Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/17/13


AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
220 PM CDT THU AUG 15 2013 .DISCUSSION... 949 AM CDT VERY FEW CHANGES MADE TO THE GOING FORECAST THIS MORNING. A COUPLE SHORT WAVES ARE PROGRESSING SOUTHEAST ACROSS NEBRASKA AND IOWA THIS MORNING...WITH THE FURTHER EAST ONE GRADUALLY SHEARING OUT FROM CENTRAL IA INTO FAR NW IL. THIS HAS AND WILL CONTINUE TO BE RESPONSIBLE FOR THE HIGH CLOUDS WHICH THE RAP MODEL HAS A GOOD HANDLE ON RIGHT NOW. HAVE GUIDED SKY GRIDS CLOSE TO ITS 500-600MB RH PREDICTION AND THAT WAS IN LINE WITH EARLIER FORECAST REASONING...KEEPING SOUTHERN AREAS NEAR YESTERDAYS HIGHS AND SLIGHTLY WARMER IN THE NORTH. HAVE JUST ADJUSTED THE HOURLY TEMPERATURE TRENDS SOME AS FAR NORTHERN AREAS MAY BE A LITTLE SLOW TO CLIMB THIS MORNING GIVEN CURRENT CLOUD TRENDS. SOUTHWEST BOUNDARY LAYER WINDS PER DOPPLER VAD AND SURFACE OBSERVATIONS HAVE BEEN AROUND 10 KT IN NORTHEAST IL WHICH SHOULD BE ENOUGH TO OFFSET THE LAKE BREEZE INTO EARLY AFTERNOON. THIS WIND SHIFT SHOULD STILL DEVELOP AND PROGRESS INLAND FOR SOME COOLING. DID ADJUST UP LAKESHORE HIGHS UPWARD DUE TO THE LATER EXPECTED DEVELOPMENT...WITH DOWNTOWN CHICAGO LIKELY PEAKING SOMEWHERE IN THE 72 TO 74 RANGE. MTF //PREV DISCUSSION... 247 AM CDT NOT MUCH CHANGE IN OVERALL FORECAST THINKING FROM PREVIOUS NIGHTS AS HIGH PRESSURE CONTINUES TO PROVIDE QUIET WEATHER WITH A GRADUAL WARMING TREND INTO EARLY NEXT WEEK AS IT DEPARTS. FOCUS WILL BE ON FORECAST SUBTLETIES INCLUDING CLOUD COVER AND SOME MINIMAL PRECIP CHANCES NEXT WEEK. EARLY MORNING WATER VAPOR IMAGERY SHOWS THE BIG CLOSED UPPER LOW THAT ORIGINALLY BROUGHT THE UNSEASONABLY COOL AIR TO THE REGION STILL SPINNING OVER JAMES BAY AND NORTHWESTERN QUEBEC...WITH A SECONDARY LOW SPINNING OVER THE GULF OF ST. LAWRENCE. UPPER RIDGING REMAINS STRETCHED FROM THE FOUR CORNERS INTO ALBERTA/SASKATCHEWAN WITH A BIG UPPER LOW OFF THE BRITISH COLUMBIA COAST MOVING NORTHWARD UP THE WESTERN FLANK OF THE RIDGE. LOCALLY...THE AREA REMAINS UNDER A NORTHWESTERLY UPPER FLOW IN WHICH SEVERAL SHORTWAVES ARE MOVING ACROSS THE PLAINS. AT THE SURFACE...HIGH PRESSURE IS CENTERED OVER NORTHERN INDIANA AND EXTENDS WEST INTO IOWA AND NORTH INTO THE CANADIAN PRAIRIES. TODAY AND TONIGHT...THE SHORTWAVES NOTED ABOVE THAT ARE TRAVERSING THE NORTHWEST UPPER FLOW OVER THE MID SECTION OF THE COUNTRY WILL PRIMARILY STAY ON A TRAJECTORY TO TAKE THE MOST FOCUSED FORCING SOUTHWEST OF THE CWA THROUGH FRIDAY. WATER VAPOR SHOWS A DECENT INFLUX OF MID/HIGH LEVEL MOISTURE SPREADING EASTWARD ACROSS THE MID AND UPPER MISSISSIPPI RIVER VALLEY WITH IR IMAGERY SHOWING A LARGE AREA OF MID AND HIGH CLOUD DRIFTING ACROSS EASTERN NEBRASKA/IOWA/MISSOURI. THE THICKER PORTION OF THIS BAND WILL LIKELY MOVE ACROSS THE SOUTHERN CWA THROUGH THE MORNING WHILE THE HIGHER AND THINNER NORTHERN EXTENT SPREADS ACROSS THE REMAINDER OF THE AREA. BY AFTERNOON...FAR NORTHERN COUNTIES SHOULD SEE THE LEAST COVERAGE WHILE SOUTHERN AREAS SEE AT LEAST SOME COVERAGE THROUGH LATE DAY. WITH HIGH PRESSURE STILL CLOSE BY WINDS WILL BE LIGHT AND MIXING WILL ONCE AGAIN BE WEAK...ESPECIALLY THANKS TO THE CLOUD COVER. GIVEN THESE LIMITING FACTORS FOR MAX WARMING...WILL ADJUST FORECAST HIGHS TO BE SIMILAR TO THOSE OF WEDNESDAY ACROSS THE SOUTHERN CWA BUT MAINTAIN THE SLIGHT WARM UP OVER NORTHERN AREAS. A LAKE BREEZE IS ONCE AGAIN EXPECTED THOUGH HAVE SOME QUESTION OF HOW QUICKLY IT WILL DO SO GIVEN THE CLOUD COVER. LOW LEVEL FLOW IS SO WEAK THOUGH THAT THERE DOES NOT LOOK TO BE A PROBLEM DEVELOPING ONE IT MAY JUST TAKE LONGER TO MOVE INLAND. THIS MAY ALLOW LAKEFRONT AREAS TO WARM UP A FEW DEGREES OVER WEDNESDAY AND REACH THE 70 DEGREE MARK. OTHERWISE...DO EXPECT SOME DIURNAL STRATOCU TO DEVELOP UNDER THE MID AND HIGH CLOUDS THOUGH IT MAY BE A BIT MORE SCATTERED IN COVERAGE THAN RECENT DAYS AND MAY TAKE A LITTLE LONGER TO DEVELOP. SOME CIRRUS MAY LINGER SOUTH TONIGHT BUT OTHERWISE EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS SO OVERNIGHT LOWS WILL ONCE AGAIN BE IN THE 50S AWAY FROM THE URBAN HEAT ISLAND. A FEW OF THE TRADITIONALLY COLDER SPOTS MAY FALL INTO THE UPPER 40S. FRIDAY AND SATURDAY...AN UPPER TROUGH AXIS WILL BE AMPLIFYING FROM LAKE MICHIGAN SOUTHWESTWARD THROUGH FRIDAY BUT THE BASE OF THE TROUGH AND ASSOCIATED FORCING WILL REMAIN WELL TO THE SOUTH AND WEST SO EXPECT A CONTINUATION OF DRY CONDITIONS. THE AIRMASS WILL MODIFY SLIGHTLY WITH H85 TEMPS WARMING A FEW DEGREES WHICH WILL ALLOW HIGHS TO WARM INTO THE MID AND UPPER 70S. EASTERLY FLOW WILL BE IN PLACE SO LAKEFRONT AREAS WILL LIKELY BE HELD INTO THE LOWER 70S. EXPECT SIMILAR CONDITIONS SATURDAY. SUNDAY THROUGH WEDNESDAY...GUIDANCE CONTINUES TO STRUGGLE WITH THE EVOLUTION OF THE NEWLY DEVELOPED UPPER TROUGH THAT WILL FOCUS OVER THE LOWER MISSISSIPPI AND OHIO RIVER VALLEYS. THE IDEA OF THIS TROUGH STAYING TO THE SOUTH THEN GRADUALLY WORKING ITS WAY NORTHEASTWARD...KEEPING ASSOCIATED FORCING...MOISTURE AND RESULTANT PRECIP CHANCES MAINLY TO THE SOUTH AND EAST OF THE AREA...HAS BEEN CONSISTENT. WOULD NOT BE SURPRISED TO SEE SOME CONTINUED VARIATION IN THE EVOLUTION OF THE TROUGH BUT WILL STICK WITH LITTLE IF ANY POP MENTION FROM SUNDAY INTO EARLY NEXT WEEK. THE GRADUAL WARMING TREND CONTINUES WITH HIGHS IN THE 80S EXPECTED BY SUNDAY AWAY FROM THE LAKE. CONFIDENCE LOWERS BY THE MIDDLE OF NEXT WEEK BUT IT DOES APPEAR THAT THE TROUGH WILL DEPART ALLOWING A PERIOD OF UPPER RIDGING TO BUILD IN SUGGESTING A FURTHER WARMING OF TEMPS. THIS WOULD ALSO KEEP PRECIP CHANCES TO THE NORTH...THOUGH IT WOULD NOT BE OUT OF THE QUESTION FOR SOMETHING TO DEVELOP AS THE RIDGE APPROACHES. MDB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * NONE. //DISCUSSION...UPDATED 18Z... HIGH PRESSURE STRETCHING FROM THE MID MS VALLEY E TO THE DELMARVA PENINSULA IS FORECASTED TO REMAIN OVER/VERY NEAR THE LOCAL AREA THROUGH FRI...AND BEYOND. RESULT IS LIGHT WINDS THROUGH THE FORECAST PERIOD...AND VERY LIGHT TO CALM TONIGHT INTO FRI MORNING. WITH ONLY A SMALL DIFFERENCE IN SURFACE TEMPERATURES BETWEEN LAND AND WATER ONLY EXPECT A WEAK LAKE BREEZE WITH VERY LITTLE MOMENTUM TO PUSH IT VERY FAR INLAND. WINDS WILL REMAIN LIGHT WHETHER THE LAKE BREEZE EVENTUALLY MAKES IT TO ORD OR MDW OR NOT DURING THE REMAINDER OF THE DAY. AN AREA OF CLODS AROUND 080 IS ASSOCIATED WITH A SHORT WAVE CURRENTLY MOVING SE OVER THE IA- MO BOARDER WILL BE DECREASING AS THE DISTURBANCE MOVES FURTHER AWAY DURING THE AFTERNOON. TRS //ORD AND MDW CONFIDENCE...UPDATED 18Z... HIGH ALL ELEMENTS EXCEPT FOR DIRECTION OF THE LIGHT WINDS. TRS //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH MONDAY...VFR. TUESDAY AND WEDNESDAY...SLIGHT CHANCE TSRA TUES NIGHT AND WEDNESDAY. RC && .MARINE... 218 PM CDT TRANQUIL CONDITIONS WILL CONTINUE OVER LAKE MICHIGAN THROUGH THE WEEKEND. VARIABLE WINDS WILL BE SEEN AT TIMES ACROSS THE SOUTHERN THIRD OF THE LAKE AS THE CANADIAN HIGH PRESSURE IN PLACE WILL HAVE THE GREATEST INFLUENCE THERE...WITH REGIONAL LAKE BREEZES EACH AFTERNOON AROUND THE LAKE PERIPHERY. SOUTHERLY WINDS WILL GRADUALLY INCREASE ACROSS THE NORTHERN PART OF THE LAKE LATE IN THE WEEKEND AND THEN EXPAND THEIR WAY SOUTHWARD EARLY NEXT WEEK AS THE HIGH DEPARTS TO THE MID-ATLANTIC. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
108 PM CDT THU AUG 15 2013 .DISCUSSION... 949 AM CDT VERY FEW CHANGES MADE TO THE GOING FORECAST THIS MORNING. A COUPLE SHORT WAVES ARE PROGRESSING SOUTHEAST ACROSS NEBRASKA AND IOWA THIS MORNING...WITH THE FURTHER EAST ONE GRADUALLY SHEARING OUT FROM CENTRAL IA INTO FAR NW IL. THIS HAS AND WILL CONTINUE TO BE RESPONSIBLE FOR THE HIGH CLOUDS WHICH THE RAP MODEL HAS A GOOD HANDLE ON RIGHT NOW. HAVE GUIDED SKY GRIDS CLOSE TO ITS 500-600MB RH PREDICTION AND THAT WAS IN LINE WITH EARLIER FORECAST REASONING...KEEPING SOUTHERN AREAS NEAR YESTERDAYS HIGHS AND SLIGHTLY WARMER IN THE NORTH. HAVE JUST ADJUSTED THE HOURLY TEMPERATURE TRENDS SOME AS FAR NORTHERN AREAS MAY BE A LITTLE SLOW TO CLIMB THIS MORNING GIVEN CURRENT CLOUD TRENDS. SOUTHWEST BOUNDARY LAYER WINDS PER DOPPLER VAD AND SURFACE OBSERVATIONS HAVE BEEN AROUND 10 KT IN NORTHEAST IL WHICH SHOULD BE ENOUGH TO OFFSET THE LAKE BREEZE INTO EARLY AFTERNOON. THIS WIND SHIFT SHOULD STILL DEVELOP AND PROGRESS INLAND FOR SOME COOLING. DID ADJUST UP LAKESHORE HIGHS UPWARD DUE TO THE LATER EXPECTED DEVELOPMENT...WITH DOWNTOWN CHICAGO LIKELY PEAKING SOMEWHERE IN THE 72 TO 74 RANGE. MTF //PREV DISCUSSION... 247 AM CDT NOT MUCH CHANGE IN OVERALL FORECAST THINKING FROM PREVIOUS NIGHTS AS HIGH PRESSURE CONTINUES TO PROVIDE QUIET WEATHER WITH A GRADUAL WARMING TREND INTO EARLY NEXT WEEK AS IT DEPARTS. FOCUS WILL BE ON FORECAST SUBTLETIES INCLUDING CLOUD COVER AND SOME MINIMAL PRECIP CHANCES NEXT WEEK. EARLY MORNING WATER VAPOR IMAGERY SHOWS THE BIG CLOSED UPPER LOW THAT ORIGINALLY BROUGHT THE UNSEASONABLY COOL AIR TO THE REGION STILL SPINNING OVER JAMES BAY AND NORTHWESTERN QUEBEC...WITH A SECONDARY LOW SPINNING OVER THE GULF OF ST. LAWRENCE. UPPER RIDGING REMAINS STRETCHED FROM THE FOUR CORNERS INTO ALBERTA/SASKATCHEWAN WITH A BIG UPPER LOW OFF THE BRITISH COLUMBIA COAST MOVING NORTHWARD UP THE WESTERN FLANK OF THE RIDGE. LOCALLY...THE AREA REMAINS UNDER A NORTHWESTERLY UPPER FLOW IN WHICH SEVERAL SHORTWAVES ARE MOVING ACROSS THE PLAINS. AT THE SURFACE...HIGH PRESSURE IS CENTERED OVER NORTHERN INDIANA AND EXTENDS WEST INTO IOWA AND NORTH INTO THE CANADIAN PRAIRIES. TODAY AND TONIGHT...THE SHORTWAVES NOTED ABOVE THAT ARE TRAVERSING THE NORTHWEST UPPER FLOW OVER THE MID SECTION OF THE COUNTRY WILL PRIMARILY STAY ON A TRAJECTORY TO TAKE THE MOST FOCUSED FORCING SOUTHWEST OF THE CWA THROUGH FRIDAY. WATER VAPOR SHOWS A DECENT INFLUX OF MID/HIGH LEVEL MOISTURE SPREADING EASTWARD ACROSS THE MID AND UPPER MISSISSIPPI RIVER VALLEY WITH IR IMAGERY SHOWING A LARGE AREA OF MID AND HIGH CLOUD DRIFTING ACROSS EASTERN NEBRASKA/IOWA/MISSOURI. THE THICKER PORTION OF THIS BAND WILL LIKELY MOVE ACROSS THE SOUTHERN CWA THROUGH THE MORNING WHILE THE HIGHER AND THINNER NORTHERN EXTENT SPREADS ACROSS THE REMAINDER OF THE AREA. BY AFTERNOON...FAR NORTHERN COUNTIES SHOULD SEE THE LEAST COVERAGE WHILE SOUTHERN AREAS SEE AT LEAST SOME COVERAGE THROUGH LATE DAY. WITH HIGH PRESSURE STILL CLOSE BY WINDS WILL BE LIGHT AND MIXING WILL ONCE AGAIN BE WEAK...ESPECIALLY THANKS TO THE CLOUD COVER. GIVEN THESE LIMITING FACTORS FOR MAX WARMING...WILL ADJUST FORECAST HIGHS TO BE SIMILAR TO THOSE OF WEDNESDAY ACROSS THE SOUTHERN CWA BUT MAINTAIN THE SLIGHT WARM UP OVER NORTHERN AREAS. A LAKE BREEZE IS ONCE AGAIN EXPECTED THOUGH HAVE SOME QUESTION OF HOW QUICKLY IT WILL DO SO GIVEN THE CLOUD COVER. LOW LEVEL FLOW IS SO WEAK THOUGH THAT THERE DOES NOT LOOK TO BE A PROBLEM DEVELOPING ONE IT MAY JUST TAKE LONGER TO MOVE INLAND. THIS MAY ALLOW LAKEFRONT AREAS TO WARM UP A FEW DEGREES OVER WEDNESDAY AND REACH THE 70 DEGREE MARK. OTHERWISE...DO EXPECT SOME DIURNAL STRATOCU TO DEVELOP UNDER THE MID AND HIGH CLOUDS THOUGH IT MAY BE A BIT MORE SCATTERED IN COVERAGE THAN RECENT DAYS AND MAY TAKE A LITTLE LONGER TO DEVELOP. SOME CIRRUS MAY LINGER SOUTH TONIGHT BUT OTHERWISE EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS SO OVERNIGHT LOWS WILL ONCE AGAIN BE IN THE 50S AWAY FROM THE URBAN HEAT ISLAND. A FEW OF THE TRADITIONALLY COLDER SPOTS MAY FALL INTO THE UPPER 40S. FRIDAY AND SATURDAY...AN UPPER TROUGH AXIS WILL BE AMPLIFYING FROM LAKE MICHIGAN SOUTHWESTWARD THROUGH FRIDAY BUT THE BASE OF THE TROUGH AND ASSOCIATED FORCING WILL REMAIN WELL TO THE SOUTH AND WEST SO EXPECT A CONTINUATION OF DRY CONDITIONS. THE AIRMASS WILL MODIFY SLIGHTLY WITH H85 TEMPS WARMING A FEW DEGREES WHICH WILL ALLOW HIGHS TO WARM INTO THE MID AND UPPER 70S. EASTERLY FLOW WILL BE IN PLACE SO LAKEFRONT AREAS WILL LIKELY BE HELD INTO THE LOWER 70S. EXPECT SIMILAR CONDITIONS SATURDAY. SUNDAY THROUGH WEDNESDAY...GUIDANCE CONTINUES TO STRUGGLE WITH THE EVOLUTION OF THE NEWLY DEVELOPED UPPER TROUGH THAT WILL FOCUS OVER THE LOWER MISSISSIPPI AND OHIO RIVER VALLEYS. THE IDEA OF THIS TROUGH STAYING TO THE SOUTH THEN GRADUALLY WORKING ITS WAY NORTHEASTWARD...KEEPING ASSOCIATED FORCING...MOISTURE AND RESULTANT PRECIP CHANCES MAINLY TO THE SOUTH AND EAST OF THE AREA...HAS BEEN CONSISTENT. WOULD NOT BE SURPRISED TO SEE SOME CONTINUED VARIATION IN THE EVOLUTION OF THE TROUGH BUT WILL STICK WITH LITTLE IF ANY POP MENTION FROM SUNDAY INTO EARLY NEXT WEEK. THE GRADUAL WARMING TREND CONTINUES WITH HIGHS IN THE 80S EXPECTED BY SUNDAY AWAY FROM THE LAKE. CONFIDENCE LOWERS BY THE MIDDLE OF NEXT WEEK BUT IT DOES APPEAR THAT THE TROUGH WILL DEPART ALLOWING A PERIOD OF UPPER RIDGING TO BUILD IN SUGGESTING A FURTHER WARMING OF TEMPS. THIS WOULD ALSO KEEP PRECIP CHANCES TO THE NORTH...THOUGH IT WOULD NOT BE OUT OF THE QUESTION FOR SOMETHING TO DEVELOP AS THE RIDGE APPROACHES. MDB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * NONE. //DISCUSSION...UPDATED 18Z... HIGH PRESSURE STRETCHING FROM THE MID MS VALLEY E TO THE DELMARVA PENINSULA IS FORECASTED TO REMAIN OVER/VERY NEAR THE LOCAL AREA THROUGH FRI...AND BEYOND. RESULT IS LIGHT WINDS THROUGH THE FORECAST PERIOD...AND VERY LIGHT TO CALM TONIGHT INTO FRI MORNING. WITH ONLY A SMALL DIFFERENCE IN SURFACE TEMPERATURES BETWEEN LAND AND WATER ONLY EXPECT A WEAK LAKE BREEZE WITH VERY LITTLE MOMENTUM TO PUSH IT VERY FAR INLAND. WINDS WILL REMAIN LIGHT WHETHER THE LAKE BREEZE EVENTUALLY MAKES IT TO ORD OR MDW OR NOT DURING THE REMAINDER OF THE DAY. AN AREA OF CLODS AROUND 080 IS ASSOCIATED WITH A SHORT WAVE CURRENTLY MOVING SE OVER THE IA- MO BOARDER WILL BE DECREASING AS THE DISTURBANCE MOVES FURTHER AWAY DURING THE AFTERNOON. TRS //ORD AND MDW CONFIDENCE...UPDATED 18Z... HIGH ALL ELEMENTS EXCEPT FOR DIRECTION OF THE LIGHT WINDS. TRS //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH MONDAY...VFR. TUESDAY AND WEDNESDAY...SLIGHT CHANCE TSRA TUES NIGHT AND WEDNESDAY. RC && .MARINE... 316 AM CDT EXPANSIVE HIGH PRESSURE WILL CONTINUE TO DOMINATE THE WEATHER PATTERN ACROSS THE LAKE THROUGH THE WEEKEND. MODESTLY STRONG SOUTHWEST WINDS OVER THE NORTH HALF EARLY THIS MORNING WILL SHIFT WEST AND THEN RETURN TO SOUTHWEST THIS AFTERNOON WHILE DIMINISHING. THE SOUTH HALF COULD SEE A BRIEF PERIOD THIS MORNING WHEN WINDS SHIFT WEST AND GUST TO 20 KT BUT OTHERWISE SOUTHWEST WINDS 15 KT OR LESS WILL DIMINISH FURTHER TONIGHT. THEREAFTER...THE NORTH HALF WILL SEE AN EXTENDED PERIOD OF SOUTHWEST WINDS OF 15 KT OR LESS AND THE SOUTH 10 KT OR LESS WITH PERIODS OF VARIABLE WINDS UNTIL SUNDAY WHEN HIGH PRESSURE FINALLY SHIFTS EAST. AS LOW PRESSURE TAKES SHAPE ACROSS THE CANADIAN PRAIRIES AND PUSHES EAST SUNDAY NIGHT INTO MONDAY...THE TIGHTER PRESSURE GRADIENT...ESPECIALLY OVER THE NORTH HALF...WILL RESULT IN INCREASED SOUTHWEST WINDS. A WARM AIR MASS OVER THE LAKE BY THAT TIME WILL LIKELY LIMIT MIXING AND GUSTS...BUT WINDS TO 25 KT ARE POSSIBLE ACROSS THE FAR NORTH ON MONDAY. RC && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
950 AM CDT THU AUG 15 2013 .DISCUSSION... 949 AM CDT VERY FEW CHANGES MADE TO THE GOING FORECAST THIS MORNING. A COUPLE SHORT WAVES ARE PROGRESSING SOUTHEAST ACROSS NEBRASKA AND IOWA THIS MORNING...WITH THE FURTHER EAST ONE GRADUALLY SHEARING OUT FROM CENTRAL IA INTO FAR NW IL. THIS HAS AND WILL CONTINUE TO BE RESPONSIBLE FOR THE HIGH CLOUDS WHICH THE RAP MODEL HAS A GOOD HANDLE ON RIGHT NOW. HAVE GUIDED SKY GRIDS CLOSE TO ITS 500-600MB RH PREDICTION AND THAT WAS IN LINE WITH EARLIER FORECAST REASONING...KEEPING SOUTHERN AREAS NEAR YESTERDAYS HIGHS AND SLIGHTLY WARMER IN THE NORTH. HAVE JUST ADJUSTED THE HOURLY TEMPERATURE TRENDS SOME AS FAR NORTHERN AREAS MAY BE A LITTLE SLOW TO CLIMB THIS MORNING GIVEN CURRENT CLOUD TRENDS. SOUTHWEST BOUNDARY LAYER WINDS PER DOPPLER VAD AND SURFACE OBSERVATIONS HAVE BEEN AROUND 10 KT IN NORTHEAST IL WHICH SHOULD BE ENOUGH TO OFFSET THE LAKE BREEZE INTO EARLY AFTERNOON. THIS WIND SHIFT SHOULD STILL DEVELOP AND PROGRESS INLAND FOR SOME COOLING. DID ADJUST UP LAKESHORE HIGHS UPWARD DUE TO THE LATER EXPECTED DEVELOPMENT...WITH DOWNTOWN CHICAGO LIKELY PEAKING SOMEWHERE IN THE 72 TO 74 RANGE. MTF && .PREV DISCUSSION... 247 AM CDT NOT MUCH CHANGE IN OVERALL FORECAST THINKING FROM PREVIOUS NIGHTS AS HIGH PRESSURE CONTINUES TO PROVIDE QUIET WEATHER WITH A GRADUAL WARMING TREND INTO EARLY NEXT WEEK AS IT DEPARTS. FOCUS WILL BE ON FORECAST SUBTLETIES INCLUDING CLOUD COVER AND SOME MINIMAL PRECIP CHANCES NEXT WEEK. EARLY MORNING WATER VAPOR IMAGERY SHOWS THE BIG CLOSED UPPER LOW THAT ORIGINALLY BROUGHT THE UNSEASONABLY COOL AIR TO THE REGION STILL SPINNING OVER JAMES BAY AND NORTHWESTERN QUEBEC...WITH A SECONDARY LOW SPINNING OVER THE GULF OF ST. LAWRENCE. UPPER RIDGING REMAINS STRETCHED FROM THE FOUR CORNERS INTO ALBERTA/SASKATCHEWAN WITH A BIG UPPER LOW OFF THE BRITISH COLUMBIA COAST MOVING NORTHWARD UP THE WESTERN FLANK OF THE RIDGE. LOCALLY...THE AREA REMAINS UNDER A NORTHWESTERLY UPPER FLOW IN WHICH SEVERAL SHORTWAVES ARE MOVING ACROSS THE PLAINS. AT THE SURFACE...HIGH PRESSURE IS CENTERED OVER NORTHERN INDIANA AND EXTENDS WEST INTO IOWA AND NORTH INTO THE CANADIAN PRAIRIES. TODAY AND TONIGHT...THE SHORTWAVES NOTED ABOVE THAT ARE TRAVERSING THE NORTHWEST UPPER FLOW OVER THE MID SECTION OF THE COUNTRY WILL PRIMARILY STAY ON A TRAJECTORY TO TAKE THE MOST FOCUSED FORCING SOUTHWEST OF THE CWA THROUGH FRIDAY. WATER VAPOR SHOWS A DECENT INFLUX OF MID/HIGH LEVEL MOISTURE SPREADING EASTWARD ACROSS THE MID AND UPPER MISSISSIPPI RIVER VALLEY WITH IR IMAGERY SHOWING A LARGE AREA OF MID AND HIGH CLOUD DRIFTING ACROSS EASTERN NEBRASKA/IOWA/MISSOURI. THE THICKER PORTION OF THIS BAND WILL LIKELY MOVE ACROSS THE SOUTHERN CWA THROUGH THE MORNING WHILE THE HIGHER AND THINNER NORTHERN EXTENT SPREADS ACROSS THE REMAINDER OF THE AREA. BY AFTERNOON...FAR NORTHERN COUNTIES SHOULD SEE THE LEAST COVERAGE WHILE SOUTHERN AREAS SEE AT LEAST SOME COVERAGE THROUGH LATE DAY. WITH HIGH PRESSURE STILL CLOSE BY WINDS WILL BE LIGHT AND MIXING WILL ONCE AGAIN BE WEAK...ESPECIALLY THANKS TO THE CLOUD COVER. GIVEN THESE LIMITING FACTORS FOR MAX WARMING...WILL ADJUST FORECAST HIGHS TO BE SIMILAR TO THOSE OF WEDNESDAY ACROSS THE SOUTHERN CWA BUT MAINTAIN THE SLIGHT WARM UP OVER NORTHERN AREAS. A LAKE BREEZE IS ONCE AGAIN EXPECTED THOUGH HAVE SOME QUESTION OF HOW QUICKLY IT WILL DO SO GIVEN THE CLOUD COVER. LOW LEVEL FLOW IS SO WEAK THOUGH THAT THERE DOES NOT LOOK TO BE A PROBLEM DEVELOPING ONE IT MAY JUST TAKE LONGER TO MOVE INLAND. THIS MAY ALLOW LAKEFRONT AREAS TO WARM UP A FEW DEGREES OVER WEDNESDAY AND REACH THE 70 DEGREE MARK. OTHERWISE...DO EXPECT SOME DIURNAL STRATOCU TO DEVELOP UNDER THE MID AND HIGH CLOUDS THOUGH IT MAY BE A BIT MORE SCATTERED IN COVERAGE THAN RECENT DAYS AND MAY TAKE A LITTLE LONGER TO DEVELOP. SOME CIRRUS MAY LINGER SOUTH TONIGHT BUT OTHERWISE EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS SO OVERNIGHT LOWS WILL ONCE AGAIN BE IN THE 50S AWAY FROM THE URBAN HEAT ISLAND. A FEW OF THE TRADITIONALLY COLDER SPOTS MAY FALL INTO THE UPPER 40S. FRIDAY AND SATURDAY...AN UPPER TROUGH AXIS WILL BE AMPLIFYING FROM LAKE MICHIGAN SOUTHWESTWARD THROUGH FRIDAY BUT THE BASE OF THE TROUGH AND ASSOCIATED FORCING WILL REMAIN WELL TO THE SOUTH AND WEST SO EXPECT A CONTINUATION OF DRY CONDITIONS. THE AIRMASS WILL MODIFY SLIGHTLY WITH H85 TEMPS WARMING A FEW DEGREES WHICH WILL ALLOW HIGHS TO WARM INTO THE MID AND UPPER 70S. EASTERLY FLOW WILL BE IN PLACE SO LAKEFRONT AREAS WILL LIKELY BE HELD INTO THE LOWER 70S. EXPECT SIMILAR CONDITIONS SATURDAY. SUNDAY THROUGH WEDNESDAY...GUIDANCE CONTINUES TO STRUGGLE WITH THE EVOLUTION OF THE NEWLY DEVELOPED UPPER TROUGH THAT WILL FOCUS OVER THE LOWER MISSISSIPPI AND OHIO RIVER VALLEYS. THE IDEA OF THIS TROUGH STAYING TO THE SOUTH THEN GRADUALLY WORKING ITS WAY NORTHEASTWARD...KEEPING ASSOCIATED FORCING...MOISTURE AND RESULTANT PRECIP CHANCES MAINLY TO THE SOUTH AND EAST OF THE AREA...HAS BEEN CONSISTENT. WOULD NOT BE SURPRISED TO SEE SOME CONTINUED VARIATION IN THE EVOLUTION OF THE TROUGH BUT WILL STICK WITH LITTLE IF ANY POP MENTION FROM SUNDAY INTO EARLY NEXT WEEK. THE GRADUAL WARMING TREND CONTINUES WITH HIGHS IN THE 80S EXPECTED BY SUNDAY AWAY FROM THE LAKE. CONFIDENCE LOWERS BY THE MIDDLE OF NEXT WEEK BUT IT DOES APPEAR THAT THE TROUGH WILL DEPART ALLOWING A PERIOD OF UPPER RIDGING TO BUILD IN SUGGESTING A FURTHER WARMING OF TEMPS. THIS WOULD ALSO KEEP PRECIP CHANCES TO THE NORTH...THOUGH IT WOULD NOT BE OUT OF THE QUESTION FOR SOMETHING TO DEVELOP AS THE RIDGE APPROACHES. MDB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * WEAK LAKE BREEZE TO DEVELOP EARLY AFTERNOON AND MOVE INLAND TO REACH ORD AND MDW MID TO LATE AFTERNOON FLIPPING LIGHT WINDS TO OUT OF THE E-SE. TRS //DISCUSSION...UPDATED 12Z... HIGH PRESSURE OVER THE REGION WILL CONTINUE THE QUIET VFR CONDITIONS. THE WEAK GRADIENT AND VERY LIGHT WINDS ALOFT SHOULD ALLOW FOR ANOTHER LAKE BREEZE TO DEVELOP AND PUSH INLAND DURING THE AFTERNOON. FAIRLY DENSE CIRRUS SHIELD OVERHEAD COULD SUPPRESS WARMING A BIT AND INITIALLY SLOW THE PROGRESSION OF THE LAKE BREEZE...SO THE EASTERLY WIND SHIFT AT ORD AND MDW COULD BE A BIT LATER IN THE AFTERNOON THAN ON WEDNESDAY AND THE BOUNDARY MAY NOT PUSH THROUGH DPA. ONCE THE SHIFT TO EAST WINDS OCCURS AT ORD AND MDW...SPEEDS SHOULD AGAIN BE MAINLY UNDER 10 KT...EXCEPT POSSIBLY SHORTLY AFTER THE LAKE BREEZE PASSAGE. SCT TO BKN VFR CU WILL DEVELOP UNDER THE CIRRUS SHIELD BEFORE CLEARING THIS EVENING. LIGHT AND VRB TO CALM WINDS AGAIN TONIGHT WILL BECOME LIGHT NORTHEAST MID TOMORROW MORNING BEFORE FLOPPING OVER TO EAST BY EARLY AFTERNOON. RC //ORD AND MDW CONFIDENCE...UPDATED 14Z... * MEDIUM ON WEAK LAKE BREEZE REACHING ORD AND MDW MID TO LATE AFTERNOON. * HIGH ON PREVAILING SPEED REMAINS BELOW 10 KT THROUGH THE DAY. TRS //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH MONDAY...VFR. TUESDAY AND WEDNESDAY...SLIGHT CHANCE TSRA TUES NIGHT AND WEDNESDAY. RC && .MARINE... 316 AM CDT EXPANSIVE HIGH PRESSURE WILL CONTINUE TO DOMINATE THE WEATHER PATTERN ACROSS THE LAKE THROUGH THE WEEKEND. MODESTLY STRONG SOUTHWEST WINDS OVER THE NORTH HALF EARLY THIS MORNING WILL SHIFT WEST AND THEN RETURN TO SOUTHWEST THIS AFTERNOON WHILE DIMINISHING. THE SOUTH HALF COULD SEE A BRIEF PERIOD THIS MORNING WHEN WINDS SHIFT WEST AND GUST TO 20 KT BUT OTHERWISE SOUTHWEST WINDS 15 KT OR LESS WILL DIMINISH FURTHER TONIGHT. THEREAFTER...THE NORTH HALF WILL SEE AN EXTENDED PERIOD OF SOUTHWEST WINDS OF 15 KT OR LESS AND THE SOUTH 10 KT OR LESS WITH PERIODS OF VARIABLE WINDS UNTIL SUNDAY WHEN HIGH PRESSURE FINALLY SHIFTS EAST. AS LOW PRESSURE TAKES SHAPE ACROSS THE CANADIAN PRAIRIES AND PUSHES EAST SUNDAY NIGHT INTO MONDAY...THE TIGHTER PRESSURE GRADIENT...ESPECIALLY OVER THE NORTH HALF...WILL RESULT IN INCREASED SOUTHWEST WINDS. A WARM AIR MASS OVER THE LAKE BY THAT TIME WILL LIKELY LIMIT MIXING AND GUSTS...BUT WINDS TO 25 KT ARE POSSIBLE ACROSS THE FAR NORTH ON MONDAY. RC && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1050 PM EDT FRI AUG 16 2013 .SYNOPSIS... AN AREA OF LOW PRESSURE JUST EAST OF THE OUTER BANKS WILL SLOWLY LIFT NORTHEAST OVERNIGHT. HOWEVER...THE FRONTAL BOUNDARY ASSOCIATED WITH IT WILL REMAIN STALLED ALONG THE CAROLINA COAST THROUGH THE WEEKEND AS PERIODIC WAVES OF PRECIPITATION RIDE NORTHWARD ALONG THIS BOUNDARY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... UPDATE AS OF 1045 PM EDT...ANOTHER STRANGE EVENING WHERE WX HAS BEEN TRENDING DRIER THAN EXPECTED. A BAND OF CLOUDS IS CURRENTLY MOVING OFF THE COAST AND A BATCH OF RAIN HAS DEVELOPED OVER THE VA TIDEWATER AND NE NC. WILL CONTINUE TO CARRY LIKELY POPS IN THIS AREA THRU EARLY AM AS PCPN EXITS. ELSEWHERE...CLEARING HAS WORKED INTO CENTRAL VA AND WILL CONTINUE TO ADVANCE EAST THRU EARLY AM. THIS CLEARING HAS ALLOWED TEMPS TO FALL A LITTLE LOWER THAN EXPECTED AND THUS HAVE LOWERED OVN LOWS A FEW DEGREES. LOWS IN THE UPR 50S NW TO THE MID 60S SE. THERE IS SOME INDICATION IN THE LATEST IR SATELLITE IMAGERY AND SFC OBS THAT CLOUDS MOVING NORTHWARD THRU CENTRAL NC WILL SPREAD OVER OUR AREA DURING THE PRE-DAWN HOURS SO WILL HAVE CLOUDS RETURNING OVERNIGHT. HOWEVER..QUESTIONS REMAIN AS TO JUST HOW MUCH PCPN WILL PUSH NORTHWARD BY DAYBREAK. LATEST NAM AND HRRR ARE NOT THAT EXCITED ABOUT RAIN GETTING NORTH OF THE HWY 58 IN SOUTHERN VA TIL AFTER 15Z SAT...SO NEXT SHIFT WILL LIKELY BE TRIMMING POPS BACK EVEN FARTHER FOR SAT MORN. PREVIOUS DISCUSSION...AN AREA OF LOW PRESSURE RESIDES JUST EAST OF THE VA/NC OUTER BANKS LATE THIS AFTERNOON AND WILL SHIFT NE OVERNIGHT...KEEPING A TRAILING FRONTAL BOUNDARY STALLED ALONG THE CAROLINA COAST THROUGH THE WEEKEND (MORE ON THAT IN THE SHORT TERM DISCUSSION). PRECIPITATION MOVING UP FROM THE SW IS HAVING A HARD TIME OVERCOMING THE COOLER AND DRIER AIR AT THE SFC FROM THE PAST SEVERAL DAYS. BEST ISENTROPIC LIFT ATTM IS LOCATED OVER THE CAROLINAS AND IS STRUGGLING TO MAKE HEADWAY INTO NE NC/SE VA. ANY PRECIP THAT MOVES INTO THE AREA THIS EVENING WILL START OUT AS SHOWERS. AS THE NIGHT PROGRESSES...ADDITIONAL ISENTROPIC LIFT MOVING NE WILL ERODE THE DRIER AIRMASS AT THE SFC AND MOISTEN THE LOW LEVELS OF THE ATMOSPHERE. AS THIS HAPPENS...PRECIPITATION MOVING INTO NE NC/SE VA OVERNIGHT WILL BECOME MORE STEADY BUT WITH ONLY LIGHT ACCUMULATIONS OF 0.15 INCHES OR LESS ANTICIPATED. BECAUSE ISENTROPIC LIFT SCENARIOS WITH STEADY PRECIPITATION HAVE A TENDENCY TO BRING RAINFALL INTO THE REGION MUCH FASTER THAN MODEL DATA...HAVE INCREASED PRECIP CHANCES FROM SOUTHWEST TO NORTHEAST BEGINNING AFTER MIDNIGHT TONIGHT. EXTENSIVE CLOUD COVER THIS EVENING AND OVERNIGHT WILL PREVENT TEMPS FROM DROPPING OFF QUICKLY AND WILL BE NEAR NORMAL WITH LOWS GENERALLY IN THE 60S (NEAR 60 FAR NW COUNTIES AND INTERIOR MD EASTERN SHORE). && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... UPPER LEVEL HIGH PRESSURE OVER THE CTRL ATLANTIC SHIFTS TWD THE SE COAST OVER THE WEEKEND. MEANWHILE...AN UPPER TROUGH WILL STAY WELL ROOTED IN THE OH/TN VALLEYS DUE TO AN AMPLIFYING RIDGE OVER THE GREAT BASIN. THE COMBINATION OF THESE UPPER LEVEL FEATURES WITH THE STALLED SFC BOUNDARY ALONG THE CAROLINA COAST WILL CAUSE MOISTURE AND SHORTWAVE ENERGY TO STREAM ACROSS THE MID ATLANTIC REGION SATURDAY THROUGH SUNDAY NIGHT. A CONTINUATION OF FAVORABLE ISENTROPIC LIFT MOVING INTO THE AREA FROM THE SOUTHWEST ON SATURDAY WILL QUICKLY SATURATE THE LOWER ATMOSPHERE AND ACT TO ENHANCE STEADY PRECIPITATION/RAINFALL. PWATS WILL GRADUALLY INCREASE THROUGH THE WEEKEND FROM ROUGHLY 0.75 INCHES NORTH TO 1.50 INCHES SOUTH FOR TONIGHT...TO AROUND 2.00 INCHES NORTH TO 2.35 INCHES SOUTH BY SUNDAY. THE BEST POTENTIAL FOR WIDESPREAD STEADY RAIN IS SATURDAY NIGHT. HOWEVER THE WEEKEND WILL NOT BE A COMPLETE WASHOUT...BUT DO EXPECT PERIODS OF RAIN THAT WILL BE MODERATE TO HEAVY AT TIMES AND MOSTLY CLOUDY TO CLOUDY SKIES. FOR SUNDAY...FORECAST MODELS ARE HINTING AT A DRY SLOT MOVING INTO NE NC AND SE VA DURING THE DAY AS THE ATLANTIC HIGH PUSHES CLOSER TO THE SOUTHEAST COAST. IF THIS OCCURS...THEN THERE COULD BE A NICE REPRIEVE FROM THE RATHER WET WEEKEND RAINS IN THE AFOREMENTIONED AREAS. AT THIS TIME...IT IS DIFFICULT TO PINPOINT EXACTLY WHERE THE DRIER CONDITIONS MAY SET UP AND HAVE THEREFORE KEPT A CHANCE OF PRECIP IN THE ONGOING FORECAST FOR SUNDAY AFTN/EVENING. DUE TO EXTENSIVE CLOUD COVER AND COOLER AMBIENT AIR DUE TO EVAPORATIVE COOLING PROCESSES...TEMPERATURES WILL BE ON THE COOL SIDE WITH HIGHS SAT/SUN GENERALLY IN THE 70S (NEAR 80 NE NC/FAR SE VA ON SUN DUE TO POTENTIAL DRY SLOT/CLEARING). THE LOWS ON SATURDAY NIGHT WILL GENERALLY BE IN THE 60S (NEAR 70 COASTAL NE NC/FAR SE VA). THE OH/TN VALLEY TROUGH AND GREAT BASIN HIGH BOTH BEGIN TO WASH OUT ON MONDAY AND APPEAR TO RESULT IN A PSEUDO-WESTERLY (OR ZONAL) FLOW. AT THIS TIME...IT SHOULD BE ENOUGH TO START PUSHING THE PERSISTENTLY RAINY WX PATTERN OUT OF THE AREA BUT NOT UNTIL TUESDAY/TUESDAY NIGHT. HIGH TEMPERATURES REBOUND INTO THE LOWER 80S SINCE A COMBINATION OF SUN AND CLOUDS ARE ANTICIPATED DURING THE DAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... STRONG UPPER-LEVEL WESTERLY FLOW PREVAILS OVER SOUTHERN CANADA THROUGH THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. UNDERNEATH THIS ZONAL FLOW...MID-LEVEL ANTICYCLONES WILL REMAIN NEARLY STATIONARY OVER THE SOUTHERN PLAINS AND WESTERN ATLANTIC. AN AREA OF (SOMEWHAT) LOWER HEIGHTS IS PROGGED OVER THE APPALACHIAN PLATEAU. HOWEVER...THE MID ATLANTIC REGION SHOULD LARGELY REMAIN UNDER THE INFLUENCE OF THE WESTERN ATLANTIC RIDGE. HENCE... PRECIPITATION POTENTIAL SHOULD BE MINIMAL (NEAR OR BELOW CLIMO) DUE TO A LACK OF LARGE SCALE FORCING FOR STORM ORGANIZATION... DESPITE A WARM AND INCREASINGLY HUMID AIRMASS. HIGH TEMPERATURES SHOULD AVERAGE AROUND SEASONAL NORMALS TUESDAY THROUGH FRIDAY (MID/UPPER 80S)...WITH A FEW 90 DEGREE HIGHS POSSIBLE IN FAVORED HOT SPOTS. LOWS SHOULD PRIMARILY RANGE FROM THE UPPER 60S TO LOW 70S. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... A TROUGH OF LOW PRES ALONG THE MID AND SOUTH ATL COAST CONTINUES TO MOVE NE AND AWAY FROM LAND...RESULTING IN NE FLOW ACROSS THE REGION IN THE LOW LEVELS. ALOFT...SWLY FLOW WILL GRADUALLY INCREASE AND RESULT IN OVERRUNNING MOISTURE THAT WILL GRADUALLY SPREAD NORTH LIKELY STARTING OVERNIGHT INTO SAT MORNING. EXACT TIMING OF THE PRECIP WILL BE TRICKY. CIGS AND VSBY WITH THE RAIN WILL START OUT AS MVFR FOR SOME TIME INITIALLY BUT TRANSITION TO IFR LATER SATURDAY MORNING AND EARLY AFTERNOON AS A WAVE OF LOW PRESSURE MOVES ALONG THE COASTAL FRONT. ONCE CONDITIONS BECOME IFR SATURDAY...THEY WILL LIKELY REMAIN IFR FOR A PERIOD OF TIME WHILE THE OVERRUNNING CONTINUES INTO THE AFTERNOON. && .MARINE... THE LATEST MSAS SURFACE ANALYSIS SHOWS A 1017MB LOW ~110NM ENE OF CAPE HATTERAS TRACKING NE ALONG A COASTAL FRONT ALIGNED PARALLEL TO THE SOUTHEAST COAST. A NE WIND (STRONGEST OFF THE CURRITUCK OUTER BANKS) IS GRADUALLY DIMINISHING AS THE LOW PULLS AWAY AND HIGH PRESSURE RETURNS FROM THE N. ANOTHER LOW (PRESENTLY OVER SOUTHERN GA) IS PROGGED TO LIFT NE ALONG THE SOUTHEAST COAST TONIGHT THROUGH SATURDAY...EVENTUALLY REACHING THE MID ATLANTIC SATURDAY NIGHT AND SUNDAY...BEFORE PULLING TO THE NE SUNDAY NIGHT. THIS PATTERN WILL MAINTAIN A PERSISTENT NE FLOW OVER THE REGION THROUGH SATURDAY NIGHT FOR THE ENTIRE AREA...AND INTO SUNDAY FOR THE NORTHERN PORTION OF THE MARINE AREA. WIND SPEEDS REMAIN CAPPED AROUND 15KT ALONG WITH SEAS/WAVES CAPPED AT 4FT/3FT. CONFIDENCE ON SCA HEADLINES REMAINS LOW...SO NO FLAGS WILL BE ISSUED. ALTHOUGH A FEW BRIEF PERIODS OF SCA WIND ARE POSSIBLE ACROSS THE LOWER BAY (4FT WAVES MOUTH OF THE BAY)...AND 5FT SEAS ARE POSSIBLE OUT NEAR 20NM IN THE OCEAN. HIGH PRESSURE RETURNS EARLY NEXT WEEK WITH LIGHT SSW FLOW RETURNING...ALONG WITH 2-3FT SEAS. PERSISTENT ONSHORE FLOW WILL RESULT IN AN ELEVATED RIP CURRENT RISK SATURDAY AND POSSIBLY INTO SUNDAY AS WELL. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH SATURDAY EVENING FOR MDZ025. NC...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH SATURDAY EVENING FOR NCZ102. VA...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH SATURDAY EVENING FOR VAZ098>100. MARINE...NONE. && $$ SYNOPSIS...BMD NEAR TERM...BMD/JDM SHORT TERM...BMD LONG TERM...AJZ AVIATION...JEF MARINE...AJZ
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
417 PM CDT THU AUG 15 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 339 PM CDT THU AUG 15 2013 MAIN FORECAST CHALLENGE IN THE SHORT TERM IS CLOUD COVER AND THE POSSIBILITY OF ANY LIGHT SHRA/SPRINKLES THROUGH EARLY THIS EVENING. OTHERWISE... QUIET WEATHER WILL CONTINUE TO BE THE THEME THROUGH FRIDAY AS WE CONTINUE TO SLOWLY WARM WITH THE BUILDING UPPER RIDGE. LATEST WATER VAPOR IMAGERY AND RAP UPPER AIR ANALYSES SHOWS THE ALL TOO FAMILIAR PATTERN OF THE UPPER RIDGE TO OUR WEST AND UPPER TROUGH TO OUR EAST. HOWEVER... FINALLY STARTING TO SEE SOME CHANGE IN THIS... WHICH WILL GET FURTHER ACCELERATED NEXT WEEK AS RIDGE BROADENS AND FLATTENS OVER THE CONUS AND EXERTS ITS MAIN PROMINENCE OVER THE CENTER PART OF THE COUNTRY. IN THE MEANTIME... WE COULD SEE SOME SHRA AND/OR SPRINKLES THROUGH EARLY THIS EVENING AS SOME LINGERING LOW LEVEL INSTABILITY HELPS PRODUCE SOME TCU WITH PERHAPS SOME PCPN MANAGING TO FALL OUT OF IT. WE WILL BEGIN TO GET INTO RETURN FLOW ON FRIDAY AS THE SURFACE HIGH MOVES INTO THE EASTERN GREAT LAKES... BUT ANY MEANINGFUL WARM ADVECTION WILL WAIT UNTIL BEYOND THAT POINT. FRIDAY SHOULD BE SIMILAR... BUT SLIGHTLY WARMER... THAN TODAY WITHOUT ANY SHRA/SPRINKLE CHANCE AS WARMER AIR ALOFT AND ASSOCIATED SUBSIDENCE WORK INTO THE AREA. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 339 PM CDT THU AUG 15 2013 MORE SUMMERLIKE PATTERN TAKES HOLD LATE IN THE WEEKEND AND LINGERS THROUGHOUT THE WEEK. THE UPPER RIDGE OVER THE PLAINS CONTINUES TO GRADUALLY EXPAND EASTWARD FRIDAY NIGHT THROUGH THE UPCOMING WEEKEND. A DRY AND WARMING PATTERN IS EXPECTED OVER THE NEXT SEVEN DAYS. SOME OF THE GUIDANCE DOES MANAGE TO GENERATE LIGHT PRECIPITATION NEAR THEN MN/SD BORDER OVER THE WEEKEND ALONG A DIFFUSE MID LEVEL BOUNDARY. THE MOISTURE MIGHT BE A BIT OVERDONE SO WILL CONTINUE TO LEAVE DRY MENTION. BY SUNDAY...HIGHS WILL BE ABOVE CLIMATE NORMALS WITH TEMPS IN THE 80S. AS MENTIONED IN OUR DISCUSSION YESTERDAY...THE CENTRAL ATLANTIC RIDGE IS EXPECTED TO DRIFT SOUTHWEST WITH TIME. THE ENSM FORECAST SUPPORTS THIS WITH KEEPING POSITIVE HEIGHT ANOMALIES FARTHER SOUTH THROUGH THE END OF THE MONTH. THIS DISPLACEMENT OF THE ATLANTIC RIDGE WILL ALLOW THE PERSISTENT EAST COAST TROUGH /OUR LOCAL NORTHWEST FLOW/ A CHANCE TO SHIFT EAST. THE MODELS COMING INTO MUCH BETTER AGREEMENT IN THE EXTENDED. WHILE THE RIDGE DOES BECOME FLATTER EARLY NEXT WEEK AS A SERIES OF SHORTWAVES TRACK JUST NORTH OF THE CANADIAN BORDER. A BOUNDARY APPROACHES THE REGION ON MONDAY...BUT ALL MODELS DISSOLVE THIS FEATURE NORTHWEST OF THE FORECAST AREA. THE OPERATIONAL GFS AND TO SOME DEGREE THE ECMWF SHOW THE A GLIMPSE OF THE WARMING TREND THIS WEEKEND WITH 80S...BUT THE WARM UP BEGINS IN EARNEST EARLY NEXT WEEK. 850 MB TEMPS GET BACK UP INTO THE UPPER TEENS AND LOWER 20S. GIVEN THE DRY ANTECEDENT CONDITIONS AND EXPECTED BUILDING RIDGE...MID TO UPPER 80S SEEM EASILY OBTAINABLE NEXT WEEK...AND WE SHOULD ONCE AGAIN SEE 90 DEGREES FOR THE FIRST TIME IN OVER A MONTH. MIXING TO 850-750 MB WITH A SLIGHT SUPER ADIABATIC LAYER GIVES NEAR RECORD TEMPS OF 95-99 DEGREES. SO...WE WILL NEED TO MONITOR THE TEMP ADVECTION AND MIXING POTENTIAL. CLOUD COVER ASIDE...THIS HAS A CHANCE TO BE A HOT STRETCH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1210 PM CDT THU AUG 15 2013 BENIGN AVIATION CONDITIONS WILL CONTINUE THROUGH THE UPCOMING FORECAST PERIOD AS HIGH PRESSURE AT THE SURFACE DRIFTS ACROSS THE AREA WHILE A RIDGE OF HIGH PRESSURE ALOFT CONTINUES TO SLOWLY BUILD INTO THE UPPER MIDWEST. VFR FLIGHT CONDITIONS ARE EXPECTED ALONG WITH LIGHT SOUTHERLY WINDS. THERE IS A SLIGHT POSSIBILITY FOR A SHOWER THIS AFTERNOON INTO EARLY EVENING... BEFORE 03Z... DUE TO SOME MARGINAL INSTABILITY. HOWEVER... ANY ACTIVITY WILL BE VERY ISOLATED AND SHOULDN/T HAVE AN IMPACT ON FLIGHT CONDITIONS GIVEN THE HIGH CLOUD BASES AND LIGHTNESS OF ANY PCPN. WITH THE SLIM CHANCE AND LACK OF EXPECTED IMPACT TO CEILINGS AND VISIBILITIES... KEPT THE MENTION OF ANYTHING OUT OF THE FORECASTS. SHOULD SOMETHING POP UP... AND AMENDMENT COULD BE ISSUED. KMSP...TAF REFLECTS EXPECTATIONS WITH LITTLE IN THE WAY OF UNCERTAINTY OUTSIDE OF THE SLIM CHANCE OF A SHRA AS MENTIONED ABOVE. /OUTLOOK FOR KMSP/ FRIDAY NIGHT THROUGH MONDAY NIGHT...VFR CONDITIONS EXPECTED. SOUTH WIND 5 TO 15 KT THROUGH SATURDAY NIGHT... BECOMING SOUTHWEST 10 TO 20 KT SUNDAY THROUGH MONDAY NIGHT... WITH SPEEDS GENERALLY ON THE LOW END OF THE RANGE AT NIGHT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...CLF LONG TERM...TRH AVIATION...JPC
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1209 AM CDT Thu Aug 15 2013 .SHORT TERM...(This Evening through Friday Afternoon) Issued at 257 PM CDT WED AUG 14 2013 The main focus in the short-term remains a series of shortwave troughs sinking southeastward across the Plains this evening, Thursday, and into early Friday. Showers and isolated storms have developed over portions of eastern Nebraska in association with a wave currently pushing southeast toward the forecast area; however, ongoing precipitation will continue to move into fairly dry air this evening, and may struggle against entrainment. Additionally, upper- level flow may push the main area of precipitation more east than south, keeping the bulk of any falling precipitation in central and southern Iowa. Short-term precipitation trends from the HRRR have been fairly consistent today, and also generally limit the south and eastward expansion of showers for this evening and tonight. For now, have kept PoPs very low and confined to far northwest Missouri prior to 06z, then have begun to increase chances in the NW to account for possible regeneration as the low-level jet kicks up early Thursday morning. The next system will follow on the heels of tonight`s as it drops down from eastern Montana on Thursday. Models continue to indicate that the reinforcement of the eastern trough by a second upper low, and the retrograding of a broad upper high, will result in more meridional flow across the Plains for Thursday and Friday. This subtle change will send the second wave a bit west of the forecast area, keeping the better rain chances mainly across portions of central and eastern Kansas. Have left some slight to low-end chance PoPs mainly across the western tier or two of counties on Thursday afternoon and Thursday night, but these could likely be cut further if model trends continue in this direction. Any precipitation that does brush the area will sink southward on Friday morning, leaving behind quiet conditions by Friday afternoon. Temperatures through the period will remain ~10 degrees below normal as cool air continues to filter down the trough and into the eastern Plains and Ohio River valley, with highs generally topping out in the upper 70s to lower 80s, and lows in the 50s to lower 60s under surface high pressure. .LONG TERM...(Friday Evening through Wednesday) Issued at 257 PM CDT WED AUG 14 2013 A quiet medium range forecast for the Central Plains as mid-level ridging currently building over the Rockies begins to move eastward. Despite the increasing heights, Saturday will likely remain below seasonal normals as surface and low-level winds remain light to southeast. By Sunday, we`ll begin to see a steady climb back to or even above normal as winds turn southerly and warmer air begins to advect northward. The first half of next week will again feature quiet conditions as mid-level flow remains weak. Temperatures will have a chance to return to the 90 degree mark by Tuesday and Wednesday, a rare feat this August. && .AVIATION...(For the 06Z TAFS through 06Z Thursday Night) Issued at 1154 PM CDT WED AUG 14 2013 Still some uncertainty about whether showers will make it far enough south to affect KMCI/KMKC...as there may not be enough ascent to adequately saturate the column. As of now it looks as though the best chance for actual precipitation will be further north toward KSTJ and points north. Regardless of showery activity expect VFR conditions to be predominant through the entire period. Will continue to monitor and amend as necessary. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...Laflin LONG TERM...Dux AVIATION...Leighton
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
