AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
845 PM EDT WED AUG 11 1999
SMALL THUNDERSTORM CLUSTER CURRENTLY MOVING S THROUGH SE AL ZONES
...WHILE CONVECTION NEAR PERRY CONTINUES TO DIE. SE AL CONVECTION
RECENTLY SHOWING DECREASED LIGHTNING STRIKE FREQUENCY...WITH A
PREPONDERANCE OF POSITIVE POLARITY STRIKES IN ITS TRAILING
STRATIFORM REGION...WHICH SUGGESTS THIS CLUSTER IS ALREADY BEGINNING
TO DISSIPATE. WATER VAPOR IMAGES SHOW SUBSIDENCE WORKING S OVER CWA
...WITH A SMALL AREA OF LIFT MOVING S OVER NRN ZONES. THIS HAS
APPARENTLY BEEN ENOUGH TO FIRE SE AL STORMS AND ISOLATED WEAK
CONVECTION NEAR ABY. 00Z KTLH SOUNDING SHOWED ONLY MODEST MID-LEVEL
WARMING ASSOCIATED WITH UPPER SUBSIDENCE. WILL ISSUE ZONE UPDATES BY
0130Z TO REMOVE MENTION OF EVENING THUNDER FOR APPROPRIATE AREAS
BASED ON RADAR TRENDS.
COASTAL WATERS FORECAST...WILL BUMP UP WIND AND SEAS BASED ON
BUOY/C-MAN DATA AND RUC PROGS. EXPECT LAND BREEZE CONVECTION
OFFSHORE OVER OUR COASTAL WATERS OVERNIGHT...SO WILL ALSO MENTION
SCATTERED SHOWERS AND THUNDERSTORMS.
TJT
FXUS62 KJAX 120034 fl
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
220 PM CDT TUE AUG 10 1999
MAIN CONCERN TNGT HVY RAINS AND THU WILL BE SVR WX.
FIRST THINGS FIRST MID LVL VORT FOUND IN PROFILER NTWRK HAS KEPT PCPN
GOING TDA MAINLY S OF I80 SETTING UP SVRL OUTFLOW BNDRYS INVOF OF ST.
MNWHILE ADVANCING S/W OUT OF SW SHULD ENTER ST LTR TNGT AND IF SRN
WRM FNT DOES MAKES ITS WAY NWRD THIS EVENING IA TOP SPOT FOR HVY
RAINS AS LO LVL INFLO INCRS 35 TO 40 KNTS AND HI PWS. MDLS DO DIFFER
ON LOCATIONS OF BNDRY HWVR DO NOT XPCT MUCH HELP WITH SHORT TERM AS
ON GOING SYNOPTIC PATTERN NOT PICKED UP WELL EVEN BY RUC APPEARS ABIT
SLO IN PCPN FIELDS AND EXACT LOCATION OF SFC FEATURES HWVR BEST MDL
ATTM. BELIEVE SRN BNDRY WL TAKE ITS TIME MOVG TNGT AND LKLY BST CHC
FOR HVY RAINS CNTRL AND S HWVR IF LO LVL FLO DVLPS AS STG AS DEPICTED
WULD XPCT BNDRY PUSH AND HVY RAINS CNTRL AND N. DEGREE OF UNCERTAINY
SO WL MENTN HVY RAINS ENTIRE CWA THO NO HEADLINE ATTM.
TMRW WL BE VRY INTERESTING AS MUCH STGNR DYNAMICS MAKES MOD RISK LOOK
LIKE GD CHC. XPCT SRN BNDRY TO BE N OF ST AND IN WARM SECTOR AHD OF
ADVANCING COLD FNT. JET ACRS AREA WITH PLENTY OF SHEAR WITH HI
CAPES. QG VECTORS STG FOR 18Z-00Z PD THU AND INFO AGN 35 TO 40 KTS.
SERIES OF S/W CROSS AREA IN SAME TIME PD. WL LKLY GO HIER POPS FOR
THU AFTN WITH SUM LINGERING INTO THE EVENING. BY FRI SYNOPTIC
PATTERN SHULD SETTLE DWN WITH HI MOVG INTO THE AREA AND DECENT CAA
AND DRIER AIR PUSHING INTO THE ST FM SW.
LOOKING AHED TO EFP PD UNSETTLED BST WORD FOR THIS FCST PD. SERIES
OF S/W WITH FNTS MOVG ACRS THE AREA. THO HI FRI NGT WL DOMINATE IN
TO SUN AT WHICH TIME S/W DROPS ACRS AREA. WL GO FOR CHC LT SUN NGT
AND INTO MON. GUID TEMPS NOT BAD.
OVERALL GUID NOT BAD THO MAYBE LO SRN IA THU WITH WARM SECTOR. WULD
ACCEPT COOL DWN THU NGT AND FRI THO MANY TIMES DRYING ON ERN EDGE OF
CWA SLO.
.DSM...NONE
FORSTER
FXUS63 KDMX 111506 AMD ia
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1005 AM CDT TUE AUG 10 1999
DYING MCC OVER NE/IA TO BE MAIN FOCUS OF THIS UPDATE...ALONG WITH
ITS EFFECTS ON TEMPS.
SATELLITE AND RADAR TELLING STORY RIGHT NOW WITH DYING MCS OVER SW
IA AND ADJOINING STATES. CURRENT MOVEMENT TO ESE RIGHT ON TRACK AS
SYSTEM IS TRYING TO STAY IN BEST INFLOW. HOWEVER PROFILERS AND
MORNING 80H RAOB DATA SHOWING IT IS NOW MOVING EAST OF LLJ...OR
WHATS LEFT OF IT...AND LLJ IS VEERING NOW. SFC OBS TELLING MUCH
DRIER STORY THAN IS THE 88D...WITH ONLY MINOR RAINFALL AMOUNTS IN SW
CWA. DYING TREND SHOULD CONTINUE. WILL HAVE TO UPDATE S/C AND
MAYBE SE CWA FOR WDLY SCT SHRA INTO THE MID AFTERNOON. LOOKING
WEST OF OMA...RADAR SHOWING CONTINUED REDEVELOPMENT BETWEEN LNK AND
GRI. THIS MAY PERSIST INTO THE AFTERNOON WITH THIS ACTIVITY
CONTINUING TO MOVE INTO WRN CWA. THIS MAY REQUIRE A LITTLE MORE
AREAL COVERAGE WORDING.
NORTH OF I-80...IT LOOKS LIKE DRY WX THRU THE AFTERNOON.
FINALLY...CLOUDS AND COLD POOL TO MAKE TEMP FCSTS A BIT TOUGH THIS
AFTERNOON. LATEST SAT PICS INDICATING A FAST THINNING OVER NRN
CWA. WARMEST TEMPS COULD VERY WELL BE UP THERE. MODELS HAVE NOT
BEEN HANDLING THIS SYSTEM AT ALL...HOWEVER...QUICK GLANCE AT 12Z RUC
DOES SHOW THE COLD POOL AT THE SFC. WILL BUMP TEMPS DOWN AT LEAST A
CAT...MAYBE A CAT AND ONE HALF.
.DSM...NONE
SEARCY
FXUS63 KDMX 110822 ia
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GOODLAND KS
1037 AM MDT (1137 AM CDT) WED AUG 11 1999
REMOVED MENTION OF MORNING FOG AND TWEAKED WINDS BASED ON CURRENT
CONDITIONS. LATEST CAPS DATA INDICATING INSTABILITY AXIS SETTING UP
OVER MY EASTERN CWA...IN LINE WITH SPC DAY1. RUC GUIDANCE SUGGESTING
WINDS WILL STAY SOUTHEAST-EAST OUT THERE...WITH TROUGH LINE FURTHER
WEST. WINDS WEST OF THE LINE WILL BE SOUTHWEST-WEST. NO NEW FWC
GUIDANCE...BUT LAMP IN LINE WITH FORECAST. ALSO ADJUSTED SKYCOVER TO
BE MORE OPTIMISTIC WITH MOSTLY/PARTLY SUNNY. NO OTHER CHANGES MADE.
.GLD...NONE.
DDT
FXUS63 KTOP 110845 ks
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
1115 AM EDT WED AUG 11 1999
14Z SFC ANALYSIS SHOWS A DIFFUSE FRONT RUNNING ACROSS EAST KENTUCKY
FROM NORTHEAST TO SOUTHWEST. JUST A BIT MORE CLOUDINESS ALONG THE FRONT
OTHERWISE...MOSTLY CLOUDY ACROSS EAST KENTUCKY. LATEST MESOETA GUIDANCE
KEEPS US DRY AND MOSTLY SUNNY DESPITE THE FRONT. THE MESOETA SOUNDING
KEEPS A MID LEVEL CAP THROUGH 00Z SUPPRESSING ANY CONVECTION. HOWEVER
THE RUC INDICATES THAT SHOWERS WILL OCCUR THIS AFTERNOON OVER FAR
SOUTHEAST KENTUCKY IN VICINITY OF THE FRONT. THE LATEST LAPS AND MSAS
GRAPHICS ACTUALLY HAS THIS AREA THE MOST STABLE. AS A RESULT WILL LEAN
TOWARD KEEPING US DRY AND CAPPED ALTHOUGH WILL HAVE TO KEEP A CLOSE EYE
ON THE SITUATION HEADING INTO THE AFTERNOON. OTHERWISE...TEMPERATURES
AND SKY CONDITION ARE ON TRACK AND THEREFORE NO UPDATE AT THIS TIME.
.JKL...NONE
GREIF
ky
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1105 AM CDT WED AUG 11 1999
12Z SOUNDINGS ARE MOIST AND UNSTABLE AGAIN WITH CAPES AROUND 3000
J/KG AND PW'S NEAR 2.2 INCHES AT KSIL AND 2.4 INCHES AT KJAN. LOCAL
DOWNBURST CHECKLIST SHOWS MODERATE POTENTIAL TODAY...SO 30 OR 35 KT
THUNDERSTORM GUSTS MAY OCCUR. UNLIKE THE LAST TWO DAYS...THERE IS NO
SURFACE TROUGH AND MAJOR BLOWUP OF CONVECTION IN THE COASTAL
WATERS...PROBABLY DUE TO LESS UPPER DIFLUENCE. HOWEVER...W TO SW
SURFACE WIND MAY ALLOW A WEAK SEA BREEZE AND LAKE BREEZE FRONT TO
COME INTO PLAY. IN ADDITION...SATELLITE LOOPS AND THE RUC ANALYSIS
SHOW A SHORTWAVE TROUGH/VORT MAX MOVING SOUTH THROUGH SW MS. CANNOT
RULE OUT THE THREAT OF LOCALLY HEAVY RAIN AND MORE CONCENTRATED
CONVECTION NEAR AND SOUTH OF LAKE PONTCHARTRAIN THIS AFTERNOON. AT
THIS TIME...DO NOT PLAN ON UPDATING CURRENT 40 TO 50 PERCENT
POPS...BUT WILL MENTION THREAT OF HEAVY RAIN AND STRONG THUNDERSTORM
GUSTS IN THE THUNDERSTORM OUTLOOK. OBNOXIOUSLY HIGH DEWPOINTS IN THE
UPPER 70S TO NEAR 80 WILL PRODUCE 105 DEGREE PLUS HEAT INDICES
THROUGH EARLY AFTERNOON...BUT INCREASING AFTERNOON CLOUDS AND
SCATTERED CONVECTION WILL COOL THINGS DOWN IN MOST AREAS.
