROM ATLANTA
   SWWD ACROSS SERN AL SHOW SBCAPE VALUES INCREASING TO AROUND 1000
   J/KG. THIS COMBINED WITH 60 TO 70 KT OF DEEP LAYER SHEAR AND STRONG
   LARGE-SCALE ASCENT SHOULD BE FAVORABLE FOR SEVERE STORM DEVELOPMENT
   WITHIN THE SQUALL-LINE. THE LINE SHOULD BE AN EFFICIENT WIND DAMAGE
   PRODUCER DUE TO 60 KT OF FLOW JUST ABOVE THE SFC. ISOLATED WIND
   GUSTS OVER 70 KT COULD OCCUR DURING THE AFTERNOON WHERE THE
   SQUALL-LINE INTERACTS WITH MODERATE INSTABILITY. A FEW TORNADOES MAY
   ALSO OCCUR ACROSS THE SRN APPALACHIAN MTNS SWWD INTO THE ECNTRL GULF
   COAST STATES ALONG THE WRN EDGE OF AN IMPRESSIVE 60 TO 70 KT
   LOW-LEVEL JET.
   
   ...CNTRL APPALACHIAN MTNS/MID-ATLANTIC...
   AN UPPER-LEVEL TROUGH WILL MOVE INTO THE MID TO UPPER MS VALLEY
   TODAY AS A POWERFUL 100 TO 125 KT MID-LEVEL JET MOVES EWD INTO THE
   OH AND TN VALLEYS. A SQUALL-LINE SHOULD BE ONGOING ALONG THE ERN
   EDGE OF THE MID-LEVEL JET FROM THE UPPER OH VALLEY EXTENDING SSWWD
   INTO CNTRL KY AND MIDDLE TN. THIS SQUALL-LINE IS FORECAST TO MOVE
   EWD ACROSS THE CNTRL APPALACHIAN MTNS THIS MORNING AND INTO THE
   VIRGINIA'S BY THIS AFTERNOON. ALTHOUGH INSTABILITY IS FORECAST TO
   REMAIN WEAK ACROSS THE CNTRL APPALACHIAN MTNS AND VIRGINIA'S...DEEP
   LAYER SHEAR AND LARGE-SCALE ASCENT IS FORECAST TO BE VERY STRONG.
   THIS SHOULD ENABLE THE SQUALL-LINE TO BE MAINTAINED THIS AFTERNOON
   WITH SOME INTENSIFICATION AS SFC TEMPS WARM AHEAD OF THE LINE.
   ALTHOUGH AN ISOLATED TORNADO THREAT CAN NOT BE RULED OUT WITH BOWING
   LINE-SEGMENTS DUE TO THE STRONG LOW-LEVEL SHEAR...THE GREATER THREAT
   SHOULD BE DAMAGING WIND GUSTS ASSOCIATED WITH THE SQUALL-LINE. THE
   SEVERE THREAT IS EXPECTED TO BE MORE ISOLATED NWD ACROSS THE
   MID-ATLANTIC WHERE INSTABILITY SHOULD BE VERY WEAK.
   
   ..BROYLES/MOSIER.. 01/30/2013

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