915 PM MDT Fri Aug 16 2013 .DISCUSSION... Update forthcoming. Have made minor changes to the sky grids. Have also expanded pop area over the extreme northwest portion of the county warning area. HRRR analysis brings very light precipitation to the area toward daybreak, likely associated with area of clouds moving through the Idaho panhandle at this time. Temperatures look reasonable. Emanuel && .AVIATION... UPDATED 2340Z. Current mix of clear skies and scattered mid- and high-level clouds across the region will continue into early evening, then expect most of the mid-level clouds to dissipate toward sunset. Areas of smoke from western MT/central ID wildland fires will keep thin veil of high clouds over southwest MT, along/south of a KHLN-to-KLWT line. Weak disturbance aloft presently located in far northwest MT will make slow eastward progress with only impact expected to be increasing clouds vcnty Rocky Mtn Front and KCTB overnight. Breezy winds of 20-25 kts will also gradually decrease toward sunset. Waranauskas && .PREV DISCUSSION...Issued 230 PM MDT Fri Aug 16 2013 Tonight through Sunday...Warm and dry conditions will continue Friday afternoon into Saturday. High pressure slowly begins to shift east in response to a weak mid level boundary passing through the region early Saturday. There will be a slight chance of some afternoon shower development over portions Central Montana Saturday and Sunday but dry lower level conditions may prevent most precipitation reaching the ground. Elevated terrain will likely have a better chance of seeing any precipitation from anything that does develop. Any storms that do develop will likely only produce gusty winds near their vicinity. Fire weather conditions are marginal at this time but very low relative humidity and afternoon breeziness add to the danger level. For additional fire weather concerns please see the Fire Weather Discussion. Temperatures look to moderate slightly over the weekend with highs dropping to the upper 80s and low 90s. Sunday night through Friday...The zones will be underneath a flat upper level high pressure ridge Sunday night and the airmass will be quite dry. The next low pressure weather system will be well west over the Eastern Pacific. The upper level ridge will move east of the zones by Tuesday afternoon and flow aloft will switch to the southwest. Moisture will again be able to move underneath the ridge and the airmass will become unstable again Wednesday afternoon, mainly over the southwest zones. Later in the week latest model runs indicate that the upper ridge will rebuild and affect the forecast area. Therefore have updated the forecast to go with warmer temperatures. There is the possibility that high temperatures could return to near 90 by late in the week for the lower elevations. Even with this change to a rebuilding upper ridge it still looks like there could be some instability so will continue with the mention of a slight chance of thunderstorms even though some guidance from the models indicates Thursday and Friday could be dry. Blank && .FIRE WEATHER... UPDATED 2030Z. Critical fire weather conditions remain possible into Friday evening before returning Saturday afternoon over Southwest and South Central Montana. Afternoon humidity will drop to very low values of 5 to 10 percent across the lower elevations with slightly higher values of 10 to 15 percent Saturday. A weak mid- level boundary passing through the region Saturday afternoon could bring somewhat breezy westerly winds, mainly along and near the Continental Divide. Not expecting a major wind shift or strong winds from these boundaries though. Breezy winds combined with low humidity could result in critical fire weather conditions Saturday afternoon. Confidence remains high for humidity less than 20 percent and around 50 percent for winds over 15 mph Saturday. As a result, will hold off on fire weather highlights at this time. && .PRELIMINARY POINT TEMPS/POPS... GTF 57 91 57 89 / 10 10 30 10 CTB 56 85 53 83 / 10 10 10 0 HLN 59 90 58 89 / 0 20 20 10 BZN 51 90 51 88 / 0 10 20 10 WEY 39 83 42 81 / 0 10 10 20 DLN 51 87 50 86 / 0 10 10 10 HVR 60 89 59 88 / 10 10 30 20 LWT 55 87 56 85 / 0 10 30 20 && .TFX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING until 9 PM MDT this evening Beaverhead... Central and Southern Lewis and Clark...Jefferson...Madison. && $$ weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
333 PM CDT THU AUG 15 2013 .SYNOPSIS... ISSUED AT 333 PM CDT THU AUG 15 2013 CURRENTLY...AN UPPER LEVEL DISTURBANCE IS MOVING SOUTH-SOUTHEAST ACROSS SOUTH DAKOTA IN NORTHWEST FLOW ALOFT. AN UPPER LEVEL RIDGE EXTENDS NORTHWARD FROM THE FOUR CORNERS REGION TO SASKATCHEWAN AND AN UPPER LEVEL LOW EXISTS OVER QUEBEC. A SURFACE BOUNDARY CURRENTLY EXTENDS NORTHWESTWARD FROM FRONTIER COUNTY THROUGH GARDEN COUNTY AND INTO NORTHWESTERN NEBRASKA. ALSO...LOW CLOUDS HAVE BEEN PERSISTENT OVER PARTS OF NORTH-CENTRAL NEBRASKA TODAY. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 333 PM CDT THU AUG 15 2013 STARTING TO SEE SOME CUMULUS DEVELOPMENT ALONG STATIONARY SURFACE BOUNDARY EXTENDING TO THE NW FROM FRONTIER COUNTY THROUGH OGALLALA AND NWWD. BELIEVE THIS WOULD BE THE BEST AREA FOR THUNDERSTORM DEVELOPMENT THIS AFTERNOON...WITH ANY STORMS MOVING SOUTHEASTWARD AT AROUND 20 KTS. MODELS INDICATE 0-6 KM SHEAR OF 30-35 KTS ALTHOUGH SPC MESOANALYSIS DATA IS SHOWING SHEAR UNDER 30 KTS AS OF 20Z. THERE MAY BE A FEW ISOLATED SEVERE STORMS THIS AFTN/EVE...BUT THE BEST CHANCE WOULD BE SOUTH OF I-80. HAVE TRIMMED POPS AND THUNDERSTORM COVERAGE A BIT ACROSS THE AREA TONIGHT BASED ON LATEST MODEL DATA AND TRENDS. HRRR MODEL FROM 18Z HAS A FEW STORMS JUST WEST OF NORTH PLATTE AND AREAS SE...MOVING SE TONIGHT. EMC WRF MODEL HAS A FAIR AMOUNT OF CONVECTION NORTH TO THE SD BORDER HOWEVER...ALTHOUGH ITS NOT AS LIKELY. THUNDERSTORMS SHOULD COME TO AN END IN THE EVENING ACROSS THE AREA AS THE UPPER LEVEL WAVE MOVES THROUGH THE REGION. MODELS ARE POINTING TOWARD MORE FOG AND LOW STRATUS TONIGHT...ESPECIALLY CENTRAL AND EAST. HAVE INCLUDED FOG IN THE FORECAST FOR MOST OF THE AREA. TOMORROW...AFTER LOW CLOUDS AND FOG HAVE DISSIPATED...FAIR SKIES AND TEMPS IN THE MID 70S EAST TO UPPER 80S WEST ARE EXPECTED. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 333 PM CDT THU AUG 15 2013 MID TERM...FRIDAY NIGHT THROUGH SUNDAY...RIDGING WILL CONTINUE TO BUILD ACROSS THE CENTRAL PLAINS FRIDAY NIGHT THROUGH SATURDAY NIGHT...WITH TEMPERATURES THE MAIN FORECAST CHALLENGE...FOLLOWED BY PRECIPITATION CHANCES IN THE FAR WEST SUNDAY AFTERNOON. FOR FRIDAY NIGHT...SURFACE HIGH PRESSURE WILL DRIFT EAST INTO THE MIDDLE MISSISSIPPI VALLEY WITH A LEE SIDE TROUGH BEGINNING TO DEEPEN ACROSS THE FRONT RANGES OF COLORADO AND WYOMING. SRLY WINDS WILL BEGIN TO INCREASE LATE FRIDAY IN RESPONSE...AND ARE NOT EXPECTED TO TOTALLY DECOUPLE FRIDAY NIGHT. THIS WILL LEAD TO SLIGHTLY WARMER MIN TEMPS SATURDAY MORNING COMPARED TO FRIDAY MORNING. THE MET AND MAV GUIDANCE ARE IN DECENT AGREEMENT WITH LOWS SATURDAY MORNING SO A BLEND WILL BE UTILIZED...THEN SCALED UPWARD A DEGREE OR TWO DUE TO INCREASED MIXING. MAV AND MET GUIDANCE TEMPS DIVERGE ON SATURDAY...WITH THE MAV 3 TO 6 DEGREES COOLER THAN THE MUCH WARMER MET. UTILIZED THE BIAS CORRECTED CONSALL GUIDANCE FOR HIGHS SATURDAY...WHICH RESULTED IN A COMPROMISE BETWEEN THE MET AND MAV NUMBERS. THIS LED TO HIGHS IN THE MIDDLE 80S IN THE EASTERN CWA...TO THE LOWER 90S IN THE PANHANDLE...WHERE DEW POINTS IN THE LOWER 50S ARE EXPECTED SAT AFTERNOON. FOR SUNDAY...HIGHS WILL MIRROR SATURDAYS FCST...WITH THE EXCEPTION OF THE EASTERN ZONES WHERE SLIGHTLY WARMER TEMPS ARE EXPECTED THANKS TO WARMER H85 AIR. HIGHS SUNDAY WILL RANGE FROM THE UPPER 80S TO LOWER 90S IN THE PANHANDLE AND FAR WEST. BY SUNDAY AFTERNOON...THE LATEST NAM IS HINTING AT BREAKING DOWN THE RIDGE AND INITIATING CONVECTION ACROSS THE PANHANDLE AND FAR WESTERN ZONES LATE SUNDAY AFTERNOON. THE LATEST GFS...KEEPS THIS CONVECTION CONFINED TO THE FRONT RANGES OF COLORADO AND WYOMING...THANKS TO VERY WEAK MID LEVEL STEERING WINDS. INHERITED FCST WAS DRY SUNDAY AFTERNOON...AND INTEND TO KEEP IT THAT WAY...EVEN IN LIGHT OF THE LATEST 12Z NAM SOLN. LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...THERE ARE TWO SCHOOLS OF THOUGHT WITH THE EXTENDED FCST...A...DRY AND VERY WARM CONDS WILL PERSIST WELL INTO THE MIDDLE OF NEXT WEEK-12Z GFS...AND B...A BREAK DOWN IN THE RIDGE ACROSS THE CENTRAL CONUS LEADING TO COOLER AND WETTER CONDS ACROSS THE AREA-ECMWF. GLANCING AT LAST NIGHTS ENSEMBLES...THE MEAN NCEP ENSEMBLE MEAN HAS A BREAKDOWN IN THE WESTERN CONUS RIDGING EARLY IN THE WEEK WITH A FAIRLY ACTIVE PATTERN DEVELOPING BY MIDWEEK. IN CONTRAST...THE OPERATIONAL GFS FROM THIS MORNING HAS A CLOSED LOW OVER THE CENTRAL CA COAST. THE LATTER SOLN...WOULD TEND TO FAVOR A DRY AND WARMER FCST AS RIDGING WILL AMPLIFY DOWNSTREAM OF THE CLOSED CA LOW. NO SURPRISE...THE LATEST MEX GUIDANCE FROM THIS MORNING HAS LOWER TO MIDDLE 90S FOR HIGHS NEXT WEEK WITH DRY CONDS EXPECTED. SINCE THE OPERATIONAL GFS IS KIND OF AN OUTLIER WITH THE ENSEMBLE FCSTS...WILL FAVOR COOLER TEMPS IN THE 80S TO LOWER 90S FOR TEMPS NEXT WEEK. AS FOR PCPN CHANCES...CAN`T SEE MORE THAN A 20 PCT CHANCE TOWARD THE MIDDLE OF NEXT WEEK...AS WEAK DYNAMICS WILL CONTINUE WELL INTO NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1229 PM CDT THU AUG 15 2013 LOW CLOUDS HAVE HUNG IN OVER KVTN TODAY. WITH THE EASTERLY SURFACE WIND...BELIEVE IT WILL CONTINUE TO BE SLOW TO ERODE IN THAT AREA. THE CIG HAS BEEN VARIABLE AT 400 TO 800 FEET...SO IT IS STARTING TO SHOW SIGNS OF LIFTING A BIT. NONETHELESS...BELIEVE BOTH KLBF AND KVTN WILL SEE IFR CONDITIONS LATE TONIGHT WITH FOG/STRATUS FORMING AS INDICATED BY THE BUFR SOUNDINGS/SREF/MOS GUIDANCE. BELIEVE THIS AFTERNOON`S THUNDERSTORMS WILL AFFECT MAINLY KLBF AS STRATUS AT KVTN WILL SLOW WARMING IN THAT AREA. WEST OF KVTN MAY SEE TSRA HOWEVER. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...KNUTSVIG SHORT TERM...KNUTSVIG LONG TERM...CLB AVIATION...KNUTSVIG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1259 PM CDT THU AUG 15 2013 .UPDATE... ISSUED AT 652 AM CDT THU AUG 15 2013 NO SUBSTANTIAL CHANGES MADE TO THE FCST...BUT DID MAKE SOME ADJUSTMENTS TO INCREASE SKY AND TIMING/LOCATION ADJUSTMENTS TO POPS. ALSO DECREASED TEMPS THRU EARLY AFTN TO SUPPRESS THE DIURNAL RISE...ACCOUNTING FOR RAIN AND CLOUDS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 431 AM CDT THU AUG 15 2013 ALOFT: NW FLOW WILL CONT OVER THE PLAINS THRU TNGT...WITHIN AN AMPLIFIED ROCKIES RIDGE/ERN USA TROF LGWV PATTERN. WV IMAGERY SHOWED A WELL-DEFINED SHRTWV TROF OVER ERN MT/NERN WY. THIS TROF WILL CONT MOVING SE TODAY AND WILL BE LOCATED ALONG THE KS/OK BORDER BY DAYBREAK FRI. SFC: 1024 MB HIGH PRES WAS OVER THE OH VALLEY EARLY THIS MRNG. THIS HIGH WILL ESSENTIALLY EXPAND E INTO THE MID-ATLANTIC...REMAINING FAIRLY STATIONARY. THE MAIN POLAR FRONT WILL ALSO REMAIN STALLED WELL S OF THE FCST AREA...OVER TX AND THE GULF COAST STATES. AN E-W ORIENTED SFC TROF WAS NOTED OVER NEB /ROUGHLY ALONG I-80/ AND ITS WRN END WAS ATTACHED TO A WEAK LEE-SIDE LOW OVER THE PANHANDLE. THIS TROF IS FCST TO REMAIN IN PLACE /UNLESS IT BECOMES MODULATED OR PARTIALLY DESTROYED BY ON-GOING CONVECTION THIS MRNG/. MEANWHILE... THE LEE-SIDE LOW WILL STRENGTHEN AND SLIDE DOWN THE HIGH PLAINS TO BE NEAR PUB BY SUNSET. FCST FOR TODAY IS ESSENTIALLY VARIABLE CLOUDS WITH APPARENTLY A COUPLE DIFFERENT OPPORTUNITIES FOR TSTMS. CONVECTIVE EVOLUTION REMAINS COMPLEX AND UNCERTAIN...ESPECIALLY THIS AFTN/EVNG DUE TO THE ON-GOING CLUSTER OF TSTMS AND ITS INFLUENCE ON FUTURE DEVELOPMENTS. EARLY THIS MRNG: FOR THE 3RD MRNG IN A ROW WE HAVE A SMALL MCS APPROACHING AND EXPECT IT TO AFFECT AREAS W AND S OF THE TRI-CITIES BETWEEN 5-9 AM. THIS WEEK HAS BEEN EXCELLENT FOR MUCH-NEEDED RAINFALL. THE 05Z HI-RES RAP AND 00Z WRF FROM THE SD SCHOOL OF MINES AND TECH LOOK EXCELLENT COMPARED TO REALITY AND HOW THIS MRNG WILL EVOLVE. THE SMALL MCS WILL CONT INTO THE FCST AREA...PROBABLY WEAKENING WITH TIME. A FEW SHWRS/POSSIBLE THUNDER? WILL ALSO CONT TO DEVELOP WITHIN THE LLJ INDUCED WAA/ISENTROPIC ASCENT AHEAD OF THE MCS. WHAT HAPPENS AFTER THIS MCS DEPARTS REMAINS UP FOR GRABS. THE REMNANT MCV WILL BE SE OF OUR KS COUNTIES THIS AFTN AND WILL NOT BE A FACTOR. THE TRAILING OUTFLOW /AND ANY POSSIBLE DIFFERENTIAL HEATING BOUNDARIES/ WILL NEED TO BE WATCHED FOR CONVECTIVE INITIATION THIS AFTN...AS WELL AS WHATEVER IS LEFT OF THE E-W ORIENTED SFC TROF. THE HI-RES RAP AND THE SYNOPTIC-SCALE MODELS FCST TSTMS OVER THE PANHANDLE THIS MRNG /POSSIBLY THE SMALL TSTM CLUSTERS CURRENTLY ON-GOING OVER ERN WY/NWRN SD?/ AND THEN INCREASE IN COVERAGE THIS AFTN AS THEY HEAD SE INTO THE FCST AREA. WHILE PWAT/S ON 00Z SOUNDINGS ARE ONLY NEAR NORMAL...THE FCST AREA LIES IN A RIBBON OF DECENT LOW-LVL MSTR /DWPTS LOW-MID 60S/. THE NAM HIGH TEMPS WERE TOO WARM GIVEN EXPECTED RAINFALL AND CLOUD COVER TODAY. SO USED THE 03Z SREF MEAN MLCAPE WHICH SUGGESTS 1500-2500 J/KG WITH THE GREATEST VALUES S AND W OF THE TRI-CITIES. THAT COULD BE TOO HIGH GIVEN THAT A PORTION OF THE INSOLATION THAT OCCURS THIS AFTN WILL GO TO EVAPORATING RAINFALL...NOT TO MENTION LEFTOVER CLOUDINESS WHICH WILL RETARD DIURNAL HEATING. OVERALL TROPOSPHERIC WINDS WILL BE WEAK...BUT DIRECTIONAL SHEAR /WITH SFC AND MID-LVL WINDS 180 APART/ WILL CONTRIBUTE TO 0-6 KM SHEAR OF 30-40 KTS /HIGHEST OVER N-CNTRL KS/. INDIVIDUAL CELL MOVEMENT WILL BE SE AT 15-20 KTS. ANY MULTICELL CLUSTERS THAT FORM COULD MOVE UP TO 40 KTS THREATENING SOME WIND DAMAGE. IF A SUPERCELL OR TWO FORMS...MOVEMENT WOULD BE SSW AROUND 20 KTS. HODOGRAPHS WILL BE NEARLY A STRAIGHT-LINE SUGGESTING SUPERCELL SPLITS A POSSIBILITY. MAIN THREATS: HAIL TO 1.75" AND STRAIGHT-LINE WINDS TO 60 MPH. AN ISOLATED TORNADO CAN/T BE COMPLETELY RULED OUT W OF A LINE FROM LEXINGTON NEB-HOLDREGE-OSBORNE KS...EITHER SUPERCELLULAR WITH 0-1 KM SRH OF 80-100 M2/S2 OR A NON-SUPERCELL TOR ASSOCIATED WITH ANY BOUNDARIES. TNGT: SVR TSTMS WILL PROBABLY BE ON-GOING DURING THE EVNG HRS...BUT SHOULD BE S-SE OF THE FCST AREA BY MIDNGT. WINDS PROBABLY TURN CALM /OR NEARLY CALM/ AFTER 2 AM. THIS THREATENS SOME FOG WHERE SKIES CLEAR. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 431 AM CDT THU AUG 15 2013 GUIDANCE SUGGESTS UPPER LEVEL RIDGING WILL PERSIST OVER THE WESTERN CONUS THROUGH SUNDAY OR MONDAY...BEFORE MOVING EAST INTO PORTIONS OF THE CENTRAL CONUS BY MID NEXT WEEK. AS A RESULT...NORTH TO NORTHWESTERLY MID TO UPPER LEVEL FLOW IS EXPECTED OVER THE CENTRAL PLAINS THROUGH MUCH OF THE LONG TERM FORECAST PERIOD...WITH THIS FLOW SUBSTANTIALLY DECREASING IN INTENSITY AS THE UPPER LEVEL RIDGE AXIS MOVES NEAR THE REGION BY EARLY TO MID NEXT WEEK. GIVEN THE ANTICIPATED LACK IN KINEMATIC FORCING DURING THE EXTENDED FORECAST PERIOD...AS SUGGESTED BY GUIDANCE...CHANCES FOR PRECIPITATION APPEAR AS THOUGH THEY WILL REMAIN LOW. THERE SEEMS TO BE PRETTY GOOD AGREEMENT BETWEEN THE NAM...EC...AND SREF-MEAN OF LINGERING OVERNIGHT CONVECTION PERHAPS IMPACTING SOUTHERN AND EASTERN PORTIONS OF OUR CWA FOR A TIME FRIDAY MORNING AND GIVEN THE ~20% POPS INHERITED FROM THE PREVIOUS FORECAST...OPTED TO KEEP THE SLIGHT-CHANCE POPS GOING FOR OUR SOUTH AND EAST 12-18Z FRIDAY. BEYOND 18Z FRIDAY...THE ONLY CHANCE AT OBSERVING MEASURABLE PRECIPITATION ACROSS THE AREA APPEARS AS THOUGH IT WILL REMAIN RELEGATED TO THE LATTER PART OF THE LONG TERM FORECAST PERIOD AS THE AXIS OF A 25-35KT 850MB JET STREAK SETS UP OVER THE AREA. LOW LEVEL THERMAL ADVECTION ALONG THIS JET STREAK AXIS COULD PROMOTE ISOLATED TO SCATTERED PRECIPITATION ACROSS THE AREA...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE OPERATIONAL GFS AND EC...ALTHOUGH IT IS WORTH MENTIONING THAT THESE MODELS DO NOT AGREE ON WHICH DAYS OR WHICH LOCATIONS ARE BETTER FAVORED FOR OBSERVING PRECIPITATION. ALLBLEND RESPONDED BY PROVIDING ~20% POPS TO MUCH OF THE CWA MONDAY NIGHT THROUGH WEDNESDAY AND GIVEN THE AFOREMENTIONED GUIDANCE...FELT THESE POPS WERE JUSTIFIED AND THUS WERE LEFT UNCHANGED FOR THE MOST PART. LITTLE CHANGE IN THE LOW LEVEL AIRMASS SHOULD PRESENT SIMILAR TEMPERATURES ACROSS OUR AREA FRIDAY AND SATURDAY. PERSISTENT SOUTHERLY LOW LEVEL FLOW AND RESULTANT THERMAL ADVECTION HOWEVER SHOULD THEN ALLOW FOR A WARMING TREND DURING THE EARLY TO MID PART OF NEXT WEEK. AS A RESULT...AFTERNOON HIGHS IN THE UPPER 70S TO LOW 80S ARE CURRENTLY FORECAST FRIDAY AND SATURDAY...WITH HIGHS CLIMBING INTO THE MID TO UPPER 80S AND EVENTUALLY THE LOWER 90S TO FINISH OUT THE LONG TERM FORECAST PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1250 PM CDT THU AUG 15 2013 WENT WITH A FAIRLY PESSIMISTIC TAF THIS AFTERNOON AS THE LATEST VISIBLE SATELLITE INDICATES IFR STRATUS IS EXPANDING SOUTHWARD. ALREADY HAVE IFR CIGS AT ODX...AND USING EXTRAPOLATION...THIS STRATUS SHOULD REACH KGRI AROUND 19Z. THEREAFTER...CONTINUE TO EXPECT THE POTENTIAL FOR A VCTS LATE THIS AFTERNOON AS CONVECTION ATTEMPTS TO BUILD ACROSS THE LOCAL AREA. HOWEVER...WITH STRATUS AROUND THROUGH THE PEAK HEATING HOURS...DO NOT THINK CONVECTION WILL BE WIDESPREAD NEAR OR NORTH OF THE TERMINAL...AND CONTINUED WITH IMPROVING CIGS TO 4KFT AND ONLY A VCTS THROUGH THE EARLY EVENING HOURS...MORE LIKELY IN RESPONSE TO SHORTWAVE DROPPING SOUTH ACROSS SOUTH DAKOTA THIS AFTERNOON. ONCE SKIES BEGIN TO CLEAR LATE TONIGHT...MODELS ARE INDICATING WE COULD SEE SOME DENSE FOG FORM...AND DID INTRODUCE LIFR CIGS AND VSBYS FOR A FEW HOURS TO ACCOUNT FOR THIS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...HALBLAUB SHORT TERM...HALBLAUB LONG TERM...BRYANT AVIATION...SAR
AREA FORECAST DISCUSSION
NWS HASTINGS NE
653 AM CDT THU AUG 15 2013 .UPDATE... ISSUED AT 652 AM CDT THU AUG 15 2013 NO SUBSTANTIAL CHANGES MADE TO THE FCST...BUT DID MAKE SOME ADJUSTMENTS TO INCREASE SKY AND TIMING/LOCATION ADJUSTMENTS TO POPS. ALSO DECREASED TEMPS THRU EARLY AFTN TU SUPPRESS THE DIURNAL RISE...ACCOUNTING FOR RAIN AND CLOUDS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 431 AM CDT THU AUG 15 2013 ALOFT: NW FLOW WILL CONT OVER THE PLAINS THRU TNGT...WITHIN AN AMPLIFIED ROCKIES RIDGE/ERN USA TROF LGWV PATTERN. WV IMAGERY SHOWED A WELL-DEFINED SHRTWV TROF OVER ERN MT/NERN WY. THIS TROF WILL CONT MOVING SE TODAY AND WILL BE LOCATED ALONG THE KS/OK BORDER BY DAYBREAK FRI. SFC: 1024 MB HIGH PRES WAS OVER THE OH VALLEY EARLY THIS MRNG. THIS HIGH WILL ESSENTIALLY EXPAND E INTO THE MID-ATLANTIC...REMAINING FAIRLY STATIONARY. THE MAIN POLAR FRONT WILL ALSO REMAIN STALLED WELL S OF THE FCST AREA...OVER TX AND THE GULF COAST STATES. AN E-W ORIENTED SFC TROF WAS NOTED OVER NEB /ROUGHLY ALONG I-80/ AND ITS WRN END WAS ATTACHED TO A WEAK LEE-SIDE LOW OVER THE PANHANDLE. THIS TROF IS FCST TO REMAIN IN PLACE /UNLESS IT BECOMES MODULATED OR PARTIALLY DESTROYED BY ON-GOING CONVECTION THIS MRNG/. MEANWHILE... THE LEE-SIDE LOW WILL STRENGTHEN AND SLIDE DOWN THE HIGH PLAINS TO BE NEAR PUB BY SUNSET. FCST FOR TODAY IS ESSENTIALLY VARIABLE CLOUDS WITH APPARENTLY A COUPLE DIFFERENT OPPORTUNITIES FOR TSTMS. CONVECTIVE EVOLUTION REMAINS COMPLEX AND UNCERTAIN...ESPECIALLY THIS AFTN/EVNG DUE TO THE ON-GOING CLUSTER OF TSTMS AND ITS INFLUENCE ON FUTURE DEVELOPMENTS. EARLY THIS MRNG: FOR THE 3RD MRNG IN A ROW WE HAVE A SMALL MCS APPROACHING AND EXPECT IT TO AFFECT AREAS W AND S OF THE TRI-CITIES BETWEEN 5-9 AM. THIS WEEK HAS BEEN EXCELLENT FOR MUCH-NEEDED RAINFALL. THE 05Z HI-RES RAP AND 00Z WRF FROM THE SD SCHOOL OF MINES AND TECH LOOK EXCELLENT COMPARED TO REALITY AND HOW THIS MRNG WILL EVOLVE. THE SMALL MCS WILL CONT INTO THE FCST AREA...PROBABLY WEAKENING WITH TIME. A FEW SHWRS/POSSIBLE THUNDER? WILL ALSO CONT TO DEVELOP WITHIN THE LLJ INDUCED WAA/ISENTROPIC ASCENT AHEAD OF THE MCS. WHAT HAPPENS AFTER THIS MCS DEPARTS REMAINS UP FOR GRABS. THE REMNANT MCV WILL BE SE OF OUR KS COUNTIES THIS AFTN AND WILL NOT BE A FACTOR. THE TRAILING OUTFLOW /AND ANY POSSIBLE DIFFERENTIAL HEATING BOUNDARIES/ WILL NEED TO BE WATCHED FOR CONVECTIVE INITIATION THIS AFTN...AS WELL AS WHATEVER IS LEFT OF THE E-W ORIENTED SFC TROF. THE HI-RES RAP AND THE SYNOPTIC-SCALE MODELS FCST TSTMS OVER THE PANHANDLE THIS MRNG /POSSIBLY THE SMALL TSTM CLUSTERS CURRENTLY ON-GOING OVER ERN WY/NWRN SD?/ AND THEN INCREASE IN COVERAGE THIS AFTN AS THEY HEAD SE INTO THE FCST AREA. WHILE PWAT/S ON 00Z SOUNDINGS ARE ONLY NEAR NORMAL...THE FCST AREA LIES IN A RIBBON OF DECENT LOW-LVL MSTR /DWPTS LOW-MID 60S/. THE NAM HIGH TEMPS WERE TOO WARM GIVEN EXPECTED RAINFALL AND CLOUD COVER TODAY. SO USED THE 03Z SREF MEAN MLCAPE WHICH SUGGESTS 1500-2500 J/KG WITH THE GREATEST VALUES S AND W OF THE TRI-CITIES. THAT COULD BE TOO HIGH GIVEN THAT A PORTION OF THE INSOLATION THAT OCCURS THIS AFTN WILL GO TO EVAPORATING RAINFALL...NOT TO MENTION LEFTOVER CLOUDINESS WHICH WILL RETARD DIURNAL HEATING. OVERALL TROPOSPHERIC WINDS WILL BE WEAK...BUT DIRECTIONAL SHEAR /WITH SFC AND MID-LVL WINDS 180 APART/ WILL CONTRIBUTE TO 0-6 KM SHEAR OF 30-40 KTS /HIGHEST OVER N-CNTRL KS/. INDIVIDUAL CELL MOVEMENT WILL BE SE AT 15-20 KTS. ANY MULTICELL CLUSTERS THAT FORM COULD MOVE UP TO 40 KTS THREATENING SOME WIND DAMAGE. IF A SUPERCELL OR TWO FORMS...MOVEMENT WOULD BE SSW AROUND 20 KTS. HODOGRAPHS WILL BE NEARLY A STRAIGHT-LINE SUGGESTING SUPERCELL SPLITS A POSSIBILITY. MAIN THREATS: HAIL TO 1.75" AND STRAIGHT-LINE WINDS TO 60 MPH. AN ISOLATED TORNADO CAN/T BE COMPLETELY RULED OUT W OF A LINE FROM LEXINGTON NEB-HOLDREGE-OSBORNE KS...EITHER SUPERCELLULAR WITH 0-1 KM SRH OF 80-100 M2/S2 OR A NON-SUPERCELL TOR ASSOCIATED WITH ANY BOUNDARIES. TNGT: SVR TSTMS WILL PROBABLY BE ON-GOING DURING THE EVNG HRS...BUT SHOULD BE S-SE OF THE FCST AREA BY MIDNGT. WINDS PROBABLY TURN CALM /OR NEARLY CALM/ AFTER 2 AM. THIS THREATENS SOME FOG WHERE SKIES CLEAR. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 431 AM CDT THU AUG 15 2013 GUIDANCE SUGGESTS UPPER LEVEL RIDGING WILL PERSIST OVER THE WESTERN CONUS THROUGH SUNDAY OR MONDAY...BEFORE MOVING EAST INTO PORTIONS OF THE CENTRAL CONUS BY MID NEXT WEEK. AS A RESULT...NORTH TO NORTHWESTERLY MID TO UPPER LEVEL FLOW IS EXPECTED OVER THE CENTRAL PLAINS THROUGH MUCH OF THE LONG TERM FORECAST PERIOD...WITH THIS FLOW SUBSTANTIALLY DECREASING IN INTENSITY AS THE UPPER LEVEL RIDGE AXIS MOVES NEAR THE REGION BY EARLY TO MID NEXT WEEK. GIVEN THE ANTICIPATED LACK IN KINEMATIC FORCING DURING THE EXTENDED FORECAST PERIOD...AS SUGGESTED BY GUIDANCE...CHANCES FOR PRECIPITATION APPEAR AS THOUGH THEY WILL REMAIN LOW. THERE SEEMS TO BE PRETTY GOOD AGREEMENT BETWEEN THE NAM...EC...AND SREF-MEAN OF LINGERING OVERNIGHT CONVECTION PERHAPS IMPACTING SOUTHERN AND EASTERN PORTIONS OF OUR CWA FOR A TIME FRIDAY MORNING AND GIVEN THE ~20% POPS INHERITED FROM THE PREVIOUS FORECAST...OPTED TO KEEP THE SLIGHT-CHANCE POPS GOING FOR OUR SOUTH AND EAST 12-18Z FRIDAY. BEYOND 18Z FRIDAY...THE ONLY CHANCE AT OBSERVING MEASURABLE PRECIPITATION ACROSS THE AREA APPEARS AS THOUGH IT WILL REMAIN RELEGATED TO THE LATTER PART OF THE LONG TERM FORECAST PERIOD AS THE AXIS OF A 25-35KT 850MB JET STREAK SETS UP OVER THE AREA. LOW LEVEL THERMAL ADVECTION ALONG THIS JET STREAK AXIS COULD PROMOTE ISOLATED TO SCATTERED PRECIPITATION ACROSS THE AREA...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE OPERATIONAL GFS AND EC...ALTHOUGH IT IS WORTH MENTIONING THAT THESE MODELS DO NOT AGREE ON WHICH DAYS OR WHICH LOCATIONS ARE BETTER FAVORED FOR OBSERVING PRECIPITATION. ALLBLEND RESPONDED BY PROVIDING ~20% POPS TO MUCH OF THE CWA MONDAY NIGHT THROUGH WEDNESDAY AND GIVEN THE AFOREMENTIONED GUIDANCE...FELT THESE POPS WERE JUSTIFIED AND THUS WERE LEFT UNCHANGED FOR THE MOST PART. LITTLE CHANGE IN THE LOW LEVEL AIRMASS SHOULD PRESENT SIMILAR TEMPERATURES ACROSS OUR AREA FRIDAY AND SATURDAY. PERSISTENT SOUTHERLY LOW LEVEL FLOW AND RESULTANT THERMAL ADVECTION HOWEVER SHOULD THEN ALLOW FOR A WARMING TREND DURING THE EARLY TO MID PART OF NEXT WEEK. AS A RESULT...AFTERNOON HIGHS IN THE UPPER 70S TO LOW 80S ARE CURRENTLY FORECAST FRIDAY AND SATURDAY...WITH HIGHS CLIMBING INTO THE MID TO UPPER 80S AND EVENTUALLY THE LOWER 90S TO FINISH OUT THE LONG TERM FORECAST PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 652 AM CDT THU AUG 15 2013 TODAY: VFR THOUGH WITH POCKETS OF BRIEF IFR VSBY AND MVFR CIGS IN SHWRS/TSTMS THRU 14Z-15Z. WHILE VSBY WILL RETURN TO VFR...THERE COULD BE A PERIOD OF MVFR CIGS AFTER THIS SHWR/TSTM ACTIVITY DEPARTS. THEN A BREAK BEFORE SCT SHWRS/TSTMS REFORM AFTER 20Z. EXPECT POCKETS OF MVFR OR IFR VSBYS. THERE IS A LOW PROBABILITY OF 1 INCH HAIL AND G50 KTS IF THE TERMINAL TAKES A DIRECT HIT. LIGHT S WINDS WILL EVENTUALLY BACK TO SE. TNGT: TSTM THREAT SHOULD BE OVER BY 03Z. THEN CLEARING WITH POTENTIAL FOR VFR TO DETERIORATE TO IFR FOG AFTER 08Z. WHILE NOT INDICATED IN THE TAF...THERE IS POTENTIAL FOR 1/4SM FG VV001. CIG CONFIDENCE: MEDIUM VSBY CONFIDENCE: LOW IN ANY TSTM AND LATE FOG WIND CONFIDENCE: HIGH WX EXCEPT NEAR ANY TSTMS WX CONFIDENCE: MEDIUM && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...HALBLAUB SHORT TERM...HALBLAUB LONG TERM...BRYANT AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
431 AM CDT THU AUG 15 2013 ...SVR TSTMS POSSIBLE THIS AFTN-EVNG THEN WE HAVE A GORGEOUS DRY WEEKEND IN STORE FOR OUTDOOR ACTIVITIES... .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 431 AM CDT THU AUG 15 2013 ALOFT: NW FLOW WILL CONT OVER THE PLAINS THRU TNGT...WITHIN AN AMPLIFIED ROCKIES RIDGE/ERN USA TROF LGWV PATTERN. WV IMAGERY SHOWED A WELL-DEFINED SHRTWV TROF OVER ERN MT/NERN WY. THIS TROF WILL CONT MOVING SE TODAY AND WILL BE LOCATED ALONG THE KS/OK BORDER BY DAYBREAK FRI. SFC: 1024 MB HIGH PRES WAS OVER THE OH VALLEY EARLY THIS MRNG. THIS HIGH WILL ESSENTIALLY EXPAND E INTO THE MID-ATLANTIC...REMAINING FAIRLY STATIONARY. THE MAIN POLAR FRONT WILL ALSO REMAIN STALLED WELL S OF THE FCST AREA...OVER TX AND THE GULF COAST STATES. AN E-W ORIENTED SFC TROF WAS NOTED OVER NEB /ROUGHLY ALONG I-80/ AND ITS WRN END WAS ATTACHED TO A WEAK LEE-SIDE LOW OVER THE PANHANDLE. THIS TROF IS FCST TO REMAIN IN PLACE /UNLESS IT BECOMES MODULATED OR PARTIALLY DESTROYED BY ON-GOING CONVECTION THIS MRNG/. MEANWHILE... THE LEE-SIDE LOW WILL STRENGTHEN AND SLIDE DOWN THE HIGH PLAINS TO BE NEAR PUB BY SUNSET. FCST FOR TODAY IS ESSENTIALLY VARIABLE CLOUDS WITH APPARENTLY A COUPLE DIFFERENT OPPORTUNITIES FOR TSTMS. CONVECTIVE EVOLUTION REMAINS COMPLEX AND UNCERTAIN...ESPECIALLY THIS AFTN/EVNG DUE TO THE ON-GOING CLUSTER OF TSTMS AND ITS INFLUENCE ON FUTURE DEVELOPMENTS. EARLY THIS MRNG: FOR THE 3RD MRNG IN A ROW WE HAVE A SMALL MCS APPROACHING AND EXPECT IT TO AFFECT AREAS W AND S OF THE TRI-CITIES BETWEEN 5-9 AM. THIS WEEK HAS BEEN EXCELLENT FOR MUCH-NEEDED RAINFALL. THE 05Z HI-RES RAP AND 00Z WRF FROM THE SD SCHOOL OF MINES AND TECH LOOK EXCELLENT COMPARED TO REALITY AND HOW THIS MRNG WILL EVOLVE. THE SMALL MCS WILL CONT INTO THE FCST AREA...PROBABLY WEAKENING WITH TIME. A FEW SHWRS/POSSIBLE THUNDER? WILL ALSO CONT TO DEVELOP WITHIN THE LLJ INDUCED WAA/ISENTROPIC ASCENT AHEAD OF THE MCS. WHAT HAPPENS AFTER THIS MCS DEPARTS REMAINS UP FOR GRABS. THE REMNANT MCV WILL BE SE OF OUR KS COUNTIES THIS AFTN AND WILL NOT BE A FACTOR. THE TRAILING OUTFLOW /AND ANY POSSIBLE DIFFERENTIAL HEATING BOUNDARIES/ WILL NEED TO BE WATCHED FOR CONVECTIVE INITIATION THIS AFTN...AS WELL AS WHATEVER IS LEFT OF THE E-W ORIENTED SFC TROF. THE HI-RES RAP AND THE SYNOPTIC-SCALE MODELS FCST TSTMS OVER THE PANHANDLE THIS MRNG /POSSIBLY THE SMALL TSTM CLUSTERS CURRENTLY ON-GOING OVER ERN WY/NWRN SD?/ AND THEN INCREASE IN COVERAGE THIS AFTN AS THEY HEAD SE INTO THE FCST AREA. WHILE PWAT/S ON 00Z SOUNDINGS ARE ONLY NEAR NORMAL...THE FCST AREA LIES IN A RIBBON OF DECENT LOW-LVL MSTR /DWPTS LOW-MID 60S/. THE NAM HIGH TEMPS WERE TOO WARM GIVEN EXPECTED RAINFALL AND CLOUD COVER TODAY. SO USED THE 03Z SREF MEAN MLCAPE WHICH SUGGESTS 1500-2500 J/KG WITH THE GREATEST VALUES S AND W OF THE TRI-CITIES. THAT COULD BE TOO HIGH GIVEN THAT A PORTION OF THE INSOLATION THAT OCCURS THIS AFTN WILL GO TO EVAPORATING RAINFALL...NOT TO MENTION LEFTOVER CLOUDINESS WHICH WILL RETARD DIURNAL HEATING. OVERALL TROPOSPHERIC WINDS WILL BE WEAK...BUT DIRECTIONAL SHEAR /WITH SFC AND MID-LVL WINDS 180 APART/ WILL CONTRIBUTE TO 0-6 KM SHEAR OF 30-40 KTS /HIGHEST OVER N-CNTRL KS/. INDIVIDUAL CELL MOVEMENT WILL BE SE AT 15-20 KTS. ANY MULTICELL CLUSTERS THAT FORM COULD MOVE UP TO 40 KTS THREATENING SOME WIND DAMAGE. IF A SUPERCELL OR TWO FORMS...MOVEMENT WOULD BE SSW AROUND 20 KTS. HODOGRAPHS WILL BE NEARLY A STRAIGHT-LINE SUGGESTING SUPERCELL SPLITS A POSSIBILITY. MAIN THREATS: HAIL TO 1.75" AND STRAIGHT-LINE WINDS TO 60 MPH. AN ISOLATED TORNADO CAN/T BE COMPLETELY RULED OUT W OF A LINE FROM LEXINGTON NEB-HOLDREGE-OSBORNE KS...EITHER SUPERCELLULAR WITH 0-1 KM SRH OF 80-100 M2/S2 OR A NON-SUPERCELL TOR ASSOCIATED WITH ANY BOUNDARIES. TNGT: SVR TSTMS WILL PROBABLY BE ON-GOING DURING THE EVNG HRS...BUT SHOULD BE S-SE OF THE FCST AREA BY MIDNGT. WINDS PROBABLY TURN CALM /OR NEARLY CALM/ AFTER 2 AM. THIS THREATENS SOME FOG WHERE SKIES CLEAR. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 431 AM CDT THU AUG 15 2013 GUIDANCE SUGGESTS UPPER LEVEL RIDGING WILL PERSIST OVER THE WESTERN CONUS THROUGH SUNDAY OR MONDAY...BEFORE MOVING EAST INTO PORTIONS OF THE CENTRAL CONUS BY MID NEXT WEEK. AS A RESULT...NORTH TO NORTHWESTERLY MID TO UPPER LEVEL FLOW IS EXPECTED OVER THE CENTRAL PLAINS THROUGH MUCH OF THE LONG TERM FORECAST PERIOD...WITH THIS FLOW SUBSTANTIALLY DECREASING IN INTENSITY AS THE UPPER LEVEL RIDGE AXIS MOVES NEAR THE REGION BY EARLY TO MID NEXT WEEK. GIVEN THE ANTICIPATED LACK IN KINEMATIC FORCING DURING THE EXTENDED FORECAST PERIOD...AS SUGGESTED BY GUIDANCE...CHANCES FOR PRECIPITATION APPEAR AS THOUGH THEY WILL REMAIN LOW. THERE SEEMS TO BE PRETTY GOOD AGREEMENT BETWEEN THE NAM...EC...AND SREF-MEAN OF LINGERING OVERNIGHT CONVECTION PERHAPS IMPACTING SOUTHERN AND EASTERN PORTIONS OF OUR CWA FOR A TIME FRIDAY MORNING AND GIVEN THE ~20% POPS INHERITED FROM THE PREVIOUS FORECAST...OPTED TO KEEP THE SLIGHT-CHANCE POPS GOING FOR OUR SOUTH AND EAST 12-18Z FRIDAY. BEYOND 18Z FRIDAY...THE ONLY CHANCE AT OBSERVING MEASURABLE PRECIPITATION ACROSS THE AREA APPEARS AS THOUGH IT WILL REMAIN RELEGATED TO THE LATTER PART OF THE LONG TERM FORECAST PERIOD AS THE AXIS OF A 25-35KT 850MB JET STREAK SETS UP OVER THE AREA. LOW LEVEL THERMAL ADVECTION ALONG THIS JET STREAK AXIS COULD PROMOTE ISOLATED TO SCATTERED PRECIPITATION ACROSS THE AREA...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE OPERATIONAL GFS AND EC...ALTHOUGH IT IS WORTH MENTIONING THAT THESE MODELS DO NOT AGREE ON WHICH DAYS OR WHICH LOCATIONS ARE BETTER FAVORED FOR OBSERVING PRECIPITATION. ALLBLEND RESPONDED BY PROVIDING ~20% POPS TO MUCH OF THE CWA MONDAY NIGHT THROUGH WEDNESDAY AND GIVEN THE AFOREMENTIONED GUIDANCE...FELT THESE POPS WERE JUSTIFIED AND THUS WERE LEFT UNCHANGED FOR THE MOST PART. LITTLE CHANGE IN THE LOW LEVEL AIRMASS SHOULD PRESENT SIMILAR TEMPERATURES ACROSS OUR AREA FRIDAY AND SATURDAY. PERSISTENT SOUTHERLY LOW LEVEL FLOW AND RESULTANT THERMAL ADVECTION HOWEVER SHOULD THEN ALLOW FOR A WARMING TREND DURING THE EARLY TO MID PART OF NEXT WEEK. AS A RESULT...AFTERNOON HIGHS IN THE UPPER 70S TO LOW 80S ARE CURRENTLY FORECAST FRIDAY AND SATURDAY...WITH HIGHS CLIMBING INTO THE MID TO UPPER 80S AND EVENTUALLY THE LOWER 90S TO FINISH OUT THE LONG TERM FORECAST PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1237 AM CDT THU AUG 15 2013 REST OF TNGT: REMOVED FOG AND LOW CIGS FROM THE TAF BASED ON LBF/OAX SOUNDINGS AS WELL AS WIND AND DWPT TRENDS FROM YESTERDAY AFTN. EXPECT VFR CIGS MAY GO SCT AT TIMES. THERE IS A CLUSTER OF TSTMS OVER THE NEB PANHANDLE THAT WILL NEED TO BE MONITORED FOR POSSIBLE INSERTION INTO THE TAF TOWARD DAWN. S WINDS UNDER 10 KTS. THU: LOW-END VFR CIGS SHOULD INCREASE TO MID-LVL CIGS FROM THE REMNANTS OF NEARBY TSTM CLUSTER. BY 18Z...CURRENT EXPECTATION IS FOR SCT VFR CU TO DEVELOP WITH CB POSSIBLE AFTER 21Z. THERE IS A LOW PROBABILITY FOR 1 INCH HAIL AND G50 KTS IF THE TERMINAL TAKES A DIRECT HIT FROM AN AFTN OR EVNG TSTM. S WINDS LESS THAN 10 KTS WILL BACK TO SE. THU EVNG: TSTM THREAT SHOULD BE OVER BY 03Z. WE ARE SEEING SIGNALS OF POSSIBLE IFR FOG AFTER 06Z. CIG CONFIDENCE: MEDIUM VSBY CONFIDENCE: HIGH WIND CONFIDENCE: HIGH WX CONFIDENCE: MEDIUM && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...HALBLAUB LONG TERM...BRYANT AVIATION...HALBLAUB
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1243 AM CDT THU AUG 15 2013 .SYNOPSIS... ISSUED AT 330 PM CDT WED AUG 14 2013 SHOWER AND THUNDERSTORM ACTIVITY CURRENTLY EXISTS ACROSS NORTH- CENTRAL NEBRASKA AND IS MOVING EASTWARD SLOWLY. NEBRASKA IS UNDER NORTHWEST FLOW ALOFT WITH AN UPPER LEVEL WAVE IN EASTERN NEBRASKA AND ANOTHER OVER MONTANA. LOW LEVEL FLOW IS GENERALLY SOUTHERLY WITH AN AREA OF LOW PRESSURE OVER THE INTERMOUNTAIN WEST AND HIGH PRESSURE OVER THE UPPER MISSISSIPPI RIVER VALLEY. A WEAK BOUNDARY EXISTS ACROSS CENTRAL NEBRASKA...RUNNING FROM HOLT COUNTY SOUTHWEST TO CHASE COUNTY. && .UPDATE... ISSUED AT 945 PM CDT WED AUG 14 2013 HAVE ADJUSTED PRECIPITATION CHANCES ACROSS THE AREA NOW THAT ISOLATED CONVECTION HAS ENDED ACROSS THE AREA...FOR NOW. HOWEVER...CONVECTIVE COMPLEXES REMAIN ACROSS SOUTHWEST SD AND NORTHEAST CO. HRRR DOES TRY TO KEEP THE SD COMPLEX TOGETHER LONG ENOUGH TO MOVE INTO THE PANHANDLE AND INTO THE CENTRAL SANDHILLS. MID LEVEL LAPSE RATES WOULD SUPPORT SOME ADDITIONAL DEVELOPMENT SO HAVE LEFT SMALL CHANCES IN FOR NOW. OTHERWISE ADDED SOME PATCHY FOG EAST OF HIGHWAY 83 WHERE SMALL TEMP/DEW POINT SPREADS EXIST. UPDATE ISSUED AT 706 PM CDT WED AUG 14 2013 HAVE UPDATED EVENING FCST TO SLIGHTLY ADJUST PRECIP CHANCES. THUNDERSTORMS SHOWING A QUICK DECREASE IN COVERAGE AND INTENSITY OVER THE LAST 15 MINS. ADDITIONAL CONVECTION FURTHER WEST WILL APPROACH THE AREA LATER THIS EVENING...BUT OVERALL MID LEVEL LAPSE RATES DOES NOT LOOK FAVORABLE AT THIS POINT BUT WILL LOOK FURTHER INTO THIS. OTHERWISE REMAINDER OF FCST LOOKS ON TRACK. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 THE THUNDERSTORM COMPLEX THAT STARTED OVER THE NORTHEAST HAS LINGERED THERE TODAY DUE TO A FAVORABLE LOW LEVEL JET...SOME MODEST ELEVATED CAPE...AND UPPER SUPPORT. A SURFACE BOUNDARY CURRENTLY RUNS FROM HOLT TO CHASE COUNTIES AND MAY BE THE FOCUS FOR A FEW THUNDERSTORMS THIS AFTERNOON/EVENING. THE SEVERE THREAT IS LOW AS DEEP SHEAR IS RUNNING AT 25 TO 30 KTS. AN ISOLATED SEVERE STORM OR TWO CANNOT BE RULED OUT...HOWEVER. AN UPPER LEVEL WAVE WILL PUSH INTO THE AREA FROM THE NORTHWEST LATE TONIGHT AND TOMORROW MORNING. AHEAD OF THIS WAVE...CLOUDS WILL INCREASE AND SO WILL A LOW LEVEL JET ACROSS WESTERN NEBRASKA. BELIEVE THERE MAY BE SOME LATE NIGHT THUNDERSTORMS ACROSS THE NORTHWEST LATE IN THE NIGHT AND EARLY TOMORROW MORNING. THE MAIN UPPER WAVE WILL DRIFT INTO CENTRAL NEBRASKA BY MIDDAY...AND SO BELIEVE ANY THUNDERSTORM ACTIVITY WOULD BE PRIMARILY DURING THE LATE MORNING TO AFTERNOON HOURS. SHEAR TOMORROW IS A LITTLE BETTER...30-35 KTS...ACROSS THE SOUTH. AS A RESULT...SPC HAS ISSUED A SLIGHT RISK FOR SEVERE WEATHER ACROSS THAT AREA FOR TOMORROW. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 FORECASTING CHALLENGES ARE LINGERING PRECIPITATION THURSDAY EVENING...FOG POTENTIAL OVERNIGHT THURSDAY NIGHT INTO FRIDAY MORNING...THEN TEMPERATURES. WITH RESPECT TO THUNDERSTORM CHANCES THURSDAY EVENING...THE MODELS ARE A LITTLE FASTER WITH SHORTWAVE ENERGY DROPPING SOUTH THURSDAY ACROSS THE DAKOTAS AND NEBRASKA. THIS WILL BRING AN EARLIER END TO PRECIPITATION BY LATE THURSDAY EVENING IN THE SRN CWA. BEHIND THE EXITING CONVECTION...CLEARING SKIES...STRONG RADIATIONAL COOLING AND MOIST BOUNDARY LAYER CONDS MAY LEAD TO THE FORMATION OF FOG OVERNIGHT THURSDAY NIGHT INTO EARLY FRIDAY MORNING. NAM AND GFS BUFR SOUNDINGS INDICATE A FAVORABLE ENVIRONMENT FOR FOG FORMATION...AS DOES THE MET AND MAV GUIDANCE ALONG AND SOUTH OF A LINE FROM BIG SPRINGS TO BARTLETT. DECIDED TO LEAVE FOG MENTION AS PATCHY ATTM...AS SREF PROBABILITIES ARE RUNNING AROUND 60 PERCENT FOR VISBYS BLO 1SM. FOR FRIDAY INTO SUNDAY NIGHT...RIDGING WILL BUILD EAST INTO THE CENTRAL AND NORTHERN PLAINS...LEADING TO NRLY FLOW ALOFT AND EFFECTIVELY CUTTING OFF ANY CHANCE FOR PCPN FRIDAY THROUGH SUNDAY. HIGHS WILL BEGIN TO CLIMB FROM THE LOWER TO MID 80S ON FRIDAY...TO THE MID 80S TO AROUND 90 BY THE END OF THE WEEKEND. FOR HIGHS AND LOWS...UTILIZED THE ADJMAV GUIDANCE AS IT HAS HAD THE BEST VERIFICATION OVER THE PAST COUPLE OF WEEKS AND AVOIDED THE HIGHER MEX NUMBERS WHICH HAD HIGHS IN THE 90S BY SUNDAY INTO MONDAY. THINKING ATTM IS THAT THE MEX NUMBERS ARE TOO HIGH GIVEN THE HIGH DEGREE OF SURFACE MOISTURE ACROSS THE AREA. RIDGING ALOFT WILL BEGIN TO BREAK DOWN SLIGHTLY EARLY NEXT WEEK AS A DISTURBANCE TRACKS ACROSS SRN CANADA. THIS FEATURE HAS TRENDED WEAKER COMPARED TO YESTERDAYS MODEL RUNS...WHICH A...FACILITATES DECREASED POPS NEXT WEEK...AND B...INCREASED HIGH TEMPS...BOTH OF WHICH WERE IMPLEMENTED WITH THIS FORECAST PACKAGE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1243 AM CDT THU AUG 15 2013 SCATTERED TSRA FROM NEAR IEN THROUGH AIA CONTINE TO DROP SOUTHEAST. FOR THE KLBF TAF SITE CONFIDENCE IS TOO LOW TO INCLUDE TSRA...BUT WILL BE MONITORED CLOSELY FOR INCLUSION BY NEXT TAF ISSUANCE. AS FOR KVTN...STORMS TO CROSS WESTERN CHERRY COUNTY...BUT SHOULD PASS SOUTHWEST OF KVTN TAF LOCATION. LOW CLOUDS ALREADY IN KVTN AREA. SREF PROBS AND EARLIER HRRR SUGGESTS VSBYS SHOULD TEMPORARILY GO DOWN TO IFR AFTER 08Z OR SO NEAR KVTN. ALSO MVFR CIGS AND 5SM BR AT KLBF 09Z-14Z. STORMS DEVELOPMENT EXPECTED IN THE AFTERNOON AT BOTH TAF SITES WITH INCLUSION FOR PROB30 20Z-01Z. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JWS SYNOPSIS...KNUTSVIG SHORT TERM...KNUTSVIG LONG TERM...CLB AVIATION...ROBERG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1237 AM CDT THU AUG 15 2013 .UPDATE... ISSUED AT 1237 AM CDT THU AUG 15 2013 POPS HAVE BEEN ADDED/ADJUSTED BASED ON LATEST RADAR TRENDS. AS WITH THE PAST 2 NGTS ANOTHER SMALL MCS IS ORGANIZING OVER THE PANHANDLE. THIS CLUSTER IS NOT ASSOCIATED WITH THE LLJ AND WILL ONLY HAVE ITS OWN COLD POOL TO KEEP IT GOING. NEW SHWRS HAVE DEVELOP FROM JYR UP TO BVN IN THE LAST HR. THESE ARE LLJ RELATED. THE 03Z HI-RES RAP HAS ALL THIS HANDLED WELL SO IT WAS USED AS A FIRST GUESS FOR POPS THRU 12Z. SOME CHANGES IN CLOUD COVER WILL NEED TO BE MADE BEFORE SUNRISE. OTHERWISE...NO CHANGES. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 CLOUDS LINGERED ACROSS MUCH OF THE AREA THIS AFTERNOON AND HAS SO FAR HELPED TO PUT A CAP ON MORE WIDESPREAD CONVECTION. THAT SAID...INSTABILITY IS BEGINNING TO BUILD...AND WITH SOME NOTABLE MOISTURE CONVERGENCE AHEAD OF DEVELOPING CONVECTION TO OUR NORTH...EXPECT THE POTENTIAL FOR ADDITIONAL DEVELOPMENT THROUGH THE LATE AFTERNOON AND EVENING HOURS. MODELS HAVE NOT HAD A GREAT HANDLE ON THIS ALL DAY...ALBEIT 12Z WRF AND LATEST HRRR BOTH ATTEMPTED TO PICK UP ON CONVECTION TO OUR NORTH...TAKING IT SOUTHWARD THROUGH THE EVENING HOURS. WHILE CONFIDENCE IS NOT PARTICULARLY HIGH...CONTINUE TO SEE THE POTENTIAL FOR SOME ADDITIONAL THUNDERSTORM ACTIVITY THROUGH THE EVENING AND INTO THE OVERNIGHT HOURS AS THERE IS PLENTY OF INSTABILITY TO TAP...ESPECIALLY WEST OF HIGHWAY 281. THAT SAID...SHEAR IS VERY WEAK...AND ANY ADDITIONAL STORMS THAT DO DEVELOP ARE NOT EXPECTED TO BE SEVERE OR WIDESPREAD. AS WE WORK TOWARDS THURSDAY MORNING AND FOCUS OF INITIAL CONVECTION SHIFTS SOUTHWARD...COULD SEE SOME PARTIAL CLEARING...AND WITH LIGHT SOUTHEASTERLY WINDS AND ELEVATED LOW LEVEL MOISTURE...DECIDED TO INSERT PATCHY FOG INTO THE FORECAST FOR THE EARLY MORNING HOURS TOMORROW. LATEST HRRR IS INDICATING POSSIBLY SOME DENSE FOG ACROSS OUR NORTH BY 09Z...BUT WITH UNCERTAINTY IN TIMING AND AMOUNT OF CLEARING...PATCHY MENTION SEEMED MORE REASONABLE FOR THE TIME BEING. AS WE WORK INTO THE DAYTIME HOURS THURSDAY...THE POTENTIAL FOR SOME STRONG/MARGINALLY SEVERE STORMS WILL BE REALIZED BY EARLY AFTERNOON AS MODELS ARE PICKING UP ON AN UPPER LEVEL SHORTWAVE DROPPING DOWN FROM THE NORTH COUPLED WITH THE PRESENCE OF A WEAK WARM FRONTAL BOUNDARY DRAPED ACROSS THE LOCAL AREA FROM NORTHWEST TO SOUTHEAST. THIS COMBINATION...WITH PLENTY OF AVAILABLE INSTABILITY...SHOULD MAKE FOR A MORE ACTIVE AFTERNOON AND EVENING...AND CONTINUED WITH MENTION OF POTENTIAL SEVERE WEATHER IN HWO THIS AFTERNOON. WHILE SHEAR IS NOT ALL THAT IMPRESSIVE...CAPE AND FORCING SHOULD BE SUFFICIENT FOR THE DEVELOPMENT OF A FEW STORMS WITH MARGINALLY SEVERE HAIL AND THUNDERSTORM WIND GUSTS. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 330 PM CDT WED AUG 14 2013 THURSDAY NIGHT THROUGH WEDNESDAY. MAIN FORECAST CONCERNS WILL BE CHANCES FOR THUNDERSTORMS ON AND OFF THROUGH THE PERIOD AND TEMPERATURES. AN UPPER LEVEL WAVE WILL CONTINUE TO MOVE THROUGH THE AREA THURSDAY NIGHT. THUNDERSTORMS WILL CONTINUE ACROSS THE AREA DURING THE EVENING BUT GRADUALLY COME TO AN END FROM NORTHWEST TO SOUTHEAST DURING THE OVERNIGHT HOURS AND INTO FRIDAY MORNING. MUCAPE REMAINS AROUND 3000 J/KG DURING THE EVENING BUT DROPS OFF LATER IN THE NIGHT. ON FRIDAY THE UPPER LEVEL RIDGE IN THE ROCKIES STARTS TO SLIDE TO THE EAST AND WITH THE RAIN MOVING OUT...TEMPERATURES WILL WARM SOME. FRIDAY NIGHT INTO SUNDAY THE UPPER LEVEL RIDGE BUILDS ACROSS THE AREA AND EXPECT DRY CONDITIONS AND TEMPERATURES WILL CONTINUE TO WARM A FEW DEGREES. AN UPPER LEVEL WAVE WILL MOVE OVER THE RIDGE SUNDAY NIGHT AND BRING A SMALL CHANCE FOR THUNDERSTORMS. THERE SHOULD BE A BRIEF BREAK FROM THUNDERSTORMS AGAIN ON MONDAY BUT ANOTHER UPPER LEVEL WAVE MOVES INTO THE AREA MONDAY NIGHT AND TUESDAY. THERE IS ALSO A WEAK COLD FRONT THAT MOVES THROUGH THE FORECAST AREA MONDAY NIGHT. THUNDERSTORMS ARE EXPECTED ALONG AND BEHIND THE COLD FRONT. DESPITE THE COLD FRONT TEMPERATURES SHOULD CONTINUE TO WARM A DEGREE OR TWO EACH DAY AS THE UPPER RIDGE SETTLES OVER THE PLAINS. TUESDAY NIGHT AND WEDNESDAY THE MODELS HAVE SOME DIFFERENCES IN THE MAIN PATTERN. THE GFS HAS AN UPPER RIDGE...WHILE THE ECMWF HAS A TROUGH MOVING THROUGH. WILL HAVE A SMALL CHANCE FOR THUNDERSTORMS FOR NOW. THE TEMPERATURE SHOULD REMAIN ABOVE NORMAL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1237 AM CDT THU AUG 15 2013 REST OF TNGT: REMOVED FOG AND LOW CIGS FROM THE TAF BASED ON LBF/OAX SOUNDINGS AS WELL AS WIND AND DWPT TRENDS FROM YESTERDAY AFTN. EXPECT VFR CIGS MAY GO SCT AT TIMES. THERE IS A CLUSTER OF TSTMS OVER THE NEB PANHANDLE THAT WILL NEED TO BE MONITORED FOR POSSIBLE INSERTION INTO THE TAF TOWARD DAWN. S WINDS UNDER 10 KTS. THU: LOW-END VFR CIGS SHOULD INCREASE TO MID-LVL CIGS FROM THE REMNANTS OF NEARBY TSTM CLUSTER. BY 18Z...CURRENT EXPECTATION IS FOR SCT VFR CU TO DEVELOP WITH CB POSSIBLE AFTER 21Z. THERE IS A LOW PROBABILITY FOR 1 INCH HAIL AND G50 KTS IF THE TERMINAL TAKES A DIRECT HIT FROM AN AFTN OR EVNG TSTM. S WINDS LESS THAN 10 KTS WILL BACK TO SE. THU EVNG: TSTM THREAT SHOULD BE OVER BY 03Z. WE ARE SEEING SIGNALS OF POSSIBLE IFR FOG AFTER 06Z. CIG CONFIDENCE: MEDIUM VSBY CONFIDENCE: HIGH WIND CONFIDENCE: HIGH WX CONFIDENCE: MEDIUM && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...HALBLAUB SHORT TERM...SAR LONG TERM...JCB AVIATION...HALBLAUB
AREA FORECAST DISCUSSION UPDATE
NWS LAS VEGAS NV