.NEW...NONE.
LA...NONE
MS...NONE.
22
FXUS64 KSHV 111548 la
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON
1035 AM EDT WED AUG 11 1999
AFTER PICKING THRU THE RUC AND LATEST LAPS SURFACE DATA...HAVE OPTED
FOR A 20 POP FOR THIS AFTERNOON. MANY OPPOSING FACTORS WITH THIS.
POSITIVE: REASNBLE S/W APPROACHING FROM THE NW. DWPTS IN THE MID TO
UPPER 60S EAST OF THE BLUE RDGE. MODFD SOUNDING HAS -5 LI AND 2000
CAPE. SAT IMGRY HAS CU FORMING IN WV AND WSTRN PA ASSOCTD WITH S/W.
SURF TROF OVR REGION.
NEGATIVE: LOW LVL WNDS OUT OF THE WEST (DOWNSLOPE) EXCPT SURF WINDS
WHICH ARE TRENDING IN THAT DIRECTION TODAY. DROUGHT...IE
PERSISTENCE. RUC HAS NO CONVCTVE PRECIP OVR THE LWX CWA TODAY. MOS
HAS 9-10 POP OVR REGION TODAY.
BOTTOM LINE...I DON/T EXPECT IT HERE...BUT I WOULD NOT BE SURPRISED
EITHER. SO...20 POP (SLIGHT CHC).
AFTER THE 10AM OBS...TEMPS LOOK GOOD EXCEPT I WILL RAISE A FEW IN
THE WEST WHERE DOWNSLOPE HAS TEMPS ALREADY 83-84 DEGS. WINDS WILL BE
SW TURNING W AROUND 10 MPH.
.LWX...NONE.
STRONG
md
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1030 PM EDT WED AUG 11 1999
FORECAST ISSUE FOR THE U.P. TONIGHT IS PRECIPITATION.
00Z SURFACE ANALYSIS SHOWS A WEAK SURFACE FRONT EXTENDING FROM A LOW
IN JAMES BAY...TO MENOMINEE COUNTY...TO SOUTHERN NORTH DAKOTA.
SCATTERED LATE AFTERNOON AND EARLY EVENING SHOWERS DEVELOPED IN THE
U.P. ALONG THIS FRONT... BUT KMQT 88D RETURNS OVER THE LAST COUPLE OF
HOURS SHOW THE SHOWERS HAVE DISSIPATED. EVEN AT THEIR STRONGEST
THESE SHOWERS PRODUCED NO LIGHTNING AND HAD QUITE WARM CLOUD TOP
TEMPERATURES ON THE IR SATELLITE IMAGERY. THE FRONT IS PARTICULARLY
WEAK AS IT CROSSED THE U.P... THE FRONT IS A COLD FRONT EAST OF THE
U.P. AND A WARM FRONT TO THE WEST. BUT HERE IN THE U.P. ITSELF
THERE IS A COL IN THE SEA LEVEL PRESSURE PATTERN THAT THE FRONT
CROSSES... AND THERE IS AN ABSENCE OF VORT MAXIMA ALOFT IN THE
REGION AND FLAT 700-300MB QVECTOR FIELD. WITHOUT THE ASSISTANCE OF
DIURNAL HEATING TO DESTABALIZE THE BOUNDARY LAYER... THE SURFACE FRONT
ALONE IS APPARENTLY TOO WEAK TO TRIGGER PRECIPITATION.
THE FRONT WILL SAG SLOWLY SOUTH TONIGHT... AND THE SERIOUS
PRECIPITATION IS SET TO BEGIN THURSDAY AS A SURFACE WARM FRONT NOW
NEAR THE KANSAS-MISSOURI BORDER APPROACHES THE AREA AND OVERRUNNING
SERVES AS A MECHANISM FOR THE U.P. 310/320K ISENTROPIC LIFT BEGINS
OVER THE U.P. BY 12Z ACCORDING TO THE 12Z ETA NGM AND AVN MODELS.
BUT NEW MESOETA AND RUC HAVE TRENDED TO A SLOWER SOLUTION. THIS IS
INTERESTING SINCE 12Z ETA SHOWED A SLOWER PROGRESSION THAN ITS
PREVIOUS 00Z RUN AS WELL. WILL LEAVE ANY MAJOR REVISION OF WET
THURSDAY ZFP FORECAST TO MIDNIGHT SHIFT... BUT MESOETA AND RUC OFFER
ENOUGH EVIDENCE FOR DELAYING RAIN DEVELOPMENT TONIGHT UNTIL VERY
VERY LATE IN THE 1ST PERIOD. WILL ALSO TAME DOWN THE POPS FROM
CATEGORICAL ACROSS THE U.P. TO LIKELY IN THE WEST AND CHANCE IN THE
EAST. 20Z FLP FOR MQT HAS A POP OF ONLY 35% BY 12Z... WILL
COMPRIMISE BETWEEN LATEST MODEL GUIDENCE AND FORECAST CONTINUITY.
.MQT...NONE.
ES
FXUS63 KAPX 120140 mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
930 PM EDT WED AUG 11 1999
WILL BE UPDATING SHORTLY TO DELAY HIGH CLOUDS MOVING INTO REGION.
PRESENT SATELLITE TRENDS SHOW THE CLOUDS TO THE WEST OF US
DISSIPATING. 21Z RUC POINTS TO THE HIGH CLOUDS MOVING INTO SE LOWER
AFTER 09Z... THUS WILL UPDATE AND GO WITH INCREASING HIGH CLOUDINESS
TOWARDS SUNRISE.
TEMPERATURES AND DEWPOINTS RUNNING A COUPLE DEGREES ABOVE WHAT THEY
WERE LAST NIGHT AT THIS TIME IN ALL OF SE LOWER EXCEPT THE TIP OF
THE THUMB AND IN THE BAY CITY/MIDLAND AND SAGINAW AREAS. HERE THE
TEMPERATURES ARE RIGHT WHERE THEY WERE LAST NIGHT AT THIS TIME...
WHILE THE DEWPOINTS ARE SLIGHTLY COOLER. SINCE I WILL BE DELAYING
THE CLOUDS UNTIL LATE TONIGHT THE TEMPERATURES IN THE SAGINAW VALLEY
AND THE THUMB WILL HAVE QUITE A BIT OF TIME TO FALL PRIOR TO THE
CLOUDS REACHING THEM. WILL LOWER OVERNIGHT LOWS IN THE TIP OF THE
THUMB TO 55 TO 60 AND CONTINUE THE AROUND 60 FOR THE SAGINAW VALLEY.
ACROSS THE REST OF SE LOWER OVERNIGHT LOWS LOOK GOOD.
.DTX...NONE.
KEYES
FXUS63 KAPX 112157 mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1125 AM EDT WED AUG 11 1999
CURRENT PACKAGE LOOKS GOOD FOR THIS AFTERNOON. WILL UPDATE TO
FRESHEN UP THE WORDING IN SOME OF OUR WIND FCSTS. 12Z RUC LOOKS TO
BE HANDLING THE FEATURES WELL THIS MORNING. EVENTHOUGH WE LOSE THE
CU AS THE LOW LEVEL MOISTURE MIXES OUT...WE WILL KEEP THE PARTLY
SUNNY WORDING...AS DEBRIS CLOUD FROM MO/IA MCC AND STORMS FROM MN
MOVES OVER THE CWFA. TEMPERATURE TRENDS ARE LOOKING GOOD AS WELL.
.APX...NONE.
LUTZ
FXUS63 KMQT 111455 mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1054 AM EDT WED AUG 11 1999
MAIN FCST CONCERN FOR THE AFTN IS SHRA POTENTIAL FOR W HALF OF FA.
VIS/IR SATELLITE IMAGES THIS MORNING SHOW CLOUDS QUICKLY STREAKING E
INTO UPPER MI. UPSTREAM...LARGE AREA OF SHRA/SCT TSRA HAVE BEEN
FIRING IN E ND/N MN IN REGION OF STRONG LOW-LEVEL CONV/WAA/
ISENTROPIC LIFT. THIS STRONG WAA AND CONV VERY EVIDENT ON MORNING
RAOB DATA. AT 850MB...KABR SOUNDING SHOWED TEMP OF 21C WITH SW WIND
AT 30 KNOTS WHILE KINL HAD TEMP OF 12C AND WNW WIND AT 25 KNOTS.
SHRA HAVE BEEN DIMINISHING AS THEY MOVE E AWAY FROM MAIN
CONV/ISENTROPIC LIFT REGION.
SO CONCERNS FOR THE AFTN WILL BE PROGRESS OF SHRA TOWARD W FA AND
THEN AFFECT OF INCREASING/THICKENING CLOUDS ON HIGH TEMPS. 12Z RUC
SHOWS AXIS OF LOW-LEVEL JET AND RESULTANT WAA/CONV/ISENTROPIC LIFT
MAKING PROGRESS E THIS AFTN. THIS WILL PUT GENESIS REGION OF SHRA
INTO NE MN BY 00Z. AS THE SHRA MOVE E...THEY WILL DIMINISH BUT WILL
CONTINUE TO MAKE PROGRESS E INTO DRIER AIRMASS DOWNSTREAM OVER FA.
EXPECT SHRA TO REACH W FA THIS AFTN...AFT 18Z FAR W AND 19Z
KEWEENAW. CURRENT FCST HAS AN EXCELLENT HANDLE ON BRINGING SCT SHRA
INTO 4 W COUNTIES THIS AFTN. ATTM...WILL NOT EXTEND MENTION OF SHRA
FARTHER E AS EVENING TIMING APPEARS ON TRACK FOR CNTRL COUNTIES.
ACROSS CNTRL/E FA...CLOUDS WILL CONTINUE TO INCREASE AND THICKEN IN
ADVANCE OF SHRA. ALTHOUGH TEMPS HAVE BEEN RISING NICELY THIS
MORNING...FAIRLY EXTENSIVE AND THICKENING CLOUD SHIELD WILL PUT THE
BRAKES ON TEMP RISE. WILL MAKE SLIGHT DOWNWARD ADJUSTMENTS IN A FEW
AREAS.
.MQT...NONE.
