AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
845 PM PDT THU AUG 19 1999
FORECASTS LOOK ON TRACK...ONLY UPDATE TO ZONES 1/3 FOR CLOUD COVER.
IR SATELLITE IMAGERY SHOWS PATCH OF MID AND HIGH CLOUDS ADVANCING
TOWARD NW CALIFORNIA AT THIS TIME ASSOCIATED WITH VORT CENTER WHICH
IS ABOUT 200 MILES W OF CAPE MENDOCINO AT THIS TIME. BOTH MESOETA
AND RUC POSITION AT 03Z TOO FAR E. CURRENT MOTION WOULD TAKE THIS
FEATURE TO THE S OREGON COAST LATE TONIGHT. WITH CONTINUED SW FLOW
ALOFT AND AN UPPER LEVEL DISTURBANCE MOVING THROUGH THE AREA...WOULD
EXPECT A DEEPENING OF THE MARINE LAYER. CLEAR TO PARTLY CLOUDY SKIES
EARLY TONIGHT WILL BECOME CLOUDY...WITH PATCHY DRIZZLE EXPECTED
TOWARD DAYBREAK. MARINE: BUOY 27 DROPPED OUT AT 00Z...LETS HOPE
ONLY TEMPORARILY. NO BIG CHANGES IN WIND NEXT 24 HOURS N OF CAPE
MENDOCINO...HOWEVER WINDS WILL SLIGHTLY INCREASE S OF THE CAPE
FRI INTO FRI NIGHT AS THE GRADIENT INCREASES.
POPS EKA 2211 CEC 2211 UKI 0000.
.EKA...NONE.
OSIENSKY
FXUS66 KHNX 192226 ca
SOUTH CENTRAL AND SOUTHEAST COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO
200 PM MDT THU AUG 19 1999
...FORECAST CHALLENGES ARE TIMING OF SHORTWAVES AND RESULTING
THUNDERSTORM CHANCES...
UPPER LEVEL RIDGE REMAINS OVER THE ROCKY MOUNTAIN REGION AND DESERT
SOUTHWEST WITH CURRENT WATER VAPOR LOOPS SHOWING GOOD FEED OF
MONSOON MOISTURE CONTINUING OVER THE REGION. SUBTLE DIFFERENCES
EXIST BETWEEN MODELS WITH STRENGTH AND PLACEMENT OF SHORTWAVES
ROTATING AROUND THE UPPER HIGH. MODELS MOST AGREE ON THE TIMING OF
MAIN SHORTWAVE MOVING THROUGH MONTANA AND NORTH DAKOTA OVERNIGHT. ETA
AND RUC ALSO SHOW ANOTHER SHORTWAVE WHICH STARTS OUT IN SOUTHWEST
UTAH AROUND 18Z AND MOVES ACROSS THE FORECAST AREA OVERNIGHT.
DIFFICULT TO PICK THIS SHORTWAVE OUT IN WATER VAPOR PICTURES...BUT
COULD BE ASSOCIATED WITH LIGHTNING ACTIVITY SHOWING UP IN CENTRAL UT.
AT ANY RATE...WITH STEALTH SHORTWAVES ROTATING AROUND THE HIGH...
COMBINED WITH MONSOON MOISTURE AND INSTABILITY...SCATTERED EVENING
THUNDERSTORMS FOR MOST AREAS IN GOING FORECAST STILL LOOKS GOOD.
IN WAKE OF PASSING SHORTWAVE THROUGH THE NORTHERN PLAINS...MODELS
BRING A WEAK NORTHERLY SURGE THROUGH THE EASTERN PLAINS FRIDAY
AFTERNOON. MODELS DISAGREE WITH THEIR HANDLING OF THIS SURFACE
FRONT. BY 00Z...ETA WEAKENS THE WIND FIELD WITH VERY DIFFUSE
SURFACE FRONT SOMEWHERE AROUND THE PALMER DIVIDE AREA. AVN/NGM SHOW
FRONT BANKED UP NEXT TO THE MOUNTAINS THEN EXTENDING NORTHEASTWARD
THROUGH THE SOUTHEAST PLAINS. ANOTHER POTENTIAL VORTICITY LOBE IS
EXPECTED TO ROTATE SOUTHWARD THROUGH THE EASTERN PLAINS DURING THE
AFTERNOON. ALTHOUGH MID AND HIGH LEVEL MOISTURE REMAIN WELL IN
PLACE...THE LOWER LEVELS MAY DRY OUT SOME WITH EITHER A NORTHERLY OR
NORTHWESTERLY DOWNSLOPE COMPONENT. ETA FORECAST CAPES RANGE UP TO
1200 J/KG AND WITH THE UNCERTAINTY OF WHERE THE SURFACE FRONT WILL
BE...WILL KEEP WITH WIDELY SCATTERED TO SCATTERED POPS IN FOR FRIDAY
AND FRIDAY NIGHT.