1055 AM PDT THU AUG 15 2013 .SYNOPSIS...MOISTURE IS EXPECTED TO INCREASE OVER THE NEXT COUPLE OF DAYS BRINGING ISOLATED THUNDERSTORMS TO PORTIONS OF MOHAVE COUNTY TODAY. THUNDERSTORM COVERAGE IS FORECAST TO EXTEND FURTHER NORTH AND EAST ON FRIDAY AS MONSOONAL MOISTURE INCREASES OVER THE REGION. TEMPERATURES WILL INCREASE A COUPLE OF DEGREES TODAY...BUT MAY LOWER A COUPLE OF DEGREES ON FRIDAY DUE TO THE ADDED CLOUD COVER. TEMPERATURES ARE FORECAST TO REMAIN AROUND NORMAL FROM SATURDAY INTO EARLY NEXT WEEK. && .UPDATE...OBSERVATIONS SHOW AN INCREASE IN MOISTURE SOUTH AND EAST OF LAS VEGAS...WITH DEWPOINTS UP APPROXIMATELY 25 DEGREES FROM YESTERDAY MORNING AT LOCATIONS SUCH AS KINGMAN...NEEDLES...AND BULLHEAD CITY. FARTHER NORTH AND WEST...THE VAST MAJORITY OF ANY INCREASE IN MOISTURE IS LIMITED TO A LAYER BETWEEN 700-500MB. NO MAJOR CHANGES WERE NEEDED THIS MORNING...OPTING TO KEEP ANY MENTION OF CONVECTION TODAY LIMITED TO THE HIGHER ELEVATIONS OF EASTERN MOHAVE COUNTY. THE MAIN REASON POPS WERE NOT INCREASED GIVEN THE MOISTURE INCREASE IS A STRONG CAP NEAR 450MB...WHICH IS EXPECTED TO PERSIST THROUGH THE DAY AND SO FAR...BASED ON SATELLITE IMAGERY...IS HOLDING. -KENNEDY- && .PREV DISCUSSION... 300 AM PDT THU AUG 15 2013 .SHORT TERM...HAD A FEW THUNDERSTORMS POP UP EARLY THIS MORNING OVER FAR SOUTHERN MOHAVE COUNTY. HARD TO DISTINGUISH ANY FEATURES ON SATELLITE...BUT THE RUC AND NEW NAM WAS SHOWING A WEAK AREA OF VORTICITY PUSHING NORTHEAST THROUGH THAT GENERAL AREA. IT COULD ALSO BE ENHANCED BY A WEAK JET STREAK PUSHING THROUGH SOUTHERN NEVADA/NORTHWEST ARIZONA. IN EITHER CASE THE MODELS INDICATE A GENERAL DOWNTREND TO THESE STORMS OVER THE NEXT FEW HOURS AS THESE FEATURES MOVE EAST OF THE AREA. MOISTURE HAS BEEN ON THE GENERAL INCREASE WITH PW SENSORS IN THE REGION SHOWING READINGS APPROACHING AN INCH. ALTHOUGH MOISTURE WILL CONTINUE TO INCREASE TODAY THINK THAT THINGS WILL BE A LITTLE TOO CAPPED TO GENERATE MUCH IN THE WAY OF ANYTHING MORE THAN AN ISOLATED THUNDERSTORM OR TWO THIS AFTERNOON...ESPECIALLY OUTSIDE OF FAR EASTERN MOHAVE COUNTY. WE WILL CERTAINLY SEE AN INCREASE IN CLOUDS OVER THE REMAINDER OF MOHAVE AND INTO CLARK COUNTY TODAY...BUT REALLY DONT EXPECT TO SEE THOSE DEVELOP INTO STORMS. BETTER MOISTURE AND INSTABILITY LOOK TO ADVECT INTO THE REGION FRIDAY AND IT LOOKS LIKE THUNDERSTORM CHANCES WILL INCREASE. MODELS INDICATE PW VALUES INCREASING TO BETWEEN 1.00-1.25 INCHES OVER MUCH OF THE EASTERN HALF OF THE CWA ALONG WITH LI VALUES BETWEEN 0/-2 AND A DECENT AMOUNT OF CAPE. HAVE GONE AHEAD AND RAISED POPS ON FRIDAY INTO THE ISOLATED TO SCATTERED CATEGORY. ALTHOUGH SOME STORMS ON FRIDAY COULD PRODUCE HEAVY RAIN...IT SEEMS THAT GUSTY WINDS AND HAIL WILL BE THE PRIMARY CONCERN...ESPECIALLY OVER MOHAVE COUNTY. TEMPERATURES WILL WARM A COUPLE OF DEGREES TODAY...BUT LOWER SLIGHTLY ON FRIDAY AS MORE CLOUD COVER SHOULD KEEP READINGS DOWN. .LONG TERM...SATURDAY THROUGH WEDNESDAY...MODELS DIVERGE AS EARLY AS SATURDAY ON THEIR HANDLING OF SOUTHERN STREAM ENERGY APPROACHING THE CENTRAL CALIFORNIA COAST. 00Z GFS/GFS ENSEMBLE MEAN ARE THE SLOWEST SOLUTIONS KEEPING A CLOSED LOW OFF THE CENTRAL CALIFORNIA COAST THROUGH MONDAY. ECMWF/GEM ARE SLIGHTLY FURTHER EAST POSITIONING TROUGH AXIS JUST INLAND INTO CALIFORNIA. OVER THE PAST FEW DAYS THE ECMWF HAS BEEN TRENDING SLOWER. SO WHAT DOES ALL THAT MEAN FOR SATURDAY THROUGH MONDAY. FAVORABLE MOISTURE AND INSTABILITY PARAMETERS WILL CONTINUE TO LIE OVER LINCOLN...NORTHEAST CLARK AND MOHAVE COUNTIES SATURDAY THROUGH MONDAY. FURTHER WEST...DECREASING INSTABILITY ASSOCIATED UNDER COLD POOL ALOFT WILL AID IN THE DEVELOPMENT OF ISOLATED SHOWERS/THUNDERSTORMS FOR THE EASTERN SLOPES OF THE SOUTHERN SIERRA OF INYO COUNTY. ON TUESDAY AND WEDNESDAY...GFS/GEM SHOW AN OPEN TROUGH INLAND ACROSS THE WESTERN GREAT BASIN WHICH WOULD SUGGEST A DRYING TREND. THE ECMWF IS THE OUTLIER SUGGESTING THE LOW OVER CENTRAL CALIFORNIA WOULD WEAKEN WITH HIGH PRESSURE RETURNING TO THE AREA. THERE WOULD BE ENOUGH RESIDUAL MID-LEVEL MOISTURE AROUND TO GENERATE CONVECTION OVER THE MOUNTAINS WITH THE ECMWF SOLUTION. WITH DIFFERENCES STILL OCCURRING MADE NO CHANGES TO TUESDAY AND WEDNESDAY AS WE AWAIT BETTER MODEL AGREEMENT. DID LOWER HIGH TEMPERATURES A DEGREE OR TWO OVER THE WEEKEND AS 00Z ECMWF NUMBERS NOT AS HIGH AS PREVIOUS RUNS. IN FACT...THE CURRENT VALUES MAY STILL BE A DEGREE OR TWO TOO WARM. && .AVIATION...FOR MCCARRAN...LIGHT WINDS WILL BECOME SOUTHEASTERLY BY EARLY AFTERNOON AROUND 8-10 KTS. THESE SOUTHEAST WINDS SHOULD CONTINUE THROUGH SUNSET BEFORE SHIFTING BACK TO THE SOUTHWEST AROUND 8-10 KTS. FEW-SCT CLOUDS DEVELOPING THIS AFTERNOON WITH ISOLATED THUNDERSTORMS AFFECTING THE PEACH SPRINGS AND MORMON MESA CORRIDORS. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...ISOLATED THUNDERSTORMS OVER PORTIONS OF MOHAVE COUNTY THROUGH TODAY WITH FEW-SCT CLOUDS AROUND 14K FEET ELSEWHERE. WINDS WILL GENERALLY REMAIN UNDER 12 KTS AND FAVOR A EAST TO SOUTHEAST DIRECTION FOR MUCH OF TODAY. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...NONE. AZ...NONE. CA...NONE. && $$ GORELOW/PIERCE FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
500 AM PDT THU AUG 15 2013 .SYNOPSIS...MOISTURE IS EXPECTED TO INCREASE OVER THE NEXT COUPLE OF DAYS BRINGING ISOLATED THUNDERSTORMS TO PORTIONS OF MOHAVE COUNTY TODAY. THUNDERSTORM COVERAGE IS FORECAST TO EXTEND FURTHER NORTH AND EAST ON FRIDAY AS MONSOONAL MOISTURE INCREASES OVER THE REGION. TEMPERATURES WILL INCREASE A COUPLE OF DEGREES TODAY...BUT MAY LOWER A COUPLE OF DEGREES ON FRIDAY DUE TO THE ADDED CLOUD COVER. TEMPERATURES ARE FORECAST TO REMAIN AROUND NORMAL FROM SATURDAY INTO EARLY NEXT WEEK. && .UPDATE...SATELLITE SHOWS MID CLOUDS DEVELOPING AS FAR NORTH AS THE LAS VEGAS VALLEY. TIME HEIGHT/FORECAST SOUNDING FOR LAS VEGAS INDICATE MOISTURE IN THE H7-H5 LAYER PERSISTING THROUGHOUT THE DAY. SO MADE SOME CHANGES TO SKY GRIDS. ALSO...INCREASED POPS ACROSS CENTRAL AND SOUTHERN MOHAVE COUNTY THROUGH 18Z AS RADAR SHOWS ISOLATED LIGHT RAIN SHOWERS CONTINUE TO DEVELOP. PIERCE && .PREV DISCUSSION... 300 AM PDT THU AUG 15 2013 .SHORT TERM...HAD A FEW THUNDERSTORMS POP UP EARLY THIS MORNING OVER FAR SOUTHERN MOHAVE COUNTY. HARD TO DISTINGUISH ANY FEATURES ON SATELLITE...BUT THE RUC AND NEW NAM WAS SHOWING A WEAK AREA OF VORTICITY PUSHING NORTHEAST THROUGH THAT GENERAL AREA. IT COULD ALSO BE ENHANCED BY A WEAK JET STREAK PUSHING THROUGH SOUTHERN NEVADA/NORTHWEST ARIZONA. IN EITHER CASE THE MODELS INDICATE A GENERAL DOWNTREND TO THESE STORMS OVER THE NEXT FEW HOURS AS THESE FEATURES MOVE EAST OF THE AREA. MOISTURE HAS BEEN ON THE GENERAL INCREASE WITH PW SENSORS IN THE REGION SHOWING READINGS APPROACHING AN INCH. ALTHOUGH MOISTURE WILL CONTINUE TO INCREASE TODAY THINK THAT THINGS WILL BE A LITTLE TOO CAPPED TO GENERATE MUCH IN THE WAY OF ANYTHING MORE THAN AN ISOLATED THUNDERSTORM OR TWO THIS AFTERNOON...ESPECIALLY OUTSIDE OF FAR EASTERN MOHAVE COUNTY. WE WILL CERTAINLY SEE AN INCREASE IN CLOUDS OVER THE REMAINDER OF MOHAVE AND INTO CLARK COUNTY TODAY...BUT REALLY DONT EXPECT TO SEE THOSE DEVELOP INTO STORMS. BETTER MOISTURE AND INSTABILITY LOOK TO ADVECT INTO THE REGION FRIDAY AND IT LOOKS LIKE THUNDERSTORM CHANCES WILL INCREASE. MODELS INDICATE PW VALUES INCREASING TO BETWEEN 1.00-1.25 INCHES OVER MUCH OF THE EASTERN HALF OF THE CWA ALONG WITH LI VALUES BETWEEN 0/-2 AND A DECENT AMOUNT OF CAPE. HAVE GONE AHEAD AND RAISED POPS ON FRIDAY INTO THE ISOLATED TO SCATTERED CATEGORY. ALTHOUGH SOME STORMS ON FRIDAY COULD PRODUCE HEAVY RAIN...IT SEEMS THAT GUSTY WINDS AND HAIL WILL BE THE PRIMARY CONCERN...ESPECIALLY OVER MOHAVE COUNTY. TEMPERATURES WILL WARM A COUPLE OF DEGREES TODAY...BUT LOWER SLIGHTLY ON FRIDAY AS MORE CLOUD COVER SHOULD KEEP READINGS DOWN. .LONG TERM...SATURDAY THROUGH WEDNESDAY...MODELS DIVERGE AS EARLY AS SATURDAY ON THEIR HANDLING OF SOUTHERN STREAM ENERGY APPROACHING THE CENTRAL CALIFORNIA COAST. 00Z GFS/GFS ENSEMBLE MEAN ARE THE SLOWEST SOLUTIONS KEEPING A CLOSED LOW OFF THE CENTRAL CALIFORNIA COAST THROUGH MONDAY. ECMWF/GEM ARE SLIGHTLY FURTHER EAST POSITIONING TROUGH AXIS JUST INLAND INTO CALIFORNIA. OVER THE PAST FEW DAYS THE ECMWF HAS BEEN TRENDING SLOWER. SO WHAT DOES ALL THAT MEAN FOR SATURDAY THROUGH MONDAY. FAVORABLE MOISTURE AND INSTABILITY PARAMETERS WILL CONTINUE TO LIE OVER LINCOLN...NORTHEAST CLARK AND MOHAVE COUNTIES SATURDAY THROUGH MONDAY. FURTHER WEST...DECREASING INSTABILITY ASSOCIATED UNDER COLD POOL ALOFT WILL AID IN THE DEVELOPMENT OF ISOLATED SHOWERS/THUNDERSTORMS FOR THE EASTERN SLOPES OF THE SOUTHERN SIERRA OF INYO COUNTY. ON TUESDAY AND WEDNESDAY...GFS/GEM SHOW AN OPEN TROUGH INLAND ACROSS THE WESTERN GREAT BASIN WHICH WOULD SUGGEST A DRYING TREND. THE ECMWF IS THE OUTLIER SUGGESTING THE LOW OVER CENTRAL CALIFORNIA WOULD WEAKEN WITH HIGH PRESSURE RETURNING TO THE AREA. THERE WOULD BE ENOUGH RESIDUAL MID-LEVEL MOISTURE AROUND TO GENERATE CONVECTION OVER THE MOUNTAINS WITH THE ECMWF SOLUTION. WITH DIFFERENCES STILL OCCURRING MADE NO CHANGES TO TUESDAY AND WEDNESDAY AS WE AWAIT BETTER MODEL AGREEMENT. DID LOWER HIGH TEMPERATURES A DEGREE OR TWO OVER THE WEEKEND AS 00Z ECMWF NUMBERS NOT AS HIGH AS PREVIOUS RUNS. IN FACT...THE CURRENT VALUES MAY STILL BE A DEGREE OR TWO TOO WARM. && .AVIATION...FOR MCCARRAN...SOUTHWEST WINDS THROUGH THIS MORNING BEFORE TURNING TO THE SOUTHEAST AROUND 8-10 KTS AFTER 19Z. THESE SOUTHEAST WINDS SHOULD CONTINUE THROUGH SUNSET BEFORE SHIFTING BACK TO THE SOUTHWEST AROUND 8-10 KTS. FEW-SCT CLOUDS DEVELOPING THIS AFTERNOON WITH ISOLATED THUNDERSTORMS AFFECTING THE PEACH SPRINGS AND MORMON MESA CORRIDORS. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...ISOLATED THUNDERSTORMS OVER PORTIONS OF MOHAVE COUNTY THROUGH TODAY WITH FEW-SCT CLOUDS AROUND 14K FEET ELSEWHERE. WINDS WILL GENERALLY REMAIN UNDER 12 KTS AND FAVOR A EAST TO SOUTHEAST DIRECTION FOR MUCH OF TODAY. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...NONE. AZ...NONE. CA...NONE. && $$ GORELOW/PIERCE FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
300 AM PDT THU AUG 15 2013 .SYNOPSIS...MOISTURE IS EXPECTED TO INCREASE OVER THE NEXT COUPLE OF DAYS BRINGING ISOLATED THUNDERSTORMS TO PORTIONS OF MOHAVE COUNTY TODAY. THUNDERSTORM COVERAGE IS FORECAST TO EXTEND FURTHER NORTH AND EAST ON FRIDAY AS MONSOONAL MOISTURE INCREASES OVER THE REGION. TEMPERATURES WILL INCREASE A COUPLE OF DEGREES TODAY...BUT MAY LOWER A COUPLE OF DEGREES ON FRIDAY DUE TO THE ADDED CLOUD COVER. TEMPERATURES ARE FORECAST TO REMAIN AROUND NORMAL FROM SATURDAY INTO EARLY NEXT WEEK. && .SHORT TERM...HAD A FEW THUNDERSTORMS POP UP EARLY THIS MORNING OVER FAR SOUTHERN MOHAVE COUNTY. HARD TO DISTINGUISH ANY FEATURES ON SATELLITE...BUT THE RUC AND NEW NAM WAS SHOWING A WEAK AREA OF VORTICITY PUSHING NORTHEAST THROUGH THAT GENERAL AREA. IT COULD ALSO BE ENHANCED BY A WEAK JET STREAK PUSHING THROUGH SOUTHERN NEVADA/NORTHWEST ARIZONA. IN EITHER CASE THE MODELS INDICATE A GENERAL DOWNTREND TO THESE STORMS OVER THE NEXT FEW HOURS AS THESE FEATURES MOVE EAST OF THE AREA. MOISTURE HAS BEEN ON THE GENERAL INCREASE WITH PW SENSORS IN THE REGION SHOWING READINGS APPROACHING AN INCH. ALTHOUGH MOISTURE WILL CONTINUE TO INCREASE TODAY THINK THAT THINGS WILL BE A LITTLE TOO CAPPED TO GENERATE MUCH IN THE WAY OF ANYTHING MORE THAN AN ISOLATED THUNDERSTORM OR TWO THIS AFTERNOON...ESPECIALLY OUTSIDE OF FAR EASTERN MOHAVE COUNTY. WE WILL CERTAINLY SEE AN INCREASE IN CLOUDS OVER THE REMAINDER OF MOHAVE AND INTO CLARK COUNTY TODAY...BUT REALLY DONT EXPECT TO SEE THOSE DEVELOP INTO STORMS. BETTER MOISTURE AND INSTABILITY LOOK TO ADVECT INTO THE REGION FRIDAY AND IT LOOKS LIKE THUNDERSTORM CHANCES WILL INCREASE. MODELS INDICATE PW VALUES INCREASING TO BETWEEN 1.00-1.25 INCHES OVER MUCH OF THE EASTERN HALF OF THE CWA ALONG WITH LI VALUES BETWEEN 0/-2 AND A DECENT AMOUNT OF CAPE. HAVE GONE AHEAD AND RAISED POPS ON FRIDAY INTO THE ISOLATED TO SCATTERED CATEGORY. ALTHOUGH SOME STORMS ON FRIDAY COULD PRODUCE HEAVY RAIN...IT SEEMS THAT GUSTY WINDS AND HAIL WILL BE THE PRIMARY CONCERN...ESPECIALLY OVER MOHAVE COUNTY. TEMPERATURES WILL WARM A COUPLE OF DEGREES TODAY...BUT LOWER SLIGHTLY ON FRIDAY AS MORE CLOUD COVER SHOULD KEEP READINGS DOWN. .LONG TERM...SATURDAY THROUGH WEDNESDAY...MODELS DIVERGE AS EARLY AS SATURDAY ON THEIR HANDLING OF SOUTHERN STREAM ENERGY APPROACHING THE CENTRAL CALIFORNIA COAST. 00Z GFS/GFS ENSEMBLE MEAN ARE THE SLOWEST SOLUTIONS KEEPING A CLOSED LOW OFF THE CENTRAL CALIFORNIA COAST THROUGH MONDAY. ECMWF/GEM ARE SLIGHTLY FURTHER EAST POSITIONING TROUGH AXIS JUST INLAND INTO CALIFORNIA. OVER THE PAST FEW DAYS THE ECMWF HAS BEEN TRENDING SLOWER. SO WHAT DOES ALL THAT MEAN FOR SATURDAY THROUGH MONDAY. FAVORABLE MOISTURE AND INSTABILITY PARAMETERS WILL CONTINUE TO LIE OVER LINCOLN...NORTHEAST CLARK AND MOHAVE COUNTIES SATURDAY THROUGH MONDAY. FURTHER WEST...DECREASING INSTABILITY ASSOCIATED UNDER COLD POOL ALOFT WILL AID IN THE DEVELOPMENT OF ISOLATED SHOWERS/THUNDERSTORMS FOR THE EASTERN SLOPES OF THE SOUTHERN SIERRA OF INYO COUNTY. ON TUESDAY AND WEDNESDAY...GFS/GEM SHOW AN OPEN TROUGH INLAND ACROSS THE WESTERN GREAT BASIN WHICH WOULD SUGGEST A DRYING TREND. THE ECMWF IS THE OUTLIER SUGGESTING THE LOW OVER CENTRAL CALIFORNIA WOULD WEAKEN WITH HIGH PRESSURE RETURNING TO THE AREA. THERE WOULD BE ENOUGH RESIDUAL MID-LEVEL MOISTURE AROUND TO GENERATE CONVECTION OVER THE MOUNTAINS WITH THE ECMWF SOLUTION. WITH DIFFERENCES STILL OCCURRING MADE NO CHANGES TO TUESDAY AND WEDNESDAY AS WE AWAIT BETTER MODEL AGREEMENT. DID LOWER HIGH TEMPERATURES A DEGREE OR TWO OVER THE WEEKEND AS 00Z ECMWF NUMBERS NOT AS HIGH AS PREVIOUS RUNS. IN FACT...THE CURRENT VALUES MAY STILL BE A DEGREE OR TWO TOO WARM. && .AVIATION...FOR MCCARRAN...SOUTHWEST WINDS THROUGH THIS MORNING BEFORE TURNING TO THE SOUTHEAST AROUND 8-10 KTS AFTER 19Z. THESE SOUTHEAST WINDS SHOULD CONTINUE THROUGH SUNSET BEFORE SHIFTING BACK TO THE SOUTHWEST AROUND 8-10 KTS. FEW-SCT CLOUDS DEVELOPING THIS AFTERNOON WITH ISOLATED THUNDERSTORMS AFFECTING THE PEACH SPRINGS AND MORMON MESA CORRIDORS. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...ISOLATED THUNDERSTORMS OVER PORTIONS OF MOHAVE COUNTY THROUGH TODAY WITH FEW-SCT CLOUDS AROUND 14K FEET ELSEWHERE. WINDS WILL GENERALLY REMAIN UNDER 12 KTS AND FAVOR A EAST TO SOUTHEAST DIRECTION FOR MUCH OF TODAY. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...NONE. AZ...NONE. CA...NONE. && $$ GORELOW/PIERCE FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1027 PM EDT FRI AUG 16 2013 .SYNOPSIS... A WARM FRONT EXTENDING FROM EASTERN GEORGIA TO JUST OFF THE CAROLINA COAST WILL LIFT NORTH AND THROUGH THE EASTERN CAROLINAS SATURDAY... ACCOMPANIED BY HEAVY RAIN AND THUNDERSTORMS. THE FRONT WILL STALL OVER THE CAROLINAS...THEN GRADUALLY DISSIPATE BY WEDNESDAY AS BERMUDA HIGH PRESSURE OFFSHORE BECOMES THE MAIN INFLUENCE ON OUR WEATHER. BELOW-NORMAL TEMPERATURES THIS WEEKEND SHOULD RETURN TO NORMAL BY TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM FRIDAY...THE PRECIPITATION LULL IS HERE WITH RAIN CURRENTLY LIMITED AREAS WEST OF I-95 PLUS A FEW SHOWERS JUST SOUTH OF KINGSTREE SC. ZOOMING OUT TO A REGIONAL RADAR DISPLAY THE NEXT SYNOPTIC FRONTAL WAVE IS ALREADY DEVELOPING WITH A LARGE AREA OF RAIN WITH EMBEDDED HEAVIER CONVECTIVE SHOWERS ACROSS SOUTHEASTERN GEORGIA AND EXTREME SOUTHERN SOUTH CAROLINA. THIS ACTIVITY SHOULD GRADUALLY SPREAD NORTH THROUGH THE LATE NIGHT HOURS...PERHAPS RUNNING AN HOUR OR TWO SLOWER THAN I ORIGINALLY THOUGHT. THE HEAVIEST RAINFALL THROUGH DAYBREAK IS STILL EXPECTED TO RUN ALONG AND SOUTH OF A LINE FROM FLORENCE TO MARION AND MYRTLE BEACH. NO SIGNIFICANT CHANGES HAVE BEEN MADE TO TEMPERATURES. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... A SURFACE WARM FRONT SOUTH OF SAVANNAH EXTENDS NORTHEASTWARD TO ABOUT 60 MILES OFF CAPE FEAR. WEST OF THIS BOUNDARY AN UNSEASONABLY COOL AIRMASS HAS BROUGHT YET ANOTHER DAY OF RECORD- BREAKING LOW DAYTIME TEMPERATURES. TODAY`S HIGH OF 76 IN WILMINGTON TIES THE COLDEST HIGH TEMPERATURE EVER SEEN ON THIS DATE... ORIGINALLY SET BACK IN 1927. IN FLORENCE...TODAY`S HIGH OF 69 DESTROYED THE OLD RECORD OF 75 SET BACK IN 1964. THE ILM FORECAST AREA IS ENTERING A LULL BETWEEN UPPER LEVEL DISTURBANCES THAT SHOULD PRODUCE RELATIVELY LITTLE RAIN OVER THE NEXT 3-4 HOURS. THE BEST ISENTROPIC LIFT BETWEEN NOW AND MIDNIGHT SHOULD REMAIN ACROSS THE SC EASTERN PIEDMONT AND SANDHILLS... EXTENDING NORTHEASTWARD ACROSS FAYETTEVILLE AND INTO EAST-CENTRAL NORTH CAROLINA. ACTIVITY OUT OVER THE OFFSHORE WATERS IS ASSOCIATED WITH INCREASING CONVECTIVE INSTABILITY AS THE COOL AIR WEST OF THE FRONT IS MODIFYING DUE TO SURFACE HEATING FROM THE 80+ DEGREE OCEAN WATER. BY MIDNIGHT...MID LEVEL WINDS SHOULD BACK TO THE SOUTH AS A NEW UPPER DISTURBANCE DIGS IN FROM THE WEST AND INCREASES ISENTROPIC LIFT ACROSS THE FRONTAL SURFACE. THIS EVEN SHOWS UP REALLY WELL LOOKING AT 200 OR 300 MB JET STREAKS AS A 75-KNOT STREAK ACROSS THE MID-ATLANTIC PLACES THE EASTERN CAROLINAS WITHIN THE FAVORED RIGHT-ENTRANCE REGION. BACKING LOW-LEVEL WINDS WILL BRING IN MODIFIED TROPICAL AIR FROM THE EAST ABOVE THE FRONTAL SURFACE... LEADING TO AN INCREASING POTENTIAL FOR HEAVIER SHOWERS AND THUNDERSTORMS EMBEDDED WITHIN THE GENERAL LIGHT TO MODERATE STRATIFORM RAIN. THIS SLUG OF HEAVIER PRECIPITATION SHOULD BEGIN ACROSS THE SANTEE RIVER JUST BEFORE MIDNIGHT...MAKING ITS WAY UP INTO SE NORTH CAROLINA A FEW HOURS BEFORE DAYBREAK. FORECAST POPS WILL REMAIN AT 100 PERCENT TONIGHT...WITH QPF IN THE 0.4 TO 0.7 INCH THROUGH DAYBREAK. WARM AIR STREAMING IN ALOFT SHOULD KEEP SURFACE TEMPERATURES FROM DROPPING MUCH OVERNIGHT. TEMPERATURES WILL HOLD IN THE MID TO UPPER 60S INLAND...WITH LOWS 70-72 NEAR THE COAST. EVAPORATIONAL COOLING POTENTIAL IS DECREASING AS THE RESERVOIR OF DRY AIR UPSTREAM IS DIMINISHING COMPARED TO THE PAST COUPLE OF DAYS. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...WITH THE FRONT IN THE VICINITY AND FAVORABLE DYNAMICS ALOFT SATURDAY LOOKS TO BE A WET DAY WITH SHOWERS AND A FEW THUNDERSTORMS. HEAVY RAIN IS POSSIBLE TOO BUT EXPECTED RAINFALL AMOUNTS...AROUND AN INCH...PRECLUDE THE NECESSITY OF A FLOOD WATCH FOR THE AREA. HAVING SAID THAT...LOCALIZED MINOR FLOODING IS POSSIBLE SATURDAY INTO SATURDAY EVENING. DUE TO EXPECTED PRECIP HAVE KEPT MAXIMUMS SATURDAY BELOW GUIDANCE WITH NUMBERS IN THE UPPER 70S TO AROUND 80 EXPECTED. MINS SATURDAY NIGHT SHOULD FALL TO AROUND 70. LATEST MODEL RUNS HAVE PUSHED THE OLD FRONT NORTH OF THE AREA BY SUNDAY SUCH THAT SHOWERS AND STORMS SHOULD BE MORE ISOLATED WITH MAXIMUM TEMPERATURES IN THE UPPER 80S. HOWEVER...THIS IS A BIT OF A CHANGE FROM PREVIOUS MODEL FORECASTS WHICH KEPT THE FRONT FARTHER SOUTH. IN LIGHT OF THIS...FORECAST REFLECTS SCATTERED SHOWERS WITH MAXIMUMS IN THE LOWER TO MIDDLE 80S. MINS SUNDAY NIGHT SHOULD BE AROUND 70 AGAIN. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 3 PM FRIDAY...MONDAY BRINGS A WEAKENING UPPER TROUGH IN THE MID LEVELS AND A DEVELOPING PIEDMONT TROUGH. GUIDANCE SHOWING A RETURN OF CLIMO TEMPS BUT THERE STILL SEEMS TO BE ENOUGH LINGERING CLOUD COVER TO KEEP VALUES A FEW DEG SHORT...AS IS CURRENTLY FORECAST. ALSO EXPECT SCATTERED SHOWERS AND MAYBE A LITTLE THUNDER AS THE RECOVERING BL MANAGES A SOME INSTABILITY. TUESDAY THROUGH THURSDAY THE UPPER RIDGE EAST OF FLORIDA REMAINS QUITE FLAT AND RETROGRADES SLIGHTLY. THE RESULTING LIGHT WESTERLY FLOW LOCALLY MAY DRY THE MID LEVELS SLIGHTLY BUT AMPLE LOW LEVEL MOISTURE REMAINS FOR SEASONABLY SCATTERED CONVECTION...IF NOT A LITTLE BIT MORE. FRIDAY MAY ALSO BE A BIT UNSETTLED FOR THE TIME OF YEAR. EC SHOWS A NEW VORT DROPPING INTO AL/GA TO BRING SW FLOW LOCALLY WHERES GFS HAS UPPER LVL REMNANTS OF GOMEX TROPICAL SYSTEM HEADING INTO THE CAROLINAS. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AS OF 00Z...LOW PRESSURE AND ASSOCIATED WARM FRONT WILL APPROACH FROM THE SOUTH TONIGHT...AND MOVE THROUGH THE COASTAL TERMINALS SATURDAY AFTERNOON. AHEAD OF THE WARM FRONT WIDESPREAD LIGHT TO MODERATE RAIN IS EXPECTED...WITH EMBEDDED SHOWERS WITH MODERATE TO HEAVY RAINFALL ALONG THE FRONT AT THE COAST. ALTHOUGH KCRE/KMYR HAVE TEMPORARILY IMPROVED TO VFR THIS EVENING PREDOMINATE MVFR CIGS EXPECTED THROUGH MIDNIGHT. AT KFLO TEMPO IFR COULD OCCUR EARLY THIS EVENING...BUT IN GENERAL IFR CIGS SHOULD HOLD OFF UNTIL 09-11Z WHEN PRECIPITATION BECOMES A BIT HEAVIER. EXPECT THE HEAVIEST OF THE PRECIPITATION AND IFR POTENTIAL AFTER SUNRISE. AT THE COASTAL TERMINALS VCTS WILL BE MOST LIKELY LATE MORNING AND AFTERNOON AS THE WARM FRONT MOVES THROUGH. AFTER THE FRONT MOVES THROUGH WINDS WILL SHIFT TO THE SW AT THE COASTAL TERMINALS WITH IMPROVEMENT TO VFR. KFLO/KLBT WILL LIKELY REMAIN MVFR THROUGH THE AFTERNOON. EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 1030 PM FRIDAY...LATEST OBSERVATIONS FROM SPRINGMAID PIER AT MYRTLE BEACH SHOW THE SMALL REGION OF STRONG NORTHEAST WINDS CONTINUE AND HAVE ACTUALLY INTENSIFIED OVER THE PAST THREE HOURS. WIND GUSTS AS HIGH AS 22 KNOTS HAVE OCCURRED IN THE PAST HOUR...WITH MUCH LIGHTER WINDS NOTED UP AT OAK ISLAND...BALD HEAD ISLAND...AND WRIGHTSVILLE BEACH. THE HRRR HAS STOPPED RUNNING (MAINTENANCE?) BUT THE LATEST RUC SHOWS THIS LOCAL WIND MAXIMUM SHIFTING NORTHEASTWARD TOWARD THE BRUNSWICK COUNTY COAST OVER THE NEXT FEW HOURS. COMPARED TO CURRENT CONDITIONS I HAVE WINDS DECREASING AFTER 1-2 AM IN THE MYRTLE BEACH AREA...BUT INCREASING TO NEAR 15 KNOTS AT OAK ISLAND AND BALD HEAD ISLAND. SEAS HAVE BUILT TO 4 FEET AT THE FRYING PAN SHOALS BUOY...AND 2-3 FT CLOSER TO SHORE. THE BULK OF THE PRECIPITATION IS CURRENTLY ACROSS THE OFFSHORE WATERS...BUT RAIN AND EMBEDDED HEAVIER SHOWERS AND THUNDERSTORMS SHOULD SPREAD NORTHWARD ACROSS THE COASTAL WATERS AFTER MIDNIGHT FROM THE CHARLESTON SC AREA. ACTIVITY MAY TAKE UNTIL NEARLY DAYBREAK TO MAKE IT NORTH OF CAPE FEAR. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... GOING BY RADAR AND SATELLITE DATA IS APPEARS THE WARM FRONT EXTENDS FROM ABOUT 60 MILES SOUTHEAST OF CAPE FEAR...TO 70 MILES EAST OF CHARLESTON. AT LEAST THAT IS WHERE THE HEAVIEST CONCENTRATION OF THUNDERSTORMS HAVE BEEN OVER THE PAST SEVERAL HOURS. LOW PRESSURE DEVELOPING ALONG THE FRONT ACROSS SOUTH GEORGIA NEAR ST SIMONS ISLAND WILL HELP PULL THE FRONT CLOSER TO THE CAROLINA COASTLINE LATE TONIGHT INTO THE DAY SATURDAY. UNSEASONABLY COOL AIR TEMPERATURES INLAND HAVE HELPED TIGHTEN THE PRESSURE GRADIENT ALONG ESPECIALLY THE SC COAST...AND THE RESULT HAS BEEN AN UNEXPECTED SWATH OF NORTHEAST SURFACE WINDS AS HIGH AS 20 KNOTS CENTERED NEAR AND JUST OFFSHORE FROM MYRTLE BEACH. THIS LOCAL MAXIMUM IN WINDS HAS BEEN PICKED UP BY THE LATEST FEW HRRR MODEL RUNS...AND IS FORECAST TO GRADUALLY DECAY AROUND MIDNIGHT TO MATCH THE STEADY 10-15 KNOT WIND BEING EXPERIENCED ELSEWHERE ALONG THE COAST. SEAS RANGE FROM 2-3 FT. MINI-SUPERCELL THUNDERSTORMS HAVE BEEN EMBEDDED WITHIN THE AREA OF RAIN OFFSHORE THIS EVENING. ACTIVITY SHOULD INCREASE NEARSHORE AFTER MIDNIGHT WITH NEARLY SOLID RAIN AND EMBEDDED THUNDERSTORMS DEVELOPING BY DAYBREAK...ESPECIALLY SOUTH OF CAPE FEAR. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...EXPECT TO SEE LIGHT NE TO E WINDS BECOME VARIABLE SATURDAY NIGHT AS A WEAK WAVE OF LOW PRESSURE MOVES THROUGH THEN BECOME S TO SW SUNDAY. SPEEDS THROUGH THE PERIOD LOOK TO RUN 10 KT OR LESS WITH SEAS OF 2 TO 3 FT. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 3 PM FRIDAY...WEST ATLANTIC HIGH PRESSURE IN PLACE ON MONDAY WITH A SECONDARY HIGH OVER THE APPALACHIANS. WITH JUST A WEAK TROUGH IN BETWEEN NEAR THE COAST WIND WILL BE VERY LIGHT AND MAYBE SOMEWHAT VARIABLE IN DIRECTION. VERY SMALL SEAS CAPPED AT 2FT. ALL OF THESE FEATURES SHOW LITTLE MOVEMENT ON TUESDAY AND WEDNESDAY AND A SIMILAR FORECAST IS ANTICIPATED. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...TRA SHORT TERM...31 LONG TERM...MBB AVIATION...MRR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
753 PM EDT FRI AUG 16 2013 .SYNOPSIS... A WARM FRONT EXTENDING FROM EASTERN GEORGIA TO JUST OFF THE CAROLINA COAST WILL LIFT NORTH AND THROUGH THE EASTERN CAROLINAS SATURDAY... ACCOMPANIED BY HEAVY RAIN AND THUNDERSTORMS. THE FRONT WILL STALL OVER THE CAROLINAS...THEN GRADUALLY DISSIPATE BY WEDNESDAY AS BERMUDA HIGH PRESSURE OFFSHORE BECOMES THE MAIN INFLUENCE ON OUR WEATHER. BELOW-NORMAL TEMPERATURES THIS WEEKEND SHOULD RETURN TO NORMAL BY TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 730 PM FRIDAY...A SURFACE WARM FRONT SOUTH OF SAVANNAH EXTENDS NORTHEASTWARD TO ABOUT 60 MILES OFF CAPE FEAR. WEST OF THIS BOUNDARY AN UNSEASONABLY COOL AIRMASS HAS BROUGHT YET ANOTHER DAY OF RECORD- BREAKING LOW DAYTIME TEMPERATURES. TODAY`S HIGH OF 76 IN WILMINGTON TIES THE COLDEST HIGH TEMPERATURE EVER SEEN ON THIS DATE... ORIGINALLY SET BACK IN 1927. IN FLORENCE...TODAY`S HIGH OF 69 DESTROYED THE OLD RECORD OF 75 SET BACK IN 1964. THE ILM FORECAST AREA IS ENTERING A LULL BETWEEN UPPER LEVEL DISTURBANCES THAT SHOULD PRODUCE RELATIVELY LITTLE RAIN OVER THE NEXT 3-4 HOURS. THE BEST ISENTROPIC LIFT BETWEEN NOW AND MIDNIGHT SHOULD REMAIN ACROSS THE SC EASTERN PIEDMONT AND SANDHILLS... EXTENDING NORTHEASTWARD ACROSS FAYETTEVILLE AND INTO EAST-CENTRAL NORTH CAROLINA. ACTIVITY OUT OVER THE OFFSHORE WATERS IS ASSOCIATED WITH INCREASING CONVECTIVE INSTABILITY AS THE COOL AIR WEST OF THE FRONT IS MODIFYING DUE TO SURFACE HEATING FROM THE 80+ DEGREE OCEAN WATER. BY MIDNIGHT...MID LEVEL WINDS SHOULD BACK TO THE SOUTH AS A NEW UPPER DISTURBANCE DIGS IN FROM THE WEST AND INCREASES ISENTROPIC LIFT ACROSS THE FRONTAL SURFACE. THIS EVEN SHOWS UP REALLY WELL LOOKING AT 200 OR 300 MB JET STREAKS AS A 75-KNOT STREAK ACROSS THE MID-ATLANTIC PLACES THE EASTERN CAROLINAS WITHIN THE FAVORED RIGHT-ENTRANCE REGION. BACKING LOW-LEVEL WINDS WILL BRING IN MODIFIED TROPICAL AIR FROM THE EAST ABOVE THE FRONTAL SURFACE... LEADING TO AN INCREASING POTENTIAL FOR HEAVIER SHOWERS AND THUNDERSTORMS EMBEDDED WITHIN THE GENERAL LIGHT TO MODERATE STRATIFORM RAIN. THIS SLUG OF HEAVIER PRECIPITATION SHOULD BEGIN ACROSS THE SANTEE RIVER JUST BEFORE MIDNIGHT...MAKING ITS WAY UP INTO SE NORTH CAROLINA A FEW HOURS BEFORE DAYBREAK. FORECAST POPS WILL REMAIN AT 100 PERCENT TONIGHT...WITH QPF IN THE 0.4 TO 0.7 INCH THROUGH DAYBREAK. WARM AIR STREAMING IN ALOFT SHOULD KEEP SURFACE TEMPERATURES FROM DROPPING MUCH OVERNIGHT. TEMPERATURES WILL HOLD IN THE MID TO UPPER 60S INLAND...WITH LOWS 70-72 NEAR THE COAST. EVAPORATIONAL COOLING POTENTIAL IS DECREASING AS THE RESERVOIR OF DRY AIR UPSTREAM IS DIMINISHING COMPARED TO THE PAST COUPLE OF DAYS. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...WITH THE FRONT IN THE VICINITY AND FAVORABLE DYNAMICS ALOFT SATURDAY LOOKS TO BE A WET DAY WITH SHOWERS AND A FEW THUNDERSTORMS. HEAVY RAIN IS POSSIBLE TOO BUT EXPECTED RAINFALL AMOUNTS...AROUND AN INCH...PRECLUDE THE NECESSITY OF A FLOOD WATCH FOR THE AREA. HAVING SAID THAT...LOCALIZED MINOR FLOODING IS POSSIBLE SATURDAY INTO SATURDAY EVENING. DUE TO EXPECTED PRECIP HAVE KEPT MAXIMUMS SATURDAY BELOW GUIDANCE WITH NUMBERS IN THE UPPER 70S TO AROUND 80 EXPECTED. MINS SATURDAY NIGHT SHOULD FALL TO AROUND 70. LATEST MODEL RUNS HAVE PUSHED THE OLD FRONT NORTH OF THE AREA BY SUNDAY SUCH THAT SHOWERS AND STORMS SHOULD BE MORE ISOLATED WITH MAXIMUM TEMPERATURES IN THE UPPER 80S. HOWEVER...THIS IS A BIT OF A CHANGE FROM PREVIOUS MODEL FORECASTS WHICH KEPT THE FRONT FARTHER SOUTH. IN LIGHT OF THIS...FORECAST REFLECTS SCATTERED SHOWERS WITH MAXIMUMS IN THE LOWER TO MIDDLE 80S. MINS SUNDAY NIGHT SHOULD BE AROUND 70 AGAIN. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 3 PM FRIDAY...MONDAY BRINGS A WEAKENING UPPER TROUGH IN THE MID LEVELS AND A DEVELOPING PIEDMONT TROUGH. GUIDANCE SHOWING A RETURN OF CLIMO TEMPS BUT THERE STILL SEEMS TO BE ENOUGH LINGERING CLOUD COVER TO KEEP VALUES A FEW DEG SHORT...AS IS CURRENTLY FORECAST. ALSO EXPECT SCATTERED SHOWERS AND MAYBE A LITTLE THUNDER AS THE RECOVERING BL MANAGES A SOME INSTABILITY. TUESDAY THROUGH THURSDAY THE UPPER RIDGE EAST OF FLORIDA REMAINS QUITE FLAT AND RETROGRADES SLIGHTLY. THE RESULTING LIGHT WESTERLY FLOW LOCALLY MAY DRY THE MID LEVELS SLIGHTLY BUT AMPLE LOW LEVEL MOISTURE REMAINS FOR SEASONABLY SCATTERED CONVECTION...IF NOT A LITTLE BIT MORE. FRIDAY MAY ALSO BE A BIT UNSETTLED FOR THE TIME OF YEAR. EC SHOWS A NEW VORT DROPPING INTO AL/GA TO BRING SW FLOW LOCALLY WHERES GFS HAS UPPER LVL REMNANTS OF GOMEX TROPICAL SYSTEM HEADING INTO THE CAROLINAS. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AS OF 00Z...LOW PRESSURE AND ASSOCIATED WARM FRONT WILL APPROACH FROM THE SOUTH TONIGHT...AND MOVE THROUGH THE COASTAL TERMINALS SATURDAY AFTERNOON. AHEAD OF THE WARM FRONT WIDESPREAD LIGHT TO MODERATE RAIN IS EXPECTED...WITH EMBEDDED SHOWERS WITH MODERATE TO HEAVY RAINFALL ALONG THE FRONT AT THE COAST. ALTHOUGH KCRE/KMYR HAVE TEMPORARILY IMPROVED TO VFR THIS EVENING PREDOMINATE MVFR CIGS EXPECTED THROUGH MIDNIGHT. AT KFLO TEMPO IFR COULD OCCUR EARLY THIS EVENING...BUT IN GENERAL IFR CIGS SHOULD HOLD OFF UNTIL 09-11Z WHEN PRECIPITATION BECOMES A BIT HEAVIER. EXPECT THE HEAVIEST OF THE PRECIPITATION AND IFR POTENTIAL AFTER SUNRISE. AT THE COASTAL TERMINALS VCTS WILL BE MOST LIKELY LATE MORNING AND AFTERNOON AS THE WARM FRONT MOVES THROUGH. AFTER THE FRONT MOVES THROUGH WINDS WILL SHIFT TO THE SW AT THE COASTAL TERMINALS WITH IMPROVEMENT TO VFR. KFLO/KLBT WILL LIKELY REMAIN MVFR THROUGH THE AFTERNOON. EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 730 PM FRIDAY...GOING BY RADAR AND SATELLITE DATA IS APPEARS THE WARM FRONT EXTENDS FROM ABOUT 60 MILES SOUTHEAST OF CAPE FEAR...TO 70 MILES EAST OF CHARLESTON. AT LEAST THAT IS WHERE THE HEAVIEST CONCENTRATION OF THUNDERSTORMS HAVE BEEN OVER THE PAST SEVERAL HOURS. LOW PRESSURE DEVELOPING ALONG THE FRONT ACROSS SOUTH GEORGIA NEAR ST SIMONS ISLAND WILL HELP PULL THE FRONT CLOSER TO THE CAROLINA COASTLINE LATE TONIGHT INTO THE DAY SATURDAY. UNSEASONABLY COOL AIR TEMPERATURES INLAND HAVE HELPED TIGHTEN THE PRESSURE GRADIENT ALONG ESPECIALLY THE SC COAST...AND THE RESULT HAS BEEN AN UNEXPECTED SWATH OF NORTHEAST SURFACE WINDS AS HIGH AS 20 KNOTS CENTERED NEAR AND JUST OFFSHORE FROM MYRTLE BEACH. THIS LOCAL MAXIMUM IN WINDS HAS BEEN PICKED UP BY THE LATEST FEW HRRR MODEL RUNS...AND IS FORECAST TO GRADUALLY DECAY AROUND MIDNIGHT TO MATCH THE STEADY 10-15 KNOT WIND BEING EXPERIENCED ELSEWHERE ALONG THE COAST. SEAS RANGE FROM 2-3 FT. MINI-SUPERCELL THUNDERSTORMS HAVE BEEN EMBEDDED WITHIN THE AREA OF RAIN OFFSHORE THIS EVENING. ACTIVITY SHOULD INCREASE NEARSHORE AFTER MIDNIGHT WITH NEARLY SOLID RAIN AND EMBEDDED THUNDERSTORMS DEVELOPING BY DAYBREAK...ESPECIALLY SOUTH OF CAPE FEAR. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...EXPECT TO SEE LIGHT NE TO E WINDS BECOME VARIABLE SATURDAY NIGHT AS A WEAK WAVE OF LOW PRESSURE MOVES THROUGH THEN BECOME S TO SW SUNDAY. SPEEDS THROUGH THE PERIOD LOOK TO RUN 10 KT OR LESS WITH SEAS OF 2 TO 3 FT. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 3 PM FRIDAY...WEST ATLANTIC HIGH PRESSURE IN PLACE ON MONDAY WITH A SECONDARY HIGH OVER THE APPALACHIANS. WITH JUST A WEAK TROUGH IN BETWEEN NEAR THE COAST WIND WILL BE VERY LIGHT AND MAYBE SOMEWHAT VARIABLE IN DIRECTION. VERY SMALL SEAS CAPPED AT 2FT. ALL OF THESE FEATURES SHOW LITTLE MOVEMENT ON TUESDAY AND WEDNESDAY AND A SIMILAR FORECAST IS ANTICIPATED. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...TRA SHORT TERM...31 LONG TERM...MBB AVIATION...MRR
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
932 PM CDT FRI AUG 16 2013 .UPDATE... ISSUED AT 932 PM CDT FRI AUG 16 2013 NO MAJOR CHANGES TO THE CURRENT FORECAST. TEMPS STILL SEEM ON TRACK TO DROP INTO THE 50S IN THE EAST TO LOW 60S OVERNIGHT. SOME OF THE MODELS SUCH AS THE HRRR AND NAM ARE SHOWING SOME FOG FORMATION OVER THE JAMES VALLEY WHICH THEN MOVES INTO OUR SOUTHWESTERN COUNTIES BRIEFLY LATER TONIGHT. SOUTHWESTERLY WINDS WILL BE PICKING UP AND THINK THAT MIXING WILL KEEP MUCH FOG FROM FORMING AND WILL LEAVE OUT OF GRIDS FOR NOW. THINK THERE COULD BE SOME STRATUS THROUGH SO KEPT SOME CLOUDS IN THE FAR SOUTH. UPDATE ISSUED AT 627 PM CDT FRI AUG 16 2013 ONLY CHANGES WERE TO TWEAK CLOUD COVER A BIT AS SOUTHERN COUNTIES HAVE HAD A BIT MORE CU THAN EXPECTED THIS EVENING. THINK THAT SKIES WILL BECOME MOSTLY CLEAR AFTER SUNSET...BUT WILL HAVE TO WATCH THE SOUTH FOR ANY STRATUS MOVING UP OUT OF SD. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 242 PM CDT FRI AUG 16 2013 CURRENT VIS IMAGERY SHOWING SCT CU DECK HAS EXPANDED WESTWARD INTO SOUTHEASTERN ND. MOSTLY CLEAR ELSEWHERE. THERE IS MORE EXTENSIVE SKY COVER OVER EASTERN SD AND FAR SW MINNESOTA....HOWEVER THE NORTHERN EDGE CONTINUES TO BECOME MORE CELLULAR. MAIN CHALLENGE TONIGHT WILL BE TEMPERATURES AND WHETHER OR NOT THE LOW LEVEL SW FLOW WILL ADVECT ANY OF THIS MOISTURE INTO MY SOUTHEASTERN ZONES. MODELED RH IN GENERAL AGREEMENT WITH BRINGING CLOUD COVER NORTHWARD BUT NO SIGNS OF CLOUDS ON GFS/NAM MOS GUIDANCE. LATE AFTERNOON AND TONIGHT...FOR CLOUD SITUATION...THINK LAST COUPLE HOURS OF HEATING THIS AFTN WILL CONTINUE TO BREAK CLOUDS UP ENOUGH OVER SD THAT THEY WILL DISSIPATE IN THE EARLY EVENING AND WE WILL BE CLEAR TONIGHT ACROSS THE AREA. OVERNIGHT LOWS WILL BE A BIT WARMER THAN LAST NIGHT WITH SOUTHERLY FLOW EXPECTED THROUGH THE NIGHT. SATURDAY AND SATURDAY NIGHT...FULL SOLAR...BREEZY SOUTHWEST WINDS AND INCREASED MIXING AS WELL AS RISING H850 TEMPS WILL RESULT IN THE FIRST ABOVE NORMAL TEMPS FOR AUGUST 2013. COULD EVEN HIT 90 IN WARM AREAS AROUND THE VALLEY. MODELS ARE SHOWING A CHANCE FOR SOME SHOWERS OR A STORM TO DEVELOP MAINLY ACROSS THE NORTH AND AFTER 09Z. HOWEVER MAIN ENERGY WITH UPPER WAVE SHOULD BE ACROSS SOUTHERN MANITOBA AND WILL KEEP CWA DRY TONIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 242 PM CDT FRI AUG 16 2013 SUNDAY AND MONDAY...ANOTHER WARM DAY IS EXPECTED WITH INSTABILITY INCREASING IN THE AFTERNOON BUT A SOLID CAP IN PLACE. MERIDIONAL FLOW WILL BRING SEVERAL MINOR WAVES ACROSS THE AREA...HOWEVER TIMING NOT CONSISTENT ENOUGH AMONGST THE MODELS TO ADD ANY POPS THROUGH 00Z MON. BEST CHANCE WILL BE IN THE EVENING IF AND WHEN THE CAP ERODES. WITH MAIN H850 FLOW OVER THE WKND OUT OF WESTERN TX/NM VS AN OPEN GULF OF MEXICO...NOT SURE DEW POINTS WILL GET HIGH ENOUGH DRG DAY SUNDAY TO GIVE US A SIGNIFICANT CHANCE OF CONVECTION SUN EVENING HOWEVER WITH GFS SHOWING A STRONG VORT MOVING ACROSS (BUT OVERDOING CONVECTION)...WILL STICK WITH CONTINUITY AND MAINTAIN CHANCE POPS MAINLY ACROSS THE SOUTH. ONCE AGAIN CONFIDENCE FOR ANYTHING SIGNIFICANT IS LOW ATTM. EXPECT MONDAY TO BE DRY. MONDAY THROUGH FRIDAY...MODELS ARE DECENT WITH OVERALL FEATURES WITH SOME DIFFERENCES TO TIMING OF CONVECTIVE CHANCES. THE GFS/ECMWF WANTS TO DEVELOP SOME STORMS BY WED/THU...WITH THE GEM REMAINING DRY THROUGH THE PERIOD. THERE WILL BE VERY WARM TEMPS ALOFT AND TEMPS WILL REMAIN WELL ABOVE NORMAL. IF THE ATMOSPHERE REMAINS CAPPED...THEN THIS WOULD LIMIT CONVECTIVE CHANCES. WE HAVE ALSO BEEN DRY FOR SOME TIME...AND OVERALL EVAPOTRANSPIRATION WILL BE QUITE LOW. IN ADDITION...THE GULF OF MEXICO REMAINS SHUT OFF...SO THIS COULD ALSO LIMIT SHOWER/STORMS UNTIL A STRONGER WAVE MOVES OVER THE AREA. WILL CONTINUE WITH LOWER CHANCES FOR STORMS BY MID WEEK...ALTHOUGH CONFIDENCE IS NOT VERY HIGH FOR WIDESPREAD RAINFALL. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 627 PM CDT FRI AUG 16 2013 VFR CONDITIONS SHOULD CONTINUE THROUGHOUT THE PERIOD. THERE IS THE CHANCE FOR SOME STRATUS AND MAYBE FOG TO MOVE OUT OF EASTERN SD INTO THE FAR SOUTHERN FORECAST AREA...BUT AT THIS POINT THINK THAT ANY RESTRICTIONS SHOULD STAY SOUTH OF THE TAF SITES. SOUTHWEST WINDS SHOULD GO DOWN A BIT AFTER SUNSET...BUT THEN PICK UP AGAIN BY MID MORNING TOMORROW AS A TROUGH OF LOW PRESSURE RAMPS UP JUST TO OUR WEST. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...JR SHORT TERM...SPEICHER LONG TERM...DK/SPEICHER AVIATION...JR
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
630 PM CDT FRI AUG 16 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 348 PM CDT FRI AUG 16 2013 STRATUS AND STRATOCU CONTINUES TO HOLD TOUGH ACROSS THE AREA THIS AFTERNOON. TOUGH CALL ON WHAT HAPPENS WITH THIS STRATUS TONIGHT. MODELS SHOW THAT THE BEST LOW LEVEL MOISTURE IS PUSHED WEST IN THE SOUTHEASTERLY FLOW. THIS WOULD SUGGEST THE BEST CHANCE OF SEEING LOW STRATUS OR FOG WOULD BE WEST OF OUR CWA...BUT IT COULD END UP AS FAR EAST AS THE JAMES RIVER. TO THE EAST...STILL THINK IT REMAINS MOSTLY CLOUDY...WITH THE CLOUD HEIGHT AROUND THE LEVEL OF THIS AFTERNOONS STRATOCU. LOWS TONIGHT SHOULD BE WARMER THAN LAST NIGHT WITH THE CLOUDS AND A BIT MORE OF A SOUTHEASTERLY BREEZE. WENT CLOSE TO THE GEM REGIONAL...WHICH HANDLED LAST NIGHT VERY WELL. THIS GIVES LOWS IN THE MID 50S TO LOW 60S...WARMEST WEST OF THE JAMES WHERE WINDS WILL BE A BIT HIGHER AND CLOUDS POTENTIALLY THICKER...AND COOLEST IN OUR EAST WHERE CLOUDS MAY BE A BIT MORE SPARSE. ON SATURDAY...STRATOCU WILL SLOWLY ERODE...BUT THINK IT WILL STILL ONLY BE PARTLY SUNNY BY AFTERNOON. THE MOST SUN SHOULD END UP WEST OF THE JAMES RIVER AND ACROSS NORTHWEST IOWA...WITH AN AREA OF MORE ABUNDANT STRATOCU IN BETWEEN. WINDS WILL ALSO PICK UP BY AFTERNOON WITH GUSTS IN THE 20 TO 25 KT RANGE. THE NAM SEEMS A BIT TO WARM WITH HIGHS GIVEN THE CLOUD COVER...WITH THE BIAS CORRECTED GRIDS AND CONSENSUS VALUES SEEMING MORE REASONABLE. THIS GIVES HIGHS IN THE UPPER 70S TO AROUND 80 EAST OF THE JAMES...WITH LOW AND A FEW MID 80S TO THE WEST. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 348 PM CDT FRI AUG 16 2013 THE UPPER RIDGE WILL CONTINUE TO BUILD OVER THE AREA ON SUNDAY AND MONDAY. THIS WILL FORCE THE SURFACE RIDGE TO SLOWLY MOVE EAST. AS IT DOES...THE SOUTHERLY WINDS WILL GRADUALLY INCREASE AND THIS WILL BRING WARMER AND MORE HUMID AIR NORTHWARD. THE ONLY QUESTION WITH THE FORECAST IS THE DEGREE OF CLOUD COVER ESPECIALLY ON SATURDAY NIGHT AND SUNDAY. AS MENTIONED ABOVE...LOOKS LIKE THERE COULD BE BE SOME LOWER CLOUDS WEST OF I-29. WITH THE LOW LEVEL JET MORE SOUTHWEST...THESE CLOUDS SHOULD ADVECT NORTHEAST. BUT THE NAM HINTS AT MORE CLOUDS FORMING OVER CENTRAL NEBRASKA OVERNIGHT AND MOVING NORTH TOWARD DAWN AND THEN SLOWLY DISSIPATING ON SUNDAY MORNING. IF CLOUDS DO PERSIST INTO SUNDAY...THEY WOULD MOST LIKELY BE BETWEEN THE JAMES AND BIG SIOUX RIVER. SO TEMPERATURES ARE A BIT MORE UNCERTAIN IN THIS AREA SINCE MORE CLOUDS WOULD RESULT IN COOLER TEMPERATURES. WILL BE SOMEWHAT OPTIMISTIC FOR SUNDAY AND HAVE PARTLY TO MOSTLY SUNNY SKIES ACROSS THE AREA. HIGHS ARE EXPECTED TO BE IN THE 80S ACROSS THE AREA WITH 90 POSSIBLE AROUND CHAMBERLAIN. A WEAK UPPER LEVEL WAVE WILL MOVE ACROSS NORTHERN SOUTH DAKOTA AND INTO MINNESOTA ON SUNDAY NIGHT. MODEL SOUNDINGS SHOW AMPLE INSTABILITY ACROSS THE AREA BUT THERE IS A REAL LACK OF A STRONG BOUNDARY TO FOCUS LIFT. WITH THE DEGREE OF CAPPING...THE GFS APPEARS OVERDONE WITH THE COVERAGE OF PRECIPITATION ON SUNDAY NIGHT INTO MONDAY. SO FAVOR A SOLUTION CLOSER TO THE NAM WITH MOST OF THE CONVECTION REMAINING ACROSS NRN SD AND DISSIPATING AS IT MOVES INTO THE MORE STABLE AIR MASS OVER WRN MN. SO DID CONTINUE WITH 20 TO 30 PERCENT POPS NORTH OF HIGHWAY 34 IN SD AFTER SUNSET ON SUNDAY NIGHT. THERE COULD BE SOME CIRRUS OVER THE AREA FROM CONVECTION OVER NRN SD. THIS COMBINED WITH ANOTHER FAIRLY STRONG LOW LEVEL JET EXPECT LOWS TO STAY IN THE 60S. ON MONDAY...THE GFS DOES SHOW THUNDERSTORMS CONTINUE INTO MONDAY BUT THE NAM AND ECMWF BASICALLY SHOW THE UPPER WAVE INTO THE MISSISSIPPI VALLEY WITH NO REAL PRECIPITATION. SIMILAR TO SUNDAY NIGHT...FOLLOWED THIS SOLUTION AND KEPT IT DRY. WITH FEWER CLOUDS AND STRONG SOUTHERLY FLOW...EXPECT TEMPERATURES TO BE 3 TO 5 DEGREES WARMER THAN SUNDAY AND DEW POINTS WILL BE APPROACHING 70 IN A FEW PLACES. IN THE EXTENDED FORECAST...TUESDAY THROUGH FRIDAY...THERE IS GOOD MODEL AGREEMENT THROUGH WEDNESDAY. HOWEVER...MODEL SOLUTIONS REALLY DIVERGE BEGINNING WEDNESDAY NIGHT AND CONTINUING THROUGH FRIDAY. THE MAIN DIFFERENCE IS THE STRENGTH OF A WAVE THAT RIDES OVER THE RIDGE LATE WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. THE 12Z OPERATIONAL GFS BASICALLY KEEPS THIS WAVE WELL NORTH OF THE AREA AND SHOWS NO COOLING WHILE THE OPERATIONAL 00Z ECMWF DIGS THIS WAVE SOUTHEAST ACROSS THE EASTERN PLAINS AND BRINGS A FAIRLY STRONG COLD FRONT THROUGH THE AREA BEFORE IT STALLS NEAR I80. THE 12Z ECMWF WAS SIMILAR BUT ABOUT 12 H SLOWER. THE GFS ENSEMBLE SHOWS THAT THE OPERATIONAL 12Z GFS RUN IS THE WARM OUTLIER AND MOST MEMBERS HAD A WEAKER VERSION OF THE FRONT SHOWN IN THE ECMWF COMING THROUGH AFTER 00Z THURSDAY. A LOOK AT THE ECMWF ENSEMBLE MOS SHOWS THAT IT WAS A COLD OUTLIER WITH MOST MEMBERS SHOWING TEMPERATURES 3 TO 5 DEGREES WARMER...IN THE 80S INSTEAD OF MID TO UPPER 70S. IN GENERAL...FAVOR THE IDEA OF A WEAKER BACKDOOR TYPE FRONT MOVING ACROSS AND LIKELY STALLING CLOSER TO THE MISSOURI RIVER. THIS WOULD BRING A CHANCE OF STORM WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...FIRST NORTH OF I90 AND EVENTUALLY SOUTH OF I90. DECIDED TO KEEP CHANCES LOW GIVEN THE LARGE UNCERTAINTY IN TIMING AND LOCATION OF THE BOUNDARY. IT WILL ALSO MEAN A GRADUAL COOLING TREND TOWARD THE END OF THE WEEK. TUESDAY AND WEDNESDAY LOOK VERY WARM WITH MOST AREAS REACHING THE 90S. IT IS NOT OUT OF THE QUESTION THAT WEDNESDAY COULD BE ANOTHER 3 TO 5 DEGREES WARMER THAN FORECAST WITH PREFRONTAL WARMING. TOWARD THE END OF THE WEEK...HIGHS LIKELY TO COOL BACK INTO THE 80S BY FRIDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 620 PM CDT FRI AUG 16 2013 STRATUS IS BEGINNING TO DISSICIPATE ACROSS THE AREA WITH THE LOSS OF DAY TIME HEATING. SKIES SHOULD BECOME PARTLY CLOUDY OVERNIGHT...THOUGH LOW LEVEL JET OF AROUND 30 KNOTS IS EXPECTED TO DEVELOP OVERNIGHT. RAP MODEL SUGGESTS RADIATIONAL FOG MAY TRY TO DEVELOP ALONG THE NEBRASKA/IOWA BORDER...BUT DOES NOT HAVE SUPPORT FROM THE OTHER MODEL SOLUTIONS. FOR NOW...LEFT 4SM IN THE TAF FOR SIOUX CITY AS AN INTERMEDIATE STEP...BUT WILL NEED TO TAKE A SECOND LOOK WITH 06Z ISSUANCE. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...CHENARD LONG TERM...SCHUMACHER AVIATION...