ROLFSON
FXUS63 KMQT 110946 mi
SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
830 PM MDT WED AUG 11 1999
UPDATED SW ZONES FOR HVY RAIN...HLN HAD 0.82 BY 01Z. RADAR STILL VRY
ACTIVE THIS EVE OVER CWA. IR SAT SHOWS CLOSED LOW OVER NW WY WHILE ALL
MODELS FM 12Z STILL INDICATED AN OPEN TROF...BUT WERE PRETTY CLOSE WITH
VORT MAX. 00Z RUC INIT UPR LOW TOO FAR N OVER W CNTRL MT. UPR LOW WL
TRACK ACROSS SRN MT OVERNIGHT. SHORT WAVE RIDGE WL BUILD INTO MT ON
THURS...THUS DECREASING SHOWER ACTIVITY. UPDATES FOR STRONGER WORDING ON
PRECIP AND POSSIBLE MINOR FLOODING IN LOW LYING AREAS. WILLIAMSON
DC/EYSSAUTIER
GTF +422 HLN +323 HVR +522
FXUS65 KBYZ 120235 mt
SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
245 AM MDT WED AUG 11 1999
UPPER LOW OVER NORTHERN CALIFORNIA THIS MORNING EXPECTED TO OPEN UP TO
NORTHERLY BRANCH OF JET AND MOVE ACROSS NORTHWEST MONTANA LATER TODAY.
A SERIES OF SHORTWAVES ON THE LEE SIDE OF THE LOW SPAWNING CONVECTION
OVER UTAH AND THIS ENERGY EXPECTED TO MOVE INTO FORECAST AREA AROUND
18Z. ON WATER VAPOR RIDGE AXIS HAS ALREADY MOVED TO SOUTHEAST MONTANA
AND CONVECTION APPEARS TO BE DEVELOPING OVER SOUTHWEST MONTANA AS
DYNAMICS BECOME MORE FAVORABLE. SURFACE/850 MB LOW NEAR KSHR EXPECTED
TO REACH WESTERN SOUTH DAKOTA BY 18Z AND RUC QUICKLY BRINGS UPSLOPE LOW
LEVEL FLOW TO FORECAST AREA THIS MORNING. PROBLEMS OF DAY ARE STRENGTH
OF AFTERNOON THUNDERSTORMS AND DRY AIR AT LOW LEVELS INITIALLY LIMITING
PRECIPITATION AMOUNTS. DEW POINTS IN GGW HAVE INCREASED INTO THE 60S
ALREADY AND EXPECT EASTERN MONTANA WILL GET INTO THE HIGHER DEWPOINTS
AFTER SUNRISE. FAVORABLE DYNAMICS WILL SPREAD ACROSS FORECAST AREA
AROUND NOON AND EXPECT THUNDERSTORMS TO DEVELOP. SHEAR PROFILES BECOME
MORE FAVORABLE LATER IN DAY BUT LAPSE RATES AND CAPES ARE NOT ALL THAT
IMPRESSIVE. HOWEVER...MESOETA HINTS AT ORGANIZED LINE OF CONVECTION
DEVLOPING AND DAY SHIFT WILL NEED TO LOOK FOR ANY 12Z RUN ADJUSTMENTS
FOR A MORE FAVORABLE ENVIRONMENT. FORECAST TEMPS LOOK PRETTY GOOD AS
700 MB TEMPS SUPPORT MAXES IN THE LOWER TO MID 80S. BETTER CHANCES FOR
PRECIPITATION TONIGHT AS MOISTURE DEEPENS IN ATMOSPHERE AND AIRMASS
REMAINS UNSTABLE. FOR THURSDAY EXPECT UPSLOPE FLOW TO BE A FACTOR
THOUGH AVIATION BUILDS PRONOUNCED RIDGE OVER CENTRAL MONTANA.
EXTENDED...A COUPLE OF STRONG SHORTWAVES FORECASTED TO MOVE ACROSS
REGION IN SOUTHWEST FLOW. GENERALLY COOLER WEATHER WILL PREVAIL WITH
PRECIPITATION THREATS EACH DAY.
BORSUM
BIL EB 085/060 078/059 082 59343
LVM .. 084/055 078/... ... 59364
HDN .. 087/058 079/... ... 59343
MLS .. 087/060 078/058 ... 59464
4BQ .. 086/060 076/... ... 59464
BHK .. 085/058 075/... ... 59464
SHR EB 083/055 076/052 080 59343
mt
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
3 PM CDT WED AUG 11 1999
...FORECAST CHALLENGES...CHC OF PRECIP/LOCALLY HEAVY RAIN/TIMING OF
FNT/TEMPS
...SYNOPSIS...LATEST SFC ANALYSIS HAS LO PRES OVR NW KS AND THE
PRIMARY SFC LO OVR NW SD. SFC DEWPOINTS WERE POOLED IN THE 70S NR
THESE LOWS AND S OF THE WRMFNT OVR NCNTL KS. THE RUC2 GRAPHICS HAS
WAA GREATEST N OF THE NRN PLNS WRMFNT...OVR ERN SD...THRU CNTRL
NEB...AND INTO CNTRL KS AND OK. CONVECTION HAS BEEN EXITING THE
CWFA AND IS JUST ABOUT TO MOVE OUT OF OUR FAR ERN COUNTIES. THE 18Z
RUC HAD THE STGR SHTWV OVR CNTRL IA...WITH ADDITIONAL DISTURBANCES
IN SE SD AND WRN NEB.
...FCST...THE ATMOSPHERE HAS STABILIZED BEHIND THE MCS...YET WITH
THE CLEARING SKIES...HOT TEMPS AND POOLING WITH THE WRMFNT...THE
MESOETA HAS AN AXIS OF UNSTABLE AIR FM SCNTRL NE INTO KS. WITH THE
MAIN LO OVR WCNTL SD THE RUC EXTENDS THE TROF INTO CNTRL NEB WITH
THE WRMFNT OVR SE NEB. WITH HI PWS NR THE NEB/KS BORDER...THREAT OF
LOCALLY HVY RAIN. WILL CONSIDER WATCH OVR THE SW COUNTY WARNING
AREA DUE TO THE HVY RAIN THIS AM. FFG IS ONLY 1 TO 1.5 INCHES. AT
THIS TIME WILL MENTION LOCALLY HVY RAIN AND BRIEF EVE SHIFT TO
POTENTIAL. DUE TO THE CONTINUED WAA CHC FOR PRECIP THIS INTO THUR
AM.
MODELS TRACK THE SFC LO ACRS SRN SD AND INTO NRN IA THUR...CARVING
OUT AN UPR TROF WHICH WILL RESULT IN PRECIP CHCS THUR. COOLER TEMPS
FOR FRI WITH GOOD CAA
.OMA...NONE
ZAPOTOCNY
FXUS63 KLBF 111959 ne
SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION...
NATIONAL WEATHER SERVICE HASTINGS NE
232 PM CDT WED AUG 11 1999
FCST CONCERN CONT TO BE CHC OF MORE TSTMS LATE THIS AFTN AND TNGHT.
WHILE FRONTAL BNDRY AND SFC LEE TROF TO OUR NORTH AND WEST EASY TO
LOCATE...BNDRY OVER CNTRL KS NOT AS EVIDENT. THERE IS A WK LOW
JUST WEST OF HILL CITY WITH THE MAIN LOW IN WRN SDAK. OUTFLOW BNDRY
FROM THIS MRNG LOOKS TO BE LIFTING NE AND IS SITUATED FROM OLU TO
TOP. HIGHER INSTABILITY PRESENTLY IN NCNTRL KS AS SEEN ON
LAPS. WATER VAPOR IMAGE HAD ANOTHER SHORTWV APPCHG THE AREA FROM ERN
CO THIS MORNING AND WAS PICKED UP ON LATEST RUC MODEL...BUT NOT VERY
WELL ON PROFILER NETWORK. THIS SEEMS TO BE MOVING INTO WCNTRL NEB
ATTM WITH NOTHING POPPING YET WHICH MAY BE BECAUSE OF MORE STABLE
AIRMASS LEFT OVER FROM LINGERING CLOUDS IN THAT PART OF THE STATE.
PROFILERS DID SHOW A UNI-DIRECTIONAL WIND PROFILE AT RWD WHILE
VEERING STILL GOING ON AT FBY. WILL HAVE TO KEEP AN EYE ON THIS
DURING LATE AFTN/EVNG FOR POSSIBLE SVR IF SOMETHING DOES POP...ESP
ALONG THE LEE TROF.
MAIN QUESTION SEEMS TO BE HOW MUCH ACTIVITY WILL GO ON WITH WEAKER
SHORTWV AND POSSIBLE BNDRY IN KS SLIDING NWD COMPARED TO OUR
NEIGHBORS TO THE NORTH WITH BETTER FORCING FROM MAIN TROF AND WELL
DEFINED BNDRY. ALONG WITH AFOREMENTIONED ITEMS...SFC TROF/COLD
FRONT TO MOVE IN FROM THE NORTH TOWARDS MORNING...IMPRESSIVE
ISENTROPIC LIFT THIS EVNG/TNGHT...AND SUBTROPICAL PLUME HAS SHIFTED
EAST OVER THE AREA TO COMBINE WITH ALREADY HIGH PRECIPITABLE WATER.
ON THE DOWN SIDE...LLJ LOOKS TO BE MORE CONDUCIVE FOR SRN MN...
UPPER JET WOULD FAVOR THE DAKOTAS/MN AND MAIN FORCING MORE NORTH.
ALSO AIR MASS STRUGGLING TO RECOVER FROM OVERNIGHT MCS AS 2 PM TEMPS
ONLY IN UPPER 70S/LOWER 80S IN NEB CWA. WHILE IN KS CWA TEMPS VARY
FROM 99 AT HAYS TO 84 IN CNK.
WILL PROBABLY KEEP POPS SIMILAR TO PREV FCST AND MAY ADD MENTION OF
LOCALLY HVY RAIN. SOME AREAS RECEIVED OVER 2 INCHES LAST NIGHT...
RADAR EST 3-5...BUT WILL PASS ON ANY FF WATCH DUE TO UNCERTAINTY OF
WHERE STORMS WILL BE. HOWEVER FFG VALUES SOMEWHAT LOW IN PARTS OF
CWA SO WILL ADVISE EVNG SHIFT.
THURS SEES THINGS DRY OUT AS FRONT PUSHES THRU RAPIDLY. IDEA OF
LOWERING TEMPS SEEMS TO BE IN LINE.
.GID...NONE.
EWALD
FXUS63 KOAX 111719 ne
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1210 PM CDT WED AUG 11 1999
UPDATED THE ZONES AND TEMP FCST TO REFLECT LATEST WX DVLPMNTS.
FIRST MCS MOVED TO THE EAST WITH RE-DEVELOPMENT OVER SCNTRL/SE NEB.