UPPER HIGH REMAINS OVER THE REGION ON SATURDAY WITH NOT MUCH
CHANGE IN THE MOISTURE FIELDS EITHER. TOO DIFFICULT THAT FAR OUT TO
TIME ANY SUBTLE UPPER LEVEL SHORTWAVES. SO WILL CONTINUE WITH THE
SCATTERED TO WIDELY SCATTERED TYPE DIURNAL THUNDERSTORMS.
EXTENDED DISCUSSION...
UPPER HIGH EXPANDS ACROSS MUCH OF THE WESTERN US THROUGH THE
EXTENDED PERIOD...WITH SHORTWAVES ROTATING AROUND THE NORTHERN AND
EASTERN PERIPHERY. FIRST OF THESE ROTATES DOWN ACROSS EASTERN
COLORADO IN NORTHWEST FLOW LATE SUNDAY INTO MONDAY...BRINGING ANOTHER
NORTHERLY SURGE THROUGH THE EASTERN PLAINS IN ITS WAKE. MOISTURE
FIELDS CONTINUE TO SHOW SUFFICIENT MID AND HIGH LEVEL MOISTURE
RECIRCULATED AROUND THE HIGH CENTER TO MAINTAIN POSSIBILITY OF
THUNDERSTORMS. UPSLOPE FLOW DEVELOPS DURING THE AFTERNOON ON
MONDAY WHICH SHOULD SHIFT FOCUS FOR THUNDERSTORMS OVER THE EASTERN
MOUNTAINS. WITH THE HIGH EXPANDING OVER THE WESTERN US...THIS
SHOULD SHUNT MOST OF THE EASTERLY WAVES THAT HAVE BEEN SO PROBLEMATIC
FOR THE MODELS TO RESOLVE WELL TO THE SOUTH OF THE FORECAST AREA.
BUT CHALLENGE WILL SHIFT TO EMBEDDED SHORTWAVES ROUNDING THE TOP OF
THE RIDGE AND MOVING ACROSS FORECAST AREA IN NORTHWEST FLOW. MRF
VORTICITY FIELDS APPEAR PRETTY BENIGN FOR TUESDAY WITH MOISTURE
DECREASING (STILL 40-50% BY 00Z IN 850-500MB LAYER RH) AS ONE WOULD
EXPECT IN A NORTHWEST FLOW PATTERN. HOWEVER...POTENTIAL VORTICITY
FIELDS REVEAL A DISTURBANCE MOVING DOWN THE EASTERN PLAINS INTO
NORTHERN SECTIONS OF THE FORECAST AREA DURING THE AFTERNOON. ALTHOUGH
DIV Q FIELDS NOT SHOWING MUCH LIFT WITH THIS FEATURE WILL CONTINUE
WITH CHANCE POPS ON TUESDAY FOR NOW. TEMPERATURES MONDAY SHOULD
BE SLIGHTLY COOLER...THEN REBOUND SOME ON TUESDAY.
.PUB...NONE.
KT
FXUS65 KPUB 191024 co
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
238 PM CDT THU AUG 19 1999
...GLOBALLY...
GLOBAL MOSAIC OF WATER VAPOR SHOWS THE LONGWAVE PATTERN CONTINUES TO
SLOWLY AMPLIFY AS THE 100+ KNOT PACIFIC JET (BASED ON DARKNESS) WORKS
ITS WAY INTO THE ALEUTIANS. THE BIG QUESTION NOW IS HOW WILL THE
IMPENDING/EVENTUAL DEVELOPMENT OF BRET AND CINDY HAVE ON THE
LONGWAVE PATTERN THROUGH THE END OF THE MONTH. ADDITIONALLY THE
TRANSITION FROM SUMMER TO FALL IS BEGINNING WHICH WILL ADD MORE
UNCERTAINTY. AS HEIGHTS CONTINUE TO SLOWLY BUILD THE VORTEX NORTH OF
THE KAMCHATKA PENINSULA WILL MOVE INTO THE BERING SEA AND KICK OUT
THE GULF OF ALASKA LOW. THIS WOULD RESULT IN A LONGWAVE TROF AROUND
160W WITH WAVELENGTH PLACING A RIDGE OVER THE WESTERN U.S. AND A
TROF ALONG THE EAST COAST.
GLOBAL MODELS ARE STARTING TO CONVERGE ON THE OUTCOME OF THE
LONGWAVE PATTERN. THE MODELS DO AGREE THAT THE PACIFIC JET WILL
RESULT IN A SINGLE POLAR JET ACROSS NORTH AMERICA AROUND THE
U.S./CANADIAN BORDER FOR THE ABOUT THE REMAINDER OF THE MONTH.