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1257 AM CDT THU AUG 15 2013 .UPDATE... 06Z AVIATION DISCUSSION UPDATED BELOW. && .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT PRETTY QUIET ACROSS THE CWA THIS AFTERNOON BUT WILL BE WATCHING THE WESTERN CWA OVER THE NEXT FEW HOURS FOR THE POTENTIAL FOR A FEW ISOLD THUNDERSHOWERS AS SHORTWAVE ENERGY APPROACHES FROM THE MIDWEST. BEST SUPPORT DOES NOT ARRIVE UNTIL LATER THIS EVENING...BUT DAYTIME HEATING ACROSS THE WESTERN CWA HAS ALLOWED MLCAPE TO APPROACH 1000 J/KG. SHEAR IS LACKING ONCE AGAIN AS HAS BEEN THE CASE THE PAST FEW DAYS. CURRENTLY SEEING A CONGESTED CU FIELD ACROSS NORTH CENTRAL SD WITH RADAR ECHOES JUST BEGINNING TO INCREASE OVER CORSON COUNTY. HRRR ACTUALLY PICKING UP ON THIS AND SHOWING A FEW POPCORN TYPE LIGHT SHOWERS OR MAYBE A MODERATE THUNDERSHOWER THROUGH LATE AFTERNOON. WILL MAINTAIN SLIGHT CHANCE POPS FOR THE WESTERN CWA THROUGH THE AFTERNOON. MAIN SHORTWAVE ENERGY APPROACHES THE REGION LATER THIS EVENING...BUT MODELS NOT TOO IMPRESSED WITH THIS FOR OUR CWA. 12Z NSSL WRF SHOWS A LINE OF SHOWERS AND STORMS MOVING INTO WESTERN SD LATER THIS EVENING BUT DIES OUT AS ITS ENTERING THE WESTERN CWA. WILL MAINTAIN SMALL POPS OVERNIGHT AS WELL...BUT HAVE TRIMMED THINGS DOWN TO DRY FOR THE EASTERN CWA AS THERE JUST DOESNT SEEM TO BE ANY SUPPORT FOR PRECIP. THERE REALLY IS NO LOW LEVEL JET TO SPEAK OF OVERNIGHT EITHER. WEAK SHORTWAVE ENERGY MOVES SOUTHEAST OVER THE AREA ON THURSDAY BUT MODELS KEEP TRENDING DRIER AND DRIER FOR THIS...TO THE POINT NOW WHERE MOST MODELS ARENT EVEN SHOWING ANY PRECIP FOR THE AREA. HAVE SCALED BACK POPS QUITE A BIT...GOING DRY IN PLACES BUT KEEPING A SLIGHT CHANCE GOING FOR MOST PLACES. AFTER THURSDAY...THE WARM UP BEGINS AS UPPER RIDGING BUILDS OVER THE HIGH PLAINS AND DAKOTAS. .LONG TERM...SATURDAY THROUGH WEDNESDAY MAIN CHALLENGE IN THE LONG TERM WILL BE PRECIP CHANCES UNDER THE DOMINANT UPPER RIDGE. MODELS ARE NOT IN GOOD AGREEMENT TODAY IN THE EXTENDED. TOSSED OUT THE GEM AS IT IS THE ONLY MODEL SHOWING A DEVELOPING TROPICAL SYSTEM IN THE GULF THIS WEEKEND. THIS MAY CONTAMINATE QPF AND PRESSURE FIELDS ALL THE WAY NORTH INTO THE DAKOTAS. GFS AND ECMWF ARE BOTH FLIP FLOPPING WITH MOISTURE FIELDS THOUGH SFC PRESSURE PROGS ARE SIMILAR. BOTH MODELS SHOW TWO TROFS MOVING ACROSS THE DAKOTAS...ONE SUNDAY NIGHT/MONDAY AND ANOTHER TUESDAY NIGHT/WEDNESDAY. HOWEVER THE GFS IS WET FOR THE FIRST AND DRY FOR THE SECOND WHILE THE ECMWF IS OPPOSITE. STUCK WITH ALLBLEND POPS SUNDAY NIGHT/MONDAY AS 30S/40S SEEM REASONABLE AT THIS POINT. WENT DRIER THAN ALLBLEND FOR THE END OF THE PERIOD BASED ON INTER OFFICE COLLABORATION. TEMPERATURES SHOULD BE ON THE RISE THROUGH THE PERIOD WITH HIGHS IN THE UPPER 80S TO LOWER 90S EXPECTED. && .AVIATION... 06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS FAIRLY TRANQUIL VFR CONDITIONS WILL CONTINUE TO PREVAIL ACROSS THE LOCAL TERMINALS AS THE REGION REMAINS BETWEEN HIGH PRESSURE TO THE EAST AND LOW PRESSURE TO THE WEST. LIGHT SOUTH TO SOUTHEAST WINDS CAN BE EXPECTED TONIGHT INTO THURSDAY. AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE OVER/NEAR THE WESTERN TAF SITES LATE TONIGHT. A TEMPORARY MVFR/IFR FOG/STRATUS CONDITION IS POSSIBLE AT ANY OF THE FOUR TERMINALS BY LATE TONIGHT INTO THURSDAY MORNING...AS LOW LEVEL MOISTURE STEADILY INCREASES ACROSS THE REGION. BY LATE THURSDAY MORNING...VFR CONDITIONS SHOULD BE RETURNING OR ONGOING AT ALL TERMINALS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...MOHR SHORT TERM...TMT LONG TERM...WISE AVIATION...MOHR WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
203 PM CDT THU AUG 15 2013 .UPDATE...FOR 18Z TAFS. && .AVIATION... WEAK INVERTED LOW-LEVEL TROUGH SET TO SWING UP INTO THE PLATEAU TODAY...THEN WORK WESTWARD TONIGHT. THIS WILL BEGIN SPREADING DEEPER MOISTURE BACK INTO THE MID-STATE AND EVENTUALLY SHOWERS WILL BEGIN TO DEVELOP...ESPECIALLY AFTER 12Z FRIDAY. INCREASED MOISTURE WILL ALSO MVFR CIGS/VSBYS IN OVERNIGHT. LOW CIGS OVERNIGHT SHOULD IMPROVE AFTER 14-15Z FRI. && .PREV DISCUSSION... /ISSUED 944 AM CDT THU AUG 15 2013/ UPDATE... LATEST HRRR IS SUPPORT OF DEVELOPING SOME SHOWER ACTIVITY ACROSS MAINLY OUR SOUTH AND EASTERN AREAS. COLD FRONT THAT MOVED THROUGH A COUPLE OF DAYS AGO IS NOW STALLED OUT JUST NORTH OF THE GULF COAST. SFC TROUGH EXTENDS NORTHWARD THROUGH EASTERN TN. MEANWHILE...SOME MID AND UPPER LEVEL TROUGHING IS NOTED ACROSS THE SOUTHEAST. UPPER LEVEL AXIS TO SET UP JUST WEST OF THE MID STATE. THIS WILL HELP TO KEEP JUST ENOUGH MOISTURE IN PLACE TO WARRANT THE POTENTIAL FOR CONVECTION. FOR THE FCST...CURRENT GRIDS LOOK TO BE IN GOOD SHAPE. CERTAINLY MORE IN THE WAY OF CLOUDINESS CAN BE EXPECTED ACROSS THE EAST AND SOUTH BUT PCLDY CONDITIONS SHOULD HOLD FOR THE MOST PART. ONLY CHANGE WILL BE TO BUMP HIGH TEMPS BY JUST 1 DEGREE OR SO. UPDATE OUT SHORTLY. PREV DISCUSSION... /ISSUED 708 AM CDT THU AUG 15 2013/ UPDATE...FOR 12Z TAFS... AVIATION... VFR CONDITIONS EXPECTED THROUGHOUT THE TAF PERIOD FOR ALL SITES. CHANCE OF SHOWERS WILL INCREASE FROM THE SOUTHEAST THIS AFTERNOON...INTRODUCING VCSH AT CSV AROUND 00Z. BEST MOISTURE WILL LIKELY REMAIN IN THE SOUTHERN AND EASTERN PORTIONS OF THE AREA...SO KEPT PRECIP OUT OF CKV AND BNA FOR NOW. PREV DISCUSSION... /ISSUED 323 AM CDT THU AUG 15 2013/ DISCUSSION...IT WAS AN UNUSUALLY COOL MORNING ACROSS THE MID STATE WITH TEMPERATURES MOSTLY IN THE 50S. THE DRY AIR AND NEAR RECORD COOL CONDITIONS WERE ASSOCIATED WITH A SURFACE HIGH PRESSURE SYSTEM CENTERED OVER THE OHIO VALLEY. THIS BREAK FROM SUMMER IS VERY TEMPORARY...AS DEEP MOISTURE SITTING SOUTHEAST OF OUR AREA IS SET TO PUSH INTO THE MID STATE OVER THE NEXT COUPLE OF DAYS. MODELS ARE IN PRETTY GOOD AGREEMENT WITH A DEVELOPING MID/UPPER TROUGH OVER THE MID MS AND TN VALLEY REGIONS OVER THE NEXT COUPLE OF DAYS. AS THIS TROUGH DEVELOPS...AN INVERTED SURFACE TROUGH OVER THE PLATEAU WILL INTENSIFY SLIGHTLY AND PULL WESTWARD...BRINGING DEEPER MOISTURE ACROSS THE MID STATE. THIS WILL SET THE STAGE FOR SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. THE FIRST CHANCE FOR RAIN WILL DEVELOP OVER OUR SOUTHEAST COUNTIES THIS AFTERNOON...JUST A 30 PERCENT CHANCE FOR SHOWERS. THE CHANCE FOR SHOWERS WILL SPREAD ACROSS THE AREA TONIGHT INTO FRIDAY. ENOUGH INSTABILITY WILL DEVELOP FOR ISOLATED THUNDERSTORM POTENTIAL FRIDAY AFTERNOON. THE CHANCE FOR SHOWERS AND STORMS WILL INCREASE INTO SATURDAY AS THE UPPER TROUGH ADVANCES. WE ARE EXPECTING A PRETTY GOOD CHANCE FOR SHOWERS...BUT NOT A TOTAL WASHOUT. THE COVERAGE OF SHOWERS WILL DIMINISH SATURDAY NIGHT...THEN INCREASE AGAIN WITH DIURNAL INFLUENCES ON SUNDAY. NO ORGANIZED OR WIDESPREAD SEVERE WX OR EXCESSIVE RAINFALL IS EXPECTED THROUGH THIS FORECAST PERIOD. BEYOND SUNDAY... THE TROUGH LIFTS OUT AND HEIGHTS BUILD ACROSS THE REGION. A BERMUDA HIGH PATTERN DEVELOPS WITH TEMPERATURES AND HUMIDITY LEVELS CLIMBING BACK TO TYPICAL SUMMER LEVELS. THERE WILL BE GENERALLY SMALL CHANCES FOR DIURNALLY DRIVEN CONVECTION. 13 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
944 AM CDT THU AUG 15 2013 .UPDATE... LATEST HRRR IS SUPPORT OF DEVELOPING SOME SHOWER ACTIVITY ACROSS MAINLY OUR SOUTH AND EASTERN AREAS. COLD FRONT THAT MOVED THROUGH A COUPLE OF DAYS AGO IS NOW STALLED OUT JUST NORTH OF THE GULF COAST. SFC TROUGH EXTENDS NORTHWARD THROUGH EASTERN TN. MEANWHILE...SOME MID AND UPPER LEVEL TROUGHING IS NOTED ACROSS THE SOUTHEAST. UPPER LEVEL AXIS TO SET UP JUST WEST OF THE MID STATE. THIS WILL HELP TO KEEP JUST ENOUGH MOISTURE IN PLACE TO WARRANT THE POTENTIAL FOR CONVECTION. FOR THE FCST...CURRENT GRIDS LOOK TO BE IN GOOD SHAPE. CERTAINLY MORE IN THE WAY OF CLOUDINESS CAN BE EXPECTED ACROSS THE EAST AND SOUTH BUT PCLDY CONDITIONS SHOULD HOLD FOR THE MOST PART. ONLY CHANGE WILL BE TO BUMP HIGH TEMPS BY JUST 1 DEGREE OR SO. UPDATE OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 708 AM CDT THU AUG 15 2013/ UPDATE...FOR 12Z TAFS... AVIATION... VFR CONDITIONS EXPECTED THROUGHOUT THE TAF PERIOD FOR ALL SITES. CHANCE OF SHOWERS WILL INCREASE FROM THE SOUTHEAST THIS AFTERNOON...INTRODUCING VCSH AT CSV AROUND 00Z. BEST MOISTURE WILL LIKELY REMAIN IN THE SOUTHERN AND EASTERN PORTIONS OF THE AREA...SO KEPT PRECIP OUT OF CKV AND BNA FOR NOW. PREV DISCUSSION... /ISSUED 323 AM CDT THU AUG 15 2013/ DISCUSSION...IT WAS AN UNUSUALLY COOL MORNING ACROSS THE MID STATE WITH TEMPERATURES MOSTLY IN THE 50S. THE DRY AIR AND NEAR RECORD COOL CONDITIONS WERE ASSOCIATED WITH A SURFACE HIGH PRESSURE SYSTEM CENTERED OVER THE OHIO VALLEY. THIS BREAK FROM SUMMER IS VERY TEMPORARY...AS DEEP MOISTURE SITTING SOUTHEAST OF OUR AREA IS SET TO PUSH INTO THE MID STATE OVER THE NEXT COUPLE OF DAYS. MODELS ARE IN PRETTY GOOD AGREEMENT WITH A DEVELOPING MID/UPPER TROUGH OVER THE MID MS AND TN VALLEY REGIONS OVER THE NEXT COUPLE OF DAYS. AS THIS TROUGH DEVELOPS...AN INVERTED SURFACE TROUGH OVER THE PLATEAU WILL INTENSIFY SLIGHTLY AND PULL WESTWARD...BRINGING DEEPER MOISTURE ACROSS THE MID STATE. THIS WILL SET THE STAGE FOR SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. THE FIRST CHANCE FOR RAIN WILL DEVELOP OVER OUR SOUTHEAST COUNTIES THIS AFTERNOON...JUST A 30 PERCENT CHANCE FOR SHOWERS. THE CHANCE FOR SHOWERS WILL SPREAD ACROSS THE AREA TONIGHT INTO FRIDAY. ENOUGH INSTABILITY WILL DEVELOP FOR ISOLATED THUNDERSTORM POTENTIAL FRIDAY AFTERNOON. THE CHANCE FOR SHOWERS AND STORMS WILL INCREASE INTO SATURDAY AS THE UPPER TROUGH ADVANCES. WE ARE EXPECTING A PRETTY GOOD CHANCE FOR SHOWERS...BUT NOT A TOTAL WASHOUT. THE COVERAGE OF SHOWERS WILL DIMINISH SATURDAY NIGHT...THEN INCREASE AGAIN WITH DIURNAL INFLUENCES ON SUNDAY. NO ORGANIZED OR WIDESPREAD SEVERE WX OR EXCESSIVE RAINFALL IS EXPECTED THROUGH THIS FORECAST PERIOD. BEYOND SUNDAY... THE TROUGH LIFTS OUT AND HEIGHTS BUILD ACROSS THE REGION. A BERMUDA HIGH PATTERN DEVELOPS WITH TEMPERATURES AND HUMIDITY LEVELS CLIMBING BACK TO TYPICAL SUMMER LEVELS. THERE WILL BE GENERALLY SMALL CHANCES FOR DIURNALLY DRIVEN CONVECTION. 13 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 21
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
723 PM CDT FRI AUG 16 2013 .DISCUSSION... Expect VFR conditions to prevail over west central Texas through the next 24 hours. && .AVIATION... Early morning convection has stabilized the atmosphere today. Soundings do hint at the possibility of FEW150 during the overnight hours, but given the lack of any evidence of this upstream on satellite imagery, will opt to maintain SKC at all terminals. Winds are expected to become light and variable overnight. && .PREV DISCUSSION... /ISSUED 336 PM CDT FRI AUG 16 2013/ SHORT TERM... /Tonight and Tomorrow/ Visible satellite imagery shows sunny skies across West Central Texas this afternoon. The latest mesoanalysis indicates a stable environment over our area, with an instability axis across South and far West Texas. The models, including the 3KM HRRR model develop scattered thunderstorms over Eastern New Mexico and far West Texas in the instability axis during the late afternoon and evening. Upper level northerly flow will keep this activity west of our area for tonight. Lows will be in the mid 60s to lower 70s. Going with a dry forecast for Saturday across the area. Isolated thunderstorms will probably fire to our west during the afternoon hours. The upper level northerly flow should keep the storms west of our area. Highs will be in the lower to mid 90s. LONG TERM... /Saturday Night through Friday/ The upper level flow will be north to northeast next week as a high pressure ridge sets up from the Southern Rockies into the Central Plains. Basically a normal summertime pattern with little upper level and mesoscale forcing. Temperatures will be near or slightly above seasonable normals. Highs will be in the 90s with lows in the upper 60s to lower 70s. Going with a dry forecast through the extended period. && .PRELIMINARY POINT TEMPS/POPS... Abilene 66 92 67 94 68 / 10 10 5 5 5 San Angelo 67 93 68 95 68 / 10 10 5 5 5 Junction 68 94 69 97 66 / 10 10 5 5 5 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ Doll/Daniels
AREA FORECAST DISCUSSION
NWS MIDLAND/ODESSA TX
633 PM CDT Fri Aug 16 2013 .AVIATION... 00Z TAF issuance... No major aviation concerns for the next 24...VFR conditions are expected at all TAF sites. There is currently come thunderstorm activity just west of CNM this evening but NM terminals do not look to be affected in the immediate future. Will need to keep an eye on any convection moving south out of Chaves county and send an update to include mention of TSRA if needed. Generally light east southeasterly winds this evening should persist overnight and into Saturday. && .PREV DISCUSSION... /ISSUED 154 PM CDT Fri Aug 16 2013/ DISCUSSION... The Mesoscale Convective Complex which clipped the western Low Rolling Plains this morning generated quite the bubble surface high and sent an outflow boundary westward across the CWA. The modified airmass behind this boundary will result in high temperatures several degrees lower than what was previously expected, especially over the eastern half of the forecast area, and will affect convection this afternoon, and more than likely, tonight. The latest RUC bears this out with a higher theta e axis at H7 shunted west of the 16/12Z operational models. Think we will still see widely scattered thunderstorms over the higher terrain through max heating, but think convection will drop into southeast New Mexico along the theta e axis overnight. Instability around 1000 J/Kg, mid level lapse rates of 7.5-8 C/Km and 0-6 Km Bulk Shear Vectors around 35kt could yield a few strong to severe storms. Since the overall threat is limited, will make a mention in the HWO. Think convection Saturday and Sunday will mainly occur over the higher terrain as an upper ridge over Arizona repositions further north over the Four Corners region, with the flow aloft over the CWA becoming more northeasterly. Storms will likely develop over the higher terrain of New Mexico each afternoon, then spread south/ southwestward under the eastern fringe of the upper ridge. Temperatures will stay near to above normal through the weekend. Models are still undecided on whether an inverted upper trough will trek westward into the area from the Gulf of Mexico next week. Will not add any rain chances at this time, but some could be added mid to late next week for such a feature if the upper ridge does not remain too strong for it to impinge upon the area. Temperatures should be near normal next week, especially the second half. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ 27
AREA FORECAST DISCUSSION
NWS AMARILLO TX
326 PM CDT THU AUG 15 2013 .DISCUSSION... LITTLE OR NO CHANGES TO THE PREVIOUS GRIDS AND FORECAST AS THE WEATHER PATTERN DOES NOT CHANGE MUCH. UPPER HIGH OVER THE FOUR CORNERS AND SOUTHWESTERN STATES THROUGH THE WEEKEND WILL MAINTAIN A NORTHWESTERLY UPPER FLOW TONIGHT...TRANSITIONING TO NORTHERLY BY FRIDAY NIGHT AND SATURDAY. LOOKING AT THE TTU-WRF...NAM...GFS...AND ECMWF...BETTER ORGANIZED CONVECTION COULD POSSIBLY HOLD OFF UNTIL AROUND 00Z FRIDAY OR LATER. THE LATEST HRRR DEVELOPS CONVECTION ACROSS THE NORTHWEST SECTIONS OF THE FORECAST AREA BY 20Z TODAY WHICH THEN MOVES SOUTHEAST ACROSS THE WESTERN AND CENTRAL TEXAS PANHANDLE AROUND 22Z TODAY TO AROUND 00Z TO 02Z FRIDAY. SINCE NOT MUCH DEVELOPING AS OF 20Z TODAY ACROSS THE PANHANDLES...THINKING THAT THE HRRR MAY BE THE ODD MODEL OUT. CONVECTION CURRENTLY OVER OKLAHOMA AND EAST CENTRAL NEW MEXICO MOVING SOUTH AND SOUTHEAST. WILL CONTINUE TO MONITOR TRENDS...BUT WITH CAPES FORECAST TO BE IN THE 1500 TO 2500 J/KG RANGE AND SURFACE DEW POINTS IN THE 60S...CANNOT RULE OUT CONVECTION DEVELOPING PRIOR TO 00Z FRIDAY. AS THE UPPER HIGH BROADENS OVER THE SOUTHWESTERN STATES OVER THE WEEKEND...THE UPPER FLOW TRANSITIONS TO NORTHERLY AND EVEN NORTHEASTERLY BRINGING A GRADUAL END TO THE CONVECTION BY SUNDAY. WARMER AND DRIER CONDITIONS SUNDAY THROUGH NEXT WEDNESDAY WITH HIGHS CLIMBING BACK UP INTO THE 90S. SCHNEIDER && .FIRE WEATHER... AN UPPER RIDGE ACROSS THE FOUR CORNERS REGION AND THE SOUTHWESTERN STATES WILL MAINTAIN A NORTHWESTERLY TO NORTHERLY UPPER FLOW ACROSS THE PANHANDLES THROUGH THE WEEKEND. SHOWERS AND THUNDERSTORMS WILL DEVELOP ACROSS SOUTHEASTERN AND EASTERN COLORADO AND WESTERN AND SOUTHWESTERN KANSAS LATER TODAY AND TONIGHT AND WILL MOVE SOUTHEAST ACROSS THE PANHANDLES. NO ELEVATED OR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED THROUGH THE MIDDLE OF NEXT WEEK AS MINIMUM AFTERNOON RELATIVE HUMIDITIES REMAIN AT OR ABOVE 20 PERCENT THROUGH THE MIDDLE OF NEXT WEEK. SCHNEIDER && .PRELIMINARY POINT TEMPS/POPS... AMARILLO TX 63 87 62 88 63 / 40 20 20 5 20 BEAVER OK 65 87 64 90 64 / 70 10 5 5 5 BOISE CITY OK 60 89 62 90 62 / 30 10 20 10 20 BORGER TX 66 89 67 90 66 / 50 10 10 5 10 BOYS RANCH TX 63 90 64 92 65 / 30 20 20 10 20 CANYON TX 62 88 61 89 63 / 40 20 20 5 20 CLARENDON TX 65 87 63 87 64 / 60 20 10 5 10 DALHART TX 59 89 62 90 61 / 30 10 20 10 20 GUYMON OK 62 89 64 90 63 / 50 10 10 5 10 HEREFORD TX 61 87 61 88 61 / 30 20 20 5 20 LIPSCOMB TX 63 85 63 87 64 / 70 10 10 5 5 PAMPA TX 63 85 62 86 62 / 50 10 10 5 10 SHAMROCK TX 63 87 62 86 63 / 70 20 10 5 5 WELLINGTON TX 65 88 64 89 65 / 70 20 10 5 5 && .AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 13/11
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1244 PM CDT Thu Aug 15 2013 .UPDATE... Increased POPS this afternoon. && .DISCUSSION... Isolated convection has formed across the Big Country early this afternoon with agitated cumulus increasing in coverage, especially northern and eastern sections. Latest HRRR develops scattered convection across the area this afternoon within a moderately unstable airmass and diminishing CIN. Given latest trends, POPS were increased to 30 percent across the eastern half of the CWA with slight chance elsewhere. Cannot rule out a strong storm or two given an increase in shear aloft and modest instability. The main threat from the stronger storms will be gusty winds with the potential for isolated severe downbursts. Aviation discussion follows. && .AVIATION... Predominantly a VFR forecast the next 24 hours. Scattered showers and thunderstorms will develop across the area this afternoon. Included VCTS at KABI, KJCT and KBBD where better coverage is expected and will monitor convective trends for necessary amendments this afternoon. Any storms will be capable of producing brief MVFR conditions along with gusty winds. A complex of storms may approach the KABI terminal from the north after 06Z tonight but confidence in this scenario is too low to mention at this time. && .PREV DISCUSSION... /ISSUED 625 AM CDT THU AUG 15 2013/ UPDATE... See 12Z aviation discussion below. AVIATION... VFR conditions should prevail across most terminals for most of the day. However, scattered thunderstorms will continue through the period. Given the uncertain timing and location of the storms, not going to mention in the forecast at this time. However, if a storm does pass over a terminal, then a quick drop to MVFR or even briefly IFR conditions will be likely. In addition, gusty winds and cloud to ground lightning will pose a threat. PREV DISCUSSION... /ISSUED 400 AM CDT THU AUG 15 2013/ SHORT TERM... Today and Tonight. Another chance of storms across the northwest Big Country this morning, and across much of the Big Country again late tonight. For the second night in a row, a complex of showers and storms is moving southeast towards the Big Country this morning. Much like earlier this morning, expect the activity to move southeast through sunrise and then quickly weaken and dissipate by mid morning. Will increase precipitation chances slightly across the area northwest of Abilene, but will wait and see how much progress the storms make before increasing them for the city itself. Other showers and storms have lingered across the Northwest Hill Country and the Northern Edwards Plateau early this morning. This activity is much more scattered and has weakened quicker than the storms farther north. At this point, will not boost pops in this southern area, and assume that they will weaken and dissipate even earlier, probably even before sunrise. Large upper level high pressure will continue across the southwest US, creating northwest and northerly flow through tonight. Models have some differences in the possibilities of more storms late tonight across the Big Country, with the NAM showing a potent shortwave generating another MCS moving south into the area late this evening and into the early morning hours. SPC is going along with this scenario and has placed a small portion of the Big Country into a Slight Risk for severe storms tonight. GFS is a little farther east with the storm complex, and slower as well, not bringing the rain into the area til near or after sunrise Friday morning. Confidence in the storm complex is fairly high, but given the uncertainty in the timing and track, will boost rain chances mainly across Haskell and Throckmorton counties for now. LONG TERM... Friday through next Wednesday. An MCS is expected to be diminishing across the northern part of the area Friday morning. How far south the complex will make it isn`t known...but it`s possible that it could be as far south as the Concho Valley and Heartland areas before finally dissipating. This argues for expanding the chance PoPs into the Concho Valley and Heartland areas for Friday, but mainly for morning activity. This complex would also likely leave an outflow boundary in the area for new thunderstorm development by Friday afternoon...so will keep the slight chance for showers and thunderstorms across the southern areas of the CWA for Friday as well. As flow aloft weakens through early next week, and the ridge expands back over the area, we continue to expect a dry forecast through next Tuesday with temperatures generally a few degrees above normal. By the middle of next week...both the GFS and EC show the easterly wave/trough currently in the western Caribbean moving into the Texas gulf coast and toward west central Texas. At this time, the main affect we will show is slightly cooler temperatures associated with lower heights from this feature for Wednesday. However...should the trough remain in tact into west central Texas, we may have another chance for showers and thunderstorms by Wednesday. && .PRELIMINARY POINT TEMPS/POPS... Abilene 92 71 95 69 92 / 30 20 30 20 5 San Angelo 94 71 97 70 94 / 20 20 20 20 5 Junction 95 72 98 71 95 / 30 20 20 10 5 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 24
AREA FORECAST DISCUSSION
NWS SPOKANE WA
459 PM PDT Fri Aug 16 2013 .SYNOPSIS... A slow moving upper level trough will keep unsettled conditions over the Inland Northwest through Saturday. The trough will pass all areas by Saturday evening and Sunday delivering locally breezy winds. Westerly flow will build over the region through the middle of the week bringing dry weather and seasonable temperatures. The weather will turn more unsettled toward the end of the next work week with a return of some thunderstorms possible. && .DISCUSSION... Tonight: The Pacific Northwest will transition to a more progressive flow pattern tonight into the weekend. An impressive looking low pressure system over the Aleutians this afternoon will direct a stronger upper level jet into the region over the next couple of days. The increase in mid and upper level flow will aid in the organization of thunderstorms over central Oregon this afternoon and evening. We will be keeping a close eye on how storms in Oregon evolve this evening, and their potential to migrate into southeast Washington. At this time, RUC analysis of instability suggests that storms will have a tough time surviving once they move off the high terrain of central and northeast Oregon. The last several runs of the NAM show thunderstorms reaching as far east as Garfield and Asotin counties this evening. Then overnight, the model regenerates elevated showers and thunderstorms along the 700-500mb baroclinic axis from northeast Oregon across the Camas Prairie to southern Shoshone county. Precipitation amounts from any late night convection should be pretty light. Model soundings suggest marginal elevated instability and rapid cell motion. Saturday and Saturday Night: On shore flow will strengthen tomorrow as a shallow open-wave trough moves inland. The models are in good agreement that there will be enough lingering low and mid level moisture over northeast Oregon and the southern Idaho Panhandle to retain a slight chance of showers and thunderstorms over the Blues, Camas Prairie and Shoshone county. There may also be enough cooling aloft with the upper trough axis to generate isolated afternoon showers and thunderstorms over the mountains near Northport, Priest Lake and Bonners Ferry. Otherwise, Saturday afternoon/evening will be one of the breezier days we have had in a while which isn`t saying much. Our recent weather pattern hasn`t produced much widespread breeziness lately. The Palouse, West Plains and Upper Columbia Basin will likely experience sustained winds up to 15 mph with gusts to around 20 mph in the afternoon. /GKoch Sunday through Wednesday evening: A fairly benign weather pattern through mid week. The Inland Northwest will be under a relatively dry westerly flow pattern. The jet stream will remain well north of the region into BC, which will place the Inland Northwest on the more stable side of the jet. Shortwave disturbances will generally bring some showers north of the region into BC through the period and may give us a little bit of wind as they do so. Temperatures will by near average with highs in the 80s for most valley locations. /SVH Thursday and Friday: A Low from Northern California is expected to pass through the SE portion of Washington and the Central ID Panhandle during this period. The models are not agreeing on the timing of the Low passing. The GFS and GEM are putting the passing on Friday morning while the ECMWF is nearly 24 hours behind. A few more model runs will hopefully resolve this issue. The models are carrying more moisture with this Low. With that in mind, the chances of receiving a wetting rain and possible isolated thunderstorm in the vicinity of the Low is increased for the Blue Mountains and Camas Prairie area. Temperatures are expected to remain around the normals for the month of August. /JDC && .AVIATION... 00Z TAFS: A mainly dry cold front will continue to push across the Inland Northwest, bringing some middle and high clouds. Thunderstorms over northeast Oregon will continue to track east- northeast and may slip across southeast WA and the lower ID Panhandle. Some may come into the vcnty of KLWS and possibly KPUW in the 03-10Z time frame. The remnants may also slip toward KGEG/KSFF/KCOE a couple hours later, but the threat is minimal at this point. Otherwise look for VFR conditions, locally breezy conditions this evening and again after 18-21Z Saturday. /J. Cote` && .PRELIMINARY POINT TEMPS/POPS... Spokane 63 84 60 83 60 83 / 10 10 10 0 0 0 Coeur d`Alene 59 84 58 83 56 83 / 10 10 10 0 0 0 Pullman 55 84 52 83 50 86 / 10 10 10 0 0 0 Lewiston 66 92 64 93 62 94 / 20 10 10 0 0 0 Colville 57 88 54 87 53 89 / 10 20 10 0 0 0 Sandpoint 55 82 53 83 50 82 / 10 10 10 0 0 0 Kellogg 58 82 57 81 56 83 / 20 10 10 0 0 0 Moses Lake 61 89 60 88 60 88 / 0 0 0 0 0 0 Wenatchee 66 87 64 88 64 88 / 0 0 0 0 0 0 Omak 61 89 61 89 61 89 / 0 10 10 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
632 PM CDT FRI AUG 16 2013 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND SATURDAY ISSUED AT 241 PM CDT FRI AUG 16 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOWS A SPRAWLING HIGH PRESSURE SYSTEM STRETCHING FROM THE NORTHERN MISSISSIPPI VALLEY TO NEW ENGLAND. AS ONE SHORTWAVE DIGS OVER THE SOUTHERN PLAINS WHILE ANOTHER SHIFTS EAST OVER MANITOBA...MID-LEVEL RIDGING IS GRADUALLY BUILDING EAST OVER THE NORTHERN PLAINS. THIS PATTERN WILL CONTINUE TO LEAD TO QUIET WEATHER OVER THE NEXT SEVERAL DAYS...MAKING CLOUDS AND TEMPS THE MAIN FORECAST CONCERN IN THE SHORT TERM. TONIGHT...HIGH PRESSURE WILL REMAIN OVER THE REGION BENEATH BUILDING HEIGHTS IN THE MID AND UPPER LEVELS. WISCONSIN WILL BE POSITIONED BETWEEN WEATHER SYSTEMS NORTH AND SOUTH OF THE REGION. WITH LOW PWATS AND MOSTLY CLEAR CONDITIONS...WILL LIKELY SEE PATCHY GROUND FOG FORM LATE TONIGHT ACROSS THE SANDY SOIL AREAS AND RIVER VALLEYS. WENT BELOW MOS GUIDANCE FOR LOWS...WHICH SHOULD BE A FEW DEGREES WARMER THAN LAST NIGHT. SATURDAY...HIGH PRESSURE THROUGH THE COLUMN WILL PROVIDE ANOTHER QUIET AND SUNNY DAY. START TO GET A LITTLE MORE RETURN FLOW ACROSS THE REGION...WHICH SHOULD LEAD TO SLIGHTLY WARMER HIGH TEMPS AND MORE HUMIDITY. HIGHS MAINLY IN THE LOW TO MID 80S...EXCEPT COOLER NEAR THE LAKE. .LONG TERM...SATURDAY NIGHT THROUGH FRIDAY ISSUED AT 241 PM CDT FRI AUG 16 2013 MODELS ARE NOW IN GOOD AGREEMENT WITH OVERALL PATTERN. THEY BRING UPPER RIDGING INTO THE NORTHERN PLAINS AND WESTERN GREAT LAKES THROUGH MIDWEEK. A SHORT WAVE TROUGH MOVING ALONG THE CANADIAN BORDER WILL SUPPRESS THE RIDGING A BIT SUNDAY NIGHT AND MONDAY AND COULD PRODUCE SCATTERED THUNDERSTORMS IN THE FAR NORTH. PROLONGED SOUTHERLY FLOW AND WARMER TEMPERATURES ALOFT WILL COMBINE TO PRODUCE VERY WARM AND MORE HUMID CONDITIONS DURING THE MIDDLE OF THE WEEK WITH THE WARMEST WEATHER SINCE MID JULY. THE HEAT SHOULD SUBSIDE AS A COLD FRONT MOVES THROUGH THURSDAY AND THURSDAY NIGHT. COOLER AND DRIER AIR EXPECTED FRIDAY THROUGH SUNDAY. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 631 PM CDT FRI AUG 16 2013 VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER OVER THE TAF PERIOD. BETWEEN 08-12Z SATURDAY MORNING...PATCHY GROUND FOG WILL IMPACT AREA AIRPORTS. FOG WILL BE THE MOST WIDESPREAD AND DENSE OVER NORTH-CENTRAL WISCONSIN. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......RDM AVIATION.......ESB
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1130 PM CDT WED AUG 14 2013 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 333 PM CDT WED AUG 14 2013 AT 3 PM...THE SATELLITE LOOP SHOWED A BROKEN DECK OF 7 TO 8K FOOT CLOUDS ACROSS THE FORECAST AREA. THE RAP SEEMS TO HAVE THE BEST HANDLE ON THESE CLOUDS AND THEY SHOW THAT THESE CLOUDS WILL GRADUALLY DISSIPATE THIS EVENING. FOR LATE TONIGHT AND THURSDAY MORNING...THE BUFKIT SOUNDINGS SHOW THAT THERE WILL BE A DEEP LAYER /UP TO 775 MB/ OF LIGHT WINDS ACROSS THE AREA. WHILE THIS WOULD BE FAVORABLE FOR THE DEVELOPMENT OF VALLEY FOG. THE NAM/WRF...GFS...AND RAP CONTINUE TO SHOW THAT THE TEMPERATURE/DEW POINT SPREAD WILL REMAIN AT OR ABOVE 1C. IN ADDITION...THE GFS AND NAM/WRF SUGGEST THAT THERE COULD BE STILL SOME CLOUDS AROUND THE REGION. AS A RESULT...WENT WITH PATCHY VALLEY FOG FOR THE MISSISSIPPI RIVER AND ITS TRIBUTARIES...AND AREAS OF FOG IN THE WISCONSIN RIVER VALLEY. ON THURSDAY...THE MODELS CONTINUE TO SHOW THAT A SHORT WAVE TROUGH WILL MOVE SOUTHEAST ACROSS SOUTHERN AND WESTERN IOWA. WEAK 925 AND 850 MB MOISTURE TRANSPORT NORTHEAST OF THIS SYSTEM WILL AID IN THE DEVELOPMENT OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS NORTHEAST IOWA...SOUTHEAST MINNESOTA...AND SOUTHWEST WISCONSIN. WITH ML CAPES LESS THAN 400 J/KG AND VERY WEAK 0-3 KM AND 0-6 KM...NONE OF THESE THUNDERSTORMS ARE EXPECTED TO BECOME SEVERE. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 333 PM CDT WED AUG 14 2013 ON FRIDAY...THE 925 MB AND 850 MB WEAK MOISTURE TRANSPORT AND 700 TO 600 MB FRONTOGENESIS REMAINS SOUTHWEST OF THE FORECAST AREA. IN ADDITION...THERE IS VERY LITTLE SURFACE MOISTURE CONVERGENCE ACROSS THE AREA. WITH THE MESO MODELS IN AGREEMENT WITH THE GEM AND ECMWF THAT THE AREA WILL REMAIN DRY...REMOVED THE PRECIPITATION CHANCES FOR THIS TIME PERIOD. ON BOTH THURSDAY AND FRIDAY NIGHTS...BOTH THE GFS AND NAM/WRF SOUNDINGS SHOW A DEEP LAYER /UP TO AT LEAST 800 MB/ OF LIGHT WINDS. THIS WOULD BE VERY FAVORABLE FOR THE DEVELOPMENT OF VALLEY FOG. HOWEVER THEY ALSO HINT THAT THERE MAY BE SOME CLOUDS AROUND THE REGION. ANOTHER FACTOR THAT MAY BE A LIMITING FACTOR IS THE AMOUNT OF MOISTURE IN THE BOUNDARY LAYER. THE NAM/WRF HAS MUCH MORE MOISTURE THAN THE GFS. DUE TO THIS UNCERTAINTY...JUST INTRODUCED PATCHY TO AREAS OF VALLEY FOG ON BOTH NIGHTS. FROM MONDAY THROUGH WEDNESDAY...THE MODELS ARE CONTINUING TO STRUGGLE WITH THE 500 MB UPPER AIR PATTERN. THE GFS AND GEM ARE SHOWING THAT THE UPPER LEVEL RIDGE REMAINS LONGER TO THE WEST THAN THE ECMWF. AS A RESULT...THE GFS AND GEM ARE FASTER AT MOVING THE COLD FRONT SOUTHEAST INTO THE FORECAST AREA. MEANWHILE THE ECMWF HAS THE FRONT REMAINING WELL NORTHWEST OF THE FORECAST AREA. SINCE THE MODELS HAVE BEEN TRENDING SLOWER DURING THIS TIME PERIOD...THE CONSENSUS OF OUR OFFICE AND THE SURROUNDING WFOS TO KEEP MOST OF THE FORECAST AREA DRY DURING THIS TIME FRAME. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1130 PM CDT WED AUG 14 2013 THE VALLEY FOG FORECAST FOR THIS MORNING AT LSE REMAINS PROBLEMATIC. THE WIND FIELD IS VERY FAVORABLE FOR VALLEY FOG...BUT SCT-OVC HIGH BASED CUMULUS PERSISTS WHICH HAS KEPT THE TEMPERATURE/DEWPOINT SPREAD JUST SLIGHTLY HIGHER THAN IDEAL. WITH VARIOUS MODELS SUCH AS THE RAP...GFS AND NAM CONTINUING TO INDICATE THE CLOUDS GOING NOWHERE...THINK ANY VALLEY FOG WILL OCCUR MORE AWAY FROM THE AIRPORT IN THE NARROWER VALLEYS...AND POSSIBLY THE NARROWER SECTION OF THE MISSISSIPPI SOUTH OF LA CROSSE. HAVE PLAYED THE FOG WITH A VCFG AND SCT003...BUT SHOULD THE CLOUDS CLEAR EARLY THIS MORNING...MORE FOG AND LOWER VISIBILITIES WILL BE REQUIRED. OTHERWISE...THESE HIGH BASED CUMULUS CLOUDS OF A SCT-BKN VARIETY SHOULD PERSIST THROUGH THE TAF PERIOD UNDER A LIGHT SURFACE WIND REGIME. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...AJ
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
541 AM EDT Sat Aug 17 2013 ...HEAVY RAINFALL AND FLOODING CONCERNS EXPECTED AGAIN TODAY... .NEAR TERM [Thru TODAY]... We continue in a very wet and unsettled pattern. During the overnight hours, shortwave energy moving from the Cntrl/Srn Gulf of Mex has energized another band of deep tropical moisture (PWATS 2.1-2.2 inches) with training cells and interacted with a stalled front producing moderate to locally heavy rains across portions of the local area, especially the Panhandle. This aggravated the flooding situation which necessitated the issuance of a flood warning for Jackson and Washington counties. RAP soundings imply that low level steering flow was switching from SW to more sly feeding more of this moisture Nwd into our AL/GA counties near the front yielding rain rates of up to 2-3 inches per hour. By 3 AM EDT, strong to severe storms began developing across the nearshore waters and this will soon move over coastal counties. All this reflected well in HRRR. The large scale pattern continues to amplify with little change in last 12 hrs providing all the ingredients necessary today for a continued widespread heavy rain event further aggravating the flooding situation. Aloft, ridge over Wrn 1/3d and deep trough over Ern 2/3rd of Conus with axis down MS Valley. A deep 580DM low will centered over MO/TN border with a trough axis extending into the northwestern Gulf of Mex. A potent vortmax over AR/TN border with 90kt upper jet round the base of the trough placing the area in the favorable right entrance region. Several small shortwaves riding down base of trough nudging it ewd. All this increasing upper lift/diffluence over mainly WRN CWA. At the same time, weal upper ridging exists over Srn FL and a low/tropical wave was located in the SW Gulf on Mex (NW of Campeche). The combination of these features has allowed for sfc-H4 SW unidirectional flow providing a deep conveyor belt of tropical moisture spreading Newd across our local area. At the surface, front remains largely stalled from Srn Walton county Nwwd to along I-10 into SE GA yielding SWLY flow. However the combination of diurnal heating plus building H5 ridging across the Wrn Atlc and FL Peninsula should lift front Nwd thru the day placing more of area in warm sector. Convergence along this boundary should continue to serve as the focus for low level lift and where heaviest rains should occur (AL/GA). Model soundings show area PWATS in excess of 2 inches. Flash flooding will remain a serious concern as activity continues to train over areas which have already received significant rainfall. As the Gulf system moves further Wwd, guidance places the highest QPF and highest PoPs over the NW third of our forecast area. With many of these areas already saturated from a very wet summer, flash flooding will continue to be closely monitored. Thus the flash flood watch remains in effect for the entire area but Ern sections should be dropped this aftn. Will have categorical PoPs for most of the area with temperatures well below normal. See the hydrology section of this product for more details on the potential. As far as strong to severe storms, the existence of a very moist boundary layer and weak lapse rates argue against these storms, however with upper trough/jet/vort, cant discount wet microbursts with gusty to damaging winds best bet. SPC keeps us in 5% severe prob. Will go with CAT POPS west half and likely POPS east half with heavy rain in grids. Under cloudy and rain conditions, Max temps to remain well below normal, from around 80 SE AL to mid to upper 80s SE Big Bend. && .SHORT TERM [Tonight Through Monday]... As the Gulf system continues to shift Wwd into Wrn Gulf, expect corridor of heaviest rain progressively sliding west and out of our forecast area as Atlc ridge progressively builds NWWD thru period. However, the continued influence of the trough along the MS Valley (even thought its deamplifying) and now SW-NE oriented quasi-stnry front should combine for sct-likely POPs thru the period. For tonight, the deep layer conveyor belt will diminish as dry air spreads into Srn periphery of upper low but FL Panhandle and SE AL will remain in a favorable position to receive additional rain, possibly moderate to heavy, and thus lingering flooding concerns. By Sun, the upper low will lift Newd towards OH River Valley but trough and front will linger while the Gulf system should be far enough west (S TX or Mex) for little impact. However, latest guidance indicates that a piece of this feature will shear Nwd strengthening H85 flow and keeping moisture in at least our Wrn CWA even with the Atlc subtropical ridge building Nwwd into our area. By Mon, upper ridge over Wrn Atlc will expand into local area while front has moved further Nwd and weakened. We will return to a more seasonal pattern of mainly aftn/eve sct seabreeze driven convection as max temps return to near climo. Will go with 60-40% NW-SE POPs tonight, 60-50% on Sun and 50-30% N-S on Mon. Lows tonight around 70. Highs Sun Mid 80s NW to around 90 SE rising on Mon to upper 80s NW to lower 90s SE. && .LONG TERM [Monday Night through Friday]... Upper trough over the Lower Mississippi Valley is forecast to linger through the first half of next week keeping a moist and unstable airmass in place over the tri-state area. This will keep PoPs relatively high through at least Tuesday. By later in the week, there is more uncertainty in the guidance as to how much ridging will build back over the region, with the ECMWF keeping the upper trough in tact and the GFS indicating a stronger ridge. Being well into the extended, will keep conditions close to climo as a compromise. && .AVIATION... [Through 06z Sunday] Low cigs and showers with embedded convection will prevail with MVFR to IFR conditions expected. && .MARINE... Winds and seas will be on the increase through the weekend especially around any convection and especially over the western waters, as a trough of low pressure lingers to the north and west. However conditions should remain below exercise caution levels through Sunday. Winds and seas will diminish early next week. && .FIRE WEATHER... Abundant moisture and rainfall will prevent red flag conditions from being met well into next week. && .HYDROLOGY... Up until this morning, except for the FL Panhandle, showers have been progressive enough and not training which has kept the flood threat low. However, this should change today as the heaviest rains of this wet period are expected with widespread average rainfall amounts of 3 to 5 inches still anticipated mainly Wrn areas. Isolated higher totals are expected, possibly upward of 5 to 8 inches in some locations. River flooding will become an increasing concern by late today and into next week, especially depending on where the heaviest rainfall ends up occurring. The current thinking is that much of the heaviest rains will occur in the lower half of the basins. Thus, if the latest forecast holds, the Choctawhatchee Basin from Geneva through Bruce would easily return to minor flood stage late in the weekend with the potential for moderate flooding from Caryville southward to Bruce early next week. The Chipola has some capacity for heavy rainfall, but if rainfall amounts trend higher than expected, minor flooding would be a possibility at Marianna and Altha early next week. Into Southeast Alabama, soils are especially saturated and area creeks and stream will quickly respond to any significant rainfall. Minor flooding along the Choctawhatchee and Pea Rivers could occur quickly in this scenario late this weekend. In Southern Georgia and the Florida Big Bend, current projections move the Apalachicola, Flint, and Ochlockonee River systems to near flood stage with anticipated rainfall, though heavier amounts would easily lead to minor flooding, especially in the lower portions of these basins where heavier rains were received in July. Lighter rainfall amounts are anticipated further east into the Withlacoochee and Suwannee River basins and the current anticipation is for these rivers to remain below flood stage into next week. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 84 71 91 74 91 / 80 60 60 50 50 Panama City 83 75 88 77 86 / 90 60 60 50 50 Dothan 81 70 86 71 88 / 90 60 60 40 50 Albany 82 71 88 73 90 / 90 60 60 30 50 Valdosta 85 70 91 73 91 / 70 60 50 40 50 Cross City 88 73 91 72 91 / 50 40 50 40 50 Apalachicola 85 78 87 79 87 / 80 60 60 50 50 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...FLASH FLOOD WATCH through this evening for Coastal Dixie- Coastal Franklin-Coastal Jefferson-Coastal Taylor-Coastal Wakulla-Gadsden-Inland Dixie-Inland Franklin-Inland Jefferson-Inland Taylor-Inland Wakulla-Lafayette-Leon- Liberty-Madison. FLASH FLOOD WATCH through Sunday evening for Calhoun-Central Walton-Coastal Bay-Coastal Gulf-Holmes-Inland Bay-Inland Gulf-Inland Walton-Jackson-South Walton-Washington. GA...FLASH FLOOD WATCH through this evening for Baker-Ben Hill- Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur- Dougherty-Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller- Mitchell-Quitman-Randolph-Seminole-Terrell-Thomas-Tift- Turner-Worth. AL...FLASH FLOOD WATCH through Sunday evening for Coffee-Dale- Geneva-Henry-Houston. GM...None. && $$ Hydrology...Block/Godsey LONG TERM...Camp AVIATION/FIRE WX...DVD REST OF DISCUSSION...BLOCK