RUC 2 DATA WAS HELPFUL IN THE SHRTTRM FCST OF RE-DVLPMNT AS
WAA/INSTABILITY WAS GRTST IN THE GRI AREA ERLIER THIS AM. THE
LATEST RUC 2 DATA HAD THE BEST INSTABILITY OVR CNTRL KS WITH A
WRMFNT. MOISTURE BLYR MOCONV WAS OVR NW KS AND HI KINDICES AND PWS
WERE OVR CNTRL KS THRU CNTRL NEB. THE 15Z RUC CONTINUED TO SHOW TWO
SFC LOWS...ONE OVR KS MOVING N TO SCNTRL NEB AND THE MAIN LO IN WRN
SD BY 00Z. IN ADDITION...THE RUC HAS ANOTHER SHRTWV MOVING INTO
CNTRL NEB THIS AFT WITH ANOTHER WAVE NR FSD. WOULD EXPECT TSRA TO
RE-DEVELOP AND FOCUS NR THE WRMFNT AND WITH THE BEST UVVS. WILL
CONTINUE CHC OF TSRA FOR TAF AND TON. LOCALLY HVY RAINS POSSIBLE
WITH HI PWS AND TRAINING OF TSRA.
.OMA...NONE
ZAPOTOCNY
FXUS63 KOAX 110852 ne
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
844 PM EDT WED AUG 11 1999
TRW FIRED ALONG THE SEABREEZE THIS AFTN & ARE BEING SUSTAINED BY THE
TAIL END OF THE VORT PASSING ACROSS MHX CWFA. MSAS SHOWING GOOD
THETA-E RIDGE RIDING UP THE CAROLINA CST W/ MAX SFC MOISTURE
CONVERGENCE COVERING MOST OF CWFA. 00Z MHX SOUNDING ON SHARP SHOWED
-12 LI...5K CAPE...2+ INCH PW...30KT WINDS OFF THE SFC & DECENT
DIRECTIONAL SHEAR. LAST FEW 88D SCANS HAVE SHOWN A WEAKENING TREND
BUT W/ THE ABOVE IN MIND...THE ACTIVITY COULD GO ON FOR AWHILE
LONGER. WILL TAILOR POPS FOR SERN NC BASED ON 88D AT PRESS TIME.
FOG STAB INDEX FROM MHX RAOB NOT TOO PROMISING OVRNGT BUT ALL THE
RAIN WILL ENHANCE CHANCES. FOR NERN SC...NOT MUCH TO SPEAK OF W/ NO
REAL DYNAMICAL SUPPORT & NO MORE DAYLIGHT. WILL PROBABLY GO POPLESS
OVRNGT. CONDITIONS SIMILAR TO LAST NITE SO WILL CONTINUE FOG MENTION.
DEWPTS IN THE MID 70S INLAND & UPR 70S-NR 80 CST. TEMPS LOOK FINE.
CWF: LATEST RUC SHOWS A MOSTLY S WIND OVRNGT WHICH SO WILL LEAN THAT
WAY AS OPPOSED TO VRB. WILL ADD A POP TO NC WATERS IF NEEDED AT PRESS
TIME.
.ILM...NONE.
LGE
FXUS62 KRAH 111839 nc
FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
915 PM CDT WED AUG 11 1999
FORECAST CHALLENGE FOR UPDATE CONTINUES TO BE LOCATION AND STRENGTH
OF TSRA OVERNIGHT. 00Z RUC CONSISTENT IN SLOW SE MOVEMENT OF WESTERN
SD LOW. ASSOCIATED WELL DIFINED BOUNDARY ALONG ND/SD BORDER FROM
LATEST SFC ANALYSIS MOVES LITTLE OVERNIGHT. TWO AREAS OF CONVECTION
OF CONCERN TONIGHT. SEVERE STORMS OVR SW ND LIKELY TO TRANSFORM INTO
AN MCS AND TRACK ALONG BOUNDARY IN ZONE OF BEST LOW LEVEL AND MOIST
CONVERGENCE AS WESTERN WAVE CONTINUES TO PUSH EAST. FROM PROFILER
NETWORK H8 LOW LEVEL JET REAMINS WELL SOUTH OF FA AND 00Z RUC
INDICATING H8 LOW LEVEL JET AND MID LEVEL FLOW MARGINAL FOR SEVERE.
HOWEVER BECAUSE OF E-W BOUNDARY AND CURRENT CONVECTION OUT WEST WILL
NEED TO MONITOR FOR POSSIBLE WIND EVENT. OTHER E-W BAND OF
CONVECTION ORIENTED ON NORTHERN EDGE OF ZONE OF ISEN LIFT FROM
300-305K SFC OVR NE ND INTO NW MN. BECAUSE OF SLOW EASTWARD
PROPAGATION AND TRAINING WILL NEED TO MONITOR FOR HEAVY RAIN. ISEN
LIFT DOES GRADUALLY SHIFT SOUTH LATER TONIGHT. EXTREME NORTHERN
AREAS IN LEAST FAVORABLE AREA FOR RAINFALL WITH DRY LOW LEVEL
NORTHEAST FLOW AND NEUTRAL TO DOWNGLIDE WHEN VIEWED FROM ISENTROPIC
SFC. WITH DRIER AIR WILL ALSO SEE COOLEST TEMPS IN THIS AREA. MAIN
CHANGES WILL BE TO TOUCH UP TSRA TIMING. WILL LOOK OVER TEMPS BUT NO
BIG CHANGES PLANNED.
.FGF...NONE.
VOELKER
FXUS63 KBIS 112003 nd
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
915 PM EDT WED AUG 11 1999
PRECIPITATION HAS TAPERED OFF OVER CWA. CLUSTER OF STORMS OVER
SERN NC MOVING TOWARD NORTHEAST SC. BELIEVE PRECIP WILL NOT MAKE IT
INTO CWA AS INDICATED BY MESO ETA. WILL DELETE SHALLOW COASTAL
FLOODING HEADLINE FROM UPDATE.
CWF: WEAK TROF JUST INLAND KEEPING FLOW S OR SW ACROSS THE WATERS
THIS EVENING. EXPECT WEAK LOW PRES TO DEVELOP ALG THE TROF OVERNIGHT
WHICH SHOULD MAINTAIN SW DIRECTION THRU THE NIGHT. SPEED WISE...SFC
PRES GRADIENT EASILY SUPPORTS 15 KT AT 00Z BUT 18Z ETA AND LATEST
RUC SHOW GRADIENT DECREASING LATE. WILL MAINTAIN 15 KT AS AVERAGE
ON UPDATE. SEAS AVERAGING 2 TO 4 FT.
NONE
.CHS...
SC...HEAT ADVISORY THURSDAY AFTERNOON SC040-042>045-047>050.
GA...HEAT ADVISORY THURSDAY AFTERNOON GA087-088-089>101-114>119-
137>141.
JH/RVT
FXUS62 KCAE 120107 sc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
851 PM EDT WED AUG 11 1999
A FEW SHRA MADE IT INTO GRAHAM AND SWAIN COUNTIES BUT DISSIPATED
QUICKLY. NO OTHER PRECIP FOR THE CWFA. 00Z SFC CHART SHOWS LEE TROF
EAST OF THE CWFA WITH MUCH DRIER DEW POINTS ACROSS OUR COUNTIES.
LATEST RUC AND 18Z ETA KEEP ATMOS DRY TONIGHT. SAT PIX SHOW SOME
CLOUDS STREAMING INTO THE AREA. TEMPS GENERALLY LOOK GOOD WITH ONLY
HALF CATEGORY CHANGES LOWER IN AVL ZONE AND HALF CATEGORY HIGHER GSP
AND CLT ZONES. WILL ALSO LOWER WINDS TO LIGHT ALL ZONES.
.GSP...NONE.
RWH
FXUS62 KCHS 111903 sc
AREA FORECAST DISCUSSION...CORRECTED FOR TYPO AT END OF MESSAGE
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
242 PM EDT WED AUG 11 1999
NO MAJOR CHANGES TO THE AFTERNOON PACKAGE, RUC AND OTHER SHORT TERM
MODELS CONTINUE TO KEEP TEMPERATURES ABOVE NORMAL. FIRST HINT OF
RAIN IN THE MODELS IS FOR FRIDAY...BUT NOT HIGH ENOUGH PROBS TO
MENTION IN THE ZONES. WITH THE DROUGHT STATEMENT BEING ISSUED
DON'T PLAN TO MENTION PRECIP UNTIL SIGNIFICANT POPS CAN BE
MENTIONED AND THAT IS SATURDAY AND SUNDAY.
AFTER THAT MRF BRINGS NEW RDG OVER AREA NEXT WEEK. SO BRINGING BACK
DRY TERMINOLOGY ON MONDAY.
DWPTS IN 60S TODAY AND FWC KEEPS THINGS FAIRLY DRY WITH NRN TRAJ.
THIS WILL KEEP HEAT INDEX VALUES BELOW THAT CRYSTALIZED 105 MARK
OVER ALL BUT EXTREME SRN PART OF CWA. NO ADVISORIES BUT WILL
HIGHLIGHT ZONES WHERE INDEX WILL GO ABOVE 100.
AVL 063/090/065/089 000
CLT 068/096/069/095 000
GSP 069/097/070/096 000
.GSP...NONE.
DICARLO
FXUS62 KGSP 111836 sc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
159 AM EDT FRI AUG 6 1999
UPDATING UPSTATE SC ZONES FOR HIGHS IN THE UPPER 90S.
WILL MENTION HEAT INDEX ONLY IN ZONES THAT ALREADY HAVE IT
IN HEADLINE. RUC INDICATES LITTLE CHANGE FOR TOMORROW.
.GSP...NONE.
FXUS62 KCHS 111348 sc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
948 AM EDT WED AUG 11 1999
WL CONT HEAT ADVISORY THRU THE AFTERNOON. XPCT HEAT INDICES 105 TO
110 ACROSS FA INTO EARLY EVE.
HIGH TIDE DEPARTURES HAVE PLAGUED AREA DURING THIS TIDE CYCLE.
SOMEWHAT OF A MYSTERY AS TO THE CAUSAL FACTOR. WL HEADLINE ZONES AND
COASTAL FCSTS WITH SHALLOW CSTL FLOODING.
HEAT WL TURN UP A NOTCH THIS AFTERNOON WITHOUT CLD COVER TO INHIBIT
INSOLATION ACROSS THE FA. TEMPS AT H5 WL CREEP UP SOME TDY AND ONLY
XPCT ANY CONVECTION LIMITED TO SEAS BRZ. RUC AND MESO OUT OF PHASE
ON S/W ENERGY PROGGED TO MOVE ACROSS THE CAROLINAS. WL ADJUST
WORDING FOR PRECIP TO LESS THAN 20 PERCENT AND ONLY MENTION ISOLATED
SHRA/TSTMS. TEMPS LOOK IN LINE...RECORD AT CHS 98 AND 99 IN SAV...
HIGH TEMPS WL BE CLOSE TO THESE LEVELS.
CWF...FCST LOOKS TO BE IN GOOD SHAPE. ONLY ANTICIPATE MINOR TWEAKS.
.CHS...
SC...HEAT ADVISORY THIS AFTERNOON SC040-042>045-047>050.
GA...HEAT ADVISORY THIS AFTERNOON GA087-088-089>101-114>119-137>141.
JCI
FXUS62 KCAE 111332 sc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
917 AM EDT WED AUG 11 1999
THE 09Z RUC SHOWED THE SHORTWAVE REMAINING NORTH OF THE FORECAST AREA
THIS AFTERNOON AND KEEPS H7 TEMPERATURES 9 TO 10 IN THE NORTH PART OF
THE AREA AND 10 TO 11 ACROSS THE SOUTH PART. MODIFYING THE FFC AND GSO
RAOBS SHOWS THE ETA FORECAST OF MIDDLE 30S K-INDEX VALUES IN THE
FORECAST AREA THIS AFTERNOON MAY BE OVERDONE. EXPECT AFTERNOON AND
EVENING TSTMS WILL REMAIN ISOLATED AT MOST DUE THE WARM MID-LEVEL
TEMPERATURES AND LACK OF MOISTURE. IF TSTMS DO DEVELOP THESE WOULD
PROBABLY OCCUR IN THE NORTHEAST PART OF THE FORECAST AREA DUE TO A WEAK
BOUNDARY AND THE SLIGHTLY COOLER MID-LEVEL TEMPERATURES.
.CAE...HEAT ADVISORY THIS AFTERNOON SCZ015-016-018-020>022-025>031-
035>038-041-GAZ040-063>065-077
RJL
FXUS62 KGSP 111305 sc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
903 AM EDT WED AUG 11 1999
NO CHANGES IN THE 10 AM PACKAGE EXPECTED. LATEST SOUNDINGS AND
CURRENT RUC SHOW STRONG CAP THAT WE AREN'T GOING TO BREAK TODAY. DRY
FORECAST WILL CONTINUE UNTIL WEEKEND WHEN TROUGH GIVES US A SHORT
RESPITE.
MRF PUTTING HIGH RIGHT ON TOP OF US NEXT WEEK. SO ANOTHER EXTENDED
HOT SPELL IN THE MAKING. NEW DROUGHT STATEMENT WILL BE ISSUED THIS
AFTERNOON.
.GSP...NONE.
DICARLO
FXUS62 KCHS 111137 AMD sc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
1019 AM EDT WED AUG 11 1999
VARYING AMOUNTS OF CLOUDS ACROSS THE NORTH COUNTRY AS SEEN ON VIS
PICS WITH LOTS OF BREAKS INDICATIVE OF DISORGANIZED WEATHER PATTERN
THIS MORNING. WILL CALL IT PARTLY SUNNY NORTHERN VT. MORE CLOUDS IN
SOUTHWEST AND SOUTHERN ZONES CLOSER TO WEAK LOW PRESSURE NEAR ROC AND
WEAK WARM FRONT EXTENDING SOUTHEAST INTO SOUTHERN NEW ENGLAND THOUGH
SFC CONVECTIVE HEATING MAY BREAK THAT UP A BIT. TEMPERATURES
GENERALLY IN THE 70S PER CURRENT TEMPS AND SOUNDINGS.
RUC INDICATES UPPER LEVEL TROF ALREADY PASSING THROUGH THE AREA
WITH SLIGHT RIDGING UPSTREAM. THERE IS SOME POTENTIAL INSTABILITY
JUST SOUTH OF OUR FORECAST AREA AS INDICATED ON ALY SOUNDING MODIFIED
SFC T/TD OF 72/60 IS ENOUGH TO POP A SHOWER...MORE THAN THAT WOULD
RESULT IN THUNDER. RUC/03Z ETA INDICATE THAT WOULD NOT HAPPEN IN
NORTHERN SECTIONS AND NO THUNDER NORTH OF VT/MA BORDER AND NW TO ART
VCNTY WARM FRONT.
BEST CHANCE POPS SW AND S CLOSEST TO WARM FRONT FROM OGS SLK RUT
VSF. WILL LEAVE OUT ANY THUNDER AS INSTABILITY JUST NOT ENOUGH.
WORKZONES AVBL IN ADMBTV.
.BTV...NONE.
SISSON
vt
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
315 PM EDT WED AUG 11 1999
AWIPS VISIBLE SATELLITE LOOP INDCTD THAT CU HAD DEVELOPED MAINLY
ALONG THE MOUNTAINS. REGIONAL 88D IMAGE INDICATED A FEW SHOWERS IN
NRN WEST VIRGINIA AROUND BURNSVILLE AREA AND A CELL OR TWO IN
AMHERST. THIS PCPN WAS DEVELOPING AHEAD OF A WEAK SURFACE COLD
FRONT. BOTH MM5 SE AND RUC HINTED AT ISOLATED SHOWERS FOR THE
WESTERN MOUNTAINS THIS EVE. QUESTION OF HOW FAR SOUTH TO BRING
ISOLATED SHOWERS IN THE WEST ? WE WILL BE KEEPING A LIGHT POP FOR SE
WV AND ALLEGHANY HIGHLAND THIS EVENING. DRY WX EXPECTED IN THE MIDDLE
OF THE CWA. INSTABILITY INCREASES IN THE FAR EASTERN EDGE OF RNK
CWA...MAY ADD 20 EVENING POP FOR THE PIEDMONT. SURFACE FRONT WILL
CONTINUE IT MARCH EAST. MAIN SHORTWAVE WILL DROP SOUTHEAST AND PIVOT
ACROSS THE UPPER TROF. A WEAK FRONT WILL BECOME PARALLEL TO THE FLOW
AS IT SLIDES EASTWARD. HAVE A GUD EVENING.
.RNK...
VA...NONE.
NC...NONE.
WV...NONE.
KK
FXUS61 KAKQ 111438 va
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
937 PM CDT WED AUG 11 1999
UPDATE COMING TO ADDRESS PRECIPITATION CONCERNS TONIGHT. PRECIPITATION
THAT WAS MOVING ACROSS IOWA HAS DIED OFF...WITH FORECAST AREA CURRENTLY
DRY. NEW CONVECTION FIRED OVER EASTERN NEBRASKA AND WAS MOVING
NORTHEAST ACROSS SOUTHWEST IOWA. 00Z RUC MODEL INITIALIZED WELL AND
COVERS SURFACE PATTERN AND QPF QUITE WELL. IT EXPANDS THIS AREA OF
PRECIPITATION AS IT MOVES FURTHER EAST...AND STILL GETS IT INTO
NORTHEAST IOWA AND PERHAPS SOUTHEAST MINNESOTA/SOUTHWEST WISCONSIN BY
MORNING. PROFILERS SHOW LOW LEVEL JET INCREASING ACROSS THE PLAINS...
WITH NOSE APPROACHING SLATER WHERE LIGHT WINDS HAVE NOW COME AROUND
SOUTHERLY. WILL ADJUST POPS AND PRECIPITATION WORDING DOWN SOME TONIGHT
TO ACCOUNT FOR LATEST THINKING.
NO OTHER SIGNIFICANT CHANGES.
.LSE...NONE.
WELVAERT
FXUS63 KMKX 120158 AMD wi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
3 PM CDT WED AUG 11 1999
...FORECAST CHALLENGES...CHC OF PRECIP/LOCALLY HEAVY RAIN/TIMING OF
FNT/TEMPS
...SYNOPSIS...LATEST SFC ANALYSIS HAS LO PRES OVR NW KS AND THE
PRIMARY SFC LO OVR NW SD. SFC DEWPOINTS WERE POOLED IN THE 70S NR
THESE LOWS AND S OF THE WRMFNT OVR NCNTL KS. THE RUC2 GRAPHICS HAS
WAA GREATEST N OF THE NRN PLNS WRMFNT...OVR ERN SD...THRU CNTRL
NEB...AND INTO CNTRL KS AND OK. CONVECTION HAS BEEN EXITING THE
CWFA AND IS JUST ABOUT TO MOVE OUT OF OUR FAR ERN COUNTIES. THE 18Z
RUC HAD THE STGR SHTWV OVR CNTRL IA...WITH ADDITIONAL DISTURBANCES
IN SE SD AND WRN NEB.
...FCST...THE ATMOSPHERE HAS STABILIZED BEHIND THE MCS...YET WITH
THE CLEARING SKIES...HOT TEMPS AND POOLING WITH THE WRMFNT...THE
MESOETA HAS AN AXIS OF UNSTABLE AIR FM SCNTRL NE INTO KS. WITH THE
MAIN LO OVR WCNTL SD THE RUC EXTENDS THE TROF INTO CNTRL NEB WITH
THE WRMFNT OVR SE NEB. WITH HI PWS NR THE NEB/KS BORDER...THREAT OF
LOCALLY HVY RAIN. WILL CONSIDER WATCH OVR THE SW COUNTY WARNING
AREA DUE TO THE HVY RAIN THIS AM. FFG IS ONLY 1 TO 1.5 INCHES. AT
THIS TIME WILL MENTION LOCALLY HVY RAIN AND BRIEF EVE SHIFT TO
POTENTIAL. DUE TO THE CONTINUED WAA CHC FOR PRECIP THIS INTO THUR
AM.
MODELS TRACK THE SFC LO ACRS SRN SD AND INTO NRN IA THUR...CARVING
OUT AN UPR TROF WHICH WILL RESULT IN PRECIP CHCS THUR. COOLER TEMPS
FOR FRI WITH GOOD CAA
.OMA...NONE
ZAPOTOCNY
FXUS63 KLBF 111959 ne
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
312 AM CDT THU AUG 12 1999
PRECIPITATION CHANCES FOR TODAY INTO THIS EVENING IS MAIN CONCERN ALONG
WITH TEMPERATURES.
06Z SURFACE MAP SHOWING ONE AREA OF LOW PRESSURE NEAR HILL CITY WITH
WARM FRONT CURVING ALONG KS/NEB BORDER INTO NORTHWEST MISSOURI.