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
530 AM EDT SAT AUG 17 2013 .SYNOPSIS... 08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFIED UPPER LEVEL PATTERN IN PLACE OVER THE EASTERN HALF OF THE NATION...HIGHLIGHTED BY A DEEP TROUGH AXIS ALONG AND JUST EAST OF THE MS VALLEY. CLOSER TO HOME...WEAK UPPER LEVEL RIDGING EXISTS OVER THE SOUTHERN HALF OF THE FLORIDA PENINSULA. FLOW BETWEEN THESE TWO FEATURES CONTINUES TO PUMP UP ABUNDANT AND DEEP TROPICAL MOISTURE ACROSS THE EASTERN GULF AND OVER THE FL PENINSULA. AT THE SURFACE...A WEAK PRESSURE GRADIENT IS IN PLACE BETWEEN THE SUBTROPICAL RIDGE AXIS TO OUR EAST AND NORTHEAST AND A WELL DEFINED SURFACE TROUGH/WEAK LOW ACROSS THE CENTRAL/WESTERN GULF. THIS SURFACE TROUGH TURNS EAST FROM THE MS DELTA AREA ALONG THE NE GULF COAST/I-10 CORRIDOR. LOW LEVEL FOCUS JUST SOUTH OF THIS TROUGH AXIS COMBINED WITH UPPER LEVEL SUPPORT AHEAD OF THE DIGGING MID/UPPER TROUGH IS FORCING A LARGE AREA OF CONVECTION THIS MORNING ACROSS THE NE GULF/APALACHEE BAY. TO BE HONEST...MOST OF THE RELIABLE GUIDANCE MODELS ARE NOT HANDLING THIS CONVECTIVE BLOWUP WELL AT ALL. THE ONLY MODEL THAT IS STARTING TO COME IN LINE WITH THIS FEATURE IS THE 3KM HRRR (HIGH RESOLUTION RAPID REFRESH) DUE TO ITS SOPHISTICATED RADAR INITIALIZATION METHODS. HAVE UPDATED THE FORECAST OVER THE NORTHERN MARINE ZONES AND NORTHERN NATURE COAST ZONES TO INCREASE POPS THROUGH MID-MORNING IN LINE WITH THIS LATEST HRRR FORECAST. LEVY COUNTY LOOKS TO BE RIGHT ON THE BORDER OF THIS AXIS OF FOCUS FOR CONVECTION...AND WILL HAVE A FAIRLY TIGHT GRADIENT IN THE RAIN CHANCES FROM WEST TO EAST ACROSS THE COUNTY. ELSEWHERE...OVER LAND CONDITIONS ARE RATHER QUIET IN THIS PRE-DAWN HOUR. STARTING TO SEE A FEW SHOWERS DEVELOPING OVER THE WATER FURTHER SOUTH OFF THE COASTS OF SARASOTA/CHARLOTTE AND LEE COUNTIES. THESE MORE SCT SHOWERS SHOULD MAINLY STAY OFFSHORE THROUGH MID-MORNING. && .SHORT TERM (TODAY THROUGH MONDAY)... TODAY...AS DISCUSSED ABOVE...THE MOST DIFFICULT FORECAST ZONES THIS MORNING WILL BE NORTH OF TAMPA BAY TOWARD CITRUS/LEVY COUNTY IN CLOSEST PROXIMITY TO THE LOW LEVEL TROUGH FOCUS AND UPPER LEVEL SUPPORT. BASED ON RADAR TRENDS AND LATEST HRRR FORECAST...THE HEAVIEST RAINFALL SHOULD STAY JUST WEST OF LEVY COUNTY AND MOVE UP THROUGH APALACHEE BAY...HOWEVER CERTAINLY EXPECTING SHOWERS TO BE MOVING ACROSS THOSE COUNTY IN THE NEXT SEVERAL HOURS...AND HAVE RAISED POPS FOR THIS AREA. THE HRRR DOES TRANSITION BACK TO AGREEMENT WITH THE LARGER SCALE GUIDANCE FOR THE SECOND HALF OF THE DAY AND REPOSITIONS THE HEAVIEST RAINFALL POTENTIAL BACK TOWARD THE FL PANHANDLE. FURTHER SOUTH UNDER INCREASING INFLUENCE OF THE UPPER RIDGE...THE FORECAST WILL TRANSITION TO ONE MORE REPRESENTATIVE OF A MID AUGUST DAY. WEAK RIDGING IS IN PLACE BUT CERTAINLY IS NOT ENOUGH TO SIGNIFICANTLY SUPPRESS CONVECTION. WITH A LIGHT SOUTHEAST LOW LEVEL FLOW...WILL FOLLOW A RAINFALL FORECAST CONSISTENT WITH PREFERRED ENHANCEMENT ALONG THE WEST COAST SEA-BREEZE. THIS PATTERN GENERALLY FEATURES THE EARLIEST CONVECTION IN THE AFTERNOON BREAKING OUT / MOVING INTO THE SOUTHERN /SOUTH-CENTRAL ZONES...AND THEN RIPPLING NORTHWARD ALONG THE I-75 CORRIDOR TOWARD THE TAMPA BAY AREA BY LATE AFTERNOON/EARLY EVENING. WE HAVE BEEN TRICKED THE PAST FEW DAYS WITH A PATTERN THAT SHOULD HAVE SUPPORTED ABUNDANT DIURNAL SHOWER ACTIVITY...AND COVERAGE HAS BEEN LESS THAN EXPECTED. ONCE AGAIN...TODAY LOOKS AS IF THERE IS NOT MUCH TO HOLD BACK THE STORMS DURING THE AFTERNOON. MID-LEVEL LAPSE RATES ARE NOT GREAT...BUT THIS SHOULD HAVE MORE INFLUENCE HOLDING BACK STORM INTENSITY RATHER THAN COVERAGE. ONLY OTHER CONCERN WOULD BE IF ENOUGH MID/HIGH LEVEL CLOUDS HOLD ON TO KEEP ANY DEFINED SEA-BREEZE FROM FORMING. THIS WOULD LESSEN THE OVERALL LATE DAY CONVERGENCE AND RESULTING THUNDERSTORM COVERAGE. IT IS DIFFICULT AND RISKY TO PREDICT THAT NO SEABREEZE WILL FORM THIS TIME OF YEAR...ESPECIALLY WITH LESS THAN 15 KNOTS OF BOUNDARY LAYER FLOW...WHICH IS USUALLY WHAT IT TAKES TO START PREVENTING INLAND PENETRATION. WE SHALL SEE...BUT ITS HARD BASED ON THE ENVIRONMENT NOT TO FORECAST AN ACTIVE (50-60%) AFTERNOON/EVENING OF STORMS. TONIGHT...EVENING STORMS ALONG THE I-75 CORRIDOR SHOULD PUSH OFFSHORE...BUT MAY LINGER FOR AT LEAST A FEW HOURS AFTER SUNSET...DEPENDING ON JUST HOW LATE IN THE DAY CONVECTION FIRES. IT DOES LOOK LIKE BY MIDNIGHT MOST IF NOT ALL THE ACTIVITY WILL HAVE TRANSITIONED OFFSHORE AND LEAVE MOST OF OUR LAND ZONES WITH A QUIET OVERNIGHT PERIOD. SUNDAY/MONDAY...UPPER PATTERN WILL DEAMPLIFY WITH TIME INTO THE EARLY PORTION OF NEXT WEEK ALLOWING THE UPPER RIDGE TO BUILD NORTH OVER THE ENTIRE FL PENINSULA. AT THE SAME TIME...THE SURFACE RIDGE WILL ALSO SHIFT FURTHER NORTH KEEPING OUR AREA IN A STEADY EASTERLY FLOW PATTERN. THE FORECAST FOR SUNDAY AND MONDAY WILL BE SIMILAR DUE TO THE SIMILAR SYNOPTIC PATTERNS AND FEATURE GENERALLY QUIET MORNING HOURS GIVING WAY TO INCREASING CHANCES FOR MAINLY LATE DAY/EVENING STORMS. THE EASTERLY FLOW HAS BEEN A RECURRING THEME THIS SUMMER AND IS ONE OF OUR MORE ACTIVE PATTERNS FOR THUNDERSTORMS. BOTH DAYS WILL FEATURE ABOVE CLIMO POPS OF 50-60% FOR THESE STORMS. IT IS IMPORTANT TO NOTE THAT NEITHER SUNDAY OR MONDAY WILL BE A WASHOUT AS MOST OF THESE DAYS WILL BE DRY...HOWEVER THE CHANCES ARE JUST ON THE HIGHER SIDE THAT THE PREDICTED THUNDERSTORM COVERAGE WILL PROVIDE A BRIEF DOWNPOUR AT MANY LOCATIONS. && .LONG TERM (TUESDAY THROUGH FRIDAY)... AN U/L RIDGE OVER THE WESTERN ATLANTIC WILL HOLD ACROSS FLORIDA TUESDAY...AND WILL WEAKEN WEDNESDAY AND THURSDAY AS A WEAK U/L TROUGH SINKS OVER THE SOUTHEAST U.S. AND PERSISTS INTO FRIDAY WITH SLIGHTLY LOWER HEIGHTS OVER THE FLORIDA PENINSULA. A STRONG U/L RIDGE OVER THE SOUTHERN PLAINS WILL BEGIN TO PUSH EAST SATURDAY AND WILL BUILD OVER WEST CENTRAL AND SOUTHWEST FLORIDA THROUGH THE WEEKEND. AT THE SURFACE...HIGH PRESSURE OVER THE MID ATLANTIC COAST WILL PRODUCE EASTERLY BOUNDARY LAYER FLOW ACROSS THE FLORIDA PENINSULA THROUGH THE PERIOD. TYPICAL SUMMERTIME PATTERN EACH DAY WITH THE WEST COAST SEA BREEZE BEING HELD OVER THE COASTAL COUNTIES OF WEST CENTRAL AND SOUTHWEST FLORIDA...WITH THE EAST COAST SEA BREEZE MOVING ACROSS THE PENINSULA AND COLLIDING WITH THE WEST COAST SEA BREEZE DURING THE LATE AFTERNOON/EARLY EVENING EACH DAY. SCATTERED TO NUMEROUS AFTERNOON THUNDERSTORMS EACH DAY WITH THE HIGHEST POPS OVER THE COASTAL COUNTIES. BOUNDARY LAYER WINDS MAY WEAKEN A BIT FRIDAY AND SATURDAY WHICH WOULD ALLOW THE WEST COAST SEA BREEZE TO PUSH SLIGHTLY FURTHER INLAND. STRONG CONVERGENCE ALONG THE WEST COAST SEA BREEZE BOUNDARY COMBINED WITH STRONG DAYTIME HEATING MAY ALLOW AN ISOLATED PULSE SEVERE THUNDERSTORM TO DEVELOP EACH AFTERNOON. TEMPERATURES WILL RUN A FEW DEGREES ABOVE CLIMATIC NORMALS EACH DAY. && .AVIATION... VFR CONDITIONS WILL PREVAIL THROUGH EARLY THIS MORNING. SCT LCL BKN 020-030 WILL DEVELOP MID TO LATE MORNING LIFTING TO 030-035 THIS AFTERNOON. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS VCNTY ALL TERMINALS THIS AFTERNOON...WITH LCL MVFR CIGS AND IFR VSBYS. && .MARINE... THE FORECAST WATERS WILL RESIDE WITHIN A ZONE OF SOUTHEAST FLOW BETWEEN THE SUBTROPICAL RIDGE AXIS TO OUR EAST AND NORTHEAST AND A WEAK AREA OF LOW PRESSURE AND SURFACE TROUGH OVER THE CENTRAL GULF OF MEXICO. BY THE EARLY PORTION OF NEXT WEEK...THE RIDGE AXIS WILL MOVE EVEN FURTHER NORTH AND PLACE OUR REGION IN A ZONE OF MORE CONSISTENT EASTERLY FLOW. && .FIRE WEATHER... TYPICAL SUMMER CONDITIONS ARE IN THE FORECAST THROUGH THE WEEKEND. EASTERLY FLOW WILL RESULT IN AN ACTIVE AFTERNOON AND EVENING THUNDERSTORM PATTERN THROUGH THE NEXT SEVERAL DAYS. RELATIVE HUMIDITY VALUES ARE EXPECTED TO REMAIN WELL ABOVE CRITICAL LEVELS. && .PRELIMINARY POINT TEMPS/POPS... TPA 92 79 92 78 / 50 40 50 40 FMY 93 77 93 77 / 60 30 50 30 GIF 94 75 93 75 / 50 30 50 20 SRQ 92 78 93 77 / 50 40 50 40 BKV 93 74 92 75 / 60 40 50 30 SPG 93 80 91 79 / 50 40 50 40 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA LONG TERM/AVIATION...OGLESBY
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
351 AM EDT SAT AUG 17 2013 .DISCUSSION... ATLC RIDGE AXIS CURRENTLY OVER CENTRAL FL WL TRANSITION NORTH OF THE AREA DURING THE DAY...OPENING UP AN ONSHORE FLOW PATTERN THAT WILL PERSIST WELL INTO NEXT WEEK. AMPLE MOISTURE REMAINS ACROSS THE REGION WITH PWAT INVOF 2 INCHES. THE EARLY ONGOING SHRA AND ISOLD TS ALONG THE INTERIOR AND WEST COAST APPEARS ASCD WITH FORCED ASCENT ASCD WITH AN UPSTREAM WAVE ALONG THE NRN GULF COAST. TODAYS FORECAST WL FAVOR INTERIOR FOR BEST RAIN CHCS DUE TO DEEPENING ONSHORE PATTERN AND BEST BOUNDARY INTERACTION POTENTIAL. MARGINAL INSTABILITY SHOULD BE AIDED BY PREVIOUSLY MENTIONED UPSTREAM WAVE AND MID RANGE SCT COVERAGE OF STORMS CAN BE EXPECTED INLAND TAPERING BACK TO ISOLD ALONG THE SPACE COAST SWD TO LAKE OKEE AND THE TREASURE COAST...WHERE MARINE SOURCE PCPN MAY BE THE MAIN MECHANISM FOR ANY MEASURABLE PRECIP. EXPECT HIGHS IN THE LOWER TO MID 90S INLAND AND AROUND 90 AT THE COAST. AS DUSK APPROACHES PRECIP POTENTIAL WL DIMINISH AND EVENTUALLY TRANSITION TO THE COAST WHERE ONSHORE MOVING SHOWERS WL AFFECT SOME AREAS INTO EARLY SUN. HIGHEST CHCS WL BE ALONG S CST WHERE MOST FAVORABLE ONSHORE TRAJECTORY WL EXIST. SUN-MON... CENTRAL FL WILL UNDERGO A SHIFT TO A DRIER WX PATTERN AS THE LIFTING H30-H20 JET OVER THE APPALACHIANS ALLOWS THE ATLC RIDGE AXIS TO REPOSITION ITSELF OVER THE DEEP SOUTH BY DAYBREAK SUN. POSITION WILL BE STABLE AS UPSTREAM JET ENERGY OVER THE SRN TIER STATES IS QUITE WEAK AND WILL NOT BE ABLE DO DISLODGE IT. POSITION OF THE RIDGE AXIS WILL GENERATE A DEEP AND STEADY E/SE FLOW ACRS CENTRAL FL...A PATTERN THAT FAVORS THE WEST PENINSULA FOR DIURNAL CONVECTION RATHER THAN THE EAST DUE LARGELY TO THE EARLY FORMATION AND DIFFUSE NATURE OF THE RESULTING EAST COAST SEA BREEZE. FURTHERMORE...LATEST RUC ANALYSIS SHOWS A NOTEWORTHY DROP IN DEEP LYR RH APPROACHING THE SRN BAHAMAS THAT WILL WORK ITS WAY INTO THE FL PENINSULA TO START THE UPCOMING WEEK. GFS MODEL SOUNDINGS CONFIRM THE ANTICIPATED DRY TREND...DROPPING PWAT VALUES FROM ARND 2.0" AT 12Z SUN TO ARND 1.7" BY 12Z MON. EVEN THE HIGHER PWAT VALUES ARE SUN ARE SOMEWHAT DECEIVING AS GFS INDICATES THE MOISTURE WILL BE EVENLY DISTRIBUTED THRU THE COLUMN... NOT CONCENTRATED IN THE LOW/MID LVLS WHERE IT WOULD SUPPORT HIGHER AMOUNTS OF DIURNAL CONVECTION. STORM POTENTIAL WILL REMAIN LOW AS THE ERLY FLOW TAPS AN AIRMASS WITH NEGLIGIBLE MID LVL VORTICITY OR OF UPR LVL JET SUPPORT. THERMODYNAMIC PROFILE MAY PROVIDE SOME PUNCH AS UPSTREAM H50 TEMPS DROP INTO THE -7C TO -8C RANGE AND H85-H50 LAPSE RATES STEEPEN TO 6.0-6.5C/KM. HOWEVER...ANY STRONG ACTIVITY WOULD TEND TO FORM W OF THE FL TURNPIKE AS THE DEEP ERLY FLOW WILL PUSH THE SEA BREEZE RAPIDLY INLAND. PRECIP COVERAGE AOB 40PCT WITH HIGHEST COVERAGE OVER THE INTERIOR SUN AFTN TO GIVE A NOD TO THE AFOREMENTIONED HIGHER PWAT VALUES. ONSHORE FLOW WILL KEEP MAX TEMPS IN THE U80S/L90 ALONG THE COAST... INTERIOR WARMING TO THE L/M90S. MIN TEMPS L/M70S. TUE-FRI... LITTLE CHANGE TO THE CURRENT PHILOSOPHY...STABLE POSITION OF THE ATLC RIDGE AXIS WILL MAINTAIN A DEEP ERLY FLOW ACRS CENTRAL FL FOR MUCH OF THE WEEK THAT WILL FOCUS DIURNAL CONVECTION OVER THE W PENINSULA. POPS 30-40PCT...HIGHER OVER THE INTERIOR DUE TO THE EARLY FORMATION OF THE EAST COAST SEA BREEZE. MAX TEMPS WITHIN A DEG OR TWO OF CLIMO AVG...MIN TEMPS 3-5F ABV AVG DUE TO THE PERSISTENT ONSHORE FLOW. && .AVIATION... ISOLD EARLY SHOWERS WITH ASCD CIGS NR 035-040FT NR ISM-LEE THROUGH 14Z TRANSITION TO ADTL SHOWERS WITH A FEW STORMS MOVING NWD FM 15Z THROUGH 18Z WILL FILL IN ACROSS PRIMARILY INTERIOR SECTIONS AWAY FROM THE E COAST THE REGION THROUGH MID AFTN. BEST PERIOD FOR SCT MVFR AND ISOLD IFR CONDS AT TAF SITES WL OCCUR FM 18Z-22Z AND INLAND. OCNL CIGS FM 025-035 WL OCCUR IN SHOWERS ALONG WITH OCNL-FRQT LTG AND WND G30-35KT IN ANY STRONGER TS. && .MARINE... FAVORABLE SEA HGHTS FOR SMALL CRAFT DURIN THE DAY WITH INDICATED SIG WV CURRENTLY MEASURING 1-2 FT AND LIKELY 2-3 FT OVER THE OUTERMOST WATERS. SLOWLY INCREASING HGHTS CAN BE EXPECTED INTO TONIGHT WITH DEVELOPMENT OF ONSHORE GRADIENT WINDS AS HIGH PRESSURE LIFTS NORTH OF THE REGION. SUN-WED...ATLC RIDGE WILL REPOSITION ITSELF OVER THE DEEP SOUTH BY DAYBREAK WHERE IT WILL REMAIN THRU MIDWEEK. RIDGE POSITION WILL GENERATE A STEADY STATE GENTLE TO MODERATE E/SE BREEZE. THESE WINDS WILL PUSH A SMALL ERLY SWELL INTO THE LCL ATLC...KEEPING SEAS 3-4FT THRU MON. SEAS WILL SUBSIDING TO 2-3FT NEARSHORE AND 3-4FT OFFSHORE TUE THE SWELL DAMPENS. ISOLD SHRAS/ TSRAS THRU THE PD. && .PRELIMINARY POINT TEMPS/POPS... DAB 91 76 89 77 / 30 20 30 20 MCO 94 76 93 76 / 40 20 40 20 MLB 92 78 89 79 / 30 30 30 20 VRB 91 77 90 77 / 30 30 30 20 LEE 92 76 93 77 / 40 20 40 20 SFB 94 76 93 77 / 40 20 40 20 ORL 94 77 93 77 / 40 20 40 20 FPR 90 76 90 78 / 30 30 30 20 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM...PENDERGRAST LONG TERM....BRAGAW
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
339 AM EDT Sat Aug 17 2013 ...HEAVY RAINFALL AND FLOODING CONCERNS EXPECTED AGAIN TODAY... .NEAR TERM [Thru TODAY]... We continue in a very wet and unsettled pattern. During the overnight hours, shortwave energy moving from the Cntrl/Srn Gulf of Mex has energized another band of deep tropical moisture (PWATS 2.1-2.2 inches) with training cells and interacted with a stalled front producing moderate to locally heavy rains across portions of the local area, especially the Panhandle. This aggravated the flooding situation which necessitated the issuance of a flood warning for Jackson and Washington counties. RAP soundings imply that low level steering flow was switching from SW to more sly feeding more of this moisture Nwd into our AL/GA counties near the front yielding rain rates of up to 2-3 inches per hour. By 3 AM EDT, strong to severe storms began developing across the nearshore waters and this will soon move over coastal counties. The large scale pattern continues to amplify with little change in last 12 hrs providing all the ingredients necessary today for a continued widespread heavy rain event further aggravating the flooding situation. Aloft, ridge over Wrn 1/3d and deep trough over Ern 2/3rd of Conus with axis down MS Valley. A deep 580DM low will centered over NE Missouri with a trough axis extending into the northwestern Gulf of Mex. A potent vortmax over AR/TN border with 90kt upper jet round the base of the trough placing the area in the favorable right entrance region. Several small shortwaves riding down base of trough nudging it ewd. All this increasing upper lift/diffluence over mainly WRN CWA. At the same time, a low/tropical wave was located in the SW Gulf on Mex (NW of Campeche). The combination of these features has allowed for sfc-H4 SW unidirectional flow providing a deep conveyor belt of tropical moisture spreading Newd across our local area. At the surface, front remains largely stalled from Srn Walton county Nwwd to just south of Marianna/Bainbridge into SE GA yielding SWLY flow. However the combination of diurnal heating plus building H5 ridging across the Wrn Atlc and FL Peninsula should lift front Nwd thru the day placing more of area in warm sector. Convergence along this boundary should continue to serve as the focus for low level lift and where heaviest rains should occur. Model soundings show area PWATS in excess of 2 inches. Flash flooding will remain a serious concern as activity continues to train over areas which have already received significant rainfall. As the Gulf system moves further Wwd, guidance places the highest QPF and highest PoPs over the NW third of our forecast area. With many of these areas already saturated from a very wet summer, flash flooding will continue to be closely monitored. Thus the flash flood watch remains in effect for the entire area but Ern sections should may be dropped by this aftn. Will have categorical PoPs for most of the area with temperatures well below normal. See the hydrology section of this product for more details on the potential. As far as strong to severe storms, the existence of a very moist boundary layer and weak lapse rates argue against these storms, however with upper trough/jet/vort, cant discount wet microbursts with gusty to damaging winds best bet. SPC keeps us in 5% severe prob. Will go with CAT POPS west half and likely POPS east half with heavy rain in grids. Under cloudy and rain conditions, Max temps to remain well below normal, from around 80 SE AL to mid to upper 80s SE Big Bend. && .SHORT TERM [Tonight Through Monday]... As the Gulf system continues to shift Wwd into Wrn Gulf, expect heavy rain to decrease from E-W with the corridor of heaviest rain progressively sliding to west of our forecast area. However, the continued influence of the trough along the MS Valley (even thought its deamplifying) and now SW-NE oriented quasi-stnry front should combine for sct-likely POPs thru the period. For tonight, the deep layer conveyor belt will diminish but FL Panhandle and SE AL will remain in a favorable position to receive additional heavy rain and lingering flooding concerns. By Sun, the upper low will lift newd towards OH River Valley but trough and front will linger while the Gulf system should be far enough west for little impact. However, latest guidance indicates that a piece of this feature will shear Nwd strengthening H85 flow and keeping moisture in at least our Wrn CWA even with the Atlc subtropical ridge building Nwwd into our area. By Mon, upper ridge over Wrn Atlc will build into local area. We will return to a more seasonal pattern of sct seabreeze driven convection as POPs decrease and max temps will return to near climo. Will go with 60-40% NW-SE POPs tonight, 60-50% on Sun and 50-30% N-S on Mon. Lows tonight around 70. Highs Sun Mid 80s NW to around 90 SE rising on Mon to upper 80s NW to lower 90s SE. && .LONG TERM [Monday Night through Friday]... Upper trough over the Lower Mississippi Valley is forecast to linger through the first half of next week keeping a moist and unstable airmass in place over the tri-state area. This will keep PoPs relatively high through at least Tuesday. By later in the week, there is more uncertainty in the guidance as to how much ridging will build back over the region, with the ECMWF keeping the upper trough in tact and the GFS indicating a stronger ridge. Being well into the extended, will keep conditions close to climo as a compromise. && .AVIATION... [Through 06z Sunday] Low cigs and showers with embedded convection will prevail with MVFR to IFR conditions expected. && .MARINE... Winds and seas will be on the increase through the weekend especially around any convection and especially over the western waters, as a trough of low pressure lingers to the north and west. However conditions should remain below exercise caution levels through Sunday. Winds and seas will diminish early next week. && .FIRE WEATHER... Abundant moisture and rainfall will prevent red flag conditions from being met well into next week. && .HYDROLOGY... Up until this morning, except for the FL Panhandle, showers have been progressive enough and not training which has kept the flood threat low. However, this should change today as the heaviest rains of this wet period are expected with widespread average rainfall amounts of 3 to 5 inches still anticipated mainly Wrn areas. Isolated higher totals are expected, possibly upward of 5 to 8 inches in some locations. River flooding will become an increasing concern by late today and into next week, especially depending on where the heaviest rainfall ends up occurring. The current thinking is that much of the heaviest rains will occur in the lower half of the basins. Thus, if the latest forecast holds, the Choctawhatchee Basin from Geneva through Bruce would easily return to minor flood stage late in the weekend with the potential for moderate flooding from Caryville southward to Bruce early next week. The Chipola has some capacity for heavy rainfall, but if rainfall amounts trend higher than expected, minor flooding would be a possibility at Marianna and Altha early next week. Into Southeast Alabama, soils are especially saturated and area creeks and stream will quickly respond to any significant rainfall. Minor flooding along the Choctawhatchee and Pea Rivers could occur quickly in this scenario late this weekend. In Southern Georgia and the Florida Big Bend, current projections move the Apalachicola, Flint, and Ochlockonee River systems to near flood stage with anticipated rainfall, though heavier amounts would easily lead to minor flooding, especially in the lower portions of these basins where heavier rains were received in July. Lighter rainfall amounts are anticipated further east into the Withlacoochee and Suwannee River basins and the current anticipation is for these rivers to remain below flood stage into next week. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 84 71 91 74 91 / 80 60 60 50 50 Panama City 83 75 88 77 86 / 90 60 60 50 50 Dothan 81 70 86 71 88 / 90 60 60 40 50 Albany 82 71 88 73 90 / 90 60 60 30 50 Valdosta 85 70 91 73 91 / 70 60 50 40 50 Cross City 88 73 91 72 91 / 50 40 50 40 50 Apalachicola 85 78 87 79 87 / 80 60 60 50 50 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...FLASH FLOOD WATCH through this evening for Coastal Dixie- Coastal Franklin-Coastal Jefferson-Coastal Taylor-Coastal Wakulla-Gadsden-Inland Dixie-Inland Franklin-Inland Jefferson-Inland Taylor-Inland Wakulla-Lafayette-Leon- Liberty-Madison. FLASH FLOOD WATCH through Sunday evening for Calhoun-Central Walton-Coastal Bay-Coastal Gulf-Holmes-Inland Bay-Inland Gulf-Inland Walton-Jackson-South Walton-Washington. GA...FLASH FLOOD WATCH through this evening for Baker-Ben Hill- Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur- Dougherty-Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller- Mitchell-Quitman-Randolph-Seminole-Terrell-Thomas-Tift- Turner-Worth. AL...FLASH FLOOD WATCH through Sunday evening for Coffee-Dale- Geneva-Henry-Houston. GM...None. && $$ Hydrology...Block/Godsey LONG TERM...Camp AVIATION/FIRE WX...DVD REST OF DISCUSSION...BLOCK
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
207 AM EDT SAT AUG 17 2013 .SYNOPSIS... LOW PRESSURE WILL SLOWLY MOVE NORTHEAST ALONG THE MID ATLANTIC COAST THIS WEEKEND. HIGH PRESSURE RETURNS EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... WILL BE MAKING SIGNIFICANT CHANGES TO THE GRIDS THROUGH 00Z SUN WITH THE 1 AM UPDATE. MAIN CHANGE WILL TO LWR RAIN CHANCES ACROSS THE NRN HALF OF FA AND LIMITING IT TO SAT AFTRN. IT MAY NOT RAIN AT ALL ACROSS THE LW MD ERN SHORE UNTIL SAT EVE. RAIN CHANCES SLOWLY INCRS THROUGH THE DAY ACROSS THE SOUTH. THIS ALL BASED ON LATEST DATA WHERE THE MODELS ARE SHOWING DRYER AIR FROM THE HIGH PRS OVR THE AREA WINNING OUT ACROSS THE FA THRU AT LEAST 18Z. PVS DSCN: UPDATE AS OF 1045 PM EDT...ANOTHER STRANGE EVENING WHERE WX HAS BEEN TRENDING DRIER THAN EXPECTED. A BAND OF CLOUDS IS CURRENTLY MOVING OFF THE COAST AND A BATCH OF RAIN HAS DEVELOPED OVER THE VA TIDEWATER AND NE NC. WILL CONTINUE TO CARRY LIKELY POPS IN THIS AREA THRU EARLY AM AS PCPN EXITS. ELSEWHERE...CLEARING HAS WORKED INTO CENTRAL VA AND WILL CONTINUE TO ADVANCE EAST THRU EARLY AM. THIS CLEARING HAS ALLOWED TEMPS TO FALL A LITTLE LOWER THAN EXPECTED AND THUS HAVE LOWERED OVN LOWS A FEW DEGREES. LOWS IN THE UPR 50S NW TO THE MID 60S SE. THERE IS SOME INDICATION IN THE LATEST IR SATELLITE IMAGERY AND SFC OBS THAT CLOUDS MOVING NORTHWARD THRU CENTRAL NC WILL SPREAD OVER OUR AREA DURING THE PRE-DAWN HOURS SO WILL HAVE CLOUDS RETURNING OVERNIGHT. HOWEVER..QUESTIONS REMAIN AS TO JUST HOW MUCH PCPN WILL PUSH NORTHWARD BY DAYBREAK. LATEST NAM AND HRRR ARE NOT THAT EXCITED ABOUT RAIN GETTING NORTH OF THE HWY 58 IN SOUTHERN VA TIL AFTER 15Z SAT...SO NEXT SHIFT WILL LIKELY BE TRIMMING POPS BACK EVEN FARTHER FOR SAT MORN. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/... UPPER LEVEL HIGH PRESSURE OVER THE CTRL ATLANTIC SHIFTS TWD THE SE COAST OVER THE WEEKEND. MEANWHILE...AN UPPER TROUGH WILL STAY WELL ROOTED IN THE OH/TN VALLEYS DUE TO AN AMPLIFYING RIDGE OVER THE GREAT BASIN. THE COMBINATION OF THESE UPPER LEVEL FEATURES WITH THE STALLED SFC BOUNDARY ALONG THE CAROLINA COAST WILL CAUSE MOISTURE AND SHORTWAVE ENERGY TO STREAM ACROSS THE MID ATLANTIC REGION SATURDAY THROUGH SUNDAY NIGHT. A CONTINUATION OF FAVORABLE ISENTROPIC LIFT MOVING INTO THE AREA FROM THE SOUTHWEST ON SATURDAY WILL QUICKLY SATURATE THE LOWER ATMOSPHERE AND ACT TO ENHANCE STEADY PRECIPITATION/RAINFALL. PWATS WILL GRADUALLY INCREASE THROUGH THE WEEKEND FROM ROUGHLY 0.75 INCHES NORTH TO 1.50 INCHES SOUTH FOR TONIGHT...TO AROUND 2.00 INCHES NORTH TO 2.35 INCHES SOUTH BY SUNDAY. THE BEST POTENTIAL FOR WIDESPREAD STEADY RAIN IS SATURDAY NIGHT. HOWEVER THE WEEKEND WILL NOT BE A COMPLETE WASHOUT...BUT DO EXPECT PERIODS OF RAIN THAT WILL BE MODERATE TO HEAVY AT TIMES AND MOSTLY CLOUDY TO CLOUDY SKIES. FOR SUNDAY...FORECAST MODELS ARE HINTING AT A DRY SLOT MOVING INTO NE NC AND SE VA DURING THE DAY AS THE ATLANTIC HIGH PUSHES CLOSER TO THE SOUTHEAST COAST. IF THIS OCCURS...THEN THERE COULD BE A NICE REPRIEVE FROM THE RATHER WET WEEKEND RAINS IN THE AFOREMENTIONED AREAS. AT THIS TIME...IT IS DIFFICULT TO PINPOINT EXACTLY WHERE THE DRIER CONDITIONS MAY SET UP AND HAVE THEREFORE KEPT A CHANCE OF PRECIP IN THE ONGOING FORECAST FOR SUNDAY AFTN/EVENING. DUE TO EXTENSIVE CLOUD COVER AND COOLER AMBIENT AIR DUE TO EVAPORATIVE COOLING PROCESSES...TEMPERATURES WILL BE ON THE COOL SIDE WITH HIGHS SAT/SUN GENERALLY IN THE 70S (NEAR 80 NE NC/FAR SE VA ON SUN DUE TO POTENTIAL DRY SLOT/CLEARING). THE LOWS ON SATURDAY NIGHT WILL GENERALLY BE IN THE 60S (NEAR 70 COASTAL NE NC/FAR SE VA). THE OH/TN VALLEY TROUGH AND GREAT BASIN HIGH BOTH BEGIN TO WASH OUT ON MONDAY AND APPEAR TO RESULT IN A PSEUDO-WESTERLY (OR ZONAL) FLOW. AT THIS TIME...IT SHOULD BE ENOUGH TO START PUSHING THE PERSISTENTLY RAINY WX PATTERN OUT OF THE AREA BUT NOT UNTIL TUESDAY/TUESDAY NIGHT. HIGH TEMPERATURES REBOUND INTO THE LOWER 80S SINCE A COMBINATION OF SUN AND CLOUDS ARE ANTICIPATED DURING THE DAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... STRONG UPPER-LEVEL WESTERLY FLOW PREVAILS OVER SOUTHERN CANADA THROUGH THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. UNDERNEATH THIS ZONAL FLOW...MID-LEVEL ANTICYCLONES WILL REMAIN NEARLY STATIONARY OVER THE SOUTHERN PLAINS AND WESTERN ATLANTIC. AN AREA OF (SOMEWHAT) LOWER HEIGHTS IS PROGGED OVER THE APPALACHIAN PLATEAU. HOWEVER...THE MID ATLANTIC REGION SHOULD LARGELY REMAIN UNDER THE INFLUENCE OF THE WESTERN ATLANTIC RIDGE. HENCE... PRECIPITATION POTENTIAL SHOULD BE MINIMAL (NEAR OR BELOW CLIMO) DUE TO A LACK OF LARGE SCALE FORCING FOR STORM ORGANIZATION... DESPITE A WARM AND INCREASINGLY HUMID AIRMASS. HIGH TEMPERATURES SHOULD AVERAGE AROUND SEASONAL NORMALS TUESDAY THROUGH FRIDAY (MID/UPPER 80S)...WITH A FEW 90 DEGREE HIGHS POSSIBLE IN FAVORED HOT SPOTS. LOWS SHOULD PRIMARILY RANGE FROM THE UPPER 60S TO LOW 70S. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... A NEARLY STATIONARY COASTAL FRONT HAS ORIENTED ALONG THE SE COAST AS HIGH PRESSURE REMAINS OVER THE NE STATES. THE RESULT IS CONTINUED NELY ONSHORE FLOW OVER THE LOCAL AREA. VISIBLE ON IR SATELLITE AND SFC OBS...IS A WAVE OF LOW PRESSURE LIFTING ALONG THE FRONT. INCREASING MOISTURE AND THE LIFTING WAVE WILL PROVIDE A BETTER FOCUS FOR SHOWERS BEGINNING THIS MORNING OVER NC AND SPREADING NWD DURING THE DAY. FOR THIS MORNING...MID/HIGH LEVEL CLOUDS WILL CONTINUE TO STREAM IN FROM THE SOUTH. LOW CLOUDS WILL ALSO LIFT FROM NC INTO SE VA/NE NC...RESULTING IN MVFR/LOCALLY IFR CIGS THROUGH 12Z (KECG EXPECTED TO REMAIN IFR THROUGH 12Z). THEREAFTER...EXPECT MIXING TO LIFT LOCALIZED IFR CIGS TO MVFR...WITH MVFR CIGS (1500-2500 FT AGL) THROUGH MUCH OF THE DAY WITH PRECIP. ELSEWHERE ...BKN-OVC SKIES WITH DECKS 4-7K FT AGL EXPECTED IN ADVANCE OF THE LIFTING WAVE. AS PRECIP MOVES IN...CIGS WILL LIKELY FALL TO MVFR (1500-2500 FT AGL) AND REMAIN THROUGH THE TAF PERIOD. EXACT TIMING OF THE PRECIP REMAINS TRICKY ATTM...SO WILL ADJUST TAFS BASED ON LATEST GUIDANCE/TRENDS. WINDS WILL REMAIN OUT OF THE NE-E GENERALLY 10 TO 15 KT. UNSETTLED CONDITIONS WILL CONTINUE THROUGH THE WEEKEND AS THE COASTAL FRONT REMAINS NEARLY STATIONARY. HIGH PRESSURE WILL REMAIN TO THE NORTH WITH NE-E FLOW OVER THE LOCAL AREA. && .MARINE... THE LATEST MSAS SURFACE ANALYSIS SHOWS A 1017MB LOW ~110NM ENE OF CAPE HATTERAS TRACKING NE ALONG A COASTAL FRONT ALIGNED PARALLEL TO THE SOUTHEAST COAST. A NE WIND (STRONGEST OFF THE CURRITUCK OUTER BANKS) IS GRADUALLY DIMINISHING AS THE LOW PULLS AWAY AND HIGH PRESSURE RETURNS FROM THE N. ANOTHER LOW (PRESENTLY OVER SOUTHERN GA) IS PROGGED TO LIFT NE ALONG THE SOUTHEAST COAST TONIGHT THROUGH SATURDAY...EVENTUALLY REACHING THE MID ATLANTIC SATURDAY NIGHT AND SUNDAY...BEFORE PULLING TO THE NE SUNDAY NIGHT. THIS PATTERN WILL MAINTAIN A PERSISTENT NE FLOW OVER THE REGION THROUGH SATURDAY NIGHT FOR THE ENTIRE AREA...AND INTO SUNDAY FOR THE NORTHERN PORTION OF THE MARINE AREA. WIND SPEEDS REMAIN CAPPED AROUND 15KT ALONG WITH SEAS/WAVES CAPPED AT 4FT/3FT. CONFIDENCE ON SCA HEADLINES REMAINS LOW...SO NO FLAGS WILL BE ISSUED. ALTHOUGH A FEW BRIEF PERIODS OF SCA WIND ARE POSSIBLE ACROSS THE LOWER BAY (4FT WAVES MOUTH OF THE BAY)...AND 5FT SEAS ARE POSSIBLE OUT NEAR 20NM IN THE OCEAN. HIGH PRESSURE RETURNS EARLY NEXT WEEK WITH LIGHT SSW FLOW RETURNING...ALONG WITH 2-3FT SEAS. PERSISTENT ONSHORE FLOW WILL RESULT IN AN ELEVATED RIP CURRENT RISK SATURDAY AND POSSIBLY INTO SUNDAY AS WELL. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH THIS EVENING FOR MDZ025. NC...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH THIS EVENING FOR NCZ102. VA...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH THIS EVENING FOR VAZ098>100. MARINE...NONE. && $$ SYNOPSIS...BMD NEAR TERM...JDM/MPR SHORT TERM...BMD LONG TERM...AJZ AVIATION...SAM MARINE...AJZ
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1202 AM EDT SAT AUG 17 2013 .SYNOPSIS... LOW PRESSURE WILL SLOWLY MOVE NORTHEAST ALONG THE MID ATLANTIC COAST THIS WEEKEND. HIGH PRESSURE RETURNS EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... WILL BE MAKING SIGNIFICANT CHANGES TO THE GRIDS THROUGH 00Z SUN WITH THE 1 AM UPDATE. MAIN CHANGE WILL TO LWR RAIN CHANCES ACROSS THE NRN HALF OF FA AND LIMITING IT TO SAT AFTRN. IT MAY NOT RAIN AT ALL ACROSS THE LW MD ERN SHORE UNTIL SAT EVE. RAIN CHANCES SLOWLY INCRS THROUGH THE DAY ACROSS THE SOUTH. THIS ALL BASED ON LATEST DATA WHERE THE MODELS ARE SHOWING DRYER AIR FROM THE HIGH PRS OVR THE AREA WINNING OUT ACROSS THE FA THRU AT LEAST 18Z. PVS DSCN: UPDATE AS OF 1045 PM EDT...ANOTHER STRANGE EVENING WHERE WX HAS BEEN TRENDING DRIER THAN EXPECTED. A BAND OF CLOUDS IS CURRENTLY MOVING OFF THE COAST AND A BATCH OF RAIN HAS DEVELOPED OVER THE VA TIDEWATER AND NE NC. WILL CONTINUE TO CARRY LIKELY POPS IN THIS AREA THRU EARLY AM AS PCPN EXITS. ELSEWHERE...CLEARING HAS WORKED INTO CENTRAL VA AND WILL CONTINUE TO ADVANCE EAST THRU EARLY AM. THIS CLEARING HAS ALLOWED TEMPS TO FALL A LITTLE LOWER THAN EXPECTED AND THUS HAVE LOWERED OVN LOWS A FEW DEGREES. LOWS IN THE UPR 50S NW TO THE MID 60S SE. THERE IS SOME INDICATION IN THE LATEST IR SATELLITE IMAGERY AND SFC OBS THAT CLOUDS MOVING NORTHWARD THRU CENTRAL NC WILL SPREAD OVER OUR AREA DURING THE PRE-DAWN HOURS SO WILL HAVE CLOUDS RETURNING OVERNIGHT. HOWEVER..QUESTIONS REMAIN AS TO JUST HOW MUCH PCPN WILL PUSH NORTHWARD BY DAYBREAK. LATEST NAM AND HRRR ARE NOT THAT EXCITED ABOUT RAIN GETTING NORTH OF THE HWY 58 IN SOUTHERN VA TIL AFTER 15Z SAT...SO NEXT SHIFT WILL LIKELY BE TRIMMING POPS BACK EVEN FARTHER FOR SAT MORN. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... UPPER LEVEL HIGH PRESSURE OVER THE CTRL ATLANTIC SHIFTS TWD THE SE COAST OVER THE WEEKEND. MEANWHILE...AN UPPER TROUGH WILL STAY WELL ROOTED IN THE OH/TN VALLEYS DUE TO AN AMPLIFYING RIDGE OVER THE GREAT BASIN. THE COMBINATION OF THESE UPPER LEVEL FEATURES WITH THE STALLED SFC BOUNDARY ALONG THE CAROLINA COAST WILL CAUSE MOISTURE AND SHORTWAVE ENERGY TO STREAM ACROSS THE MID ATLANTIC REGION SATURDAY THROUGH SUNDAY NIGHT. A CONTINUATION OF FAVORABLE ISENTROPIC LIFT MOVING INTO THE AREA FROM THE SOUTHWEST ON SATURDAY WILL QUICKLY SATURATE THE LOWER ATMOSPHERE AND ACT TO ENHANCE STEADY PRECIPITATION/RAINFALL. PWATS WILL GRADUALLY INCREASE THROUGH THE WEEKEND FROM ROUGHLY 0.75 INCHES NORTH TO 1.50 INCHES SOUTH FOR TONIGHT...TO AROUND 2.00 INCHES NORTH TO 2.35 INCHES SOUTH BY SUNDAY. THE BEST POTENTIAL FOR WIDESPREAD STEADY RAIN IS SATURDAY NIGHT. HOWEVER THE WEEKEND WILL NOT BE A COMPLETE WASHOUT...BUT DO EXPECT PERIODS OF RAIN THAT WILL BE MODERATE TO HEAVY AT TIMES AND MOSTLY CLOUDY TO CLOUDY SKIES. FOR SUNDAY...FORECAST MODELS ARE HINTING AT A DRY SLOT MOVING INTO NE NC AND SE VA DURING THE DAY AS THE ATLANTIC HIGH PUSHES CLOSER TO THE SOUTHEAST COAST. IF THIS OCCURS...THEN THERE COULD BE A NICE REPRIEVE FROM THE RATHER WET WEEKEND RAINS IN THE AFOREMENTIONED AREAS. AT THIS TIME...IT IS DIFFICULT TO PINPOINT EXACTLY WHERE THE DRIER CONDITIONS MAY SET UP AND HAVE THEREFORE KEPT A CHANCE OF PRECIP IN THE ONGOING FORECAST FOR SUNDAY AFTN/EVENING. DUE TO EXTENSIVE CLOUD COVER AND COOLER AMBIENT AIR DUE TO EVAPORATIVE COOLING PROCESSES...TEMPERATURES WILL BE ON THE COOL SIDE WITH HIGHS SAT/SUN GENERALLY IN THE 70S (NEAR 80 NE NC/FAR SE VA ON SUN DUE TO POTENTIAL DRY SLOT/CLEARING). THE LOWS ON SATURDAY NIGHT WILL GENERALLY BE IN THE 60S (NEAR 70 COASTAL NE NC/FAR SE VA). THE OH/TN VALLEY TROUGH AND GREAT BASIN HIGH BOTH BEGIN TO WASH OUT ON MONDAY AND APPEAR TO RESULT IN A PSEUDO-WESTERLY (OR ZONAL) FLOW. AT THIS TIME...IT SHOULD BE ENOUGH TO START PUSHING THE PERSISTENTLY RAINY WX PATTERN OUT OF THE AREA BUT NOT UNTIL TUESDAY/TUESDAY NIGHT. HIGH TEMPERATURES REBOUND INTO THE LOWER 80S SINCE A COMBINATION OF SUN AND CLOUDS ARE ANTICIPATED DURING THE DAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... STRONG UPPER-LEVEL WESTERLY FLOW PREVAILS OVER SOUTHERN CANADA THROUGH THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. UNDERNEATH THIS ZONAL FLOW...MID-LEVEL ANTICYCLONES WILL REMAIN NEARLY STATIONARY OVER THE SOUTHERN PLAINS AND WESTERN ATLANTIC. AN AREA OF (SOMEWHAT) LOWER HEIGHTS IS PROGGED OVER THE APPALACHIAN PLATEAU. HOWEVER...THE MID ATLANTIC REGION SHOULD LARGELY REMAIN UNDER THE INFLUENCE OF THE WESTERN ATLANTIC RIDGE. HENCE... PRECIPITATION POTENTIAL SHOULD BE MINIMAL (NEAR OR BELOW CLIMO) DUE TO A LACK OF LARGE SCALE FORCING FOR STORM ORGANIZATION... DESPITE A WARM AND INCREASINGLY HUMID AIRMASS. HIGH TEMPERATURES SHOULD AVERAGE AROUND SEASONAL NORMALS TUESDAY THROUGH FRIDAY (MID/UPPER 80S)...WITH A FEW 90 DEGREE HIGHS POSSIBLE IN FAVORED HOT SPOTS. LOWS SHOULD PRIMARILY RANGE FROM THE UPPER 60S TO LOW 70S. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... A TROUGH OF LOW PRES ALONG THE MID AND SOUTH ATL COAST CONTINUES TO MOVE NE AND AWAY FROM LAND...RESULTING IN NE FLOW ACROSS THE REGION IN THE LOW LEVELS. ALOFT...SWLY FLOW WILL GRADUALLY INCREASE AND RESULT IN OVERRUNNING MOISTURE THAT WILL GRADUALLY SPREAD NORTH LIKELY STARTING OVERNIGHT INTO SAT MORNING. EXACT TIMING OF THE PRECIP WILL BE TRICKY. CIGS AND VSBY WITH THE RAIN WILL START OUT AS MVFR FOR SOME TIME INITIALLY BUT TRANSITION TO IFR LATER SATURDAY MORNING AND EARLY AFTERNOON AS A WAVE OF LOW PRESSURE MOVES ALONG THE COASTAL FRONT. ONCE CONDITIONS BECOME IFR SATURDAY...THEY WILL LIKELY REMAIN IFR FOR A PERIOD OF TIME WHILE THE OVERRUNNING CONTINUES INTO THE AFTERNOON. && .MARINE... THE LATEST MSAS SURFACE ANALYSIS SHOWS A 1017MB LOW ~110NM ENE OF CAPE HATTERAS TRACKING NE ALONG A COASTAL FRONT ALIGNED PARALLEL TO THE SOUTHEAST COAST. A NE WIND (STRONGEST OFF THE CURRITUCK OUTER BANKS) IS GRADUALLY DIMINISHING AS THE LOW PULLS AWAY AND HIGH PRESSURE RETURNS FROM THE N. ANOTHER LOW (PRESENTLY OVER SOUTHERN GA) IS PROGGED TO LIFT NE ALONG THE SOUTHEAST COAST TONIGHT THROUGH SATURDAY...EVENTUALLY REACHING THE MID ATLANTIC SATURDAY NIGHT AND SUNDAY...BEFORE PULLING TO THE NE SUNDAY NIGHT. THIS PATTERN WILL MAINTAIN A PERSISTENT NE FLOW OVER THE REGION THROUGH SATURDAY NIGHT FOR THE ENTIRE AREA...AND INTO SUNDAY FOR THE NORTHERN PORTION OF THE MARINE AREA. WIND SPEEDS REMAIN CAPPED AROUND 15KT ALONG WITH SEAS/WAVES CAPPED AT 4FT/3FT. CONFIDENCE ON SCA HEADLINES REMAINS LOW...SO NO FLAGS WILL BE ISSUED. ALTHOUGH A FEW BRIEF PERIODS OF SCA WIND ARE POSSIBLE ACROSS THE LOWER BAY (4FT WAVES MOUTH OF THE BAY)...AND 5FT SEAS ARE POSSIBLE OUT NEAR 20NM IN THE OCEAN. HIGH PRESSURE RETURNS EARLY NEXT WEEK WITH LIGHT SSW FLOW RETURNING...ALONG WITH 2-3FT SEAS. PERSISTENT ONSHORE FLOW WILL RESULT IN AN ELEVATED RIP CURRENT RISK SATURDAY AND POSSIBLY INTO SUNDAY AS WELL. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH SATURDAY EVENING FOR MDZ025. NC...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH SATURDAY EVENING FOR NCZ102. VA...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH SATURDAY EVENING FOR VAZ098>100. MARINE...NONE. && $$ SYNOPSIS...MPR NEAR TERM...JDM/MPR SHORT TERM...BMD LONG TERM...AJZ AVIATION...JEF MARINE...AJZ
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1040 PM MDT Fri Aug 16 2013 AVIATION SECTION UPDATED .DISCUSSION... Update forthcoming. Have made minor changes to the sky grids. Have also expanded pop area over the extreme northwest portion of the county warning area. HRRR analysis brings very light precipitation to the area toward daybreak, likely associated with area of clouds moving through the Idaho panhandle at this time. Temperatures look reasonable. Emanuel && .AVIATION... UPDATED 0440Z. Current satellite imagery shows weak upper level trough stretching from southeast Alberta to the ID Panhandle moving faster and bringing greater cloud coverage than forecast models had been indicating. Not a big impact given that ceilings should remain above 10000 ft, but enough to adjust cloud timing and coverage in latest KCTB/KGTF/KHVR TAFs. Have also added mention of VCTS vcnty KCTB tomorrow aftn. Elsewhere, smoke from wildland fires in the western portion of Montana and from eastern Idaho will keep thin layers of high clouds over central and southwest MT overnight and much of tomorrow. Surface winds remaining light through the overnight hours. Waranauskas && .PREV DISCUSSION...Issued 230 PM MDT Fri Aug 16 2013 Tonight through Sunday...Warm and dry conditions will continue Friday afternoon into Saturday. High pressure slowly begins to shift east in response to a weak mid level boundary passing through the region early Saturday. There will be a slight chance of some afternoon shower development over portions Central Montana Saturday and Sunday but dry lower level conditions may prevent most precipitation reaching the ground. Elevated terrain will likely have a better chance of seeing any precipitation from anything that does develop. Any storms that do develop will likely only produce gusty winds near their vicinity. Fire weather conditions are marginal at this time but very low relative humidity and afternoon breeziness add to the danger level. For additional fire weather concerns please see the Fire Weather Discussion. Temperatures look to moderate slightly over the weekend with highs dropping to the upper 80s and low 90s. Sunday night through Friday...The zones will be underneath a flat upper level high pressure ridge Sunday night and the airmass will be quite dry. The next low pressure weather system will be well west over the Eastern Pacific. The upper level ridge will move east of the zones by Tuesday afternoon and flow aloft will switch to the southwest. Moisture will again be able to move underneath the ridge and the airmass will become unstable again Wednesday afternoon, mainly over the southwest zones. Later in the week latest model runs indicate that the upper ridge will rebuild and affect the forecast area. Therefore have updated the forecast to go with warmer temperatures. There is the possibility that high temperatures could return to near 90 by late in the week for the lower elevations. Even with this change to a rebuilding upper ridge it still looks like there could be some instability so will continue with the mention of a slight chance of thunderstorms even though some guidance from the models indicates Thursday and Friday could be dry. Blank && .FIRE WEATHER... UPDATED 2030Z. Critical fire weather conditions remain possible into Friday evening before returning Saturday afternoon over Southwest and South Central Montana. Afternoon humidity will drop to very low values of 5 to 10 percent across the lower elevations with slightly higher values of 10 to 15 percent Saturday. A weak mid- level boundary passing through the region Saturday afternoon could bring somewhat breezy westerly winds, mainly along and near the Continental Divide. Not expecting a major wind shift or strong winds from these boundaries though. Breezy winds combined with low humidity could result in critical fire weather conditions Saturday afternoon. Confidence remains high for humidity less than 20 percent and around 50 percent for winds over 15 mph Saturday. As a result, will hold off on fire weather highlights at this time. && .PRELIMINARY POINT TEMPS/POPS... GTF 57 91 57 89 / 10 10 30 10 CTB 56 85 53 83 / 10 10 10 0 HLN 59 90 58 89 / 0 20 20 10 BZN 51 90 51 88 / 0 10 20 10 WEY 39 83 42 81 / 0 10 10 20 DLN 51 87 50 86 / 0 10 10 10 HVR 60 89 59 88 / 10 10 30 20 LWT 55 87 56 85 / 0 10 30 20 && .TFX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING until 9 PM MDT this evening Beaverhead... Central and Southern Lewis and Clark...Jefferson...Madison. && $$ weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS BISMARCK ND