WATER VAPOR SHOWING PLUME OF DEEPER MOISTURE EXTENDING FROM SW TEXAS
AND WRN OK...THROUGH CENTRAL KS INTO IOWA. LASTEST MSAS MOISTURE
CONVERGENCE UNDER THIS PLUME AND ALONG FRONTAL BOUNDARY OVER
NORTHERN COUNTIES...TRAILING TO THE SOUTHWEST. RADAR HAS SEEN
ACTIVITY ON THE INCREASE OVER NORTH CENTRAL CWA AND FLARES UP AT
TIMES OVER THE NORTHEAST...ALL IN AREAS OF WARM ADVECTION AND THETA
ADVECTION. RUC ALSO SHOWING WEAK UPPER IMPULSE IN THE CENTER PART
OF STATE EJECTING NORTHEAST. WILL PROBABLY WORD THE NORTH CENTRAL
AND AT LEAST NORTHERN PARTS OF NORTHEAST WITH SCATTERED CONVECTION
THIS MORNING...AND A CHANCE OVER THE REMAINDER OF CWA. FOR THE
AFTERNOON HOURS...MODELS TAKE STRONG UPPER SHORTWAVE ACROSS THE
NORTHERN PLAINS WITH A LOBE EXTENDING SOUTHWARD ACROSS EASTERN
PORTIONS OF CWA...TROF/FRONTAL BOUNDARY WORKS INTO EASTERN PORTIONS
OF CWA AS WELL...THUS WILL KEEP AT LEAST SOME 30 PERCENT POPS FOR
THE EAST CENTRAL AND PARTS OF THE NORTHEAST...THE NORTH CENTRAL AND
BORDER COUNTIES OF NORTHEAST WILL HAVE PCPN ONLY IN THE MORNING
HOURS. THE LAST FEW DAYS HAVE HAD IMPRESSIVE CAPES...3500-4000 OVER
THE CWA BUT ALSO HAVE HAD WARM MID LEVEL TEMPS TO CAP CONVECTION.
FOR THIS AFTERNOON...AVN AND NGM TO A LESSER DEGREE SHOWING SLIGHTLY
COOLER 700 MB TEMPS BY 24 HOURS. IF COVECTION FIRES...COULD
POSSIBLY SEE SOME SEVERE BUT THE BETTER CHANCES WILL BE TO THE NORTH
AND EAST WHERE UPPER DYNAMICS AND WIND FIELDS MORE FAVORABLE. FOR
TONIGHT...CURRENT FORECAST HAS CHANCES OF PCPN INTO THE EVENING
HOURS OVER THE NORTHEAST BUT WILL PROBABLY CONFINE THIS TO JUST THE
EAST CENTRAL DURING THE EVENING HOURS WHERE BOUNDARY AND TAIL END OF
UPPER SUPPORT COULD KEEP ACTIVITY GOING. MODELS DRAGGING SOME MID
LEVEL RH SOUTHWARD ACROSS THE AREA ON FRIDAY WITH THE NGM EVEN
SHOWING SOME QPF STRATLING THE KANSAS-NEBRASKA BORDER...FOR NOW WILL
KEEP THE PARTLY CLOUDY GOING.
TEMPERATURE-WISE...SOUTHERLY WINDS KEEPING TEMPERATURES IN THE UPPER
70S TO LOWER 80S AS OF 3 AM. YESTERDAYS HIGHS TO THE SOUTH OF WARM
FRONT WERE IN THE UPPER 90S TO AROUND 105 DEGREES. MAY HAVE TO UP
GOING FORECAST INTO THE 95 TO 100 DEGREE RANGE...AT LEAST FOR THE
EASTERN PORTIONS OF CWA. GOING FORECAST OF LOWS IN THE MIDDLE TO
UPPER 60S LOOKS OK FOR NOW...NGM HIGHS ON FRIDAY LOOK A BIT HIGH AND
WILL GO MORE WITH COMPROMISE WITH HIGHS IN THE MIDDLE TO UPPER 80S.
.TOP...NONE
FRANTZ
FXUS63 KICT 120717 ks
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1130 AM EDT THU AUG 12 1999
TODAY/S PROBLEM HAS BEEN HANDLING THE CLOUD DEBRIS FROM THE MCC
ENTERING THE S LP AND FIGURING OUT WHEN THE RAIN BEGINS. 12Z RUC
LOOKS LIKE IT HAS BEEN HANDLING THE FEATURES PRETTY WELL. 12Z NGM
AND ETA LOOK PRETTY SIMILAR TO THE RUC FOR THE FIRST 12 HOURS. HIGH
CLOUDS WILL CONTINUE TO STREAM ACROSS THE AREA...BUT THE LOW LEVEL
MOISTURE IS LACKING AT THE MOMENT. WARM ADVECTION AND SOME HEATING
BY THE SUN WILL HELP TO DEVELOP SHOWERS DURING THE AFTERNOON...BUT AS
FAR AS THE RAIN DEVELOPING MODELS SEEM TO AGREE THAT IT DOESN/T
HAPPEN UNTIL 00Z OR LATER. SO...THIS MEAN THAT WE ARE CHANGING THE
RAIN TO AFTERNOON SHOWERS AND WILL ADD IT INTO THE REST OF THE
ZONES. WILL MENTION THUNDER LATE IN THE AFTERNOON IN CASE HEATING THIS
AFTERNOON DESTABILIZES THINGS BY LATER IN THE PERIOD.
.APX...NONE.
LUTZ
FXUS63 KMQT 121452 mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1050 AM EDT THU AUG 12 1999
...TIMING OF RAIN STILL THE MAIN CONCERN...
...AT 14Z 1000MB SFC LO OVER SD WAS SLOWLY PRODDING EAST.
MEANWHILE...MUCH TO THE PREVIOUS SHIFTS' DISMAY...SUNSHINE HAS
BROKEN OUT OVER N WI AND OVER MUCH OF THE U.P. TEMPS WHERE THE SUN
IS OUT ARE ALREADY IN THE LOW 70S..SO BUMPED UP TEMPS SOME 5-7
DEGREES IN RESPONSE TO THIS. AM CONCERNED THAT THE EXTRA SOLAR HEATING
MAY DESTABILIZE THE ATMOSPHERE ENOUGH TO PRODUCE MORE WIDESPREAD
THUNDER THAN WAS PREVIOUSLY FORECAST. MODIFIED RUC SOUNDINGS IN THE
SOUTHERN TIER SHOW 800-1000 J/KG OF CAPE WITH TEMPS IN THE MID
70S...SO I BEEFED UP THE THUNDER WORDING IN THE SOUTH.
.MQT...NONE.
ALTOE
FXUS63 KDTX 121446 mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
925 AM EDT THU AUG 12 1999
...WILL UPDATE FORECAST FOR SW COUNTIES TO PUT IN SHOWERS...
LARGE AREA OF SHOWERS MOVING ACROSS LAKE MI AT 13Z AND DOES NOT SEEM
TO BE DRYING OUT MUCH. LATEST RUC SHOWS SHTWV ASSOC WITH NRN PART
OF COMPLEX OVER EXTREME NRN IL/SRN WI. ALSO RUC INDICATES GOOD
DIVEGENCE ASSOC QUASI-COUPLE JET STRUCTURE ON SRN STREAM JET (EXIT
SEGEMENT OVER WRN PA/WV AND ENTRENCE SEGMENT COMING INTO IOWA). RUC
ALSO SHOWS GOOD 850 THTE ADV OVER LK MI BUT WEAKENS SOME AS IT GETS
INTO SW MI. SOUNDINGS FROM DTX AND I-SPOT SHOW FAIR AMOUNT OF DRY
AIR BELOW 600 MB AHEAD OF SYSTEM AND RUC INDICATES 700 WILL NOT
MOISTEN AS FAST AS SHTWV IS MOVING. THUS RAIN AREA WILL DIMINISH AS
IT MOVES ACROSS SRN 1/3 OF LWR MI.
BOTTOM LINE... WILL HAVE SHWRS LIKELY NEAR I-94/BTL AND WEST. CHC
SHWRS I-96 TO JXN.
.GRR...NONE
WDM
FXUS63 KDTX 121132 mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1030 PM EDT WED AUG 11 1999
FORECAST ISSUE FOR THE U.P. TONIGHT IS PRECIPITATION.
00Z SURFACE ANALYSIS SHOWS A WEAK SURFACE FRONT EXTENDING FROM A LOW
IN JAMES BAY...TO MENOMINEE COUNTY...TO SOUTHERN NORTH DAKOTA.
SCATTERED LATE AFTERNOON AND EARLY EVENING SHOWERS DEVELOPED IN THE
U.P. ALONG THIS FRONT... BUT KMQT 88D RETURNS OVER THE LAST COUPLE OF
HOURS SHOW THE SHOWERS HAVE DISSIPATED. EVEN AT THEIR STRONGEST
THESE SHOWERS PRODUCED NO LIGHTNING AND HAD QUITE WARM CLOUD TOP
TEMPERATURES ON THE IR SATELLITE IMAGERY. THE FRONT IS PARTICULARLY
WEAK AS IT CROSSED THE U.P... THE FRONT IS A COLD FRONT EAST OF THE
U.P. AND A WARM FRONT TO THE WEST. BUT HERE IN THE U.P. ITSELF
THERE IS A COL IN THE SEA LEVEL PRESSURE PATTERN THAT THE FRONT
CROSSES... AND THERE IS AN ABSENCE OF VORT MAXIMA ALOFT IN THE
REGION AND FLAT 700-300MB QVECTOR FIELD. WITHOUT THE ASSISTANCE OF
DIURNAL HEATING TO DESTABALIZE THE BOUNDARY LAYER... THE SURFACE FRONT
ALONE IS APPARENTLY TOO WEAK TO TRIGGER PRECIPITATION.
THE FRONT WILL SAG SLOWLY SOUTH TONIGHT... AND THE SERIOUS
PRECIPITATION IS SET TO BEGIN THURSDAY AS A SURFACE WARM FRONT NOW
NEAR THE KANSAS-MISSOURI BORDER APPROACHES THE AREA AND OVERRUNNING
SERVES AS A MECHANISM FOR THE U.P. 310/320K ISENTROPIC LIFT BEGINS
OVER THE U.P. BY 12Z ACCORDING TO THE 12Z ETA NGM AND AVN MODELS.
BUT NEW MESOETA AND RUC HAVE TRENDED TO A SLOWER SOLUTION. THIS IS
INTERESTING SINCE 12Z ETA SHOWED A SLOWER PROGRESSION THAN ITS
PREVIOUS 00Z RUN AS WELL. WILL LEAVE ANY MAJOR REVISION OF WET
THURSDAY ZFP FORECAST TO MIDNIGHT SHIFT... BUT MESOETA AND RUC OFFER
ENOUGH EVIDENCE FOR DELAYING RAIN DEVELOPMENT TONIGHT UNTIL VERY
VERY LATE IN THE 1ST PERIOD. WILL ALSO TAME DOWN THE POPS FROM
CATEGORICAL ACROSS THE U.P. TO LIKELY IN THE WEST AND CHANCE IN THE
EAST. 20Z FLP FOR MQT HAS A POP OF ONLY 35% BY 12Z... WILL
COMPRIMISE BETWEEN LATEST MODEL GUIDENCE AND FORECAST CONTINUITY.
.MQT...NONE.