324 AM CDT SAT AUG 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE POTENTIAL FOR FOG AND LOW CLOUDS AT KJMS AND KBIS ARE THE PRIMARY CONCERNS FOR THE 06Z FORECAST. AREAS JUST EAST OF KJMS HAVE BECOME NEARLY SATURATED AT THE SURFACE WITH LOW TEMPERATURE / DEWPOINT SPREADS EARLY THIS MORNING. THE LATEST HRRR AND NAM NUMERICAL GUIDANCE SUGGESTS THERE COULD BE FOG DEVELOPMENT AT KJMS...AND WILL SHOW THAT IN THE LATEST TAF. LESSER CHANCES FOR VISIBILITY REDUCTIONS ARE SHOWN AT KBIS...AND WILL CARRY VCFG TO SUGGEST FOG COULD BE IN THE AREA EARLY THIS MORNING. THE REMAINDER OF THE FORECASTS WILL BE VFR. WINDS WILL BE FROM A SOUTHERLY DIRECTION TO START...BUT WESTERN AERODROMES WILL SEE A SHIFT TO THE NORTHWEST LATER IN THE PERIOD AS A FRONTAL BOUNDARY MOVES INTO THE REGION. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...CK LONG TERM...KS AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1225 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 1225 AM CDT SAT AUG 17 2013 EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS PATCHY STRATUS IN EASTERN SOUTH DAKOTA HAS DIMINISHED OVER THE PAST FEW HOURS. THE LATEST HOURLY TEMPERATURE / DEWPOINT PLOT SHOWS AREAS JUST EAST OF THE FORECAST AREA HAVE BECOME NEARLY SATURATED...AND WOULD EXPECT ADJACENT AREAS IN THE JAMES RIVER VALLEY TO SHOW A SIMILAR TREND EARLY THIS MORNING. THE GOING FORECAST ALREADY HAS PATCHY FOG IN THAT AREA...AND AFTER LOOKING AT THE HRRR DECIDED TO EXPAND THE FOG A LITTLE FARTHER WEST. WILL ADJUST THE TEMPERATURE / DEWPOINT SPREADS ACCORDINGLY...OTHERWISE MADE ONLY MINOR ADJUSTMENTS TO THE GRIDS. UPDATE ISSUED AT 924 PM CDT FRI AUG 16 2013 MINOR CHANGES IN HOURLY TEMPERATURES TO REFLECT CURRENT TRENDS. OTHERWISE ONGOING FORECAST FOR TONIGHT IS ON TRACK. CLEAR SKIES AND SOUTH WINDS EXPECTED FOR THE REST OF TONIGHT...EXCEPT THE POSSIBILITY OF SOME FOG AND PERHAPS LOW CLOUDS MOVING INTO THE JAMES RIVER VALLEY LATE TONIGHT. LATER SHIFTS WILL MONITOR ANY FOG OR LOW CLOUDS FORMING AND MOVING NORTHWARD FROM EASTERN SOUTH DAKOTA AND NEBRASKA. UPDATE ISSUED AT 629 PM CDT FRI AUG 16 2013 SURFACE HIGH PRESSURE OVER IOWA AND LOW PRESSURE IN THE LEE OF THE ROCKIES WAS KEEPING A SOUTHERLY WIND FLOW ACROSS THE DAKOTAS. DRY AIR ALOFT WITH THE UPPER LEVEL RIDGE BUILDING WILL KEEP SKIES MOSTLY CLEAR THIS EVENING. CURRENT FORECAST ON TRACK WITH NO CHANGES. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 337 PM CDT FRI AUG 16 2013 MID/UPPER LEVEL RIDGING OVER THE WESTERN GREAT PLAINS WILL CONTINUE TO GENERATE A DRY AND TRANQUIL WEATHER PATTERN OVER WESTERN AND CENTRAL NORTH DAKOTA THROUGH THE PERIOD. WEAK GRADIENT FLOW COMBINED WITH ABUNDANT LOW-LEVEL MOISTURE SHOULD ALLOW FOR PATCHY FOG DEVELOPMENT ACROSS THE JAMES RIVER BASIN AFTER MIDNIGHT TONIGHT. IT SHOULD BE QUICK TO BURN OFF AFTER SUNRISE SATURDAY MORNING. ABOVE NORMAL TEMPERATURES ARE EXPECTED SATURDAY AS WAA DEVELOPS AHEAD OF A SURFACE TROUGH. THE SURFACE TROUGH AXIS/BOUNDARY IS PROGGED TO ENTER NORTHWESTERN NORTH DAKOTA BY SATURDAY AFTERNOON. EVEN THOUGH THERE IS ENOUGH INSTABILITY AND DEEP LAYER SHEAR FOR CONVECTIVE DEVELOPMENT...A DRY PUSH ALOFT SHOULD INHIBIT AFTERNOON CONVECTION. THEREFORE...KEPT THE FORECAST DRY NORTHWEST FOR SATURDAY AFTERNOON. HOWEVER...WOULD NOT BE SURPRISED IF A THUNDERSTORM DEVELOPED ALONG THE BOUNDARY DURING THE LATE SATURDAY AFTERNOON/EARLY EVENING HOURS. WILL CONTINUE TO MONITOR THE CAP STRENGTH AS THE TIME GETS CLOSER. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 337 PM CDT FRI AUG 16 2013 WESTERLY ZONAL FLOW WILL ESTABLISH ITSELF EARLY IN THE PERIOD...AS THE UPPER LEVEL RIDGE CONTINUES TO FLATTEN. SEVERAL EMBEDDED WEAK IMPULSES...DEPICTED BY BOTH THE 12Z ECWMF AND GFS...WILL MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY. EVEN THOUGH THERE WILL BE AMPLE CAPE...SUFFICIENT DEEP LAYER SHEAR AND MODEST BOUNDARY LAYER MOISTURE...12Z NAM/GFS BUFR SOUNDINGS CONTINUE TO SUGGEST THAT A WARM LAYER WILL BE PRESENT ALOFT...ENOUGH TO SUPPRESS CONVECTION FROM FIRING ACROSS THE NORTHWEST BETWEEN 00Z AND 06Z SUNDAY. THE WARM LAYER ALOFT/CAPPING INVERSION MAY BE OVERCOME ONCE THE AFOREMENTIONED IMPULSES TRAVERSE THE AREA SUNDAY AND EARLY MONDAY...ALLOWING CONVECTION TO FIRE ALONG AND AHEAD OF A WEAK COLD FRONT FORECAST TO MOVE SOUTH. HAVE OPTED TO LEAVE SLIGHT CHANCE POPS IN FOR NOW AND WILL CONTINUE TO MONITOR OVER THE NEXT FEW MODEL RUNS. MONDAY AND TUESDAY...WESTERLY ZONAL FLOW CONTINUES. EVEN WITH THE WEAK COLD FRONTAL PASSAGE...H850 TEMPERATURES WILL REMAIN WARM BETWEEN 20 TO 22 C...WARMING TO BETWEEN 24 AND 26 C TUESDAY WHILE THE UPPER LEVEL RIDGE NUDGES NORTH. THIS WILL TRANSLATE TO SURFACE TEMPERATURES IN THE 90S. SIGNIFICANT DIFFERENCES DEVELOP BETWEEN THE 12Z GFS AND ECWMF WEDNESDAY AND CONTINUES THROUGH THE REMAINDER OF THE PERIOD REGARDING A STRONG COLD FRONTAL PASSAGE. THE 12Z ECWMF IS MORE AGGRESSIVE PROPAGATING THIS FEATURE SOUTH WEDNESDAY...SUGGESTING THAT SURFACE HIGH PRESSURE FROM CANADA WILL BUILD SOUTH IN ITS WAKE AND COOLING H850 TEMPS BY OVER TEN DEGREES C. HOWEVER...THE 12Z GFS DELAYS THE PASSAGE OF THE COLD FRONT UNTIL THURSDAY MORNING/AFTERNOON. AS A CONSEQUENCE...THERE IS A 10C DIFFERENCE BETWEEN THESE MODELS WEDNESDAY...AND THURSDAY ACROSS THE SOUTH...WITH THE GFS CONTINUING 20 TO 22 C H850 TEMPS (MID TO UPPER 90S AND ISOLATED 100 DEGREE READINGS AT THE SURFACE)...WHILE THE ECWMF SUGGESTS AN END TO THE HEAT...COOLING H850 TEMPS TO BETWEEN 14 TO 17 C (80S AT THE SURFACE WEDNESDAY AND COOLING TO THE 70S ON THURSDAY). THUS HAVE STUCK WITH THE ALLBLEND SOLUTION GIVEN THE SIGNIFICANT DISAGREEMENT BETWEEN THE GFS AND ECWMF. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1225 AM CDT SAT AUG 17 2013 THE POTENTIAL FOR FOG AND LOW CLOUDS AT KJMS AND KBIS ARE THE PRIMARY CONCERNS FOR THE 06Z FORECAST. AREAS JUST EAST OF KJMS HAVE BECOME NEARLY SATURATED AT THE SURFACE WITH LOW TEMPERATURE / DEWPOINT SPREADS EARLY THIS MORNING. THE LATEST HRRR AND NAM NUMERICAL GUIDANCE SUGGESTS THERE COULD BE FOG DEVELOPMENT AT KJMS...AND WILL SHOW THAT IN THE LATEST TAF. LESSER CHANCES FOR VISIBILITY REDUCTIONS ARE SHOWN AT KBIS...AND WILL CARRY VCFG TO SUGGEST FOG COULD BE IN THE AREA EARLY THIS MORNING. THE REMAINDER OF THE FORECASTS WILL BE VFR. WINDS WILL BE FROM A SOUTHERLY DIRECTION TO START...BUT WESTERN AERODROMES WILL SEE A SHIFT TO THE NORTHWEST LATER IN THE PERIOD AS A FRONTAL BOUNDARY MOVES INTO THE REGION. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CK SHORT TERM...TM LONG TERM...LTH AVIATION...CK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1135 PM CDT FRI AUG 16 2013 .UPDATE... ISSUED AT 1135 PM CDT FRI AUG 16 2013 TEMPS HAVE BEEN FALLING A BIT FASTER THAN EXPECTED IN THE NORTHWESTERN COUNTIES...SO CUT LOWS A FEW DEGREES IN THAT AREA. WINDS CONTINUE TO BE SOUTHERLY IN DIRECTION...AND THERE HAS BEEN SOME DECENT MIXING. DEW POINT DEPRESSIONS HAVE BEEN CLOSE TO ZERO AROUND VALLEY CITY AND COOPERSTOWN. STILL THINK THAT THE BEST CHANCE FOR FOG WILL BE IN THE JAMES RIVER VALLEY...BUT SOME IN OUR SOUTHWESTERN COUNTIES IS NOT OUT OF THE QUESTION. INCLUDED A BRIEF PATCHY MENTION DURING THE EARLY MORNING HOURS. UPDATE ISSUED AT 932 PM CDT FRI AUG 16 2013 NO MAJOR CHANGES TO THE CURRENT FORECAST. TEMPS STILL SEEM ON TRACK TO DROP INTO THE 50S IN THE EAST TO LOW 60S OVERNIGHT. SOME OF THE MODELS SUCH AS THE HRRR AND NAM ARE SHOWING SOME FOG FORMATION OVER THE JAMES VALLEY WHICH THEN MOVES INTO OUR SOUTHWESTERN COUNTIES BRIEFLY LATER TONIGHT. SOUTHWESTERLY WINDS WILL BE PICKING UP AND THINK THAT MIXING WILL KEEP MUCH FOG FROM FORMING AND WILL LEAVE OUT OF GRIDS FOR NOW. THINK THERE COULD BE SOME STRATUS THROUGH SO KEPT SOME CLOUDS IN THE FAR SOUTH. UPDATE ISSUED AT 627 PM CDT FRI AUG 16 2013 ONLY CHANGES WERE TO TWEAK CLOUD COVER A BIT AS SOUTHERN COUNTIES HAVE HAD A BIT MORE CU THAN EXPECTED THIS EVENING. THINK THAT SKIES WILL BECOME MOSTLY CLEAR AFTER SUNSET...BUT WILL HAVE TO WATCH THE SOUTH FOR ANY STRATUS MOVING UP OUT OF SD. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 242 PM CDT FRI AUG 16 2013 CURRENT VIS IMAGERY SHOWING SCT CU DECK HAS EXPANDED WESTWARD INTO SOUTHEASTERN ND. MOSTLY CLEAR ELSEWHERE. THERE IS MORE EXTENSIVE SKY COVER OVER EASTERN SD AND FAR SW MINNESOTA....HOWEVER THE NORTHERN EDGE CONTINUES TO BECOME MORE CELLULAR. MAIN CHALLENGE TONIGHT WILL BE TEMPERATURES AND WHETHER OR NOT THE LOW LEVEL SW FLOW WILL ADVECT ANY OF THIS MOISTURE INTO MY SOUTHEASTERN ZONES. MODELED RH IN GENERAL AGREEMENT WITH BRINGING CLOUD COVER NORTHWARD BUT NO SIGNS OF CLOUDS ON GFS/NAM MOS GUIDANCE. LATE AFTERNOON AND TONIGHT...FOR CLOUD SITUATION...THINK LAST COUPLE HOURS OF HEATING THIS AFTN WILL CONTINUE TO BREAK CLOUDS UP ENOUGH OVER SD THAT THEY WILL DISSIPATE IN THE EARLY EVENING AND WE WILL BE CLEAR TONIGHT ACROSS THE AREA. OVERNIGHT LOWS WILL BE A BIT WARMER THAN LAST NIGHT WITH SOUTHERLY FLOW EXPECTED THROUGH THE NIGHT. SATURDAY AND SATURDAY NIGHT...FULL SOLAR...BREEZY SOUTHWEST WINDS AND INCREASED MIXING AS WELL AS RISING H850 TEMPS WILL RESULT IN THE FIRST ABOVE NORMAL TEMPS FOR AUGUST 2013. COULD EVEN HIT 90 IN WARM AREAS AROUND THE VALLEY. MODELS ARE SHOWING A CHANCE FOR SOME SHOWERS OR A STORM TO DEVELOP MAINLY ACROSS THE NORTH AND AFTER 09Z. HOWEVER MAIN ENERGY WITH UPPER WAVE SHOULD BE ACROSS SOUTHERN MANITOBA AND WILL KEEP CWA DRY TONIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 242 PM CDT FRI AUG 16 2013 SUNDAY AND MONDAY...ANOTHER WARM DAY IS EXPECTED WITH INSTABILITY INCREASING IN THE AFTERNOON BUT A SOLID CAP IN PLACE. MERIDIONAL FLOW WILL BRING SEVERAL MINOR WAVES ACROSS THE AREA...HOWEVER TIMING NOT CONSISTENT ENOUGH AMONGST THE MODELS TO ADD ANY POPS THROUGH 00Z MON. BEST CHANCE WILL BE IN THE EVENING IF AND WHEN THE CAP ERODES. WITH MAIN H850 FLOW OVER THE WKND OUT OF WESTERN TX/NM VS AN OPEN GULF OF MEXICO...NOT SURE DEW POINTS WILL GET HIGH ENOUGH DRG DAY SUNDAY TO GIVE US A SIGNIFICANT CHANCE OF CONVECTION SUN EVENING HOWEVER WITH GFS SHOWING A STRONG VORT MOVING ACROSS (BUT OVERDOING CONVECTION)...WILL STICK WITH CONTINUITY AND MAINTAIN CHANCE POPS MAINLY ACROSS THE SOUTH. ONCE AGAIN CONFIDENCE FOR ANYTHING SIGNIFICANT IS LOW ATTM. EXPECT MONDAY TO BE DRY. MONDAY THROUGH FRIDAY...MODELS ARE DECENT WITH OVERALL FEATURES WITH SOME DIFFERENCES TO TIMING OF CONVECTIVE CHANCES. THE GFS/ECMWF WANTS TO DEVELOP SOME STORMS BY WED/THU...WITH THE GEM REMAINING DRY THROUGH THE PERIOD. THERE WILL BE VERY WARM TEMPS ALOFT AND TEMPS WILL REMAIN WELL ABOVE NORMAL. IF THE ATMOSPHERE REMAINS CAPPED...THEN THIS WOULD LIMIT CONVECTIVE CHANCES. WE HAVE ALSO BEEN DRY FOR SOME TIME...AND OVERALL EVAPOTRANSPIRATION WILL BE QUITE LOW. IN ADDITION...THE GULF OF MEXICO REMAINS SHUT OFF...SO THIS COULD ALSO LIMIT SHOWER/STORMS UNTIL A STRONGER WAVE MOVES OVER THE AREA. WILL CONTINUE WITH LOWER CHANCES FOR STORMS BY MID WEEK...ALTHOUGH CONFIDENCE IS NOT VERY HIGH FOR WIDESPREAD RAINFALL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1135 PM CDT FRI AUG 16 2013 ANY LOWER CIGS AND VIS SHOULD STAY SOUTH OF THE TAF SITES WITH VFR CONDITIONS PREVAILING AND SOME MID AND HIGH CLOUDS. SOUTH WINDS AROUND 10 KTS WILL PICK UP BY MID MORNING WITH GUSTS UP TO 25 KTS POSSIBLE. WINDS SHOULD DIMINISH AGAIN TOMORROW EVENING. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...JR SHORT TERM...SPEICHER LONG TERM...DK/SPEICHER AVIATION...JR
AREA FORECAST DISCUSSION
NWS MIDLAND/ODESSA TX
1222 AM CDT Sat Aug 17 2013 .DISCUSSION... See Aviation Discussion below. && .AVIATION... VFR conditions will prevail next 24 hours. Latest radar loop shows convection N of KHOB diminishing, and remnants look to pass NE of the terminal. Otherwise, another widespread CU field is expected to develop today 16-19Z, w/bases 7-8 kft agl. && .PREV DISCUSSION... /ISSUED 633 PM CDT Fri Aug 16 2013/ AVIATION... 00Z TAF issuance... No major aviation concerns for the next 24...VFR conditions are expected at all TAF sites. There is currently come thunderstorm activity just west of CNM this evening but NM terminals do not look to be affected in the immediate future. Will need to keep an eye on any convection moving south out of Chaves county and send an update to include mention of TSRA if needed. Generally light east southeasterly winds this evening should persist overnight and into Saturday. PREV DISCUSSION... /ISSUED 154 PM CDT Fri Aug 16 2013/ DISCUSSION... The Mesoscale Convective Complex which clipped the western Low Rolling Plains this morning generated quite the bubble surface high and sent an outflow boundary westward across the CWA. The modified airmass behind this boundary will result in high temperatures several degrees lower than what was previously expected, especially over the eastern half of the forecast area, and will affect convection this afternoon, and more than likely, tonight. The latest RUC bears this out with a higher theta e axis at H7 shunted west of the 16/12Z operational models. Think we will still see widely scattered thunderstorms over the higher terrain through max heating, but think convection will drop into southeast New Mexico along the theta e axis overnight. Instability around 1000 J/Kg, mid level lapse rates of 7.5-8 C/Km and 0-6 Km Bulk Shear Vectors around 35kt could yield a few strong to severe storms. Since the overall threat is limited, will make a mention in the HWO. Think convection Saturday and Sunday will mainly occur over the higher terrain as an upper ridge over Arizona repositions further north over the Four Corners region, with the flow aloft over the CWA becoming more northeasterly. Storms will likely develop over the higher terrain of New Mexico each afternoon, then spread south/ southwestward under the eastern fringe of the upper ridge. Temperatures will stay near to above normal through the weekend. Models are still undecided on whether an inverted upper trough will trek westward into the area from the Gulf of Mexico next week. Will not add any rain chances at this time, but some could be added mid to late next week for such a feature if the upper ridge does not remain too strong for it to impinge upon the area. Temperatures should be near normal next week, especially the second half. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ 44
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1140 PM CDT FRI AUG 16 2013 .DISCUSSION... See aviation discussion below. && .AVIATION... VFR will prevail the next 24 hours with light winds through the period. && .PREV DISCUSSION... /ISSUED 723 PM CDT FRI AUG 16 2013/ DISCUSSION... Expect VFR conditions to prevail over west central Texas through the next 24 hours. AVIATION... Early morning convection has stabilized the atmosphere today. Soundings do hint at the possibility of FEW150 during the overnight hours, but given the lack of any evidence of this upstream on satellite imagery, will opt to maintain SKC at all terminals. Winds are expected to become light and variable overnight. PREV DISCUSSION... /ISSUED 336 PM CDT FRI AUG 16 2013/ SHORT TERM... /Tonight and Tomorrow/ Visible satellite imagery shows sunny skies across West Central Texas this afternoon. The latest mesoanalysis indicates a stable environment over our area, with an instability axis across South and far West Texas. The models, including the 3KM HRRR model develop scattered thunderstorms over Eastern New Mexico and far West Texas in the instability axis during the late afternoon and evening. Upper level northerly flow will keep this activity west of our area for tonight. Lows will be in the mid 60s to lower 70s. Going with a dry forecast for Saturday across the area. Isolated thunderstorms will probably fire to our west during the afternoon hours. The upper level northerly flow should keep the storms west of our area. Highs will be in the lower to mid 90s. LONG TERM... /Saturday Night through Friday/ The upper level flow will be north to northeast next week as a high pressure ridge sets up from the Southern Rockies into the Central Plains. Basically a normal summertime pattern with little upper level and mesoscale forcing. Temperatures will be near or slightly above seasonable normals. Highs will be in the 90s with lows in the upper 60s to lower 70s. Going with a dry forecast through the extended period. && .PRELIMINARY POINT TEMPS/POPS... Abilene 66 92 67 94 68 / 10 10 5 5 5 San Angelo 67 93 68 95 68 / 10 10 5 5 5 Junction 68 94 69 97 66 / 10 10 5 5 5 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 24
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1003 PM PDT Fri Aug 16 2013 .SYNOPSIS... A slow moving upper level trough will keep unsettled conditions over the Inland Northwest through Saturday. The trough will pass all areas by Saturday evening and Sunday delivering locally breezy winds. Westerly flow will build over the region through the middle of the week bringing dry weather and seasonable temperatures. The weather will turn more unsettled toward the end of the next work week with a return of some thunderstorms possible. && .DISCUSSION... Evening update: widely scattered to isolated showers and thunderstorms have been found across northeast Oregon and portions of the lower Idaho Panhandle this evening. In the past hour or so more activity has been developing and moving into parts of southeast WA, including Whitman county. The current trajectory suggest some may also slip as far north as southern Spokane and Kootenai county. I`m not thinking they will reach to the Spokane Metro at this time, but there is the a small potential they could clip the Post Falls or Coeur d`Alene area. Timing suggests entering southern Spokane county around 11 pm. These are quick movers, so may produce some brief heavy rain and gusty winds, maybe a little bit of hail. Much of this activity has been found under a ribbon of modest instability and jet streak and subtle mid-level disturbance moving along the slowly-advancing cold front. The RUC13 (and other guidance) continues to show some elevated CAPE and a ribbon of favorable high level total totals across the southeast through the night. Hence the continuing isolated shower and thunder threat through the night. /J. Cote` && .AVIATION... 06Z TAFS: A front will continue to push across the Inland Northwest, bringing some middle and high clouds, as well as the risk for some widely sct to isolated -shra/-tsra. The highest threat among TAF sites will be around KLWS/KPUW...and perhaps KCOE but some may also be found in the vcnty of KGEG/KSFF through the overnight. The main threat, aside from lightning, will be possible gusty winds. Otherwise look for VFR conditions, locally breezy after 18-21Z Saturday, subsiding again late. /J. Cote` && .PRELIMINARY POINT TEMPS/POPS... Spokane 63 84 60 83 60 83 / 10 10 10 0 0 0 Coeur d`Alene 59 84 58 83 56 83 / 10 10 10 0 0 0 Pullman 55 84 52 83 50 86 / 20 10 10 0 0 0 Lewiston 66 92 64 93 62 94 / 20 10 10 0 0 0 Colville 57 88 54 87 53 89 / 10 20 10 0 0 0 Sandpoint 55 82 53 83 50 82 / 10 10 10 0 0 0 Kellogg 58 82 57 81 56 83 / 20 10 10 0 0 0 Moses Lake 61 89 60 88 60 88 / 10 0 0 0 0 0 Wenatchee 66 87 64 88 64 88 / 10 0 0 0 0 0 Omak 61 89 61 89 61 89 / 0 10 10 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1110 PM CDT FRI AUG 16 2013 UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE .SHORT TERM...TONIGHT AND SATURDAY ISSUED AT 241 PM CDT FRI AUG 16 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOWS A SPRAWLING HIGH PRESSURE SYSTEM STRETCHING FROM THE NORTHERN MISSISSIPPI VALLEY TO NEW ENGLAND. AS ONE SHORTWAVE DIGS OVER THE SOUTHERN PLAINS WHILE ANOTHER SHIFTS EAST OVER MANITOBA...MID-LEVEL RIDGING IS GRADUALLY BUILDING EAST OVER THE NORTHERN PLAINS. THIS PATTERN WILL CONTINUE TO LEAD TO QUIET WEATHER OVER THE NEXT SEVERAL DAYS...MAKING CLOUDS AND TEMPS THE MAIN FORECAST CONCERN IN THE SHORT TERM. TONIGHT...HIGH PRESSURE WILL REMAIN OVER THE REGION BENEATH BUILDING HEIGHTS IN THE MID AND UPPER LEVELS. WISCONSIN WILL BE POSITIONED BETWEEN WEATHER SYSTEMS NORTH AND SOUTH OF THE REGION. WITH LOW PWATS AND MOSTLY CLEAR CONDITIONS...WILL LIKELY SEE PATCHY GROUND FOG FORM LATE TONIGHT ACROSS THE SANDY SOIL AREAS AND RIVER VALLEYS. WENT BELOW MOS GUIDANCE FOR LOWS...WHICH SHOULD BE A FEW DEGREES WARMER THAN LAST NIGHT. SATURDAY...HIGH PRESSURE THROUGH THE COLUMN WILL PROVIDE ANOTHER QUIET AND SUNNY DAY. START TO GET A LITTLE MORE RETURN FLOW ACROSS THE REGION...WHICH SHOULD LEAD TO SLIGHTLY WARMER HIGH TEMPS AND MORE HUMIDITY. HIGHS MAINLY IN THE LOW TO MID 80S...EXCEPT COOLER NEAR THE LAKE. .LONG TERM...SATURDAY NIGHT THROUGH FRIDAY ISSUED AT 241 PM CDT FRI AUG 16 2013 MODELS ARE NOW IN GOOD AGREEMENT WITH OVERALL PATTERN. THEY BRING UPPER RIDGING INTO THE NORTHERN PLAINS AND WESTERN GREAT LAKES THROUGH MIDWEEK. A SHORT WAVE TROUGH MOVING ALONG THE CANADIAN BORDER WILL SUPPRESS THE RIDGING A BIT SUNDAY NIGHT AND MONDAY AND COULD PRODUCE SCATTERED THUNDERSTORMS IN THE FAR NORTH. PROLONGED SOUTHERLY FLOW AND WARMER TEMPERATURES ALOFT WILL COMBINE TO PRODUCE VERY WARM AND MORE HUMID CONDITIONS DURING THE MIDDLE OF THE WEEK WITH THE WARMEST WEATHER SINCE MID JULY. THE HEAT SHOULD SUBSIDE AS A COLD FRONT MOVES THROUGH THURSDAY AND THURSDAY NIGHT. COOLER AND DRIER AIR EXPECTED FRIDAY THROUGH SUNDAY. && .AVIATION...FOR 06Z TAF ISSUANCE ISSUED AT 1107 PM CDT FRI AUG 16 2013 HIGH PRESSURE AND VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER THROUGH MOST OF THIS TAF PERIOD. THE EXCEPTION WILL BE OVERNIGHT...WHEN SOME SOME PATCHY GROUND FOG WILL IMPACT THE REGION THROUGH ABOUT 12Z/SAT. THE FOG SHOULD BE MOST WIDESPREAD AND DENSE OVER NORTH CENTRAL WISCONSIN. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......RDM AVIATION.......KIECKBUSCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
555 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 555 AM CDT SAT AUG 17 2013 HELD OFF AS LONG AS WE COULD...BUT KUEX NOW INDICATES ISOLATED SHOWER ACTIVITY DEVELOPING OVER ROOKS COUNTY. MEAGER ELEVATED POTENTIAL INSTABILITY IS ALSO SUGGESTED BY RAP ANALYSIS PROXIMITY SOUNDINGS AND THUS...OCCASIONAL LIGHTNING/THUNDER ALSO CANNOT BE RULED OUT. WENT AHEAD WITH 20% POPS UNTIL 13Z FOR OUR EXTREME SOUTHWESTERN CWA. THE LOW LEVEL JET SHOULD QUICKLY DIMINISH POST- SUNRISE THUS ALLOWING FOR DIMINISHING SHOWER AND THUNDERSTORM ACTIVITY. REMAINDER OF THE FORECAST WAS LEFT UNCHANGED. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 346 AM CDT SAT AUG 17 2013 OVERNIGHT MAP ANALYSIS INDICATES MID TO UPPER LEVEL LONGWAVE RIDGING OVER THE WESTERN CONUS...WITH A TROUGH OVER THE EAST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM THE WEST-CENTRAL CONUS...NORTHEAST INTO SOUTHWEST AND SOUTH CENTRAL CANADA...AND THEN SOUTHEAST ACROSS THE PLAINS...AND FINALLY EAST/NORTHEAST ACROSS THE SOUTHEASTERN CONUS AND ON INTO THE EASTERN CONUS. MID TO UPPER LEVEL FLOW OVER THE CENTRAL PLAINS REMAINS FROM THE NORTH/NORTHWEST AS A RESULT...BUT IS NOT PARTICULARLY STRONG ONLY MAXING OUT AT AROUND 45KTS NEAR 200MB PER 00Z SOUNDING DATA FROM KLBF AND KOAX. WATER VAPOR IMAGERY ALSO SHOWS THE AFOREMENTIONED LONGWAVE RIDGE AND TROUGH...WITH INCREASED VALUES OF MID LEVEL MOISTURE FLOWING ALONG THE MID LEVEL JET AXIS. AT THE SURFACE A LARGE AREA OF HIGH BAROMETRIC PRESSURE EXISTS OVER THE MISSOURI AND MID MISSISSIPPI RIVER VALLEYS. LOW LEVEL FLOW ACROSS OUR AREA REMAINS FROM THE SOUTHEAST AS A RESULT. LOW LEVEL THERMAL ADVECTION ALONG THE AXIS OF A ~30KT 850MB JET AXIS IS HELPING PROMOTE ISOLATED SHOWER AND THUNDERSTORM ACTIVITY OVER PORTIONS OF WESTERN KANSAS THIS MORNING. ALTHOUGH THIS ACTIVITY HAS REMAINED SOUTHWEST OF OUR CWA SO FAR TONIGHT...GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF- MEAN ALL SUGGEST THE LOW LEVEL JET STREAK AXIS WILL VEER MORE INTO OUR AREA TOWARDS 12Z. THE NAM AND EC BOTH SUGGEST LIGHT PRECIPITATION WILL BE REALIZED OVER EXTREME SOUTHWESTERN PORTIONS OF OUR CWA...A SOLUTION ALSO SUPPORTED TO AN EXTENT BY THE HRRR AND 1KM WRF-NMM. ALL THAT BEING SAID...CONFIDENCE OF ANY ONE LOCATION ACROSS OUR CWA...INCLUDING OUR SOUTHWESTERN CWA...ACTUALLY OBSERVING MEASURABLE RAINFALL REMAINS VERY LOW AND AS A RESULT...WILL CONTINUE WITH THE DRY FORECAST FOR EARLY THIS MORNING AND CONTINUE TO MONITOR. FOR THE REST OF TODAY AND TONIGHT...AN OVERALL LACK IN KINEMATIC FORCING SHOULD PRESENT DRY CONDITIONS TO OUR AREA THROUGH TONIGHT. MUCH LIKE THIS MORNING HOWEVER...THE ONLY EXCEPTION COULD BE ACROSS OUR WEST/SOUTHWEST 06-12Z SUNDAY AS THE AXIS OF ~30KT 850MB JET STREAK ONCE AGAIN DEVELOPS OVER PORTIONS OF THE CENTRAL HIGH PLAINS. THAT BEING SAID...QPF FIELDS FROM VARIOUS MODELS DO NOT SUGGEST MEASURABLE PRECIPITATION WILL BE REALIZED ANYWHERE ACROSS OUR CWA AND GIVEN THIS...WILL GO AHEAD AND MAINTAIN A DRY FORECAST THROUGH 12Z SUNDAY AND LET FUTURE SHIFTS REEVALUATE THE POTENTIAL NEED FOR LOW POPS DURING THE EARLY MORNING HOURS ON SUNDAY. CLOUD COVER REALLY KEPT TEMPERATURES ACROSS OUR CWA ON THE COOL SIDE DURING THE DAY FRIDAY. THE STRATUS DECK HAS NOT BEEN NEARLY AS DENSE AS EXPECTED TONIGHT HOWEVER AND THE CURRENT THINKING IS THIS STRATUS SHOULD DISSIPATE AND LIFT BY MID TO LATE MORNING WHICH SHOULD ALLOW FOR WARMER AFTERNOON HIGHS. GUIDANCE FROM THE MET...MAV...AND ECS SEEMS TO HAVE A GOOD HANDLE ON THIS AND TAKING AN EVEN AVERAGE OF THE THREE PROVIDES AFTERNOON HIGH TEMPERATURES IN THE UPPER 70S TO NEAR 80 ACROSS MUCH OF THE CWA. CLEARER SKIES SHOULD ALLOW FOR A SLIGHTLY COOLER OVERNIGHT LOWS TONIGHT WHEN COMPARED TO EARLY THIS MORNING...WITH OVERNIGHT LOWS IN THE UPPER 50S TO NEAR 60 CURRENTLY FORECAST FOR MOST LOCATIONS TONIGHT. FINALLY...NEAR-ZERO LOW LEVEL DEW POINT DEPRESSIONS AND A FAIRLY LIGHT SOUTH/SOUTHEAST LOW LEVEL WIND FIELD COULD PROMOTE PATCHY FOG ACROSS THE AREA TOWARDS SUNRISE SUNDAY. VISIBILITY RESTRICTION IS NOT EXPECTED TO BE SIGNIFICANT...BUT WILL GO AHEAD WITH PATCHY FOG IN THE GRIDS BEGINNING 09Z SUNDAY. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 346 AM CDT SAT AUG 17 2013 A RELATIVELY QUIET WEATHER PATTERN WILL BECOME EVIDENT BEGINNING SUNDAY AS HIGH PRESSURE CONTINUES TO SLIDE OVER THE REGION FROM THE INTERMOUNTAIN WEST. WATER VAPOR IMAGERY DEPICTS A 500MB TROUGH OVER THE EASTERN PART OF THE CONUS...WHILE HIGH PRESSURE IS BUILDING IN OVER MOST OF THE WESTERN CONUS. THERE IS A SHORT WAVE TROUGH EVIDENT OVER THE PACIFIC NORTHWEST AS WELL. MODELS ARE IN GOOD AGREEMENT WITH REGARDS TO HIGH PRESSURE BUILDING IN FROM THE WEST TO CONTINUE. THIS PATTERN WILL MAKE FOR WARMER DAYS AHEAD WITH TEMPERATURES FORECAST TO BE MORE SEASONABLE THAN THE PREVIOUS WEEK. THE PATTERN OVER THE NEXT WEEK IS SHOWING UNFAVORABLE CONDITIONS FOR ANY PRECIPITATION AND HENCE A DRY FORECAST THROUGH MOST OF THE EXTENDED AS HIGH PRESSURE DOMINATES THE REGION. THURSDAY NIGHT INTO FRIDAY APPEARS TO BE THE ONLY DAY SHOWING ANY CHANCE FOR PRECIPITATION...BUT THE LATEST RUNS OF THE GFS AND EC ARE BOTH BEGINNING TO SHOW DRY CONDITIONS IN THE EXTENDED. SINCE THIS IS THE FIRST RUN OF THE EC AND GFS AGREEING IN FAVOR OF DRIER CONDITIONS...I WILL LEAVE THE SLIGHT CHANCES IN THERE FOR THURSDAY NIGHT INTO FRIDAY UNTIL SOME CONSISTENCY EVOLVES. DONT WANT A FLIP FLOP SCENARIO DEVELOPING. I CAN SEE THESE POPS GETTING YANKED IF THIS TREND CONTINUES INTO DAY SHIFT THOUGH. SEEMS VERY REASONABLE TO HAVE THE DRY FORECAST BASED ON THE HIGH PRESSURE STILL PROGGED TO BE NEARLY CENTERED OVER THE CENTRAL PLAINS REGION COME FRIDAY. WITH THE HELP OF HIGH PRESSURE BUILDING IN OVER THE REGION...TEMPERATURES WILL BE MORE SEASONABLE THROUGH THE EXTENDED. SUNDAY WILL BE THE COOLEST DAY OVER THE FORECAST PERIOD...WITH HIGHS RANGING FROM THE LOWER 80S TO UPPER 80S. MONDAY WILL BE SLIGHTLY WARMER. BUT BY TUESDAY...HIGH TEMPERATURES NEAR 90 DEGREES WILL BE THE NORM THROUGH AT LEAST FRIDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 555 AM CDT SAT AUG 17 2013 VFR CONDITIONS FORECAST THROUGH THE NEXT 24 HOURS. STRATUS...WHICH WAS EXPECTED TO PERSIST OVER PORTIONS OF SOUTH CENTRAL NEBRASKA...HAS MATERIALIZED MORE OVER WESTERN NEBRASKA. LATEST GUIDANCE SUGGESTS THIS STRATUS WILL REMAIN TO THE WEST OF GRI BEFORE DISSIPATING LATER THIS MORNING. GIVEN THE LATEST OBSERVATIONS FROM ACROSS THE REGION...AS WELL AS MODEL GUIDANCE...OPTED TO GO WITH VFR CONDITIONS THROUGH THE TAF PERIOD. THIS WILL NEED TO BE CLOSELY MONITORED THROUGH THE NEXT 3-6 HOURS TO ENSURE THE STRATUS OUT WEST DOES NOT PUSH EAST CLOSER TO GRI...BUT OTHERWISE VFR CONDITIONS SHOULD PERSIST AT GRI. THE SURFACE WIND WILL REMAIN FROM THE SOUTHEAST DURING THE TAF PERIOD...GENERALLY IN THE 6-10KT RANGE. PATCHY FOG WILL BE POSSIBLE TOWARDS SUNRISE SUNDAY...BUT AT THIS TIME SIGNIFICANT VISIBILITY RESTRICTION IS NOT EXPECTED AT KGRI...THUS THE P6SM VISIBILITY FORECAST THROUGHOUT THE TAF. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...BRYANT SHORT TERM...BRYANT LONG TERM...GUERRERO AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1055 AM EDT SAT AUG 17 2013 .SYNOPSIS... SURFACE HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL EXTEND SOUTHWARD INTO THE PIEDMONT OF CAROLINAS THROUGH SUNDAY. MEANWHILE WEAK WAVES OF LOW PRESSURE WILL DEVELOP AND MOVE ALONG A STALLED FRONT ACROSS GEORGIA AND COASTAL CAROLINA. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1055 AM SATURDAY... ...CHILLY AND UNSETTLED WEATHER TODAY... SCATTERED TO NUMEROUS PATCHES OF LIGHT RAIN AND DRIZZLE ARE NOTED ON THE KRAX WSR-88D THIS MORNING. THE PRECIPITATION IS LARGELY BEING DRIVEN BY MODEST LOW LEVEL ISENTROPIC LIFT WITH A FAIRLY STRONG SOUTHWESTERLY FLOW ALOFT. THE ISENTROPIC LIFT CAN BE SEEN IN THE 12 UTC KGSO RAOB AND IN THE HMT-SEPS PROJECT VERTICAL PROFILER NEAR NEW BERN. NWP DATA AND TRENDS IN THE NEW BERN PROFILER SUGGEST THAT THE BEST LOW LEVEL FORCING FOR ASCENT WILL SHIFT INTO THE EASTERN PIEDMONT AND COASTAL PLAIN DURING THE NEXT 6 HOURS AND HAVE ACCORDINGLY INCREASED AND FOCUSED NEAR TERM POPS THERE. AFTER THIS PERIOD THERE WILL LIKELY BE A DECREASE IN PRECIP COVERAGE ACROSS THE SOUTHEASTERN AND EASTERN PORTIONS OF THE RAH CWA AS HIGH RES NWP GUIDANCE...PRIMARILY RECENT RUNS OF THE HRRR AND THE 00UTC NSSL WRF-ARW INDICATE. ANOTHER BATCH OF PRECIPITATION IS LIKELY TO PUSH INTO THE SOUTHWESTERN AND WESTERN PIEDMONT LATE THIS AFTERNOON AND EVENING AS ANOTHER PERTURBATION IN THE SOUTHWEST FLOW ALOFT APPROACHES AND ENHANCES THE LOW LOW/MID-LEVEL ASCENT. WHILE RAINFALL AMOUNTS HAVE BEEN SOMEWHAT LIGHT...THEY APPEAR SUFFICIENT TO SUSTAIN AND LOCK IN THE COLD AIR DAMMING AIR MASS ACROSS THE PIEDMONT. BASED ON RECENT OBSERVATIONS HAVE ADJUSTED TEMPS UP A DEGREE OR SO INTO THE 66 TO 76 DEGREE RANGE WHICH IS MORE THAN 10 DEGREES BELOW NORMAL. HAVE REDUCED QPF AMOUNTS A BIT TODAY GIVEN THE ISENTROPIC LIFT APPEARS WEAKER THAN PROGGED 12 TO 36 HOURS AGO AND RADAR AMOUNTS HAVE IN GENERAL BEEN LESS THAN EXPECT. STILL RAIN TOTALS FOR THIS EVENT BEGINNING AT MIDNIGHT WILL LIKELY RANGE BETWEEN A QUARTER AND A HALF INCH. -BLAES TONIGHT...BULK OF RAIN EARLY IN THE EVENING SHOULD OCCUR ACROSS THE NORTHERN AND WESTERN PIEDMONT AS 850MB WARM FRONT GRADUALLY PIVOTS NORTHWEST THROUGH THIS REGION. THE WARMER AIR ALOFT OVER THE RELATIVELY COOL SFC AIR MASS SHOULD RESULT IN AREAS OF FOG ACROSS THE PIEDMONT OVERNIGHT ALONG WITH PATCHES OF LIGHT RAIN. RAIN COVERAGE SHOULD BE LESS OVER THE COASTAL PLAIN AND SANDHILLS. MIN TEMPS IN THE MID 60S NW TO NEAR 70 SE. -WSS && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 310 AM SATURDAY... SUNDAY AND SUNDAY NIGHT...MAIN SHEAR AXIS ALOFT MIGRATES WESTWARD TO A POSITION OVER THE FOOTHILLS INTO THE WESTERN PIEDMONT. AIR MASS PLENTY MOIST ENOUGH TO SUPPORT THE DEVELOPMENT OF SCATTERED-NUMEROUS SHOWERS. FARTHER EAST...MODEL GUIDANCE HINTING AT SOME MID-UPPER LEVEL DRYING TAKING PLACE. IF THIS WERE TO OCCUR...BREAKS IN OVERCAST MAY DESTABILIZE THE LOW LEVEL AIR MASS ENOUGH TO GENERATE SCATTERED SHOWERS AND A FEW THUNDERSTORMS. MODEL GUIDANCE CURRENTLY SUGGEST INSTABILITY AS MARGINAL AT BEST THOUGH BULK SHEAR VALUES SUFFICIENT (30-40KTS) FOR THE DEVELOPMENT OF ORGANIZED CONVECTION. MODEL SFC DATA ALSO DEPICT A WEAK SURFACE BOUNDARY IN VICINITY OF THE COASTAL PLAIN SUNDAY AFTERNOON-EVENING. ANY STORMS THAT FORM AND MOVE ALONG THIS FEATURE MAY EXHIBIT SOME ROTATION. LACK OF SUFFICIENT WIND SPEED SHOULD LIMIT SEVERE POTENTIAL. TEMPS SUNDAY HIGHLY DEPENDENT ON ANY BREAKS IN THE OVERCAST AND EXTENT OF SHOWER ACTIVITY. MOS GUIDANCE HINTING AT SOME RECOVERY OF THE AIR MASS ESPECIALLY IN THE COASTAL PLAIN. FAVOR WAITING TO SEE THE EXTENT OF RAIN COVERAGE TODAY AND DEVELOPMENT OF CAD BEFORE RAISING TEMPS TOO MUCH ON SUNDAY. PLAN TO MAINTAIN MAX TEMPS FROM PREVIOUS FORECAST WITH LOWER 70S NW TO THE LOWER 80S SE. SHOWER CHANCES DWINDLE SUNDAY NIGHT AS SHEAR AXIS WEAKENS IN RESPONSE TO RISING HEIGHTS FROM THE BUILDING SUBTROPICAL RIDGE TO OUR EAST AND AIR MASS NOT AS SATURATED. PLAN TO MAINTAIN A CHANCE TO SLIGHT CHANCE POPS ACROSS THE REGION (HIGHEST IN THE WEST-NW). MIN TEMPS MID-UPPER 60S. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 310 AM SATURDAY... MONDAY THROUGH TUESDAY NIGHT: THE CLOSED LOW CURRENTLY OVER THE LOWER MS RIVER VALLEY IS FORECAST TO OPEN AND LIFT TOWARDS OUR REGION THIS WEEKEND AND SLOWLY MOVE ACROSS OUR AREA MONDAY INTO TUESDAY. THIS FEATURE ALONG WITH ABUNDANT MOISTURE (PW`S OF AROUND 2") IN ADVANCE OF THE SYSTEM SHOULD SET THE STAGE FOR AT LEAST SCATTERED AFTERNOON AND EVENING SHOWERS AND STORMS ACROSS CENTRAL NC ON MONDAY AREAWIDE. TUESDAY THE HIGHEST CONCENTRATION OF SHOWERS AND STORMS IS EXPECTED ACROSS THE SOUTHERN/SOUTHEASTERN HALF OF CENTRAL NC AS THE SHEAR SLOWLY MOVES ACROSS THE AREA. THUS... WE KEEP CHANCE AFTERNOON AND EVENING POPS FOR ALL LOCATIONS MONDAY. TUESDAY WILL DO THE SAME... BUT WILL ADVERTISE LOW CHANCE POPS ACROSS THE NORTH/NORTHWEST AS THE SHEAR AXIS SLOWLY SHIFTS SOUTH/SOUTHEASTWARD ACROSS THE AREA ON TUESDAY... USHERING DRY AIR ALOFT. TEMPERATURES DURING THIS TIME FRAME WILL REBOUND AS ANY LINGERING SURFACE BOUNDARIES ACROSS THE REGION BEGIN TO WASHOUT. HOWEVER... WE MAY SEE THE FAR NORTHWEST PIEDMONT HANG ONTO A RESIDUAL CAD AIRMASS FOR MOST OF THE DAY MONDAY. THUS... WILL SHOW TEMPS RANGING FROM THE UPPER 70S TO NEAR 80 FAR NW TO UPPER 80S SE. TUESDAY EXPECTED WE WILL SEE MID TO UPPER 80S ACROSS THE AREA. LOW TEMPS DURING THIS TIMEFRAME WILL BE NEAR NORMAL... IN THE UPPER 60S TO LOWER 70S. WEDNESDAY THROUGH FRIDAY: THE LINGERING SHEAR AXIS IS EXPECTED TO EITHER REMAIN ACROSS OUR SOUTHERN COUNTIES OR PUSH JUST TO THE SOUTH OF OUR REGION WHILE WEAKENING ON WEDNESDAY INTO THURSDAY. THROUGH 84 HOURS BOTH THE NAM AND GFS SHOW THIS AFOREMENTIONED SHEAR AXIS ACROSS OUR REGION IN A ENE TO WSW FASHION... WHILE THE ECMWF IS SLOWER AND HAS THE FEATURE BACK ACROSS THE HIGHER TERRAIN AT THIS TIME... BEFORE SETTLING THIS FEATURE SOUTH/SOUTHEASTWARD INTO OUR AREA ON TUESDAY AFTERNOON INTO TUESDAY NIGHT THEN LINGERING THE FEATURE ACROSS SOUTHERN PORTIONS OF THE AREA ON WEDNESDAY. THUS... EXPECT THE BEST CHANCE OF SEEING ANY SHOWERS AND STORMS ON WEDNESDAY WILL BE ACROSS SOUTHERN PORTIONS OF THE AREA. THE FORECAST BECOMES MORE UNCLEAR ON THURSDAY INTO FRIDAY... FIRST WITH THE TRACK AN EVOLUTION OF TWO SEPARATE S/W FEATURES. THE GFS ATTEMPTS TO BRING SOME FORM OF S/W ENERGY (POSSIBLY FROM THE REMNANTS OF THE SYSTEM CURRENTLY LOCATION IN THE GULF OF MEXICO) AROUND THE EXPANDING SUB-TROPICAL RIDGE ACROSS THE DEEP SOUTH AND INTO OUR AREA ON THURSDAY INTO THURSDAY NIGHT... WHILE THE LATEST ECMWF (12Z/16TH) HAS A WEAK S/W DROPPING SOUTHWARD OUT OF THE GREAT LAKES ON WEDNESDAY AND MOVING ACROSS THE MID-ATLANTIC REGION LATE THURSDAY INTO FRIDAY. GIVEN THIS AND WPC IS ADVERTISING A BETTER CHANCE OF SHOWERS AND STORMS THAT DAY ACROSS OUR AREA WILL HOLD ONTO CHANCE POPS FOR THURSDAY. ON FRIDAY... THE GFS AND ECMWF DIFFER WITH REGARD TO THE NEXT APPROACHING COLD FRONT... WITH THE GFS BRINGING A FRONT INTO THE AREA BY LATE FRIDAY... WITH THE ECMWF MUCH SLOWER. FOR NOW WILL KEEP POPS AS IS FOR FRIDAY LOW END CHANCE/SLIGHT CHANCE ACROSS THE AREA. TEMPS DURING THIS TIME SHOULD BE NEAR NORMAL... UPPER 80S TO NEAR 90 FOR HIGHS WITH LOWS IN THE UPPER 60S TO LOWER 70S. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 655 AM SATURDAY... WARM MOIST AIR BEING LIFTED OVER THE COOL DRY STABLE AIR MASS AT THE SURFACE HAS CAUSED LOW CLOUDS AND AREAS OF RAIN TO DEVELOP ACROSS CENTRAL NC SINCE 09Z. WIDESPREAD MVFR CEILINGS EXPECTED BY MID-LATE MORNING ACROSS ALL OF CENTRAL NC WITH POCKETS OF IFR CEILING PROBABLE THIS AFTERNOON. THE LIKELIHOOD OF IFR CEILINGS BY DUSK APPEARS TO BE A GOOD BET WITH PATCHES OF RAIN PERSISTING WELL INTO THE EVENING HOURS BEFORE AREAS OF DRIZZLE AND FOG LIMIT THE VISIBILITY. SUNDAY WILL START OUT WITH LOW CEILINGS IN THE LIFR/IFR RANGE. BY AFTERNOON...COULD SEE SOME IMPROVEMENT...ESPECIALLY IN VICINITY OF KFAY AND KRWI WHERE BASES MAY LIFT TO THE HIGH END MVFR/LOW END VFR BY MID-LATE AFTERNOON. FARTHER WEST...CEILINGS WILL LIKELY BE IN THE MVFR CATEGORY ALL DAY ALONG WITH SPOTTY LIGHT RAIN OR RAIN SHOWERS. AFTERNOON HEATING MAY TRIGGER AN ISOLATED THUNDERSTORM OR TWO IN THE COASTAL PLAIN. MVFR CONDITIONS DUE TO CEILINGS WILL PERSIST SUNDAY NIGHT INTO EARLY MONDAY WITH A PERIOD OF IFR CEILINGS HIGHLY PROBABLY. HEATING SHOULD RAISE CLOUD BASES TO THE HIGH END MVFR IN THE TRIAD WITH LOW END VFR BASES ANTICIPATED ELSEWHERE. ADDITIONAL HEATING OF THE MOIST AIR MASS SHOULD TRIGGER SCATTERED CONVECTION...MAINLY IN THE SANDHILLS AND COASTAL PLAIN MONDAY AFTERNOON...DIMINISHING MONDAY EVENING. AVIATION WEATHER CONDITIONS WILL GRADUALLY IMPROVE TUESDAY AND WEDNESDAY. WHILE PERIODS OF MVFR CEILINGS STILL ANTICIPATED DURING THE OVERNIGHT INTO THE EARLY MORNING HOURS...PERIODS OF VFR CONDITIONS WILL LENGTHEN IN DURATION. SCATTERED AFTERNOON-EARLY EVENING CONVECTION IS ALSO PROBABLE. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...BLAES/WSS SHORT TERM...WSS LONG TERM...BSD AVIATION...WSS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1007 AM EDT SAT AUG 17 2013 .SYNOPSIS... COOL AND WET WEATHER WILL CONTINUE FOR MUCH OF THE WEEKEND AS DEEP TROPICAL MOISTURE STREAMS NORTHWARD ALONG A FRONTAL BOUNDARY. CONDITIONS MORE TYPICAL OF LATE AUGUST WILL DEVELOP NEXT WEEK AS THE FRONT SLOWLY DISSIPATES AND BERMUDA HIGH PRESSURE BECOMES THE MAIN INFLUENCE ON OUR WEATHER. && .NEAR TERM /THROUGH TONIGHT/... AS OF 10 AM SATURDAY...A FRONT REMAINS POSITIONED OFFSHORE. UNSEASONABLY COOL TEMPERATURES ARE EXPECTED AGAIN TODAY AS CLOUDS BLANKET THE FORECAST AREA FOR MOST OF THE DAY. HIGHS ARE ONLY EXPECTED TO REACH THE MID AND UPPER 70S. A LARGE AREA OF SHOWERS AND A FEW THUNDERSTORMS...COINCIDENT WITH A WAVE OF LOW PRESSURE MOVING UP A STALLED OFFSHORE FRONT...WAS PROGRESSING TO THE NORTHEAST LATE THIS MORNING. THE BRUNT OF THIS CONVECTION WILL MOVE ACROSS THE WATERS AND OFFSHORE THROUGH THE AFTERNOON. HOWEVER...THE WESTERN FRINGES OF THIS ACTIVITY WILL SKIRT THE COAST AS THE AREA EXPANDS...ESPECIALLY THE CAPE FEAR AREA. THUS...FOR THE NEXT SEVERAL HOURS...EXPECT THE COVERAGE OF SHOWERS TO INCREASE...ESPECIALLY ALONG AND EAST OF A LINE FROM CRE TO CPC AND EYF. A THUNDERSTORM CAN NOT BE RULED OUT ALTHOUGH MOST OF THE THUNDERSTORM ACTIVITY IS EXPECTED TO REMAIN ON THE WARM SIDE OF THE OFFSHORE FRONT. DEVELOPING SUBSIDENCE DOWNSTREAM OF THIS ACTIVITY IS EXPECTED TO HELP SQUELCH CONVECTION WEST OF THE AFOREMENTIONED LINE FOR THE NEXT SEVERAL HOURS. WILL SHOW POPS EVENTUALLY TRENDING HIGHER IN THESE AREAS DURING THE AFTERNOON. A SERIES OF WAVES MOVING ALONG THE FRONT AND INDUCED BY UPPER LEVEL DISTURBANCES RIDING UP THE LEADING EDGE OF AN UNSEASONABLY DEEP H/5 EAST COAST TROUGH WILL KEEP THE WEATHER UNSETTLED. OVERRUNNING PATTERN IN PLACE FOR THE PAST FEW DAYS STILL VERY EVIDENT...WITH A DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND MOIST EASTERLY FLOW CLOSER TO THE SURFACE. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 315 AM SATURDAY...THE FA WILL LIE IN BETWEEN THE WESTERN ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM BOTH THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID AND UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW PRESSURE IS PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL TROF/FRONT ORIENTED NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL TO THE CAROLINA COASTS. THE LOW DEPARTS TO THE NE OFF THE DELMARVA COAST BY DAYBREAK MONDAY. UPSTAIRS...THE CUTOFF LOW ACROSS THE CENTRAL PART OF THE U.S. OPENS UP INTO A PROGRESSIVE POSITIVELY TILTED S/W TROF WHICH REACHES THE NE AND MID-ATLANTIC STATES LATE MONDAY NIGHT. AT THE SFC ON SUNDAY...WEAK HIGH PRESSURE IS PROGGED TO AFFECT THE FA. ONE WOULD THINK THAT WE ARE SAFE FROM ANY PCPN OCCURRENCE ON MONDAY. HOWEVER...MOISTURE REMAINS IN ABUNDANCE ACROSS THE FA. WEAK 5H VORTICIES ARE PROGGED TO PUSH ACROSS THE FA MONDAY INTO MONDAY NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION EITHER DAY WILL RESULT IN FURTHER DESTABILIZATION OF THE ATM LOCALLY. AS A RESULT OF ALL THIS SAID...POPS SUNDAY AND MONDAY WILL BE IN THE MODERATE TO HIGH CHANCE CATEGORY. THIS IS IN GOOD AGREEMENT WITH BOTH THE NAM AND GFS MOS GUIDANCE. FOR MAX TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM MOS GUIDANCE WHEN COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS GUIDANCE QUITE SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR OUTPUT. THE LATEST HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM CWA...INDICATES BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A FLOOD WATCH IS NOT RECOMMENDED...BUT AS GROUNDS FURTHER BECOME SATURATED...WILL HAVE TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC FUTURE PCPN FORECASTS COME IN AT MODEST TO HIGH LEVELS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 315 AM SATURDAY...THE OPENED UP UPPER TROF WILL JUST BECOME A MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT OF THE UPPER WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF MOISTURE...HAVING BEEN STRETCHED APART WILL DROP SE-WARD...AND CROSS THE FA DURING WEDNESDAY. BEWARE THE NW FLOW...AN ADAGE THAT HAS COME TO LIGHT WHEN DEALING WITH CONVECTION DROPPING SE-WARD FROM UPSTREAM. A MCC OR MCS USUALLY IS THE CULPRIT WITH THIS TYPE MID/UPPER LEVEL FLOW. CHANCE POPS WILL CONTINUE FOR TUE AND WED. BY THU AND FRI...MODELS DIVERGE FROM ONE ANOTHER WITH THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH THE RE-TURN OF MOISTURE AND INCREASING POPS. REMAINED RATHER SOMEWHAT LOW-KEY WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE UNCERTAINTY. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY IFR... HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF MVFR...PARTICULARLY AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW OFFSHORE THAT WILL MOVE SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL IS NOT ALL THAT ENTHUSED WITH THE PRECIP TODAY...WITH MAINLY ONLY SCATTERED ACTIVITY. BASED ON THE CURRENT RADAR...THIS SCENARIO SEEMS REASONABLE. VISIBILITIES IN THE RAIN COULD LOWER TO IFR...BUT PREDOMINATELY MVFR. WINDS ARE A BIT MORE NORTHERLY THAN PREVIOUSLY THOUGHT...PARTICULARLY INLAND ON THE BACK SIDE OF THE SURFACE LOW. LOOK FOR THE WINDS TO SHIFT MORE NORTHWESTERLY AS THE LOW EXITS THE REGION THIS AFTERNOON. EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 10 AM SATURDAY...A FRONT REMAINS STALLED OFFSHORE LATE THIS MORNING. THIS FRONT IS EXPECTED TO MOVE BACK ACROSS THE WATERS AS WAVES OF LOW PRESSURE MOVE UP ALONG THE BOUNDARY. THUS EASTERLY WINDS ARE EXPECTED TO VEER TO A MORE SOUTHERLY DIRECTION THROUGH THE AFTERNOON AND THEN TO SOUTHWEST FOR A TIME. WINDS WILL VEER TO W OR NW TONIGHT AS A WAVE OF LOW PRESSURE CLOSES OFF AND MOVES TO OUR N. WIND SPEEDS WILL GENERALLY BE AROUND 10 KT OR LESS. SEAS OF 2 TO 3 FT WILL PERSIST. NUMEROUS TO WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS WILL RESULT IN POOR VISIBILITIES INTO TONIGHT. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY. EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO 3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND DRIVEN WAVES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...RJD SHORT TERM...DCH LONG TERM...DCH AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1059 AM EDT SAT AUG 17 2013 .SYNOPSIS... COOL AND WET WEATHER WILL CONTINUE FOR MUCH OF THE WEEKEND AS DEEP TROPICAL MOISTURE STREAMS NORTHWARD ALONG A FRONTAL BOUNDARY. CONDITIONS MORE TYPICAL OF LATE AUGUST WILL DEVELOP NEXT WEEK AS THE FRONT SLOWLY DISSIPATES AND BERMUDA HIGH PRESSURE BECOMES THE MAIN INFLUENCE ON OUR WEATHER. && .NEAR TERM /THROUGH TONIGHT/... AS OF 10 AM SATURDAY...A FRONT REMAINS POSITIONED OFFSHORE. UNSEASONABLY COOL TEMPERATURES ARE EXPECTED AGAIN TODAY AS CLOUDS BLANKET THE FORECAST AREA FOR MOST OF THE DAY. HIGHS ARE ONLY EXPECTED TO REACH THE MID AND UPPER 70S. A LARGE AREA OF SHOWERS AND A FEW THUNDERSTORMS...COINCIDENT WITH A WAVE OF LOW PRESSURE MOVING UP A STALLED OFFSHORE FRONT...WAS PROGRESSING TO THE NORTHEAST LATE THIS MORNING. THE BRUNT OF THIS CONVECTION WILL MOVE ACROSS THE WATERS AND OFFSHORE THROUGH THE AFTERNOON. HOWEVER...THE WESTERN FRINGES OF THIS ACTIVITY WILL SKIRT THE COAST AS THE AREA EXPANDS...ESPECIALLY THE CAPE FEAR AREA. THUS...FOR THE NEXT SEVERAL HOURS...EXPECT THE COVERAGE OF SHOWERS TO INCREASE...ESPECIALLY ALONG AND EAST OF A LINE FROM CRE TO CPC AND EYF. A THUNDERSTORM CAN NOT BE RULED OUT ALTHOUGH MOST OF THE THUNDERSTORM ACTIVITY IS EXPECTED TO REMAIN ON THE WARM SIDE OF THE OFFSHORE FRONT. DEVELOPING SUBSIDENCE DOWNSTREAM OF THIS ACTIVITY IS EXPECTED TO HELP SQUELCH CONVECTION WEST OF THE AFOREMENTIONED LINE FOR THE NEXT SEVERAL HOURS. WILL SHOW POPS EVENTUALLY TRENDING HIGHER IN THESE AREAS DURING THE AFTERNOON. A SERIES OF WAVES MOVING ALONG THE FRONT AND INDUCED BY UPPER LEVEL DISTURBANCES RIDING UP THE LEADING EDGE OF AN UNSEASONABLY DEEP H/5 EAST COAST TROUGH WILL KEEP THE WEATHER UNSETTLED. OVERRUNNING PATTERN IN PLACE FOR THE PAST FEW DAYS STILL VERY EVIDENT...WITH A DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND MOIST EASTERLY FLOW CLOSER TO THE SURFACE. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 315 AM SATURDAY...THE FA WILL LIE IN BETWEEN THE WESTERN ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM BOTH THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID AND UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW PRESSURE IS PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL TROF/FRONT ORIENTED NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL TO THE CAROLINA COASTS. THE LOW DEPARTS TO THE NE OFF THE DELMARVA COAST BY DAYBREAK MONDAY. UPSTAIRS...THE CUTOFF LOW ACROSS THE CENTRAL PART OF THE U.S. OPENS UP INTO A PROGRESSIVE POSITIVELY TILTED S/W TROF WHICH REACHES THE NE AND MID-ATLANTIC STATES LATE MONDAY NIGHT. AT THE SFC ON SUNDAY...WEAK HIGH PRESSURE IS PROGGED TO AFFECT THE FA. ONE WOULD THINK THAT WE ARE SAFE FROM ANY PCPN OCCURRENCE ON MONDAY. HOWEVER...MOISTURE REMAINS IN ABUNDANCE ACROSS THE FA. WEAK 5H VORTICIES ARE PROGGED TO PUSH ACROSS THE FA MONDAY INTO MONDAY NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION EITHER DAY WILL RESULT IN FURTHER DESTABILIZATION OF THE ATM LOCALLY. AS A RESULT OF ALL THIS SAID...POPS SUNDAY AND MONDAY WILL BE IN THE MODERATE TO HIGH CHANCE CATEGORY. THIS IS IN GOOD AGREEMENT WITH BOTH THE NAM AND GFS MOS GUIDANCE. FOR MAX TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM MOS GUIDANCE WHEN COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS GUIDANCE QUITE SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR OUTPUT. THE LATEST HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM CWA...INDICATES BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A FLOOD WATCH IS NOT RECOMMENDED...BUT AS GROUNDS FURTHER BECOME SATURATED...WILL HAVE TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC FUTURE PCPN FORECASTS COME IN AT MODEST TO HIGH LEVELS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 315 AM SATURDAY...THE OPENED UP UPPER TROF WILL JUST BECOME A MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT OF THE UPPER WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF MOISTURE...HAVING BEEN STRETCHED APART WILL DROP SE-WARD...AND CROSS THE FA DURING WEDNESDAY. BEWARE THE NW FLOW...AN ADAGE THAT HAS COME TO LIGHT WHEN DEALING WITH CONVECTION DROPPING SE-WARD FROM UPSTREAM. A MCC OR MCS USUALLY IS THE CULPRIT WITH THIS TYPE MID/UPPER LEVEL FLOW. CHANCE POPS WILL CONTINUE FOR TUE AND WED. BY THU AND FRI...MODELS DIVERGE FROM ONE ANOTHER WITH THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH THE RE-TURN OF MOISTURE AND INCREASING POPS. REMAINED RATHER SOMEWHAT LOW-KEY WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE UNCERTAINTY. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY IFR... HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF MVFR...PARTICULARLY AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW OFFSHORE THAT WILL MOVE SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL IS NOT ALL THAT ENTHUSED WITH THE PRECIP TODAY...WITH MAINLY ONLY SCATTERED ACTIVITY. BASED ON THE CURRENT RADAR...THIS SCENARIO SEEMS REASONABLE. VISIBILITIES IN THE RAIN COULD LOWER TO IFR...BUT PREDOMINATELY MVFR. WINDS ARE A BIT MORE NORTHERLY THAN PREVIOUSLY THOUGHT...PARTICULARLY INLAND ON THE BACK SIDE OF THE SURFACE LOW. LOOK FOR THE WINDS TO SHIFT MORE NORTHWESTERLY AS THE LOW EXITS THE REGION THIS AFTERNOON. EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 10 AM SATURDAY...A FRONT REMAINS STALLED OFFSHORE LATE THIS MORNING. THIS FRONT IS EXPECTED TO MOVE BACK ACROSS THE WATERS AS WAVES OF LOW PRESSURE MOVE UP ALONG THE BOUNDARY. THUS EASTERLY WINDS ARE EXPECTED TO VEER TO A MORE SOUTHERLY DIRECTION THROUGH THE AFTERNOON AND THEN TO SOUTHWEST FOR A TIME. WINDS WILL VEER TO W OR NW TONIGHT AS A WAVE OF LOW PRESSURE CLOSES OFF AND MOVES TO OUR N. WIND SPEEDS WILL GENERALLY BE AROUND 10 KT OR LESS. SEAS OF 2 TO 3 FT WILL PERSIST. NUMEROUS TO WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS WILL RESULT IN POOR VISIBILITIES INTO TONIGHT. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY. EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO 3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND DRIVEN WAVES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...RJD SHORT TERM...DCH LONG TERM...DCH AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
716 AM EDT SAT AUG 17 2013 .SYNOPSIS... A WARM FRONT EXTENDING FROM EASTERN GEORGIA TO JUST OFF THE CAROLINA COAST WILL LIFT NORTH AND THROUGH THE EASTERN CAROLINAS TODAY...AND BE ACCOMPANIED BY HEAVY RAIN AND THUNDERSTORMS. THE FRONT OR TROF OF LOW PRESSURE WILL STALL OVER THE CAROLINAS...THEN GRADUALLY DISSIPATE BY WEDNESDAY AS BERMUDA HIGH PRESSURE OFFSHORE BECOMES THE MAIN INFLUENCE ON OUR WEATHER. BELOW-NORMAL TEMPERATURES THIS WEEKEND SHOULD RETURN TO NORMAL BY TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 6:30 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: UNSEASONABLY COOL TEMPERATURES WITH CLOUDY SKIES AND THE CERTAINTY OF PRECIPITATION WILL BE THE RULE FOR TODAY AS A QUASI-STATIONARY FRONT WAVERS OVER THE COASTAL PLAIN. AT THE SURFACE THIS MORNING THE QUASI-STATIONARY FRONT EXTENDS ALONG THE COAST FROM THE OUTER BANKS TO NEAR SAVANNAH...THEN INLAND ACROSS SOUTHERN GEORGIA. A SERIES OF WAVES MOVING ALONG THE FRONT ARE INDUCED BY UPPER DISTURBANCES RIDING UP THE LEADING EDGE OF AN UNSEASONABLY DEEP H/5 TROUGH NOW DOMINATING EASTERN CONUS. OVERRUNNING PATTERN IN PLACE PAST FEW DAYS STILL VERY EVIDENT...WITH A DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND MOIST EASTERLY FLOW CLOSER TO THE SURFACE. A WEDGE OF HIGH PRESSURE WILL CONTINUE TO EXTEND SW ALONG THE APPALACHIANS THROUGH THE PERIOD. CONSENSUS OF GUIDANCE HAS A CLOSED LOW FORMING FROM AN OPEN WAVE ALONG THE FRONT TODAY...ULTIMATELY LIFTING THE NORTHERN PORTION OF THE FRONT NORTH AND EFFECTIVELY PUTTING THE COASTAL CAROLINAS IN THE WARM SECTOR OF THE SYSTEM FOR A BRIEF TIME. MODEL SOUNDINGS CONTINUE TO SHOW A VERY MOIST AIRMASS WITH P/W VALUES IN THE 2.25 INCH RANGE. COMBINATION OF A SATURATED COLUMN...FAVORABLE DYNAMICS AND THE FRONTAL BOUNDARY WILL MAKE FOR A VERY RAINY DAY. GIVEN THIS SCENARIO...100 POPS ARE CERTAINLY WARRANTED. HAVE MAINTAINED THE POSSIBILITY THAT THUNDERSTORMS COULD PRODUCE HEAVY RAIN TODAY AND TONIGHT. TEMPERATURES WILL CONTINUE TO RUN WELL BELOW NORMAL...WITH HIGHS RANGING FROM THE LOWER AND MID 70S INLAND TO THE UPPER 70S AT THE COAST...AND LOWS RANGING FROM THE MID 60S TO AROUND 70. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 315 AM...FOR SUNDAY THE FA WILL LIE IN BETWEEN THE WESTERN ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM BOTH THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID AND UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW PRESSURE IS PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL TROF/FRONT ORIENTED NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL TO THE CAROLINA COASTS. THE LOW DEPARTS TO THE NE OFF THE DELMARVA COAST BY DAYBREAK MONDAY. UPSTAIRS...THE CUTOFF LOW ACROSS THE CENTRAL PART OF THE U.S. OPENS UP INTO A PROGRESSIVE POSITIVELY TILTED S/W TROF WHICH REACHES THE NE AND MID-ATLANTIC STATES LATE MONDAY NIGHT. AT THE SFC ON SUNDAY...WEAK HIGH PRESSURE IS PROGGED TO AFFECT THE FA. ONE WOULD THINK THAT WE ARE SAFE FROM ANY PCPN OCCURRENCE ON MONDAY. HOWEVER...MOISTURE REMAINS IN ABUNDANCE ACROSS THE FA. WEAK 5H VORTICIES ARE PROGGED TO PUSH ACROSS THE FA MONDAY INTO MONDAY NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION EITHER DAY WILL RESULT IN FURTHER DESTABILIZATION OF THE ATM LOCALLY. AS A RESULT OF ALL THIS SAID...POPS SUNDAY AND MONDAY WILL BE IN THE MODERATE TO HIGH CHANCE CATEGORY. THIS IS IN GOOD AGREEMENT WITH BOTH THE NAM AND GFS MOS GUIDANCE. FOR MAX TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM MOS GUIDANCE WHEN COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS GUIDANCE QUITE SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR OUTPUT. THE LATEST HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM CWA...INDICATES BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A FLOOD WATCH IS NOT RECOMMENDED...BUT AS GROUNDS FURTHER BECOME SATURATED...WILL HAVE TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC FUTURE PCPN FORECASTS COME IN AT MODEST TO HIGH LEVELS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 315 AM SATURDAY...FOR TUESDAY...THE OPENED UP UPPER TROF WILL JUST BECOME A MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT OF THE UPPER WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF MOISTURE...HAVING BEEN STRETCHED APART WILL DROP SE- WARD...AND CROSS THE FA DURING WEDNESDAY. BEWARE THE NW FLOW...AN ADAGE THAT HAS COME TO LIGHT WHEN DEALING WITH CONVECTION DROPPING SE-WARD FROM UPSTREAM. A MCC OR MCS USUALLY IS THE CULPRIT WITH THIS TYPE MID/UPPER LEVEL FLOW. CHANCE POPS WILL CONTINUE FOR TUE AND WED. BY THU AND FRI...MODELS DIVERGE FROM ONE ANOTHER WITH THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH THE RE-TURN OF MOISTURE AND INCREASING POPS. REMAINED RATHER SOMEWHAT LOW-KEY WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE UNCERTAINTY. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY IFR...HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF MVFR...PARTICULARLY AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW OFFSHORE THAT WILL MOVE SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL IS NOT ALL THAT ENTHUSED WITH THE PRECIP TODAY...WITH MAINLY ONLY SCATTERED ACTIVITY. BASED ON THE CURRENT RADAR...THIS SCENARIO SEEMS REASONABLE. VISIBILITIES IN THE RAIN COULD LOWER TO IFR...BUT PREDOMINATELY MVFR. WINDS ARE A BIT MORE NORTHERLY THAN PREVIOUSLY THOUGHT...PARTICULARLY INLAND ON THE BACK SIDE OF THE SURFACE LOW. LOOK FOR THE WINDS TO SHIFT MORE NORTHWESTERLY AS THE LOW EXITS THE REGION THIS AFTERNOON. EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 6:30 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: THE PRESENCE OF A QUASI-STATIONARY FRONT OVER THE COASTAL PLAN OF THE EASTERN CAROLINAS WILL KEEP WINDS GENERALLY LIGHT THROUGH THE PERIOD. WINDS WILL BE IN THE 10 KT RANGE...WITH SEAS OF 2 TO 3 FT. BIGGEST THREAT OVER THE COASTAL WATERS TODAY WILL BE FROM HEAVY RAIN AND ISOLATED THUNDERSTORMS...ESPECIALLY DURING THE DAYLIGHT HOURS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY. EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO 3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND DRIVEN WAVES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...DCH NEAR TERM...REK SHORT TERM...DCH LONG TERM...DCH AVIATION...43 MARINE...DCH/REK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1041 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 1041 AM CDT SAT AUG 17 2013 LOW CLOUDS AND PATCHY FOG ARE LINGERING OVER SOUTH CENTRAL AND SOUTHEASTERN NORTH DAKOTA LONGER THAN ANTICIPATED. AS A RESULT...UPDATED THE FORECAST TO CONTINUE THE CLOUDY AND PATCHY FOG CONDITIONS PRIMARILY ACROSS THE JAMES RIVER BASIN THROUGH THE MID-DAY HOURS. THIS SHOULD ALSO HAMPER MORNING TEMPERATURE WARMING TRENDS. HOWEVER...ONCE THE LOW CLOUDS AND FOG BURN OFF...TEMPERATURES SHOULD RAPIDLY INCREASE THIS AFTERNOON. UPDATE ISSUED AT 830 AM CDT SAT AUG 17 2013 SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND SOUTHEASTERN NORTH DAKOTA. THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS AS VERTICAL MIXING COMMENCES. UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013 THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 636 AM CDT SAT AUG 17 2013 IFR/LIFR CONDITIONS IN LOW CLOUDS OVER KBIS-KJMS WILL GRADUALLY IMPROVE TO VFR BY MIDDAY. ONCE THE FOG AND STRATUS EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL BOUNDARY CROSSES THE AREA. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TM SHORT TERM...CK LONG TERM...KS AVIATION...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
830 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 830 AM CDT SAT AUG 17 2013 SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND SOUTHEASTERN NORTH DAKOTA. THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS AS VERTICAL MIXING COMMENCES. UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013 THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 636 AM CDT SAT AUG 17 2013 EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE. WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL BOUNDARY CROSSES THE AREA. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TM SHORT TERM...CK LONG TERM...KS AVIATION...CK
AREA FORECAST DISCUSSION...CORRECTED
NWS BISMARCK ND
645 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 636 AM CDT SAT AUG 17 2013 THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 636 AM CDT SAT AUG 17 2013 EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE. WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL BOUNDARY CROSSES THE AREA. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KS SHORT TERM...CK LONG TERM...KS AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
636 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 636 AM CDT SAT AUG 17 2013 THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 13Z THEN BEGINNING TO DISSIPATED THROUGH 18Z. THUS HAVE ADJUSTED SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 636 AM CDT SAT AUG 17 2013 EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE. WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL BOUNDARY CROSSES THE AREA. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KS SHORT TERM...CK LONG TERM...KS AVIATION...CK
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
905 AM CDT SAT AUG 17 2013 .UPDATE... EARLIER SHOWER AND TSTM ACTIVITY HAS LIFTED OFF TO THE NORTH. A BAND OF VERY LIGHT SHOWER ACTIVITY APPEARS TO BE WORKING NORTHWARD ACROSS CENTRAL AREAS. OVERALL HOWEVER...MODELS ARE ZONING IN ON A PERIOD OF SUBSIDENCE THROUGH THE MORNING HOURS. HOWEVER...BY AFTERNOON SUBSIDENCE WILL BEGIN TO GIVE WAY TO A SLIGHTLY UPWARD OMEGA FIELD AND THUS...SHOULD STILL SEE CONVECTIVE ACTIVITY INCREASE. HRRR IN SUPPORT OF REDEVELOPMENT AS WELL. FOR THE GRID UPDATE...WILL TWEAK POPS DOWN FOR THE PRE 18Z PERIOD. OTW...LITTLE ADJUSTMENTS NEEDED. MOSTLY CLOUDY SKIES SHOULD PREVAIL AND THUS THE EXPECTED HIGH TEMPS IN THE LOWER 80S STILL LOOKS REASONABLE. && .PREV DISCUSSION... /ISSUED 649 AM CDT SAT AUG 17 2013/ UPDATE...FOR 12Z AVIATION FORECASTS. AVIATION...CKV AND BNA RECEIVED LOCALLY HEAVY RAINFALL LAST NIGHT AND MAY SEE A BRIEF PERIOD OF SOME RAG TAG IFR OR MVFR CIGS EARLY THIS MORNING. OTHERWISE, EXPECT VFR CIGS THROUGHOUT THE TAF PERIOD. SOME BRIEF VIS RESTRICTIONS ARE LIKELY WITH ANY SHRA OR ISOLATED TSRA THAT MIGHT PASS OVER A MID STATE TERMINAL. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 21
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1048 AM CDT SAT AUG 17 2013 .UPDATE...ANOTHER QUIET DAY IN STORE FOR SOUTHERN WISCONSIN. CHANGES IN THE TODAY PERIOD WERE LIMITED TO ADJUSTING FOR TRENDS. SKY COVER WAS BUMPED UP A BIT...WITH AT LEAST SCATTERED CUMULUS EXPECTED GIVEN PROXIMITY SOUNDINGS AND RESIDUAL LOW-LEVEL MOISTURE...CU RULE...AND GOES-R PG WRF ABI SYNTHETIC IMAGERY. GIVEN HIGHS YESTERDAY AND RAP PROXIMITY SOUNDINGS...NEAR GROUND SUPERADIABATIC LAPSE RATES ARE ANTICIPATED. THIS WILL RESULT IN FORECAST HIGHS REMAINING AROUND 80/LOW 80S AWAY FROM THE LAKESHORE COUNTIES...TO MID/UPPER 70S FAR EAST. ET && .AVIATION/18Z TAFS/...VFR CONDITIONS ARE EXPECTED THIS AFTERNOON AND THIS EVENING ACROSS TAF SITES...AND AGAIN FOR MOST OF SUNDAY. HIGH PRESSURE WILL REMAIN SOUTHEAST OF THE REGION THROUGH THE WEEKEND. THE HIGH WILL BRING QUIET WEATHER. SCATTERED DIURNAL CUMULUS CLOUDS ARE EXPECTED THIS AFTERNOON AND AGAIN SUNDAY AFTERNOON. LIGHT SOUTHEAST WINDS ARE EXPECTED THIS AFTERNOON INTO THE EARLY EVENING...THEN BECOMING LIGHT/CALM TONIGHT INTO EARLY SUNDAY. LIGHT SOUTH WINDS ARE EXPECTED AT MADISON ON SUNDAY...WITH LIGHT SOUTHEAST WINDS AT THE EASTERN SITES. FOG WITH VISIBILITIES DOWN TO OR BELOW AIRPORT MINIMUMS ARE EXPECTED AT KENOSHA BY 05Z SUNDAY...LINGERING UNTIL AROUND 13Z SUNDAY. MAY SEE FOG WITH VISIBILITIES DOWN TO ALTERNATE MINIMUMS AT TIMES AT WAUKESHA FROM 09Z UNTIL 12Z SUNDAY. MADISON AND MILWAUKEE MAY SEE VFR FOG DURING THIS TIME. WOOD && .PREV DISCUSSION... /ISSUED 326 AM CDT SAT AUG 17 2013/ SHORT TERM... TODAY AND TONIGHT...FORECAST CONFIDENCE HIGH AT THE SFC...HIGH PRESSURE WILL CONTINUE TO PREVAIL FROM NEW ENGLAND WWD INTO PORTIONS OF THE UPPER MS RIVER VALLEY...INCLUDING SRN WI. ALOFT...AN UPPER LOW WILL REMAIN OVER THE MID MS RIVER VALLEY WITH SOME RIDGING AND WARMING ALOFT THAT WILL OVERSPREAD SRN WI FROM THE NRN PLAINS. THIS WILL RESULT IN LESS CU DEVELOPMENT THAN RECENT DAYS WITH A CONTINUED DRY AND WARMING AIRMASS IN PLACE. NEAR GROUND SUPERADIABATIC LAPSE RATES WITH 925 MB TEMPS AROUND 19C YIELDS LOWER 80S FOR TODAY INLAND FROM THE LAKE BREEZE. LAKE BREEZE WILL DEVELOP BY 15Z SIMILAR TO YESTERDAY. GOOD RADIATIONAL COOLING CONDITIONS ONCE AGAIN TNT BUT AIRMASS IS FAIRLY DRY SO EXPECT GROUND FOG ONLY IN THE TYPICAL LOW LYING AREAS. SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE HIGH. SURFACE HIGH PRESSURE WILL CONTINUE TO HOLD STRONG OVER THE GREAT LAKES REGION THROUGH EARLY NEXT WEEK BRINGING MOSTLY CLEAR SKIES AND DRY WEATHER. MEANWHILE...A WEAK MID LEVEL LOW WILL DRIFT ACROSS THE OHIO RIVER VALLEY AND ALLOW FOR THAT STRONG AND WARM RIDGE OVER THE WESTERN U.S. TO NOSE INTO SOUTHERN WISCONSIN. LOOK FOR A GRADUAL WARMING TREND THROUGH THIS PERIOD...FROM AROUND 80 SUNDAY TO THE UPPER 80S/90 ON WEDNESDAY. A FEW WEAK UPPER TROUGHS ARE FORECAST BY THE MODELS TO RIDE OVER THE RIDGE AND PASS ACROSS THE GREAT LAKES NEXT WEEK. THE FIRST WAVE MONDAY NIGHT WILL BE DRY WITH PLENTY OF AGREEMENT BETWEEN THE MODELS WHERE THEY ALL SHOW A STRONG CAP AROUND 750MB. LONG TERM... WEDNESDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM TO LOW. THERE IS A STRONG UPPER TROUGH THAT WILL RIDE OVER THE RIDGE THROUGH SOUTHERN CANADA MID WEEK. THIS WILL BE OUR NEXT WEATHER MAKER AS IT REACHES LAKE SUPERIOR WED NIGHT. THERE ARE SOME SIGNIFICANT DIFFERENCES BETWEEN THE MODELS FOR WED NIGHT/THU NOW. THE GFS PHASES THAT UPPER TROUGH WITH A WEAKER SHORTWAVE MOVING THROUGH THE NORTHERN PLAINS/UPPER MIDWEST AND DROPS A COLD FRONT ALL THE WAY DOWN THROUGH WI INTO IA AND IL. THE LATEST 00Z ECMWF DOES NOT PHASE THOSE TWO FEATURES SO THE FRONT SAGS INTO SOUTHERN WI ON THU AND THEN GETS PUSHED BACK NORTH FOR FRI. THE CANADIAN MODEL IS SOMEWHERE IN BETWEEN. THE ECMWF WOULD SUGGEST THAT AT LEAST THE SOUTHERN HALF OF THE MKX FORECAST AREA WOULD STAY DRY AND VERY WARM THROUGH THE LATTER HALF OF NEXT WEEK...HIGHS IN THE LOWER 90S. THE GFS SUGGESTS A PERIOD OF THUNDERSTORMS ALONG THE FRONT AND THEN COOLING BACK OFF INTO THE UPPER 70S ON FRI. STAY TUNED. AVIATION/12Z TAFS/...DENSE FOG AT KENW WILL CONTINUE UNTIL SUNRISE...THEN QUICKLY BURN OFF. POSSIBLY BRIEF MVFR VSBYS MAY OCCUR AT KMSN AND KUES AROUND SUNRISE. OTHERWISE FEW-SCT FAIR WX CU AROUND 6-8 KFT DURING THE AFTERNOON. ANOTHER CLEAR NIGHT WITH HIGH PRESSURE IN CONTROL. FOG EXPECTED IN THE TYPICAL LOW LYING AREAS SO EXPECT KENW TO HAVE DENSE FOG AT TIMES LATE AT NIGHT WITH MVFR VSBYS POSSIBLY AROUND SUNRISE SUNDAY AT KMSN AND KUES. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ UPDATE...ET/WOOD TODAY/TONIGHT AND AVIATION/MARINE...GEHRING SUNDAY THROUGH FRIDAY...MRC
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
351 PM EDT SAT AUG 17 2013 .DISCUSSION... THROUGH TONIGHT...EAST COAST SEA BREEZE WILL SPARK SCATTERED STORMS OVER THE INTERIOR AND VOLUSIA NEXT FEW HOURS...THEN STORMS SHOULD PUSH DIMINISH SHORTLY AFTER SUNSET. SUBSIDENCE ASSOCD WITH SEA BREEZE CIRCULATION WILL KEEP COASTAL SECTIONS FROM BREVARD TO MARTIN COUNTIES DRY THE REST OF THE AFTERNOON. THE LOW LEVEL RIDGE WILL LIFT NORTH OF THE AREA TONIGHT AND PRODUCE A SYNOPTIC E/SE FLOW OF 10-14 KNOTS. THIS SHOULD BE SUFFICIENT FLOW COMBINED WITH HIGH MOISTURE TO PRODUCE A FEW ATLC SHOWERS THAT COULD REACH THE COAST OVERNIGHT SO HAVE DRAWN A 20 POP ALONG THE COAST. A WARM NIGHT WITH LOWS IN THE MID TO UPPER 70S...EVEN SOME LOWER 80S BEACHSIDE. SUN-MON...(PREVIOUS) CENTRAL FL WILL UNDERGO A SHIFT TO A DRIER WX PATTERN AS THE LIFTING H30-H20 JET OVER THE APPALACHIANS ALLOWS THE ATLC RIDGE AXIS TO REPOSITION ITSELF OVER THE DEEP SOUTH BY DAYBREAK SUN. POSITION WILL BE STABLE AS UPSTREAM JET ENERGY OVER THE SRN TIER STATES IS QUITE WEAK AND WILL NOT BE ABLE DO DISLODGE IT. POSITION OF THE RIDGE AXIS WILL GENERATE A DEEP AND STEADY E/SE FLOW ACRS CENTRAL FL...A PATTERN THAT FAVORS THE WEST PENINSULA FOR DIURNAL CONVECTION RATHER THAN THE EAST DUE LARGELY TO THE EARLY FORMATION AND DIFFUSE NATURE OF THE RESULTING EAST COAST SEA BREEZE. FURTHERMORE...LATEST RUC ANALYSIS SHOWS A NOTEWORTHY DROP IN DEEP LYR RH APPROACHING THE SRN BAHAMAS THAT WILL WORK ITS WAY INTO THE FL PENINSULA TO START THE UPCOMING WEEK. GFS MODEL SOUNDINGS CONFIRM THE ANTICIPATED DRY TREND...DROPPING PWAT VALUES FROM ARND 2.0" AT 12Z SUN TO ARND 1.7" BY 12Z MON. EVEN THE HIGHER PWAT VALUES ARE SUN ARE SOMEWHAT DECEIVING AS GFS INDICATES THE MOISTURE WILL BE EVENLY DISTRIBUTED THRU THE COLUMN... NOT CONCENTRATED IN THE LOW/MID LVLS WHERE IT WOULD SUPPORT HIGHER AMOUNTS OF DIURNAL CONVECTION. STORM POTENTIAL WILL REMAIN LOW AS THE ERLY FLOW TAPS AN AIRMASS WITH NEGLIGIBLE MID LVL VORTICITY OR OF UPR LVL JET SUPPORT. THERMODYNAMIC PROFILE MAY PROVIDE SOME PUNCH AS UPSTREAM H50 TEMPS DROP INTO THE -7C TO -8C RANGE AND H85-H50 LAPSE RATES STEEPEN TO 6.0-6.5C/KM. HOWEVER...ANY STRONG ACTIVITY WOULD TEND TO FORM W OF THE FL TURNPIKE AS THE DEEP ERLY FLOW WILL PUSH THE SEA BREEZE RAPIDLY INLAND. PRECIP COVERAGE AOB 40PCT WITH HIGHEST COVERAGE OVER THE INTERIOR SUN AFTN TO GIVE A NOD TO THE AFOREMENTIONED HIGHER PWAT VALUES. ONSHORE FLOW WILL KEEP MAX TEMPS IN THE U80S/L90 ALONG THE COAST... INTERIOR WARMING TO THE L/M90S. MIN TEMPS L/M70S. TUE-FRI... LITTLE CHANGE TO THE CURRENT PHILOSOPHY...STABLE POSITION OF THE ATLC RIDGE AXIS WILL MAINTAIN A DEEP ERLY FLOW ACRS CENTRAL FL FOR MUCH OF THE WEEK THAT WILL FOCUS DIURNAL CONVECTION OVER THE W PENINSULA. POPS 30-40PCT...HIGHER OVER THE INTERIOR DUE TO THE EARLY FORMATION OF THE EAST COAST SEA BREEZE. MAX TEMPS WITHIN A DEG OR TWO OF CLIMO AVG...MIN TEMPS 3-5F ABV AVG DUE TO THE PERSISTENT ONSHORE FLOW. && .AVIATION... SCT TSRA AT LEE/MCO/SFB THROUGH 23Z. ISOLD SHRA MAY APPROACH COASTAL TAFS OVERNIGHT BUT COVERAGE DOES NOT WARRANT MENTION IN TAFS. COULD SEE TEMPO MVFR CIGS 13Z-16Z SUN ALONG WITH ISOLD SHRA AS DIFFUSE SEA BREEZE DEVELOPS...FOLLOWED BY SCATTERED SHRA/TSRA FOCUSED ON THE INTERIOR AFT 16Z. && .MARINE... ATLC RIDGE WILL REPOSITION ITSELF NORTH OF THE WATERS TONIGHT WHERE IT WILL REMAIN THRU MIDWEEK. THIS RIDGE POSITION WILL GENERATE A STEADY STATE GENTLE TO MODERATE E/SE BREEZE. THESE WINDS WILL PUSH A SMALL ERLY SWELL INTO THE LCL ATLC...BUILDING SEAS UP TO 4 FT OFFSHORE SUN NIGHT AND MONDAY...3 FT NEARSHORE. SEAS WILL GRADUALLY SUBSIDE TUE-WED AS THE SWELL DAMPENS. ISOLD SHRA/TSRA THRU THE PD. && .PRELIMINARY POINT TEMPS/POPS... DAB 76 89 77 90 / 20 40 20 30 MCO 76 93 75 93 / 20 40 10 30 MLB 78 90 78 91 / 20 30 20 30 VRB 77 91 76 90 / 20 20 20 30 LEE 76 94 76 94 / 20 50 20 40 SFB 77 93 76 93 / 20 40 10 30 ORL 77 93 77 93 / 20 40 10 30 FPR 76 90 76 90 / 20 20 20 30 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ PUBLIC/MARINE/FIRE WX/AVIATION...KELLY IMPACT WX/RADAR...WEITLICH
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
320 PM EDT Sat Aug 17 2013 .NEAR TERM [This Evening and Tonight]... A broken band of heavy rain showers and even a few thunderstorms continues to slowly shift east with time this afternoon across the forecast area (and our Florida zones in particular). The stronger convective cells appear to be situated along a composite outflow boundary / quasi-stationary front, with trailing light-moderate stratiform rain behind that (encompassing much of the western half of our forecast area). Therefore, high PoPs were maintained through the evening hours, particularly in the western two-thirds of our area. The high-resolution guidance including recent runs of the HRRR and our local TAE-WRF appears to be doing a poor job representing ongoing conditions. They dissipate the convection far too fast and have generally dry conditions advertised over our area around 19-20 UTC. Therefore, we expect that the ongoing rain and storms will linger for at least another few hours. The guidance (including global models) indicates that the rain and storms will consolidate back to the west later this evening and tonight. Therefore, the Flash Flood Watch was kept as is - which expires for our GA and eastern FL zones at 03 UTC, with much of the heavy rainfall after that time expected west of those areas. This will have to be closely monitored this evening, though. Given the environment (high PWATs, efficient rain processes), the threat of flash flooding continues across the area wherever heavier rain bands can set up. && .SHORT TERM [Sunday through Monday Night]... The quasi-stationary front may begin to slowly shift a bit further west on Sunday and lose its character as a low-level ridge builds into the Southeast from the Atlantic Ocean. Therefore, there should be less of a large-scale focusing mechanism for convection tomorrow (or it should be situated just north and west of our area). However, guidance still shows relatively high PoPs with continued high PWAT environment and southerly low-level flow. Therefore, we maintained likely PoPs over much of the area. A similar story exists for Monday, although with slightly more uncertainty we opted for high chance (50%) PoPs instead - but it could end up being another high coverage day for rain. Daytime temperatures should continue to be a little cooler than normal. && .LONG TERM [Tuesday through Saturday]... Southeast low-level flow gradually backs to more of an easterly direction as an upper level ridge builds into the region. This should equate to more suppressed convective activity with time, and overall PoPs show a decreasing trend through the extended forecast. However, there should still be daily thunderstorm chances. Temperatures will be closer to normal, perhaps warming to slightly above normal by later in the week. && .AVIATION [through 18 UTC Sunday]... Low CIGS and showers with embedded convection will prevail with MVFR-IFR conditions expected to continue this evening at ECP, DHN, and ABY and develop later overnight and tomorrow at TLH and VLD. Brief periods of LIFR CIGS and vsbys are expected in the heaviest bouts of rain. && .MARINE... With some breezy southeast winds being observed over the western waters at the moment (peak winds to near 20 knots), we have inserted a SCEC headline through tonight west of AAF. The winds will be slightly weaker in the eastern half of our coastal zones, but could still approach 15 knots at times. Winds and seas will lessen somewhat tomorrow morning, followed by a stretch of easterly flow with winds around 10 knots and seas 3 feet or less. && .FIRE WEATHER... Abundant moisture and rainfall will prevent red flag conditions from being met well into next week. && .HYDROLOGY... Widespread rain with some heavier bands continues this afternoon across much of the area. A lot of the rain over the western half of our area has been due to a band of heavier rain showers and a few thunderstorms. This band has been producing rain rates of up to 2-3 inches per hour, but has been showing steady eastward progression. Therefore, flash flooding issues have been isolated (so far) to urban areas around Panama City. The rain and storms should continue into the evening - possibly affecting areas further to the east - but then will eventually re-consolidate back to the west after midnight and into tomorrow. Given the widespread nature of the moderate to heavy rainfall, many river systems around the area should see notable rises and increased flows, except for perhaps the far southeast part of our area in Taylor, Lafayette, and Dixie counties. The rivers, as of a week ago, were running at lower levels than what we had seen for most of July, so it has taken a considerable amount of rain to move some to even a bankfull status. Flooding issues will be determined by the location of the heaviest rainfall over the next 1-2 days, although a few rivers that may be particularly at risk include: Choctawhatchee, Shoal, Apalachicola. The most up to date, specific river forecast information can be found on the AHPS web page at: http:/water.weather.gov/ahps2/index.php?wfo=tae. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 72 90 73 91 73 / 60 60 30 50 30 Panama City 76 87 76 88 76 / 60 60 40 50 30 Dothan 71 86 72 89 72 / 70 70 30 50 30 Albany 71 88 72 90 72 / 70 60 30 50 30 Valdosta 71 90 72 91 72 / 60 50 30 50 30 Cross City 73 90 72 91 72 / 40 50 40 40 30 Apalachicola 78 87 77 86 77 / 50 50 40 50 30 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...FLASH FLOOD WATCH until 11 PM EDT this evening for all zones east of the Apalachicola River. FLASH FLOOD WATCH through Sunday evening for all zones west of the Apalachicola River. GA...FLASH FLOOD WATCH until 11 PM EDT this evening for all zones. AL...FLASH FLOOD WATCH through Sunday evening for all zones. GM...None. && $$ Lamers/Moore
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
346 PM EDT SAT AUG 17 2013 ...WET PATTERN TO CONTINUE FOR THE REMAINDER OF THE WEEKEND... .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... LOW LEVEL FLOW OVER 300K ISENTROPIC SURFACE HAS BECOME MORE SOUTHERLY AND CROSS FLOW ALLOWING FOR ENHANCED LIFT NORTH OF FRONTAL BOUNDARY OVER SOUTH GEORGIA. ENTRENCHED WEDGE ALSO PROVIDING FOR ADDITIONAL FOCUS FOR THE DEVELOPMENT OF WIDESPREAD LIGHT TO MODERATE RAIN OVER THE AREA. IN SITU CONDITIONS WITHIN WEDGE ONLY HELPING TO STRENGTHEN ITS GRIP ON THE LOCAL AREA WITH TEMPS REMAINING IN THE 60S FOR ALL OF NORTH GEORGIA. HAVE PRETTY MUCH KEPT STEADY TEMPS IN THE FORECAST FOR THE SHORT TERM PERIOD WHICH IS SOME 3 TO 6 DEGREES BELOW MODEL GUIDANCE WHICH IS NOT PERFORMING WELL WITH THIS SUMMER WEDGE SCENARIO. FOR TONIGHT...AXIS OF PRECIP SHOULD REMAIN IN ROUGHLY THE SAME LOCATION AS MAIN FEATURES ARE STEADY STATE THROUGH THE OVERNIGHT HOURS. EXPECT AT LEAST SOME DIURNAL INFLUENCES TO PRECIP COVERAGE AND WILL GRADUALLY DECREASE...BUT KEEP A LARGE AREA OF LIKELY THROUGH SUNDAY MORNING. GFS AS WELL AS SHORT TERM HRRR AND WRF IN AGREEMENT IN DEPICTING A STRONG SHORTWAVE PUSHING OUT OF THE GULF TOWARD DAYBREAK SUNDAY IN CONJUNCTION WITH A POSSIBLE BREAKDOWN OF WEDGE FOR THE EXTREME SOUTHERN SECTIONS. SHOULD SEE REDEVELOPMENT OF SHOWERS ON THE WEST SIDE OF THE FORECAST AREA WITH CONVECTIVE ELEMENTS INCREASING AS WELL WHICH WILL LEAD TO HIGHER RAINFALL RATES FROM COLUMBUS TO MACON. UPPER LEVEL FEATURE WILL LIFT NORTH THROUGH LA GRANGE AND ATLANTA INTO THE AFTERNOON WITH CATEGORICAL POPS EXPECTED ONCE AGAIN. BEST CAPE REMAINS TO THE SOUTH BUT THE ADDITION OF SHORTWAVE ENERGY COULD HELP OVERCOME A LACK OF INSTABILITY FOR THE NORTH AND WILL NEED TO BE MONITORED CLOSELY. AT THE VERY LEAST...POTENTIAL FOR HEAVIER SUSTAINED SHOWERS WILL INCREASE SUNDAY. WILL LET MID SHIFT TAKE ANOTHER LOOK BUT MAY NEED TO EXTEND FLOOD WATCH THROUGH THE REMAINDER OF SUNDAY. PRETTY MUCH THE SAME INTO SUNDAY NIGHT WITH FOCUS SHIFTING TO NORTHWEST GA WITH SHORTWAVE. HAVE BACKED OFF OF CATEGORICAL AS DIURNAL INFLUENCES SHOULD STILL BE IN PLAY BUT STILL PAINTING LIKELY FOR THE FIRST PART OF THE OVERNIGHT PERIOD. DEESE .LONG TERM /MONDAY THROUGH SATURDAY/... CHANGES TO THE LONG TERM ARE MINOR. HAVE TWEAKED POPS BASED OFF THE LATEST MODELS. OTHER THAN THAT...ADJUSTED TEMPERATURES DOWN A DEGREE OR SO FROM GUIDANCE FOR MONDAY. PREVIOUS DISCUSSION FOLLOWS. 11 /ISSUED AT 452 AM EDT SAT AUG 17 2013/ THE GFS AND ECMWF MODELS REMAIN CONSISTENT IN CONTINUING THIS WET PATTERN THROUGH THE WEEKEND AND INTO NEXT WEEK. THE STATIONARY FRONT OVER SOUTH GA WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY/TUE THEN GRADUALLY DISSIPATE. AN EASTERLY LOW LEVEL FLOW WITH ATLANTIC MOISTURE AND OVERRUNNING TROPICAL MOISTURE FROM THE GULF WILL COMBINE WITH A SERIES OF UPPER LEVEL DISTURBANCES TO PRODUCE WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS THROUGH WED/THU. BEST TIMING FOR HEAVY RAIN WILL BE IN THE SHORT TERM BUT DEEP TROPICAL MOISTURE REMAIN OVER THE REGION THROUGH DAY 6/7. PRECIPITABLE WATERS REMAIN IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE MODELS ARE TRYING TO ERODE THE WEDGE A BIT TO FAST ALLOWING INSTABILITIES TO INCREASE ACROSS THE AREA MONDAY. THERE APPEARS TO BE NO EROSION MECHANISM AND REINFORCEMENT OF THE COLD AIR DAMMING IS LIKELY TO CONTINUE WITH SOLAR SHELTERING FROM OVERRUNNING MOISTURE AND ANY EVAPORATIONAL COOLING. THIS WEDGE SHOULD CONTINUE AT LEAST INTO EARLY NEXT WEEK ALLOWING INSTABILITY INDICES TO STAY LOW FOR THIS TIME OF YEAR. WILL DEFINITELY NEED TO WATCH THIS AS IT WILL PLAY A BIG ROLE IN OUR WEATHER PATTERN. TEMPS SHOULD BEGIN TO REBOUND BY TUE BUT STILL STAY A BIT BELOW SEASONAL NORMS. 01 && .HYDROLOGY... WITH CHANGING MODEL DEPICTIONS OF PRECIP PATTERN COMES CHANGES IN ANTICIPATED HEAVIEST PRECIP CORE. EXPECTING CONVECTIVE ELEMENTS TO EMANATE OUT OF THE GULF TONIGHT AND TRANSITION ON THE WESTERN SIDE OF THE FORECAST AREA SUNDAY. THIS WILL PUT US SLIGHTLY OUT OF PHASE WITH CURRENT FLOOD WATCH BUT FEELING IS THAT EVEN AREAS OVER THE SOUTH THAT RECEIVE LESS RAINFALL COULD STILL REALIZE FLOODING GIVEN EXTREMELY LOW FLASH FLOOD GUIDANCE VALUES. HAVE FLOOD WATCH GOING THROUGH 12Z SUNDAY NIGHT WITH POSSIBLE EXPANSION BY MID SHIFT IN BOTH TIME AND AREA. && .CLIMATE... RECORDS FOR 08-17 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAHN 105 1954 73 1939 76 2010 60 1967 2007 1948 1995 KATL 101 2007 74 1939 76 2010 62 1948 1954 1892 2000 1892 1995 KCSG 102 2000 82 1979 78 2001 66 1961 KMCN 103 2000 76 1939 77 2010 60 1967 1954 1952 RECORDS FOR 08-18 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAHN 103 1995 70 1905 76 1946 62 1979 1976 1964 KATL 101 2000 70 1981 80 2000 62 1964 1995 1905 1879 KCSG 104 2000 78 1981 78 2000 62 1948 1995 KMCN 104 2000 75 1981 77 2000 63 1948 1905 1995 1951 RECORDS FOR 08-19 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAHN 105 1925 75 1981 75 1934 61 1976 KATL 99 1925 69 1897 76 2010 63 1879 2007 1993 KCSG 100 2000 78 1992 78 2010 64 1958 1977 KMCN 101 1983 77 1977 77 1999 64 2006 1925 1976 RECORDS FOR 08-20 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAHN 107 1925 75 1976 77 1983 59 1943 1953 KATL 100 1925 77 1953 80 1925 59 1927 1927 KCSG 102 1983 78 1981 77 2010 66 1961 1948 KMCN 105 1925 74 1897 76 2010 62 1943 1983 1936 && .AVIATION... 18Z UPDATE... PRECIPITATION SHIELD WHICH NOW ENCOMPASSES ALL THE AREA TAF SITES HAS RESULTED IN LOWER CIGS AND VSBYS MAINTAINING THEMSELVES THIS AFTERNOON. MOST SITES ARE IN THE IFR RANGE WITH BRIEF DIPS INTO LIFR AS HEAVIER SHRA PASS THROUGH. LOOKS LIKE A PERSISTENCE FORECAST THIS CYCLE WITH IFR TO CONTINUE INTO THE EVENING HOURS...TRANSITIONING TO A LONG PERIOD OF LIFR INTO THE OVERNIGHT PERIOD. SHRA SHOULD EASE BY LATE THIS EVENING BUT ADDITIONAL SHRA EXPECT BY MID MORNING SUNDAY. //ATL CONFIDENCE...18Z UPDATE... MEDIUM ON CIGS. HIGH ON REMAINING ELEMENTS. DEESE && .PRELIMINARY POINT TEMPS/POPS... ATHENS 64 71 68 82 / 100 70 50 40 ATLANTA 64 72 69 81 / 80 100 70 50 BLAIRSVILLE 61 69 64 78 / 80 100 70 40 CARTERSVILLE 64 71 68 82 / 70 100 70 40 COLUMBUS 69 81 72 85 / 80 80 60 50 GAINESVILLE 63 71 68 79 / 80 100 70 40 MACON 68 79 71 85 / 100 60 50 50 ROME 66 71 69 84 / 60 100 70 40 PEACHTREE CITY 66 73 69 82 / 80 100 70 50 VIDALIA 69 82 72 87 / 100 40 30 50 && .FFC WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR THE FOLLOWING ZONES: BALDWIN...BIBB...BLECKLEY...BUTTS...CHATTAHOOCHEE... CRAWFORD...CRISP...DODGE...DOOLY...EMANUEL...GLASCOCK...GREENE... HANCOCK...HARRIS...HOUSTON...JASPER...JEFFERSON...JOHNSON... JONES...LAMAR...LAURENS...MACON...MARION...MERIWETHER...MONROE... MONTGOMERY...MORGAN...MUSCOGEE...PEACH...PIKE...PULASKI... PUTNAM...SCHLEY...STEWART...SUMTER...TALBOT...TALIAFERRO... TAYLOR...TELFAIR...TOOMBS...TREUTLEN...TROUP...TWIGGS...UPSON... WARREN...WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES... WILKINSON. && $$ SHORT TERM...DEESE LONG TERM....11 AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1230 PM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 555 AM CDT SAT AUG 17 2013 HELD OFF AS LONG AS WE COULD...BUT KUEX NOW INDICATES ISOLATED SHOWER ACTIVITY DEVELOPING OVER ROOKS COUNTY. MEAGER ELEVATED POTENTIAL INSTABILITY IS ALSO SUGGESTED BY RAP ANALYSIS PROXIMITY SOUNDINGS AND THUS...OCCASIONAL LIGHTNING/THUNDER ALSO CANNOT BE RULED OUT. WENT AHEAD WITH 20% POPS UNTIL 13Z FOR OUR EXTREME SOUTHWESTERN CWA. THE LOW LEVEL JET SHOULD QUICKLY DIMINISH POST- SUNRISE THUS ALLOWING FOR DIMINISHING SHOWER AND THUNDERSTORM ACTIVITY. REMAINDER OF THE FORECAST WAS LEFT UNCHANGED. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 346 AM CDT SAT AUG 17 2013 OVERNIGHT MAP ANALYSIS INDICATES MID TO UPPER LEVEL LONGWAVE RIDGING OVER THE WESTERN CONUS...WITH A TROUGH OVER THE EAST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM THE WEST-CENTRAL CONUS...NORTHEAST INTO SOUTHWEST AND SOUTH CENTRAL CANADA...AND THEN SOUTHEAST ACROSS THE PLAINS...AND FINALLY EAST/NORTHEAST ACROSS THE SOUTHEASTERN CONUS AND ON INTO THE EASTERN CONUS. MID TO UPPER LEVEL FLOW OVER THE CENTRAL PLAINS REMAINS FROM THE NORTH/NORTHWEST AS A RESULT...BUT IS NOT PARTICULARLY STRONG ONLY MAXING OUT AT AROUND 45KTS NEAR 200MB PER 00Z SOUNDING DATA FROM KLBF AND KOAX. WATER VAPOR IMAGERY ALSO SHOWS THE AFOREMENTIONED LONGWAVE RIDGE AND TROUGH...WITH INCREASED VALUES OF MID LEVEL MOISTURE FLOWING ALONG THE MID LEVEL JET AXIS. AT THE SURFACE A LARGE AREA OF HIGH BAROMETRIC PRESSURE EXISTS OVER THE MISSOURI AND MID MISSISSIPPI RIVER VALLEYS. LOW LEVEL FLOW ACROSS OUR AREA REMAINS FROM THE SOUTHEAST AS A RESULT. LOW LEVEL THERMAL ADVECTION ALONG THE AXIS OF A ~30KT 850MB JET AXIS IS HELPING PROMOTE ISOLATED SHOWER AND THUNDERSTORM ACTIVITY OVER PORTIONS OF WESTERN KANSAS THIS MORNING. ALTHOUGH THIS ACTIVITY HAS REMAINED SOUTHWEST OF OUR CWA SO FAR TONIGHT...GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF- MEAN ALL SUGGEST THE LOW LEVEL JET STREAK AXIS WILL VEER MORE INTO OUR AREA TOWARDS 12Z. THE NAM AND EC BOTH SUGGEST LIGHT PRECIPITATION WILL BE REALIZED OVER EXTREME SOUTHWESTERN PORTIONS OF OUR CWA...A SOLUTION ALSO SUPPORTED TO AN EXTENT BY THE HRRR AND 1KM WRF-NMM. ALL THAT BEING SAID...CONFIDENCE OF ANY ONE LOCATION ACROSS OUR CWA...INCLUDING OUR SOUTHWESTERN CWA...ACTUALLY OBSERVING MEASURABLE RAINFALL REMAINS VERY LOW AND AS A RESULT...WILL CONTINUE WITH THE DRY FORECAST FOR EARLY THIS MORNING AND CONTINUE TO MONITOR. FOR THE REST OF TODAY AND TONIGHT...AN OVERALL LACK IN KINEMATIC FORCING SHOULD PRESENT DRY CONDITIONS TO OUR AREA THROUGH TONIGHT. MUCH LIKE THIS MORNING HOWEVER...THE ONLY EXCEPTION COULD BE ACROSS OUR WEST/SOUTHWEST 06-12Z SUNDAY AS THE AXIS OF ~30KT 850MB JET STREAK ONCE AGAIN DEVELOPS OVER PORTIONS OF THE CENTRAL HIGH PLAINS. THAT BEING SAID...QPF FIELDS FROM VARIOUS MODELS DO NOT SUGGEST MEASURABLE PRECIPITATION WILL BE REALIZED ANYWHERE ACROSS OUR CWA AND GIVEN THIS...WILL GO AHEAD AND MAINTAIN A DRY FORECAST THROUGH 12Z SUNDAY AND LET FUTURE SHIFTS REEVALUATE THE POTENTIAL NEED FOR LOW POPS DURING THE EARLY MORNING HOURS ON SUNDAY. CLOUD COVER REALLY KEPT TEMPERATURES ACROSS OUR CWA ON THE COOL SIDE DURING THE DAY FRIDAY. THE STRATUS DECK HAS NOT BEEN NEARLY AS DENSE AS EXPECTED TONIGHT HOWEVER AND THE CURRENT THINKING IS THIS STRATUS SHOULD DISSIPATE AND LIFT BY MID TO LATE MORNING WHICH SHOULD ALLOW FOR WARMER AFTERNOON HIGHS. GUIDANCE FROM THE MET...MAV...AND ECS SEEMS TO HAVE A GOOD HANDLE ON THIS AND TAKING AN EVEN AVERAGE OF THE THREE PROVIDES AFTERNOON HIGH TEMPERATURES IN THE UPPER 70S TO NEAR 80 ACROSS MUCH OF THE CWA. CLEARER SKIES SHOULD ALLOW FOR A SLIGHTLY COOLER OVERNIGHT LOWS TONIGHT WHEN COMPARED TO EARLY THIS MORNING...WITH OVERNIGHT LOWS IN THE UPPER 50S TO NEAR 60 CURRENTLY FORECAST FOR MOST LOCATIONS TONIGHT. FINALLY...NEAR-ZERO LOW LEVEL DEW POINT DEPRESSIONS AND A FAIRLY LIGHT SOUTH/SOUTHEAST LOW LEVEL WIND FIELD COULD PROMOTE PATCHY FOG ACROSS THE AREA TOWARDS SUNRISE SUNDAY. VISIBILITY RESTRICTION IS NOT EXPECTED TO BE SIGNIFICANT...BUT WILL GO AHEAD WITH PATCHY FOG IN THE GRIDS BEGINNING 09Z SUNDAY. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 346 AM CDT SAT AUG 17 2013 A RELATIVELY QUIET WEATHER PATTERN WILL BECOME EVIDENT BEGINNING SUNDAY AS HIGH PRESSURE CONTINUES TO SLIDE OVER THE REGION FROM THE INTERMOUNTAIN WEST. WATER VAPOR IMAGERY DEPICTS A 500MB TROUGH OVER THE EASTERN PART OF THE CONUS...WHILE HIGH PRESSURE IS BUILDING IN OVER MOST OF THE WESTERN CONUS. THERE IS A SHORT WAVE TROUGH EVIDENT OVER THE PACIFIC NORTHWEST AS WELL. MODELS ARE IN GOOD AGREEMENT WITH REGARDS TO HIGH PRESSURE BUILDING IN FROM THE WEST TO CONTINUE. THIS PATTERN WILL MAKE FOR WARMER DAYS AHEAD WITH TEMPERATURES FORECAST TO BE MORE SEASONABLE THAN THE PREVIOUS WEEK. THE PATTERN OVER THE NEXT WEEK IS SHOWING UNFAVORABLE CONDITIONS FOR ANY PRECIPITATION AND HENCE A DRY FORECAST THROUGH MOST OF THE EXTENDED AS HIGH PRESSURE DOMINATES THE REGION. THURSDAY NIGHT INTO FRIDAY APPEARS TO BE THE ONLY DAY SHOWING ANY CHANCE FOR PRECIPITATION...BUT THE LATEST RUNS OF THE GFS AND EC ARE BOTH BEGINNING TO SHOW DRY CONDITIONS IN THE EXTENDED. SINCE THIS IS THE FIRST RUN OF THE EC AND GFS AGREEING IN FAVOR OF DRIER CONDITIONS...I WILL LEAVE THE SLIGHT CHANCES IN THERE FOR THURSDAY NIGHT INTO FRIDAY UNTIL SOME CONSISTENCY EVOLVES. DONT WANT A FLIP FLOP SCENARIO DEVELOPING. I CAN SEE THESE POPS GETTING YANKED IF THIS TREND CONTINUES INTO DAY SHIFT THOUGH. SEEMS VERY REASONABLE TO HAVE THE DRY FORECAST BASED ON THE HIGH PRESSURE STILL PROGGED TO BE NEARLY CENTERED OVER THE CENTRAL PLAINS REGION COME FRIDAY. WITH THE HELP OF HIGH PRESSURE BUILDING IN OVER THE REGION...TEMPERATURES WILL BE MORE SEASONABLE THROUGH THE EXTENDED. SUNDAY WILL BE THE COOLEST DAY OVER THE FORECAST PERIOD...WITH HIGHS RANGING FROM THE LOWER 80S TO UPPER 80S. MONDAY WILL BE SLIGHTLY WARMER. BUT BY TUESDAY...HIGH TEMPERATURES NEAR 90 DEGREES WILL BE THE NORM THROUGH AT LEAST FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1221 PM CDT SAT AUG 17 2013 WILL CONTINUE TO SEE THE POTENTIAL FOR SOME LOWER LEVEL/MVFR CLOUD COVER TO AFFECT THE TERMINAL AREA THROUGH THE AFTERNOON HOURS...BUT IT DOESNT LOOK TO BE A SOLID DECK SO WILL KEEP AS A TEMPO MENTION...AND CEILINGS SHOULD LIFT AS WE GET TOWARD LATER THIS AFTERNOON. MODELS SHOWING THE REDEVELOPMENT OF STRATUS TONIGHT BEING WEST OF THE TERMINAL...SO HAVE THE OVERNIGHT HOURS INTO TOMORROW VFR AT THIS POINT. WINDS THROUGH THE TAF PERIOD WILL REMAIN SOUTHERLY...AS THE AREA SITS BETWEEN HIGH PRESSURE FROM ERN NEB UP INTO THE NERN CONUS...AND LOW PRESSURE OVER THE ROCKIES/HIGH PLAINS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...BRYANT SHORT TERM...BRYANT LONG TERM...GUERRERO AVIATION...ADO