ES
FXUS63 KAPX 120140 mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1030 AM CDT THU AUG 12 1999
MAIN FCST CHALLENGE IS WITH CLOUD TRENDS. THIS IS BECAUSE WE ARE
SETTING UP FOR A MAJOR SEVERE WX EVENT SHOULD WE GET SFC HEATING.
LATEST SFC ANALYSIS SHOWS MAIN LOW JUST SW OF ABR...WITH WARM FRONT
EXTENDING SE INTO WRN IA. ANOTHER QSTNRY FRONT WAS ALONG NRN EDGE OF
FCST AREA. MAJOR DRY PUNCH ACRS NRN NEBRASKA PER 12Z LBF SOUNDING...
WITH UPR LOW OVR ND. 6.7IR IMAGERY SHOWS MAJOR VORTICITY MAXIMA OVR
NW NEB...AND 12Z RUC EJECTS THIS FEATURE ACRS SRN MN THIS AFTERNOON.
IN ADDITION...50-70KT 500-300MB WIND MAX DEVELOPS...WITH THE EXIT
REGION DIVERGENCE OVR THE TWIN CITIES BY 00Z.
SHOULD CLOUDS ERODE ENOUGH TO ALLOW FOR SFC HEATING...DEWPOINTS NEAR
70 WILL YIELD CAPES NR 4000 J/KG SRN MN THIS AFTN. FEEL THAT ETA IS
TOO FAR SOUTH WITH TRACK OF THE SFC LOW...DUE TO TROUBLE RESOLVING
WARM FRONT TO THE SOUTH. BEST PRESSURE FALLS AT 15Z ARE OVR CNTRL MN
NR THE NRN BOUNDARY...AND WOULD EXPECT LOW TO TRACK THAT DIRECTION.
THIS PLACES MUCH OF CWA UNDER WARM SECTOR THIS AFTN.
SECOND PROBLEM IS WITH THE UNSEASONABLY STG UPR LOW. PER COORD
WITH SPC...WITH 50H TEMPS DROPPING TO -10 DEG C AND STG VORTICITY...
WOULD SEEM LIKE A POTENTIAL SITUATION FOR MINI-SUPERCELL STRUCTURES
ON STORMS IN CNTRL MN WITH INCREASING THREAT OF HAIL/WEAK TORNADOES.
OVERALL...SEEMS THAT PBL MOISTURE WILL REMAIN HIGH THROUGH THE DAY.
WITH MCS OUTFLOW MODIFIED AIR TO OUT SOUTH ADVECTING IN...LOW
CLOUDS/STRATUS SHOULD REMAIN IN PLACE...LIMITING SFC HEATING.
HOPEFULLY...THIS WILL PREVENT A SVR WX OUTBREAK. HOWEVER...DUE TO
TIME OF YEAR/STRENGTH OF DYNAMICS...WILL MAINTAIN HIGH POPS AND KEEP
SVR WX WORDING IN ZONES.
MPX WILL RELEASE A SPECIAL 18Z SOUNDING TODAY. DATA AVAILABLE NEAR
130 PM CDT.
.MSP...NONE.
DAVIS
FXUS63 KDLH 121519 mn
FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
945 AM CDT THU AUG 12 1999
SATELLITE VAPOR IMAGERY CONTINUES TO SHOW UPPER RIDGE OVER THE
REGION WITH SHORT WAVES HEADING WEST OVER THE EASTERN GULF.
LOOKING AT THE SOUNDING NO CAP TODAY. AFTERNOON MODIFICATIONS SHOW LIFTED
INDEXES AT -7...PRECIPITABLE WATER AT 2.2 INCHES...WITH A HAIL INDEX OF
36,400 FEET. UPPER PLOTS SHOW THE RIDGE CENTER OVER THE REGION WITH
WARM TEMPERATURES ALOFT...WHICH SHOULD LIMIT CONVECTIVE COVERAGE.
12Z RUC MODEL SHOWS MEAN MOISTURE MAINLY OVER THE CENTRAL AND SOUTH
MISSISSIPPI...WITH RATHER DRY READINGS OVER NORTHEAST LOUISIANA AND EXTREME
SOUTHEAST ARKANSAS. SO WITH GOOD AFTERNOON SOUNDING INDICES AND NO REAL
CAP...HAVE OPTED TO INCREASE POPS SLIGHTLY OVER THE CENTRAL AND
SOUTH.
.JAN...
MS...NONE.
LA...NONE.
AR...NONE.
17
FXUS74 KJAN 120828 ms
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1000 AM EDT THU AUG 12 1999
FORECASTS FOR AFTERNOON LOOK GOOD FOR MOST PART. MAY ADJUST SKY CONDITIONS
A FEW LOCATIONS BASED ON LATEST SATELLITE TRENDS BEFORE ISSUANCE.
RUC AND MESO ETA SHOWING LEFT OVER VORT MAX FROM MCS IN MIDWEST
DRIFTING INTO NORTHERN SECTIONS OF CWFA LATER THIS AFTERNOON...WITH
SOME VERY WEAK DPVA BUT LITTLE OMEGA UPLIFT SHOWING UP. FORECAST
TEMPS ALOFT VERY WARM HOWEVER...WITH AREA WELL CAPPED. IT WOULD TAKE
SOME REAL GOOD LOW LEVEL MOISTURE CONVERGENCE TO OVERCOME CAP AND
GET ANY PRECIPITATION TO DEVELOP.
NO MORNING RAOB FROM ATLANTA...BUT NASHVILLE AND GREENSBORO QUITE
UNSTABLE WITH DEWPOINTS MODIFIED TO NEAR 70. CURRENTLY...LOW LEVELS
MUCH DRIER THAN THAT OVER NORTHERN PORTIONS OF CWFA BUT DO HAVE
DEWPOINTS NEAR 70 OVER SOUTHERN SECTIONS. WITH MIXING THIS
AFTERNOON...SOUTHERN SECTIONS MAY DRY OUT MORE...SO NOT MUCH CHANCE
FOR FIRING ANYTHING BUT AN ISOLATED STORM...MAINLY EXTREME SOUTHERN
PORTIONS.
TEMPS SHOULD CONTINUE TO BE HOT AND SIMILAR TO YESTERDAY.
.GSP...NONE.
RBN
FXUS62 KCHS 120728 sc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1040 AM CDT THU AUG 12 1999
MAIN FORECAST CONCERN...SEVERE POTENTIAL FOR LATE AFTERNOON AND
EVENING.
15Z SURFACE ANALYSIS INDICATED SURFACE LOW OVER EASTERN SOUTH
DAKOTA...WHILE WARM FRONTAL BOUNDARY EXTENDING ACROSS SOUTHWEST IA
TOWARD ST LOUIS. IN THE UPPER LEVELS...WATER VAPOR SATELLITE IMAGERY
SHOWED VORTICITY MAXIMUM ACROSS NORTHERN PLAINS WITH PRONOUNCED DRYING
ADVANCING INTO WESTERN IOWA AND SOUTHWEST MN. GOES SOUNDER IMAGERY
INDICATED ATMOSPHERE BECOMING UNSTABLE ACROSS THIS SAME AREA WITH
LIFTED INDICES OF MINUS 4 TO MINUS 6.
12Z RUC...ETA AND NGM SHOWED SURFACE LOW TO BE ALONG MN/IOWA BORDER
NEAR ALBERT LEA MN BY 00Z THIS EVENING...WHILE WARM FRONT EXTENDS
ACROSS EASTERN IOWA INTO NORTHERN IL. LOW CLOUDS ASSOCIATED WITH 900 MB
MOISTURE FORECAST TO REMAIN NORTH OF THE FRONT ACROSS MUCH OF OUR
FORECAST AREA THROUGH THE AFTERNOON. UPPER LEVEL DRYING ANTICIPATED TO
CONTINUE PUSHING ACROSS IOWA AND SOUTHERN MN.
ANTICIPATING BEST THREAT OF SEVERE WEATHER ACROSS NORTHEAST IOWA AND
PERHAPS SOUTHWEST CORNER OF WI LATE THIS AFTERNOON AND EVENING. PRIMARY
THREAT WILL BE LARGE HAIL AND DAMAGING WIND ALONG WITH POSSIBILITY OF
ISOLATED TORNADOES. THIS DUE TO PROXIMITY OF FRONT AND STRONG HELICITY
NEAR THE BOUNDARY. ELSEWHERE...SOUTHEAST MN INTO CENTRAL WI...STILL
EXPECTING A CHANCE OF SEVERE WEATHER BUT TO A LESSER EXTENT DUE TO MORE
CLOUDS PREVENTING ATMOSPHERE FROM DESTABILIZING AS MUCH AS AREAS FURTHER
SOUTH.
NOT MUCH CHANGE TO ZONES EXPECTED WITH THIS MORNING UPDATE...WHICH
WILL BE ISSUED BY 11 AM.
.LSE...NONE.
THOMPSON
FXUS63 KGRB 120834 wi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
120 PM EDT THU AUG 12 1999
CURRENT...A MOISTURE DISCONTINUITY IS EVIDENT ON VSBL IMAGERY ACROSS
THE SRN MOST FA. A SHARP LINE DELINEATES AN AREA OF CU CLOUD STREET
DEVELOPMENT TO THE SOUTH AND MOSTLY SUNNY CONDITIONS TO THE NORTH.
THE LINE EXTENDS FROM FLAGLER BEACH THROUGH THE OCALA NATIONAL
FOREST THROUGH OCALA TO THE CEDAR KEYS. THIS BOUNDARY HAS BEEN
SHIFTING SLOWLY NORTH AND THINK IT WILL EXTEND S OF HIGHWAY 16 BY
MAX HEATING. ALSO THE ATLANTIC SEA BREEZE IS DEVELOPING FROM PONTE
VEDRA SOUTH. THESE SHOULD BE THE MOST LIKELY AREAS FOR AFTERNOON
CONVECTION. RUC SHOWS THE SFC MOISTURE DIVERGENCE OVER SE GA AND
THAT LOOKS LIKE IT'S GOING TO BE THE HOT SPOT BY THE END OF THE DAY.