AREA FORECAST DISCUSSION
NWS RALEIGH NC
230 PM EDT SAT AUG 17 2013 .SYNOPSIS... SURFACE HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL EXTEND SOUTHWARD INTO THE PIEDMONT OF CAROLINAS THROUGH SUNDAY. MEANWHILE WEAK WAVES OF LOW PRESSURE WILL DEVELOP AND MOVE ALONG A STALLED FRONT ACROSS GEORGIA AND COASTAL CAROLINA. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1055 AM SATURDAY... ...CHILLY AND UNSETTLED WEATHER TODAY... SCATTERED TO NUMEROUS PATCHES OF LIGHT RAIN AND DRIZZLE ARE NOTED ON THE KRAX WSR-88D THIS MORNING. THE PRECIPITATION IS LARGELY BEING DRIVEN BY MODEST LOW LEVEL ISENTROPIC LIFT WITH A FAIRLY STRONG SOUTHWESTERLY FLOW ALOFT. THE ISENTROPIC LIFT CAN BE SEEN IN THE 12 UTC KGSO RAOB AND IN THE HMT-SEPS PROJECT VERTICAL PROFILER NEAR NEW BERN. NWP DATA AND TRENDS IN THE NEW BERN PROFILER SUGGEST THAT THE BEST LOW LEVEL FORCING FOR ASCENT WILL SHIFT INTO THE EASTERN PIEDMONT AND COASTAL PLAIN DURING THE NEXT 6 HOURS AND HAVE ACCORDINGLY INCREASED AND FOCUSED NEAR TERM POPS THERE. AFTER THIS PERIOD THERE WILL LIKELY BE A DECREASE IN PRECIP COVERAGE ACROSS THE SOUTHEASTERN AND EASTERN PORTIONS OF THE RAH CWA AS HIGH RES NWP GUIDANCE...PRIMARILY RECENT RUNS OF THE HRRR AND THE 00UTC NSSL WRF-ARW INDICATE. ANOTHER BATCH OF PRECIPITATION IS LIKELY TO PUSH INTO THE SOUTHWESTERN AND WESTERN PIEDMONT LATE THIS AFTERNOON AND EVENING AS ANOTHER PERTURBATION IN THE SOUTHWEST FLOW ALOFT APPROACHES AND ENHANCES THE LOW LOW/MID-LEVEL ASCENT. WHILE RAINFALL AMOUNTS HAVE BEEN SOMEWHAT LIGHT...THEY APPEAR SUFFICIENT TO SUSTAIN AND LOCK IN THE COLD AIR DAMMING AIR MASS ACROSS THE PIEDMONT. BASED ON RECENT OBSERVATIONS HAVE ADJUSTED TEMPS UP A DEGREE OR SO INTO THE 66 TO 76 DEGREE RANGE WHICH IS MORE THAN 10 DEGREES BELOW NORMAL. HAVE REDUCED QPF AMOUNTS A BIT TODAY GIVEN THE ISENTROPIC LIFT APPEARS WEAKER THAN PROGGED 12 TO 36 HOURS AGO AND RADAR AMOUNTS HAVE IN GENERAL BEEN LESS THAN EXPECT. STILL RAIN TOTALS FOR THIS EVENT BEGINNING AT MIDNIGHT WILL LIKELY RANGE BETWEEN A QUARTER AND A HALF INCH. -BLAES TONIGHT...BULK OF RAIN EARLY IN THE EVENING SHOULD OCCUR ACROSS THE NORTHERN AND WESTERN PIEDMONT AS 850MB WARM FRONT GRADUALLY PIVOTS NORTHWEST THROUGH THIS REGION. THE WARMER AIR ALOFT OVER THE RELATIVELY COOL SFC AIR MASS SHOULD RESULT IN AREAS OF FOG ACROSS THE PIEDMONT OVERNIGHT ALONG WITH PATCHES OF LIGHT RAIN. RAIN COVERAGE SHOULD BE LESS OVER THE COASTAL PLAIN AND SANDHILLS. MIN TEMPS IN THE MID 60S NW TO NEAR 70 SE. -WSS && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 310 AM SATURDAY... SUNDAY AND SUNDAY NIGHT...MAIN SHEAR AXIS ALOFT MIGRATES WESTWARD TO A POSITION OVER THE FOOTHILLS INTO THE WESTERN PIEDMONT. AIR MASS PLENTY MOIST ENOUGH TO SUPPORT THE DEVELOPMENT OF SCATTERED-NUMEROUS SHOWERS. FARTHER EAST...MODEL GUIDANCE HINTING AT SOME MID-UPPER LEVEL DRYING TAKING PLACE. IF THIS WERE TO OCCUR...BREAKS IN OVERCAST MAY DESTABILIZE THE LOW LEVEL AIR MASS ENOUGH TO GENERATE SCATTERED SHOWERS AND A FEW THUNDERSTORMS. MODEL GUIDANCE CURRENTLY SUGGEST INSTABILITY AS MARGINAL AT BEST THOUGH BULK SHEAR VALUES SUFFICIENT (30-40KTS) FOR THE DEVELOPMENT OF ORGANIZED CONVECTION. MODEL SFC DATA ALSO DEPICT A WEAK SURFACE BOUNDARY IN VICINITY OF THE COASTAL PLAIN SUNDAY AFTERNOON-EVENING. ANY STORMS THAT FORM AND MOVE ALONG THIS FEATURE MAY EXHIBIT SOME ROTATION. LACK OF SUFFICIENT WIND SPEED SHOULD LIMIT SEVERE POTENTIAL. TEMPS SUNDAY HIGHLY DEPENDENT ON ANY BREAKS IN THE OVERCAST AND EXTENT OF SHOWER ACTIVITY. MOS GUIDANCE HINTING AT SOME RECOVERY OF THE AIR MASS ESPECIALLY IN THE COASTAL PLAIN. FAVOR WAITING TO SEE THE EXTENT OF RAIN COVERAGE TODAY AND DEVELOPMENT OF CAD BEFORE RAISING TEMPS TOO MUCH ON SUNDAY. PLAN TO MAINTAIN MAX TEMPS FROM PREVIOUS FORECAST WITH LOWER 70S NW TO THE LOWER 80S SE. SHOWER CHANCES DWINDLE SUNDAY NIGHT AS SHEAR AXIS WEAKENS IN RESPONSE TO RISING HEIGHTS FROM THE BUILDING SUBTROPICAL RIDGE TO OUR EAST AND AIR MASS NOT AS SATURATED. PLAN TO MAINTAIN A CHANCE TO SLIGHT CHANCE POPS ACROSS THE REGION (HIGHEST IN THE WEST-NW). MIN TEMPS MID-UPPER 60S. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 310 AM SATURDAY... MONDAY THROUGH TUESDAY NIGHT: THE CLOSED LOW CURRENTLY OVER THE LOWER MS RIVER VALLEY IS FORECAST TO OPEN AND LIFT TOWARDS OUR REGION THIS WEEKEND AND SLOWLY MOVE ACROSS OUR AREA MONDAY INTO TUESDAY. THIS FEATURE ALONG WITH ABUNDANT MOISTURE (PW`S OF AROUND 2") IN ADVANCE OF THE SYSTEM SHOULD SET THE STAGE FOR AT LEAST SCATTERED AFTERNOON AND EVENING SHOWERS AND STORMS ACROSS CENTRAL NC ON MONDAY AREAWIDE. TUESDAY THE HIGHEST CONCENTRATION OF SHOWERS AND STORMS IS EXPECTED ACROSS THE SOUTHERN/SOUTHEASTERN HALF OF CENTRAL NC AS THE SHEAR SLOWLY MOVES ACROSS THE AREA. THUS... WE KEEP CHANCE AFTERNOON AND EVENING POPS FOR ALL LOCATIONS MONDAY. TUESDAY WILL DO THE SAME... BUT WILL ADVERTISE LOW CHANCE POPS ACROSS THE NORTH/NORTHWEST AS THE SHEAR AXIS SLOWLY SHIFTS SOUTH/SOUTHEASTWARD ACROSS THE AREA ON TUESDAY... USHERING DRY AIR ALOFT. TEMPERATURES DURING THIS TIME FRAME WILL REBOUND AS ANY LINGERING SURFACE BOUNDARIES ACROSS THE REGION BEGIN TO WASHOUT. HOWEVER... WE MAY SEE THE FAR NORTHWEST PIEDMONT HANG ONTO A RESIDUAL CAD AIRMASS FOR MOST OF THE DAY MONDAY. THUS... WILL SHOW TEMPS RANGING FROM THE UPPER 70S TO NEAR 80 FAR NW TO UPPER 80S SE. TUESDAY EXPECTED WE WILL SEE MID TO UPPER 80S ACROSS THE AREA. LOW TEMPS DURING THIS TIMEFRAME WILL BE NEAR NORMAL... IN THE UPPER 60S TO LOWER 70S. WEDNESDAY THROUGH FRIDAY: THE LINGERING SHEAR AXIS IS EXPECTED TO EITHER REMAIN ACROSS OUR SOUTHERN COUNTIES OR PUSH JUST TO THE SOUTH OF OUR REGION WHILE WEAKENING ON WEDNESDAY INTO THURSDAY. THROUGH 84 HOURS BOTH THE NAM AND GFS SHOW THIS AFOREMENTIONED SHEAR AXIS ACROSS OUR REGION IN A ENE TO WSW FASHION... WHILE THE ECMWF IS SLOWER AND HAS THE FEATURE BACK ACROSS THE HIGHER TERRAIN AT THIS TIME... BEFORE SETTLING THIS FEATURE SOUTH/SOUTHEASTWARD INTO OUR AREA ON TUESDAY AFTERNOON INTO TUESDAY NIGHT THEN LINGERING THE FEATURE ACROSS SOUTHERN PORTIONS OF THE AREA ON WEDNESDAY. THUS... EXPECT THE BEST CHANCE OF SEEING ANY SHOWERS AND STORMS ON WEDNESDAY WILL BE ACROSS SOUTHERN PORTIONS OF THE AREA. THE FORECAST BECOMES MORE UNCLEAR ON THURSDAY INTO FRIDAY... FIRST WITH THE TRACK AN EVOLUTION OF TWO SEPARATE S/W FEATURES. THE GFS ATTEMPTS TO BRING SOME FORM OF S/W ENERGY (POSSIBLY FROM THE REMNANTS OF THE SYSTEM CURRENTLY LOCATION IN THE GULF OF MEXICO) AROUND THE EXPANDING SUB-TROPICAL RIDGE ACROSS THE DEEP SOUTH AND INTO OUR AREA ON THURSDAY INTO THURSDAY NIGHT... WHILE THE LATEST ECMWF (12Z/16TH) HAS A WEAK S/W DROPPING SOUTHWARD OUT OF THE GREAT LAKES ON WEDNESDAY AND MOVING ACROSS THE MID-ATLANTIC REGION LATE THURSDAY INTO FRIDAY. GIVEN THIS AND WPC IS ADVERTISING A BETTER CHANCE OF SHOWERS AND STORMS THAT DAY ACROSS OUR AREA WILL HOLD ONTO CHANCE POPS FOR THURSDAY. ON FRIDAY... THE GFS AND ECMWF DIFFER WITH REGARD TO THE NEXT APPROACHING COLD FRONT... WITH THE GFS BRINGING A FRONT INTO THE AREA BY LATE FRIDAY... WITH THE ECMWF MUCH SLOWER. FOR NOW WILL KEEP POPS AS IS FOR FRIDAY LOW END CHANCE/SLIGHT CHANCE ACROSS THE AREA. TEMPS DURING THIS TIME SHOULD BE NEAR NORMAL... UPPER 80S TO NEAR 90 FOR HIGHS WITH LOWS IN THE UPPER 60S TO LOWER 70S. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 230 PM SATURDAY... HIGH CONFIDENCE OF ADVERSE AVIATION CONDITIONS THROUGH MOST OF THE 24 HOUR TAF PERIOD. MULTIPLE AREAS OF RAIN AND AN ASSOCIATED COOL AND MOIST AIR MASS WILL RESULT IN LOW CEILINGS AND REDUCED VISIBILITIES DURING THE NEXT 24 HOURS. IFR TO LIFR CONDITIONS AT THE TAF LOCATIONS THIS AFTERNOON AREA ASSOCIATED WITH AREAS OF LIGHT TO BRIEFLY HEAVIER RAIN THAT WILL PERSIST INTO THE EVENING. THE LARGE AREA OF SHOWERS ACROSS THE COASTAL PLAIN AND SANDHILLS WILL GRADUALLY MOVE AWAY FROM THE AREA THIS EVENING WITH ANOTHER BATCH OF SHOWERS MOVING INTO THE WESTERN PIEDMONT FROM THE SOUTHWEST THIS EVENING AND PERSISTING INTO THE OVERNIGHT HOURS. OUTSIDE OF THE LARGE AREAS OF RAIN...MORE SCATTERED SHOWERS OR PATCHY DRIZZLE WITH AREAS OF FOG CAN BE EXPECTED. SUNDAY WILL START OFF WITH LOW CEILINGS IN THE LIFR/IFR RANGE. BUT SOME IMPROVEMENT IS POSSIBLE...ESPECIALLY ACROSS THE COASTAL PLAIN NEAR KFAY AND KRWI WHERE BASES MAY LIFT TO THE HIGH END MVFR/LOW END VFR RANGE DURING THE MID TO LATE AFTERNOON. FARTHER WEST IN THE WESTERN PIEDMONT...LOW CEILINGS AND AREAS OF FOG/MIST WILL PERSIST THROUGH MUCH OF THE DAY WITH IFR CONDITIONS DURING THE MORNING SLOWLY IMPROVING TO MVFR BY AFTERNOON. LOOKING FURTHER AHEAD...LINGERING LOW CLOUDS AND SHOWERS ARE EXPECTED LATE SUNDAY THROUGH MONDAY...ESPECIALLY ACROSS THE INTERIOR PIEDMONT. CONDITIONS ARE EXPECTED TO GENERALLY IMPROVE DURING THE MID TO LATE WEEK PERIOD. MAINLY SCATTERED AFTERNOON OR EVENING CONVECTION IS POSSIBLE...ESPECIALLY ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...BLAES/WSS SHORT TERM...WSS LONG TERM...BSD AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS BISMARCK ND
349 PM CDT SAT AUG 17 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 343 PM CDT SAT AUG 17 2013 THE MAIN FORECAST CHALLENGE FOR THE PERIOD WILL BE THE PRECIP CHANCES LATER THIS EVENING AND AGAIN ON SUNDAY. A WEAK SURFACE BOUNDARY IS BEGINNING TO ENTER WESTERN NORTH DAKOTA THIS AFTERNOON. A STRONG CAP IN PLACE SHOULD INHIBIT AFTERNOON CONVECTION ALONG THE BOUNDARY. HOWEVER...AS THIS BOUNDARY PUSHES INTO CENTRAL NORTH DAKOTA THIS EVENING...THUNDERSTORMS COULD DEVELOP OVER NORTH CENTRAL NORTH DAKOTA PROXIMATE TO THE BEST UPPER LEVEL DYNAMICS AND WEAKEST CAP. THE 12Z ECMWF/NAM AND 17Z HRRR PROG THIS SCENARIO SO DECIDED TO KEEP SLIGHT CHANCE POPS IN THE GRIDS NORTH CENTRAL TONIGHT. SOME STORMS COULD BECOME STRONG SO WILL HIGHLIGHT THIS THREAT IN THE HWO FOR NOW. AS THE BOUNDARY MOVES INTO EASTERN NORTH DAKOTA SUNDAY...IT IS PROGGED TO BECOME STALLED ACROSS CENTRAL NORTH DAKOTA. AN UPPER WAVE IS FORECAST TO MOVE OVER NORTH DAKOTA THROUGH THE DAY SUNDAY. AS IT DOES...THE CHANCES FOR THUNDERSTORMS WILL GRADUALLY OVERSPREAD THE STATE FROM WEST TO EAST. STORMS SHOULD REMAIN BELOW SEVERE CRITERIA THROUGH SUNDAY AFTERNOON...BUT COULD STRENGTHEN TO SEVERE SUNDAY EVENING. SEE LONG TERM DISCUSSION BELOW FOR MORE DETAILS. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 343 PM CDT SAT AUG 17 2013 THE MAIN FORECAST HIGHLIGHT FOR THE EXTENDED PERIOD WILL BE THE POTENTIAL FOR SEVERE THUNDERSTORMS SUNDAY EVENING. THEREAFTER...PROGRESSIVE WEST TO SOUTHWEST FLOW WITH MULTIPLE EMBEDDED UPPER LEVEL IMPULSES IS FORECAST THROUGH THE REMAINDER OF THE PERIOD. 12Z MODEL DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH MID BEFORE SOLUTIONS DIVERGE LATE WEEK. THE POTENTIAL FOR SEVERE THUNDERSTORMS WILL INCREASE SUNDAY EVENING AS THE COMBINED FORCING FROM THE SURFACE FRONTAL BOUNDARY AND UPPER LEVEL WAVE ERODES THE CAP. THIS FORCING SHOULD BE SUFFICIENT ENOUGH TO BREAK THE CAP BY EARLY SUNDAY EVENING AND ALLOW CONVECTION TO FIRE ALONG THE SURFACE FRONTAL BOUNDARY. THE ANTECEDENT ENVIRONMENT WILL BE FAVORABLE FOR THE DEVELOPMENT OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL AND MOST OF EASTERN NORTH DAKOTA...WITH ML CAPE FORECAST TO BE NEAR 2000 J/KG BY LATE SUNDAY AFTERNOON/EVENING...INCREASING BOUNDARY LAYER MOISTURE (DEWPOINTS INCREASING INTO THE 60S)...AND 0-6 KM BULK SHEAR TO BE IN THE 25 TO 35 M/S RANGE. FURTHERMORE...THE LATEST DAY 2 OUTLOOK FROM SPC HAS PARTS OF CENTRAL AND MOST OF EASTERN NORTH DAKOTA IN THE SLIGHT RISK. HAIL AND DAMAGING WINDS LOOK TO BE THE MAIN THREATS AND AT THIS TIME WILL HIGHLIGHT THE POSSIBILITY OF SEVERE THUNDERSTORMS IN THE HWO AND STATE FORECAST. FOLLOWING THE FRONTAL PASSAGE/SHORTWAVE MONDAY...DAYTIME UPPER LEVEL RIDGING WILL GIVE WAY TO WESTERLY FLOW ALOFT. THIS WILL CONTINUE THROUGH TUESDAY EVENING AHEAD OF THE EXPECTED COLD FRONT WEDNESDAY AND THURSDAY. CANNOT RULE OUT THE POSSIBILITY OF THUNDERSTORMS/SHOWERS ACROSS THE AREA...AS SEVERAL WEAK IMPULSES MOVE OVER THE STATE. PRECIPITATION CHANCES WILL THEN INCREASE AS A COLD FRONT AND AN UPPER LEVEL SHORT WAVE APPROACH NORTHERN NORTH DAKOTA LATE TUESDAY NIGHT/EARLY WEDNESDAY MORNING...AND AS THEY MOVE OVER THE AREA WEDNESDAY. SIMILAR TO PREVIOUS RUNS...THE 12Z ECWMF CONTINUES TO PAINT A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER THE WEST AND CENTRAL. HOWEVER...THE 12Z GFS CONTINUES TO KEEP NORTH DAKOTA DRY AS IT FORECASTS UPPER LEVEL RIDGING TAKING PLACE. WILL KEEP THE ALLBLEND SOLUTION...TO SPLIT THE DIFFERENCE BETWEEN THE ECWMF AND GFS. FOR FRIDAY AND SATURDAY...PRECIPITATION CHANCES WILL CONTINUE AS SOUTHWESTERLY FLOW TAKES HOLD. MEANWHILE...H850 TEMPERATURES WILL INCREASE TO BETWEEN +26 AND +30 C ON TUESDAY. THIS WILL TRANSLATE TO SURFACE TEMPERATURES IN THE 90S...WITH NEAR 100 DEGREE READING FOR FAR SOUTHERN NORTH DAKOTA. COOLER TEMPERATURES ARE FORECAST ONCE THE COLD FRONT PASSES THROUGH THE AREA WEDNESDAY...WHERE TEMPERATURES ARE EXPECTED TO BE MAINLY IN THE 80S DURING THE DAY AND UPPER 50S/LOWER 60S AT NIGHT THROUGH SATURDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 103 PM CDT SAT AUG 17 2013 VFR CONDITIONS WILL PREVAIL ACROSS NORTH DAKOTA THROUGH THE TAF PERIOD. THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS NEAR KMOT THIS EVENING. CONFIDENCE IS LOW REGARDING AVIATION IMPACTS. THEREFORE...ONLY INCLUDED VCTS IN THE KMOT TAF BETWEEN 00Z-05Z. FURTHERMORE...IFR CIGS/VSBYS COULD DEVELOP NEAR KJMS BETWEEN 11Z- 13Z. CONFIDENCE IS LOW IN THIS MATERIALIZING AND WILL THEREFORE LEAVE OUT OF THE KJMS TAF FOR NOW. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...TM LONG TERM...LTH AVIATION...AC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
103 PM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 103 PM CDT SAT AUG 17 2013 STRATUS DECK OVER THE JAMES RIVER BASIN IS BEGINNING TO ERODE AWAY WITH THE ONSET OF DAYTIME HEATING. THE LOW CLOUDS SHOULD DISSIPATE BY 2 PM CDT. OTHERWISE...ONLY MODIFIED THE HOURLY SENSIBLE WEATHER GRIDS BASED ON CURRENT OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT. UPDATE ISSUED AT 1041 AM CDT SAT AUG 17 2013 LOW CLOUDS AND PATCHY FOG ARE LINGERING OVER SOUTH CENTRAL AND SOUTHEASTERN NORTH DAKOTA LONGER THAN ANTICIPATED. AS A RESULT...UPDATED THE FORECAST TO CONTINUE THE CLOUDY AND PATCHY FOG CONDITIONS PRIMARILY ACROSS THE JAMES RIVER BASIN THROUGH THE MID-DAY HOURS. THIS SHOULD ALSO HAMPER MORNING TEMPERATURE WARMING TRENDS. HOWEVER...ONCE THE LOW CLOUDS AND FOG BURN OFF...TEMPERATURES SHOULD RAPIDLY INCREASE THIS AFTERNOON. UPDATE ISSUED AT 830 AM CDT SAT AUG 17 2013 SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND SOUTHEASTERN NORTH DAKOTA. THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS AS VERTICAL MIXING COMMENCES. UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013 THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 103 PM CDT SAT AUG 17 2013 VFR CONDITIONS WILL PREVAIL ACROSS NORTH DAKOTA THROUGH THE TAF PERIOD. THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS NEAR KMOT THIS EVENING. CONFIDENCE IS LOW REGARDING AVIATION IMPACTS. THEREFORE...ONLY INCLUDED VCTS IN THE KMOT TAF BETWEEN 00Z-05Z. FURTHERMORE...IFR CIGS/VSBYS COULD DEVELOP NEAR KJMS BETWEEN 11Z- 13Z. CONFIDENCE IS LOW IN THIS MATERIALIZING AND WILL THEREFORE LEAVE OUT OF THE KJMS TAF FOR NOW. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TM SHORT TERM...CK LONG TERM...KS AVIATION...AC
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1237 PM CDT SAT AUG 17 2013 .UPDATE...FOR 18Z AVIATION. && .AVIATION...18Z TAF DISCUSSION. A WEAK INVERTED TROUGH IS PROVIDING DECENT LOW LEVEL MOISTURE TRANSPORT INTO THE STATE TODAY. THIS MEANS MOSTLY CLOUDY SKIES WILL CONTINUE FOR MOST OF...IF NOT ALL...OF THIS PERIOD. IN ADDITION...THERE SHOULD BE JUST ENOUGH HEATING TO HELP SPARK A FEW SHOWERS THIS AFTERNOON. THE MAJORITY OF THIS ACTIVITY SHOULD REMAIN ALONG AND WEST OF INTERSTATE 65 AS AN UPPER LEVEL LOW CENTERED OVER THE MISSISSIPPI RIVER WILL BE THE PROVIDER OF THE LIFT. LATER TONIGHT...WIDESPREAD SHOWERS ARE EXPECTED TO START MOVING INTO THE EASTERN HALF OF THE STATE FROM THE SOUTHEAST. WILL GO AHEAD AND PREVAIL NOT ONLY THIS RAIN...BUT ASSOCIATED FLIGHT CATEGORY DEGRADATION STARTING BY 03Z THIS EVENING AT KCSV. KCKV/KBNA WILL ALSO SEE REDUCED FLIGHT CATEGORIES...WITH SOME LIFR POSSIBLE AROUND DAYBREAK AT KCKV. WINDS WILL REMAIN LIGHT...MAINLY OUT OF THE SOUTHEAST. UNGER && .PREV DISCUSSION... /ISSUED 905 AM CDT SAT AUG 17 2013/ UPDATE... EARLIER SHOWER AND TSTM ACTIVITY HAS LIFTED OFF TO THE NORTH. A BAND OF VERY LIGHT SHOWER ACTIVITY APPEARS TO BE WORKING NORTHWARD ACROSS CENTRAL AREAS. OVERALL HOWEVER...MODELS ARE ZONING IN ON A PERIOD OF SUBSIDENCE THROUGH THE MORNING HOURS. HOWEVER...BY AFTERNOON SUBSIDENCE WILL BEGIN TO GIVE WAY TO A SLIGHTLY UPWARD OMEGA FIELD AND THUS...SHOULD STILL SEE CONVECTIVE ACTIVITY INCREASE. HRRR IN SUPPORT OF REDEVELOPMENT AS WELL. FOR THE GRID UPDATE...WILL TWEAK POPS DOWN FOR THE PRE 18Z PERIOD. OTW...LITTLE ADJUSTMENTS NEEDED. MOSTLY CLOUDY SKIES SHOULD PREVAIL AND THUS THE EXPECTED HIGH TEMPS IN THE LOWER 80S STILL LOOKS REASONABLE. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 27
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
247 PM EDT SAT AUG 17 2013 .SYNOPSIS... A RIDGE OF HIGH PRESSURE WILL REMAIN SITUATED ALONG THE LEE OF THE CENTRAL APPALACHIANS. AN AREA OF LOW PRESSURE WILL PROGRESS NORTHEAST ALONG THE STALLED FRONTAL BOUNDARY THAT EXTENDED FROM GEORGIA TO THE COAST OF THE CAROLINAS. AN ACTIVE WEATHER PATTERN WILL CONTINUE INTO THE EARLY PART OF NEXT WEEK AS A TROUGH OF LOW PRESSURE APPROACHES THE REGION FROM THE WEST. && .NEAR TERM /THROUGH SUNDAY/... AS OF 230 PM EDT SATURDAY... EARLY THIS AFTERNOON...AREAS OF RAIN WERE EXPANDING IN COVERAGE IN RESPONSE TO THE NEXT UPPER LEVEL WAVE APPROACHING IN THE UPPER LEVEL SOUTHWEST FLOW. MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT THAT ISENTROPIC LIFT ON THE 305K SFC SIGNIFICANTLY INCREASES BETWEEN NOW AND EARLY TONIGHT. AS A RESULT...HAVE RAMPED UP POPS THROUGH THE EVENING HOURS...WITH PRECIPITATION ARRIVING LAST IN THE GREENBRIER VALLEY. WITH ABUNDANT CLOUDS AND WIDESPREAD PRECIP...EXPECT A SMALL DROP IN TEMPS TONIGHT AND GENERALLY WENT ABV GUIDANCE FOR LOWS. ON SUNDAY...WE BEGIN TO BECOME UNDER THE INFLUENCE OF THE WEAKENING UPPER LEVEL WAVE IN THE OHIO VALLEY. THE 850-700MB FLOW VEERS TO THE WEST WHICH REDUCES THE MOISTURE DEPTH. HOWEVER...WITH A SHALLOW WEDGE STILL EXPECTED TO BE IN PLACE...AREAS OF DRIZZLE/LIGHT RAIN WILL CONTINUE SUNDAY. A FEW BREAKS IN THE CLOUDS MAY BE SEEN IN THE FAR SOUTHWEST AND THE FAR SOUTHERN PORTION OF THE FORECAST AREA...BUT ONLY A SMALL RISE IN TEMPS IS ANTICIPATED AND WENT BELOW GUIDANCE AT MOST LOCATIONS FOR HIGHS SUNDAY. FORECAST HIGHS ARE A FEW DEGREES ABOVE THE RECORD MINIMUM HIGH TEMPS FOR AUGUST 18TH (SEE CLIMATE SECTION) && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... AS OF 230 PM EDT SATURDAY... THE UPPER TROUGH THAT HAS BEEN LINGERING OVER THE MID-MISSISSIPPI VALLEY WILL MAKE GRADUAL PROGRESSION EASTWARD DURING THIS PART OF THE FORECAST. AS IT DOES...THE FLOW AND THE AIRMASS IN ADVANCE OF IT WILL HAVE PLENTIFUL GULF OF MEXICO MOISTURE AND LINGERING OUTFLOW BOUNDARIES FROM PRIOR CONVECTION. THE RESULT IS EXPECTED TO BE SCATTERED SHOWERS AND A FEW THUNDERSTORMS THROUGH AT LEAST MONDAY. ON TUESDAY...WE WILL NOT HAVE A DRY FORECAST...BUT ONE THAT IS STARTING TO TREND TOWARDS LESS COVERAGE OF SHOWERS AND STORMS. A WEAKENING OF THE UPPER TROUGH AND TRANSITION TO A MORE ZONAL FLOW IS TO BLAME. TEMPERATURES WILL ALSO START TO MODERATE A BIT DURING THIS TIME PERIOD. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... AS OF 1245 PM EDT SATURDAY... DURING THIS PORTION OF THE FORECAST...MODEL GUIDANCE TRANSITIONS FROM A NEAR ZONAL FLOW ACROSS THE AREA...TO ONE THAT HAS SOME DEGREE OF A NORTHWEST FLOW ORIENTATION. THIS COMES WITH DIFFERENCES IN THE POSITION OF A BUILDING UPPER HIGH/RIDGE. THE GFS SOLUTION IS FARTHER WEST WITH THE HIGH...KS/MO...AND AS SUCH HAS A STEEPER ANGLE OF THE NORTHWEST FLOW OVER THE REGION...AND A BETTER SHOT FOR UPSTREAM DISTURBANCES TO HEAD INTO OR NEAR THE REGION. THE ECWMF OFFERS A SOLUTION WITH THE CENTER OF THE UPPER HIGH OVER THE LOWER OHIO VALLEY...WITH STEEPER NORTHWEST FLOW ON ITS EASTERN SIDE MORE OVER NY/PA THAN OVER OUR REGION. THE OPERATIONAL GFS SOLUTION OFFERS A COOLER AND POTENTIALLY WETTER SOLUTION AS COMPARED TO THE OPERATIONAL ECMWF. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... AS OF 120 PM EDT SATURDAY... RATHER CHAOTIC PATTERN IN THE SHORT TERM. SHALLOW WEDGE IN PLACE ALONG THE ERN SEABOARD AS PIECES OF ENERGY MOVE OVER THE AREA IN SWLY FLOW AHEAD OF CLOSED LOW OVER THE MID MISSISSIPPI VALLEY. MODEL PCPN FIELDS HAVE BEEN OVERDONE WITH THIS SYSTEM AND CURRENTLY ONLY SEEING PATCHY LIGHT PCPN NEAR KDAN. WITH SUCH A DIFFUSE PATTERN WILL NOT TRY TO GET FANCY WITH TIMING OF ELEMENTS BUT LIKING THE LATEST GFS AND HRRR RUNS FOR OVERALL TRENDS. EXPECTING PCPN TO BE ON THE INCREASE FROM THE SOUTHWEST...MAINLY FROM 00Z ON THOUGH IT LOOKS TO TAKE A BIT LONGER TO WORK INTO KLWB. AS PCPN GETS GOING CIGS AND VSBYS WILL BE COMING DOWN OVERNIGHT. EXPECTING IFR TO DEVELOP AFTER ABOUT 06ZAT ALL LOCATIONS...BUT MAINLY DUE TO CIGS AT KDAN...KLYH...AND KROA. LOOKS LIKE PCPN WILL BE TAPERING OFF TOWARD 12Z AS SFC LOW ALONG THE COAST STARTS TO PULL OFF TO THE NORTHEAST. NOT EXPECTING SIGNIFICANT WINDS THROUGH THE TAF PERIOD. AVIATION EXTENDED... WEATHER WILL REMAIN UNSETTLED THROUGH THE START OF NEXT WEEK AS AFOREMENTIONED CLOSED LOW OPENS UP AND LIFTS OUT...ALLOWING FOR SOME FLAT RIDGING BY MIDWEEK. HOWEVER...EASTERN TROF WANTS TO REDEVELOP TOWARD THE END OF THE WEEK WHICH BRINGS UNSETTLED CONDITIONS BACK TO THE AREA. EXPECT SOME LOW CIGS/VSBYS WITH NOCTURNAL FOG AND SOME DIURNAL CONVECTIVE PCPN THROUGH THE PERIOD...WITH TUESDAY AND WEDNESDAY LOOKING MOST FAVORABLE FOR AVIATORS. && .CLIMATE... AS OF 240 PM EDT SATURDAY... RECORD MINIMUM HIGH TEMPERATURES FOR AUGUST 18. CITY........RECORD/YEAR BLUEFIELD WV....70/1981 DANVILLE VA.....70/1992 LYNCHBURG VA....65/1957 BLACKSBURG VA...69/1992 ROANOKE VA......65/1957 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...DS NEAR TERM...PH SHORT TERM...DS LONG TERM...DS AVIATION...MBS CLIMATE...PH
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
125 PM EDT SAT AUG 17 2013 .SYNOPSIS... HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL REMAIN WEDGED ALONG THE EASTERN SLOPES OF THE APPALACHIANS THROUGH THIS EVENING...MAINTAINING AN EASTERLY WIND ACROSS THE AREA. SEVERAL DISTURBANCES PASSING ALONG A STALLED FRONTAL BOUNDARY TO OUR SOUTH AND EAST WILL BRING PERIODS OF RAIN TO THE AREA THROUGH THE WEEKEND. SCATTERED SHOWERS MAY PERSIST EARLY NEXT WEEK AS A TROUGH OF LOW PRESSURE MOVES EASTWARD FROM THE OHIO VALLEY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 935 AM EDT SATURDAY... DRY AIR CONTINUES TO HOLD IN PLACE...ESPECIALLY ACROSS THE MOUNTAINS WITH DEWPOINTS STILL IN THE LOW TO MID 50S. THE 12Z RNK SOUNDING INDICATED A LARGE AREA OF DRY AIR...ESPECIALLY BELOW 700MB. IN THE UPPER LEVELS OF THE ATMOSHPERE...WATER VAPOR SATELLITE IMAGERY HINTS AT A WEAK WAVE EMBEDDED EMBEDDED IN THE SOUTHWEST FLOW MOVING ACROSS EASTERN NC HELPING TO GENERATE LIGHT RAIN SOUTH OF LYH INTO THE VA SOUTHSIDE AND NORTHERN NC PIEDMONT. THE BLENDED TOTAL PRECIP WATER IMAGE SHOWS HIGHEST PWAT AIR REMAINS IN THE FAR SOUTHEAST PORTION OF THE FORECAST AREA THIS MORNING. AS THE WEAK WAVE IN NC DRIFTS NORTHEAST THIS AFTERNOON...LIGHT PRECIP OCCURRING THIS MORNING SHOULD WANE BY MIDDAY. SHOWERS MAY RE-DEVEVLOP EARLY THIS AFTERNOON UNDER AXIS OF HIGHER PWAT AIR IN THE EAST...BUT FOR THE MOUNTAINS...PRECIP MAY NOT ARRIVE UNTIL THIS EVENING/TONIGHT WHEN THE NEXT UPPER LEVEL SHORTWAVE APPROACHES FROM THE SOUTHWEST. AS A RESULT...PUSHED UP HIGH TEMPS IN THE MOUNTAINS WHERE CLOUDS WILL BE SLOWER TO ARRIVE AND DELAYED THE ARRIVAL OF PRECIP. IN THE EAST...LITTLE CHANGES WERE MADE TO THE FORECAST...BUT DID INCREASE HIGHS AT LYH WHERE READINGS ARE ALREADY A FEW DEGREES ABV THE FORECAST. SHOULD BE UNDER DEEPER MOISTURE TONIGHT WITH A COMBO OF THE UPPER SYSTEM HEADING INTO THE WEST AND BETTER ONSHORE FLOW OUT EAST WITH THE SURFACE WAVE. ALSO BETTER DIFFLUENCE ALOFT AHEAD OF A SPEED MAX PASSING PASSING JUST WEST SHOULD COINCIDE WITH THE LINGERING THETA-E GRADIENT TO SUPPORT MORE WIDESPREAD -RA AND PERHAPS SOME ELEVATED HEAVIER SHRA OVER THE COOL POOL. THUS MOSTLY LIKELY/CAT POPS OVERALL. ONLY SMALL DIURNAL TEMP CHANGES UNDER THE CLOUD CANOPY/-RA WITH LOWS UPPER 50S/LOW 60S. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 332 AM EDT SATURDAY... AN UPPER LEVEL BLOCKING RIDGE IN THE WESTERN ATLANTIC IS EXPECTED TO JOG TO THE SOUTHWEST ON SUNDAY. THIS WILL ALLOW A COASTAL LOW TO TRACK NORTHEAST ALONG THE MID ATLANTIC COAST. MOISTURE ACROSS THE REGION SHOULD BECOME SHALLOWER AS THE FOCUS WILL BE WITH THE DEPARTING SURFACE LOW. DESPITE THE REDUCTION IN MOISTURE...GRAY/DAMP CONDITIONS WILL REMAIN AS THE SURFACE WEDGE WILL STILL BE IN PLACE SUNDAY MORNING. WITH THE BLOCKING HIGH JOGGING TO THE SOUTHWEST...THE CLOSED LOW OVER THE MID MISSISSIPPI VALLEY WILL OPEN INTO A TROUGH WHILE TRACKING TO THE OHIO VALLEY SUNDAY. PRESSURE FALLS OVER THE OHIO VALLEY AND WARM AIR ADVECTION FROM THE SOUTHWEST WILL ERODE THE WEDGE THROUGH THE DAY SUNDAY. RAIN AND DRIZZLE WILL THEN GET REPLACED BY SCATTERED SHOWERS AS THE UPPER LEVEL TROUGH AND ASSOCIATED SHORT WAVES APPROACH THE REGION SUNDAY AFTERNOON AND CROSS OVER THE AREA SUNDAY NIGHT. THE TROUGH AXIS IS OVERHEAD ON MONDAY TO KEEP SCATTERED SHOWERS AND THUNDERSTORMS IN THE FORECAST...BUT THE FOCUS OF AREAL COVERAGE WILL BE ALONG THE COAST. AS WITH ALL ERODING WEDGES...TEMPERATURES WILL BE TRICKY TO FORECAST. AREAS BREAKING OUT OF THE WEDGE SHOULD SEE TEMPERATURES JUMP INTO THE MID TO UPPER 70S DURING THE AFTERNOON. AREAS REMAINING IN THE WEDGE MAY STAY IN THE 60S. LOOKING AT THE LIFTED INDEX AND LOW LEVEL FLOW...THE NAM KEEPS THE WEDGE OVER RNK NORTHEAST CORNER DEEP INTO SUNDAY NIGHT. THE GFS HAS THE WEDGE CLEARING THE PIEDMONT SOMETIME SUNDAY EVENING. IF THIS IS THE CASE...THE CITY OF LYNCHBURG AND THE CENTRAL PIEDMONT OF VIRGINIA MAY AGAIN HAVE TEMPERATURES 20F COOLER THAN NORMAL. THE WEDGE WILL BE GONE MONDAY AND TEMPERATURES WILL APPROACH NORMAL BY THE AFTERNOON. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 330 PM EDT FRIDAY... A GENERAL WEAKNESS...IN AN OTHERWISE STAGNANT...UPPER LEVEL FLOW WILL COVER THE EASTERN U.S. THROUGH MOST OF THE LONG TERM PERIOD. THE 00Z ECMWF AND CANADIAN MODELS DEPICT AN UPPER LEVEL LOW ACROSS THE OHIO VALLEY...THEN DRIFTING SOUTHEAST THROUGH THE PERIOD. THE 12Z GFS IS NOW COMING AROUND TO THIS SOLUTION WHICH WOULD RESULT IN A MORE UNSETTLED PERIOD. WITH PWATS FORECAST TO REMAIN AROUND 1.5 INCHES AND WEAK LOW LEVEL SOUTH OR SOUTHEAST FLOW IN PLACE...WOULD EXPECT A TYPICAL SUMMER PATTERN OF DAILY (MAINLY DIURNALLY DRIVEN) SHOWERS AND STORMS DRIVEN BY LOCALIZED AREAS OF LOW LEVEL CONVERGENCE EACH DAY. TEMPERATURES THROUGH THE PERIOD SHOULD BE NEAR NORMAL TO SLIGHTLY ABOVE NORMAL...ESPECIALLY LATE IN THE PERIOD WITH GEFS SHOWS 850MB TEMPS RISING 1-2 STANDARD DEVIATIONS ABV NORMAL. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 120 PM EDT SATURDAY... RATHER CHAOTIC PATTERN IN THE SHORT TERM. SHALLOW WEDGE IN PLACE ALONG THE ERN SEABOARD AS PIECES OF ENERGY MOVE OEVR THE AREA IN SWLY FLOW AHEAD OF CLOSED LOW OVER THE MID MISSISSIPPI VALLEY. MODEL PCPN FIELDS HAVE BEEN OVERDONE WITH THIS SYSTEM AND CURRENTLY ONLY SEEING PATCHY LIGHT PCPN NEAR KDAN. WITH SUCH A DIFFUSE PATTERN WILL NOT TRY TO GET FANCY WITH TIMING OF ELEMENTS BUT LIKING THE LATEST GFS AND HRRR RUNS FOR OVERALL TRENDS. EXPECTING PCPN TO BE ON THE INCREASE FROM THE SOUTHWEST...MAINLY FROM 00Z ON THOUGH IT LOOKS TO TAKE A BIT LONGER TO WORK INTO KLWB. AS PCPN GETS GOING CIGSAND VSBYS WILL BE COMING DOWN OVERNIGHT. EXPECTING IFR TO DEVELOP AFTER ABOUT 06ZAT ALL LOCATIONS...BUT MAINLY DUE TO CIGS AT KDAN...KLYH...AND KROA. LOOKS LIKE PCPN WILL BE TAPERING OFF TOWARD 12Z AS SFC LOW ALONG THE COAST STARTS TO PULL OFF TO THE NORTHEAST. NOT EXPECTING SIGNIFICANT WINDS THROUGH THE TAF PERIOD. ...AVIATION EXTENDED... WEATHER WILL REMAIN UNSETTLED THROUGH THE START OF NEXT WEEK AS AFOREMENTIONEDCLOSED LOW OPENS UP AND LIFTS OUT...ALLOWING FOR SOME FLAT RIDGING BY MIDWEEK. HOWEVER...EASTERN TROF WANTS TO REDEVELOP TOWARD THE END OF THE WEEK WHICH BRINGS UNSETTLED CONDITIONS BACK TO THE AREA. EXPECT SOME LOW CIGS/VSBYS WITH NOCTURNAL FOG AND SOME DIURNAL CONVECTIVE PCPN THROUGH THE PERIOD...WITH TUESDAY AND WEDNESDAY LOOKING MOST FAVORABLE FOR AVIATORS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/NF NEAR TERM...JH/PH SHORT TERM...RCS LONG TERM...PH AVIATION...MBS
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
536 PM CDT SAT AUG 17 2013 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND SUNDAY ISSUED AT 230 PM CDT SAT AUG 17 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE STRETCHING FROM NEW ENGLAND TO THE WESTERN GREAT LAKES. SHOWERS AND STORMS ARE OCCURRING OVER SOUTHERN CANADA WITHIN THE MAIN BELT OF WESTERLIES AND ALSO OVER THE OHIO VALLEY THANKS TO AN UPPER LEVEL LOW PRESSURE SYSTEM. CONDITIONS ARE QUIET ACROSS WISCONSIN WITH ONLY DIURNAL CU POPPING. CHANGES ARE MINIMAL OVER THE NEXT 24 HOURS...SO TEMPS AND CLOUDS REMAIN THE MAIN FORECAST CONCERNS. TONIGHT...AN UPPER LEVEL RIDGE AXIS WILL BE EXTENDING ACROSS THE NORTHERN GREAT LAKES WHILE THE SURFACE RIDGE AXIS WILL BE OVER SOUTHERN WISCONSIN. THE CENTER OF THE SURFACE HIGH WILL BE A LITTLE FARTHER TO THE EAST COMPARED TO LAST NIGHT...WHICH MAY ALLOW A SLIGHT SW WIND TO STICK AROUND. THE MAIN BELT OF WESTERLIES WILL REMAIN POSITIONED TO OUR NORTH OVER MANITOBA AND ONTARIO AND SOME HIGH CLOUDS MAY DRIFT ACROSS NORTHERN WISCONSIN. NEITHER THE WIND NOR HIGH CLOUDS SHOULD IMPACT TEMPS MUCH WHICH WILL BE A COUPLE DEGREES WARMER THAN LAST NIGHT. PATCHY GROUND FOG SHOULD ALSO DEVELOP LATE...THAT WILL BE A LITTLE MORE WIDESPREAD OVER N-C WISCONSIN COMPARED TO ELSEWHERE. SUNDAY...THOUGH RIDGING IN THE UPPER LEVELS WILL BE OVERHEAD...SURFACE HIGH PRESSURE WILL DRIFT A LITTLE FARTHER EAST IN RESPONSE TO HEIGHT FALLS OCCURRING OVER THE FAR NORTHERN PLAINS AND LAKE SUPERIOR REGION. SHOULD SEE A LITTLE MORE HIGH CLOUDS IN ADDITION TO THE DIURNAL CU THAT WILL POP MIDDAYISH. MIXING HEIGHTS ARE PROJECTED TO BE A LITTLE LOWER TOMORROW AFTERNOON...BUT LOWS WILL BE A LITTLE WARMER...SO WILL GO WITH HIGHS ABOUT A DEGREE WARMER THAN TODAY. .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY ISSUED AT 230 PM CDT SAT AUG 17 2013 UPPER RIDGING ACROSS THE WESTERN TWO THIRDS OF THE COUNTRY WILL LEAD TO WARMER TEMPERATURES BUT MINIMAL PRECIPITATION CHANCES FOR MUCH OF THE NEW WORK WEEK. THE NORTHERN STREAM ACROSS CANADA WILL BE THE PRIMARY SOURCE OF SYSTEMS WHICH MAY BRUSH OVER THE NORTHERN GREAT LAKES REGION AT TIMES. THE NAM AND GFS CONTINUE TO FOLLOW THE TREND OF A FEW WEAK SHORT WAVES GLANCING OVER NORTHERN WISCONSIN IN THE SUBTLE WAA FLOW FOR LATE TONIGHT INTO MONDAY WITH ANOTHER TOWARD TUESDAY AFTERNOON. PROGS CONTINUE TO INDICATE A STRONGER SHORT WAVE TROUGH WITH COLD FRONT SLIDING OVER THE GREAT LAKES REGION WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. TOTAL TOTALS CLIMB TO NEAR 50 ALONG AND NEAR THE FRONT...SO NO NEED TO CHANGE THE GOING THOUGHTS OF SVR POTENTIAL IN THE HWO AT THIS TIME. PCPN MAY END THURSDAY INTO THURSDAY NIGHT DEPENDING ON THE SOUTHWARD EXTENT OF THE FRONT BUT RETURN FLOW SETTING UP IN THE WAKE OF A SUBTLE HIGH PRESSURE SYSTEM WILL BRING THE POTENTIAL OF MORE SHOWERS AND STORMS BACK INTO THE AREA BY NEXT WEEKEND. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 533 PM CDT SAT AUG 17 2013 SFC HIGH WILL BE A LITTLE FARTHER OFF TO THE SE TNGT...SO THERE WL BE A BIT OF A SFC PRESSURE GRADIENT ACRS THE AREA...BUT PROBABLY NOT ENOUGH TO PREVENT DECOUPLING AND WINDS GOING CALM AT MOST LOCATIONS. EXPECT SOME MIFG TO DEVELOP AGAIN TNGT. GIVEN CHGS DESCRIBED ABV...CONDITIONS ACRS N-C WI WL BE A BIT LESS FAVORABLE THAN YDA. .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......SKOWRONSKI
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND SUNDAY ISSUED AT 230 PM CDT SAT AUG 17 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE STRETCHING FROM NEW ENGLAND TO THE WESTERN GREAT LAKES. SHOWERS AND STORMS ARE OCCURRING OVER SOUTHERN CANADA WITHIN THE MAIN BELT OF WESTERLIES AND ALSO OVER THE OHIO VALLEY THANKS TO AN UPPER LEVEL LOW PRESSURE SYSTEM. CONDITIONS ARE QUIET ACROSS WISCONSIN WITH ONLY DIURNAL CU POPPING. CHANGES ARE MINIMAL OVER THE NEXT 24 HOURS...SO TEMPS AND CLOUDS REMAIN THE MAIN FORECAST CONCERNS. TONIGHT...AN UPPER LEVEL RIDGE AXIS WILL BE EXTENDING ACROSS THE NORTHERN GREAT LAKES WHILE THE SURFACE RIDGE AXIS WILL BE OVER SOUTHERN WISCONSIN. THE CENTER OF THE SURFACE HIGH WILL BE A LITTLE FARTHER TO THE EAST COMPARED TO LAST NIGHT...WHICH MAY ALLOW A SLIGHT SW WIND TO STICK AROUND. THE MAIN BELT OF WESTERLIES WILL REMAIN POSITIONED TO OUR NORTH OVER MANITOBA AND ONTARIO AND SOME HIGH CLOUDS MAY DRIFT ACROSS NORTHERN WISCONSIN. NEITHER THE WIND NOR HIGH CLOUDS SHOULD IMPACT TEMPS MUCH WHICH WILL BE A COUPLE DEGREES WARMER THAN LAST NIGHT. PATCHY GROUND FOG SHOULD ALSO DEVELOP LATE...THAT WILL BE A LITTLE MORE WIDESPREAD OVER N-C WISCONSIN COMPARED TO ELSEWHERE. SUNDAY...THOUGH RIDGING IN THE UPPER LEVELS WILL BE OVERHEAD...SURFACE HIGH PRESSURE WILL DRIFT A LITTLE FARTHER EAST IN RESPONSE TO HEIGHT FALLS OCCURRING OVER THE FAR NORTHERN PLAINS AND LAKE SUPERIOR REGION. SHOULD SEE A LITTLE MORE HIGH CLOUDS IN ADDITION TO THE DIURNAL CU THAT WILL POP MIDDAYISH. MIXING HEIGHTS ARE PROJECTED TO BE A LITTLE LOWER TOMORROW AFTERNOON...BUT LOWS WILL BE A LITTLE WARMER...SO WILL GO WITH HIGHS ABOUT A DEGREE WARMER THAN TODAY. .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY ISSUED AT 230 PM CDT SAT AUG 17 2013 UPPER RIDGING ACROSS THE WESTERN TWO THIRDS OF THE COUNTRY WILL LEAD TO WARMER TEMPERATURES BUT MINIMAL PRECIPITATION CHANCES FOR MUCH OF THE NEW WORK WEEK. THE NORTHERN STREAM ACROSS CANADA WILL BE THE PRIMARY SOURCE OF SYSTEMS WHICH MAY BRUSH OVER THE NORTHERN GREAT LAKES REGION AT TIMES. THE NAM AND GFS CONTINUE TO FOLLOW THE TREND OF A FEW WEAK SHORT WAVES GLANCING OVER NORTHERN WISCONSIN IN THE SUBTLE WAA FLOW FOR LATE TONIGHT INTO MONDAY WITH ANOTHER TOWARD TUESDAY AFTERNOON. PROGS CONTINUE TO INDICATE A STRONGER SHORT WAVE TROUGH WITH COLD FRONT SLIDING OVER THE GREAT LAKES REGION WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. TOTAL TOTALS CLIMB TO NEAR 50 ALONG AND NEAR THE FRONT...SO NO NEED TO CHANGE THE GOING THOUGHTS OF SVR POTENTIAL IN THE HWO AT THIS TIME. PCPN MAY END THURSDAY INTO THURSDAY NIGHT DEPENDING ON THE SOUTHWARD EXTENT OF THE FRONT BUT RETURN FLOW SETTING UP IN THE WAKE OF A SUBTLE HIGH PRESSURE SYSTEM WILL BRING THE POTENTIAL OF MORE SHOWERS AND STORMS BACK INTO THE AREA BY NEXT WEEKEND. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1228 PM CDT SAT AUG 17 2013 VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER OVER THE TAF PERIOD. MOS GUIDANCE SHOWS THAT PATCHY GROUND FOG DOES NOT LOOK TO BE AS DENSE OR WIDESPREAD BETWEEN 08-12Z SUNDAY MORNING COMPARED TO THIS MORNING. STILL EXPECT MORE FOG OVER NORTH-CENTRAL WISCONSIN COMPARED TO ELSEWHERE THOUGH. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
412 PM MDT SAT AUG 17 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 412 PM MDT SAT AUG 17 2013 VISIBLE SATELLITE IMAGERY SHOWS A HIGH LAYER OF SMOKE CONTINUING TO MOVE SOUTHEAST OVER MUCH OF THE FORECAST AREA TODAY...WITH SOME CU DEVELOPING OVER THE MOUNTAINS ON THE WESTERN PERIPHERY OF THE SMOKE LAYER. LLVL INSTABILITY LOOKS WEAK OUT WEST BUT LAPSE RATES ARE QUITE STEEP WITH SFC TEMPERATURES WARMING INTO THE MID TO UPPER 80S. WITH AN UPPER LEVEL SHORTWAVE MOVING UP FROM UTAH...COULD SEE SOME MORE VIGOROUS CU TOWERS DEVELOP INTO ISOLATED SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON AND EARLY EVENING MAINLY ALONG AND WEST OF THE LARAMIE RANGE. RUC MODEL HINTS AT A FEW TRYING TO DEVELOP ACROSS THE EASTERN PLAINS AS WELL IN MOIST UPSLOPE FLOW...BUT AM NOT CONFIDENT THE CAP WILL BREAK IN THIS AREA TO DEVELOP MUCH MORE THAN VERY LIGHT SHOWERS. 12Z UPSTREAM RAOBS AND NAM FORECAST OBS SUGGEST A VERY DEEP MIXING LAYER UP TO 500 MB OR SO THIS AFTERNOON...HOWEVER WINDS ALOFT REMAIN WEAK. CURRENTLY SEEING A FEW LOCATIONS ACROSS THE REGION GUSTING 20 TO 25 MPH OR SO...AND THINK THAT WILL CONTINUE TO BE THE TREND THROUGH THE REST OF THE AFTERNOON. HUMIDITIES HAVE DROPPED TO THE UPPER SINGLE DIGITS TO LOW TEENS WITHIN THE LEESIDE TROUGH AND POINTS FURTHER WEST IN THE ZONE OF GUSTY WINDS...BUT AGAIN WINDS SHOULD REMAIN BELOW CRITICAL FIRE WEATHER THRESHOLDS SO WILL JUST CONTINUE TO MENTION HEIGHTENED FIRE WEATHER CONCERNS FOR LATE THIS AFTERNOON. THE LEESIDE PRESSURE TROUGH WILL REMAIN OVER THE CWA TONIGHT...WITH MOIST SOUTH TO SOUTHEAST FLOW TO CONTINUE OVER THE EASTERN PLAINS. WILL GO WITH THE A PERSISTENCE FORECAST WHICH MEANS THE LOW STRATUS DECK AND FOG WILL RETURN FOR EASTERN PORTIONS OF THE NEBRASKA PANHANDLE EARLY SUNDAY MORNING. SIMILAR TO THE PREVIOUS COUPLE OF NIGHTS...THE FOG COULD BE DENSE AT TIMES WITH VISIBILITIES DROPPING TO ONE HALF MILE OR LESS. THE STRATUS WILL STEADILY MIX OUT AFTER SUNRISE. A STRONGER SHORTWAVE WILL MOVE EAST ACROSS THE NORTHERN ROCKIES AND PLAINS ON SUNDAY AND WILL DROP A WEAK COOL FRONT ACROSS THE FORECAST AREA LATE SUNDAY AFTERNOON AND EVENING. AHEAD OF THE FRONT...WILL SEE BREEZY CONDITIONS RETURN TO THE FORECAST AREA IN THE AFTERNOON. GUIDANCE SUGGESTS THE RETURN OF THE MONSOONAL PLUME TOMORROW AS WELL SO AFTERNOON HUMIDITIES WILL NOT DRY OUT AS MUCH AS TODAY. HOWEVER...CONDITIONS WILL REMAIN DRY AND BREEZY ALONG AND WEST OF THE LARAMIE RANGE SO FIRE WEATHER CONCERNS WILL REMAIN ELEVATED THROUGH EARLY SUNDAY AFTERNOON. THE INCREASE IN MOISTURE AND FRONT MOVING SOUTH ACROSS THE REGION WILL BRING A BROADER COVERAGE OF SHOWERS AND TSTORMS TO THE FORECAST AREA LATE IN THE AFTERNOON AND EVENING. LOOKING AT MODERATE RAINFALL ALONG WITH GUSTY WINDS FROM THIS ACTIVITY. WINDS BEHIND THE FRONT WILL QUICKLY VEER FROM THE NORTH BACK TO THE SOUTHEAST ON MONDAY BUT WILL REMAIN RELATIVELY LIGHT UNDER WEAK FLOW ALOFT WITH MINIMAL ENERGY MOVING OVERHEAD. SO COULD SEE A FEW AFTERNOON SHOWERS AND THUNDERSTORMS ONCE AGAIN IN THIS WEAK UPSLOPE REGIME...BUT COVERAGE WILL BE LESS THAN SUNDAY DUE TO LACK OF SIGNIFICANT FORCING. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 412 PM MDT SAT AUG 17 2013 LOOKS LIKE A TRANSITION TO A MORE MOIST AND WETTER PATTERN COULD BE IN STORE FOR THE EXTENDED ESPECIALLY WEDNESDAY INTO FRIDAY. RIDGE WILL BE CENTERED AROUND COLORADO ON TUESDAY WITH THE BEST MONSOONAL MOISTURE TO THE SOUTHWEST ACROSS WESTERN COLORADO AND UTAH. BOTH THE GFS AND ECMWF HAVE THE RIDGE SHIFTING EASTWARD TOWARD THE CENTRAL PLAINS BY LATE WEDNESDAY AND INTO THURSDAY. THIS CAUSES MIDLEVEL FLOW TO GO SOUTHERLY WITH 700-500MB MOISTURE ON THE INCREASE. AT THE SAME TIME...A SFC HIGH WILL BE POSITIONED OVER THE DAKOTAS BY WEDNESDAY NIGHT WITH EAST WINDS TRANSPORTING HIGHER SFC DEWPOINTS UP ALONG THE LARAMIE RANGE. HAVE CHANCE TO SLIGHT CHANCE POPS OVER MUCH OF SOUTHEAST WY ON WEDNESDAY AND THURSDAY AFTNS AND EVENINGS WITH PW VALUES RISING UP TO AROUND 1 INCH. WHILE CAPE VALUES ARE NOT PARTICULARLY HIGH (LESS THAN 1000 J/KG)...STEERING FLOW IS WEAK (AROUND 10-15 KTS) SO HEAVY RAIN WILL BE THE PRIMARY THREAT. TUESDAY WILL LIKELY BE THE WARMEST AND DRIEST DAY BEFORE INCREASING MOISTURE AND CLOUD COVER CAUSE HIGHS TO FALL AROUND 5-10 DEGREES FOR WEDNESDAY THROUGH FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY MORNING) ISSUED AT 412 PM MDT SAT AUG 17 2013 VFR CONDITIONS WILL OCCUR OVER THE REGION TODAY AND MUCH OF TONIGHT...WITH A FEW ISOLATED THUNDERSTORMS POSSIBLE OVER THE MOUNTAINS LATE THIS AFTERNOON AND EARLY EVENING. WIND GUSTS TO AROUND 20 KTS ARE LIKELY THIS AFTERNOON AT MOST TERMINALS AND WILL EASE THROUGH THE EARLY EVENING. FOR LATE TONIGHT...PATCHY FOG AND LOW CIGS WILL MAKE A RETURN TO THE NEBRASKA PANHANDLE WITH MVFR TO IFR CONDITIONS EXPECTED IN THIS AREA. CONDITIONS WILL IMPROVE LATE SUNDAY MORNING...WITH A BROADER COVERAGE OF SHOWERS AND THUNDERSTORMS EXPECTED LATE SUNDAY AFTERNOON OVER MUCH OF THE FORECAST AREA. && .FIRE WEATHER... ISSUED AT 412 PM MDT SAT AUG 17 2013 AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL REMAIN OVERHEAD THROUGH EARLY NEXT WEEK AND WILL MAINTAIN ABOVE NORMAL TEMPERATURES THROUGH THIS TIME. MOSTLY DRY CONDITIONS WILL CONTINUE FOR THE REST OF THIS EVENING OUTSIDE OF AN ISOLATED THUNDERSTORM OR TWO DEVELOPING OVER THE MOUNTAINS. AFTERNOON HUMIDITIES HAVE DROPPED TO BETWEEN 5 AND 15 PERCENT ALONG AND WEST OF THE LARAMIE RANGE WITHIN A DRY AND WELL MIXED ENVIRONMENT. IN ADDITION...WINDS IN THIS AREA ARE GUSTING BETWEEN 20 AND 25 MPH AT TIMES. DRY CONDITIONS WILL PERSIST THROUGH LATE THIS AFTERNOON BUT WINDS SHOULD STEADILY EASE. THEREFORE...THESE HEIGHTENED FIRE WEATHER CONDITIONS ARE EXPECTED TO IMPROVE THROUGH THE REMAINDER OF TODAY. FOR SUNDAY...MORE MIDLEVEL MOISTURE WILL MOVE OVERHEAD WHICH WILL KEEP AFTERNOON HUMIDITIES BETWEEN 15 AND 20 PERCENT. GUSTS WILL ONCE AGAIN BE AROUND 20 TO 25 MPH AND WILL BECOME MORE WIDESPREAD OVER AND NEAR THE MOUNTAINS IN THE AFTERNOON. IN ADDITION...A WEAK FRONT MOVING SOUTH ACROSS THE DISTRICT WILL BRING A BETTER COVERAGE OF SHOWERS AND THUNDERSTORMS IN THE LATE AFTERNOON AND EVENING. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...RJM LONG TERM...FINCH AVIATION...RJM FIRE WEATHER...RJM