MODELS/SYNOPTIC...MODELS CONTINUE TO BE IN GOOD AGREEMENT ALOFT AND
WITH THE MAJOR FEATURES BUT CANT AGREE WRT LOW LEVEL FEATURES ACROSS
THE SERN US. THE MODELS ALL INDICATE A LARGE UPPER HIGH OVER TX WITH
A BROAD RIDGE EXTENDING E TO THE GA COAST. A SECOND HIGH CENTER IS
EMBEDDED IN THE RIDGE OVER SRN AL AND THE SUBSIDENT REGION FROM THIS
HIGH IS ENTRENCHED OVER THE FA. REALLY HARD TO SEE HOW ANYTHING IS
GOING TO BLOW THROUGH THE SUBSIDENCE INVERSION OVER SERN GA AND
EXTREME NERN FL. ADDITIONALLY...ETA SHOWS AN AREA OF NVA MOVING SWD
ACROSS THE FA INTO FRIDAY WHICH SHOULD SQUASH CLOUD DEVELOPMENT. IN
THE LOW LEVELS THE MODELS AGREE ON A TROUGH AND BROAD LOW PRESSURE
ESTABLISHING ITSELF OVER THE REGION TONIGHT. AFTERWARDS THEIR ALL
OVER THE MAP WITH WEAK FEATURES. NGM/AVN DEVELOP A LOW OFF THE CAPE
AND MOVE IT WEST WITH/AS A SFC TROUGH AND ETA MAINTAINS A SFC TROUGH
OVER THE PEN AND SLOWLY MOVES IT WEST ON SATURDAY. THIS IS REALLY
ONLY A CONCERN WRT TO THE MARINE FORECAST WIND DIRECTION AS THERE IS
LITTLE SUPPORT FOR CONVECTION OVER THE FA AND LITTLE IN THE WAY OF
COOLING LIKELY THROUGH TOMORROW. THE STRONGEST SUBSIDENCE SHOULD
SHIFT NORTH OF THE AREA IN RESPONSE TO A DEVELOPING UPPER LOW OVER
THE BAHAMAS ON SAT SO THINGS MAY GET A LITTLE COOLER AFTER
FRIDAY...DOWN INTO THE LOW TO MID 90S!
MARINE...AS NOTED ABOVE THE WIND DIRECTION WILL BE THE MAIN PROBLEM.
WINDS AND SEAS ARE BELOW 15 KT AND 5 FT...SO MAINLY AN ACADEMIC
QUESTION...BUT WILL STICK CLOSER TO ETA AND WILL NOT BITE ON A
SWITCH TO NE WINDS.
BTW FOR FRIDAY AT 8 PM...THE FWC GUIDANCE OF 87 DEGREES AND A DWPT
OF 76 DEGREES YIELDS A HEAT INDEX OF AROUND 98...JUST IN CASE ANYONE
WAS WONDERING ABOUT THAT TIME FOR ANY STRANGE REASON.
PRELIM
SSI 79/95/79/93 05000
AMG 77/100/75/96 05022
JAX 77/99/76/96 05000
GNV 76/96/75/94 05021
SANDRIK
FXUS62 KMLB 121413 fl
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
350 PM EDT THU AUG 12 1999
FCST CONCERN REVOLVES AROUND WIDESPREAD EVENT RAIN TONIGHT INTO FRI
AS STRONG SHORTWAVE PASSES.
WV IMAGERY EARLY THIS AFTN SHOWS POTENT SHORTWAVE MOVING E ACROSS
DAKOTAS. STRONG MID/UPPER LEVEL DRYING ASSOCIATED WITH UPPER JET
TRACKING NE THRU PLAINS IS ALSO CLEARLY EVIDENT. RIGHT ENTRANCE
REGION OF 110 KT UPPER JET ACROSS ONTARIO PRODUCING STRONG UPPER
DIVG ACROSS DAKOTAS/MN. RESULT IS LARGE AREA OF RA/TSRA. AT THE
SFC...LOW PRESSURE WAS LOCATED IN NE SD TO THE E OF KABR. 3HR SFC
PRESSURE TENDENCY FIELDS INDICATE LOW SHOULD CONTINUE ON GENERAL
DUE EAST COURSE AT LEAST FOR THE SHORT TERM.
MODELS ALL ALONG HAD BEEN TOO QUICK WITH THIS SYSTEM...BUT NOW THAT
THE EVENT IS PRACTICALLY HERE AT LEAST DONT HAVE TO WORRY ABOUT
TIMING DIFFICULTIES. MODELS IN GOOD OVERALL AGREEMENT ON SYSTEM AS
IT PASSES TONIGHT/FRI MORNING. 12Z ETA TRACKS LOW FARTHER N THAN
PREVIOUS RUNS AND AS A RESULT TAKES HEAVIEST RAINFALL FARTHER
N...ACROSS N END OF LK SUPERIOR RATHER THAN S OF FA. NGM/AVN...
CONSISTENT WITH THEIR PREVIOUS RUNS...TAKE LOW THRU CNTRL LOWER MI.
GIVEN CURRENT POSITION OF LOW FARTHER N THAN 6 HR FCSTS OF ALL
MODELS...WILL PLAN ON LOW TRACKING ACROSS N WI AND THEN N LK
MICHIGAN EARLY FRI MORNING. EVERYTHING COMING TOGETHER FOR A GOOD
RAIN EVENT FOR FA. PRECIPITABLE WATER INCREASES TO AROUND 1.75
INCHES THIS EVENING AS POTENT SHORTWAVE APPROACHES. WITH UPPER JET
ACROSS ONTARIO TRANSLATING E...UVM ACROSS FA WILL BE ENHANCED BY DIVG
IN RIGHT ENTRANCE REGION OF JET...ESPECIALLY DURING THE LATE
EVENING. THIS SHOULD BE THE TIME OF WIDESPREAD AND HEAVIEST
RAINFALL. LI'S REMAIN POSITIVE OVER ALL BUT FAR S FA WHERE LI'S FALL
TO 0 TO -2 AND CAPES INCREASE TO 100 TO 400 J/KG BY 06Z.
HOWEVER...GIVEN STRONG DYNAMICS AND UVM FCST BY MODELS...WILL
INCLUDE THUNDER IN FCST FOR ALL AREAS TONIGHT. THIS SEEMS PRUDENT
GIVEN OCCASIONAL THUNDER OCCURRING N OF LOW THIS AFTN.
SHORTWAVE PASSES EAST OF FA LATE FRI MORNING AND SO WILL NEED TO
CARRY MORNING PRECIP MENTION. SUBSIDENCE ARRIVES QUICKLY BEHIND
SYSTEM FRI. HOWEVER...CYCLONIC LOW-LEVEL FLOW/CAA/LINGERING
LOW-LEVEL MOISTURE WILL LIMIT CLEARING...AND ANY SUNSHINE WILL LEAD
TO CU DEVELOPMENT. CAA AND BOUNDARY LAYER WINDS 20-30 KNTS WILL MAKE
FOR A BREEZY DAY.
850 TEMPS COOL ENOUGH TO LIKELY PRODUCE SOME LK EFFECT CLOUDINESS BY
SAT MORNING. WITH THERMAL TROF PASSING LATE SAT MORNING AND SFC
RIDGE NOT ARRIVING UNTIL SAT NIGHT...SHOULD SEE SCT-BKN CU
DEVELOPMENT SAT.
IN THE EXTENDED...MRF/CANADIAN/ECMWF TRENDING SLOWER WITH WAA
PATTERN AHEAD OF NEXT SHORTWAVE TRAVERSING N PLAINS EARLY NEXT WEEK.
THIS WILL ALLOW FOR COOL NIGHT SAT NIGHT AS SFC HIGH DRIFTS ACROSS
FA. MOST AREAS SHOULD BE IN THE MID 40S. WILL DROP MENTION OF SHRA
ON SUN GIVEN SLOWER TREND OF MODELS. SHRA/TSRA CHANCE WILL COME
SUN NIGHT INTO TUE...FIRST DUE TO WAA EVENT THEN WITH PASSING OF
SHORTWAVE AND COLD FRONT. QUITE A BIT OF UNCERTAINTY WITH TIMING OF
FRONT. UKMET IS FASTEST...BRINGING FRONT THRU MON EVENING. ECMWF IS
SLOWEST...WITH PASSAGE WED MORNING. MRF/CANADIAN DEPICT PASSAGE ON
TUE. WILL GO MIDDLE GROUND AND MESH WITH GOING FCST BY CONTINUING
SHRA CHC MON AND THEN ADDING CHC TO TUE. FRONTAL BOUNDARY SHOULD
THEN SET UP WELL SOUTH OF FA AND ALLOW FOR A PARTLY CLOUDY
WED/THU.
MARINE DISC...WIND FUNNELING DOWN WEST END OF LK SUPERIOR THIS AFTN
REACHING GALE FORCE. 18Z RUC SHOWING BOUNDARY LAYER WINDS INCREASING
TO 40 KNOTS THIS EVENING AND PER COORD CALL WITH DLH...35-40KNT
WINDS ALREADY BEING REPORTED ON THE FAR W END OF LK. WILL ISSUE GALE
WARNING FOR W 1/3RD LK TONIGHT.
.MQT...GALE WARNING WEST 1/3RD LK SUPERIOR TONIGHT.
ROLFSON
FXUS63 KAPX 121921 mi
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1020 AM CDT THU AUG 12 1999
UPDATED JUST THE FSD AND SOME OF SWRN MN ZONE EARLIER TO PROLONG THE
STRATUS A BIT. OTHERWISE ZONES ARE IN PRETTY GOOD SHAPE. CRNT SFC
ANALYSIS SHOWS LOW PRES OVR THE NE QUAD OF SD...AND SAT PIX SHOWS A
DRY SLOT INTRUDING INTO SRN HALF OF CWA...GENERALLY FM I 90 SWD. RUC
HAS A GOOD HANDLE ON THIS LLVL MSTR THIS MRNG...AND PROGS A DRYING
AT THE 925 AND 850MB LVLS THIS AFTN OVR ALL OF THE CWA EXCEPT THE
NORTH. FNT PROCEEDS EWD THRU MIDDAY...AND RUC PROGS MOST OF CWA TO
SHIFT TO THE WEST AT 925 AND 850MB BY EARLY THIS AFTN. NLG PROFILER
IS ALREADY UNIDIRECTIONAL FM THE W AND WSW...WITH NO HOPE OF VEERING
LATER TDAY. WDL PROFILER SHOWS GOOD VEERING...BUT THIS WL CHANGE BY
MID TO LATE AFTN. PROG INSTABILITY FM THE RUC DOES SHOW SOME UNSTABLE
AIR IN THE FAR ERN SECTION OF CWA THIS AFTN WHERE LLVL CONV WL BE
THE GREATEST. FEEL THIS AREA HAS THE BEST CHC FOR TSTM DVLPMENT AND
SVR POSSIBILITY...AND SLIM AND NONE ELSEWHERE WITH THE UNI
DIRECTIONAL WRLY WNDS USHERING IN DRY AIR AND STRONG 850MB CAA.
HOWEVER...GIVEN THE AMNT OF STRATUS THAT IS COOLING THE AIR FM I 29
EWD...WL SEE HOW MUCH OF THIS CAN CLEAR OUT BEFORE WND SHIFT LINE
WORKS THRU. ATTM...FEEL THE SPC MDT RISK IS PROBABLY OVERDONE IN ERN
SECTION OF CWA AND WL TONE DOWN WORDING AT 11 AM SIG WX OTLK.
.FSD...NONE
FUHS
FXUS63 KABR 121457 sd