NET RESULT HERE IS TEMPERATURES MODERATING TO AROUND NORMAL THROUGH
THE END OF THE MONTH WITH PRECIPITATION LIKELY TO BE AT OR BELOW
NORMAL.
...LOCALLY...
WATER VAPOR AND PROFILER DATA SHOW DEEP CYCLONIC FLOW ACROSS THE
AREA WITH A SHORTWAVE MOVING THROUGH NORTHERN ILLINOIS. 18Z SURFACE
ANALYSIS HAS THE LOW BETWEEN KBMG AND KHNB WITH AN INVERTED TROF UP
THROUGH NORTHEAST ILLINOIS/SOUTHEAST WISCONSIN. TWO WEAK TROFS WERE
ACROSS THE FORECAST AREA...THE FIRST ENTERING INTO NORTHERN MISSOURI
WITH THE SECOND FROM NEAR KMIW BACK TOWARD KVYS. VISIBLE IMAGERY HAS
PLENTY OF SC/CU ACROSS THE AREA WITH SOME THIN SPOTS THAT WERE
ALLOWING JUST BRIEF PEEKS OF SUN. ON THE BROADER SCALE WATER VAPOR
SHOWED A TROPICAL CONNECTION THAT HAS WORKED AS FAR NORTH AND EAST
AS COLORADO/WYOMING AND NUMEROUS SHORTWAVES ARE MOVING AROUND THE
EDGE OF THE UPPER RIDGE FROM THE PAC NORTHWEST INTO THE NORTHERN
PLAINS. DVN 88D SHOWS SOME --RA/-SHRA ACROSS NORTHEAST ILLINOIS
MOVING TO THE SOUTHWEST.
PROBLEMS THIS PACKAGE ARE ESSENTIALLY CLOUDS/TEMPERATURES.
12Z MODELS APPEAR TO HAVE INITIALIZED OK BUT THE NGM/AVN IS HANDLING
THE LOW CLOUDS/RH FIELDS BETTER THAN THE ETA. QG FORCING FROM
NGM/AVN AND 15Z RUC SHOW DOWNWARD MOTION OVERNIGHT TO AID IN
BREAKING UP THE CLOUDS BUT TIME SECTIONS SHOW STILL SHOW PLENTY OF
LOW LEVEL RH WHILE THE CYCLONIC FLOW ALOFT SLOWLY RELAXES. CURRENT
SATELLITE TRENDS SHOW CLOUDS ARE STARTING TO BREAK UP BUT A FAIR
ABOUT OF CLOUD SHOULD REMAIN OVERNIGHT. THUS DECREASING CLOUDS FOR
TONIGHT LOOKS RIGHT. RAINFALL FROM YESTERDAY/LAST NIGHT SHOULD
RESULT IN SOME PATCHY LIGHT FOG LATE TONIGHT ACROSS THE AREA. FRIDAY
SHORTWAVE TOPPING THE RIDGE IN THE ROCKIES ARRIVES WITH INCREASED
HIGH LEVEL RH WITH RESPECTABLE AMOUNTS DOWN LOW AS WELL. THEREFORE A
PARTLY CLOUDY ON FRIDAY LOOKS GOOD.
MOSTLY CLEAR AND COOL FRIDAY NIGHT WITH MORE SUN ON SATURDAY.
TEMPERATURES TO SLOWLY MODERATE TO NORMAL OVER THE NEXT SEVERAL
DAYS. WARMER FWC TEMPERATURES FOR TONIGHT LOOK BETTER GIVEN CLOUDS
BUT COOLER FAN NUMBERS BEYOND TONIGHT LOOK MUCH BETTER.
...EXTENDED...
MONSOONAL MOISTURE IN THE SOUTHWEST U.S. SHOULD WORK ITS WAY INTO
THE AREA WITH A SHORTWAVE TO WORK ON THIS MOISTURE DURING MONDAY.
RIDGE SHOULD BUILD ENOUGH INTO THE AREA THAT ANY MCS/MCC THAT FORM
SHOULD REMAIN ACROSS MINNESOTA AND WISCONSIN. TEMPERATURES TO BE
RIGHT AROUND NORMAL.
COORDINATED WITH DSM...LSE...CHI...SPI.
.DVN...
NC
il
SOUTHEAST TEXAS...SOUTHWEST/CENTRAL LOUISIANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
813 PM CDT THU AUG 19 1999
THE RUC GUIDANCE SHOWS A CESSATION OF RAIN FOR THE REMAINDER OF
TONIGHT. THE RUC HIGHLIGHTS THE TUTT (TROPICAL UPPER TROPOSPHERIC
TROUGH) EDDY OVER THE LOWER WATERS OF TEXAS MOVING WEST. WITH THIS IN
MIND...I SEE NO REASON TO CHANGE THE CURRENT FORECAST PACKAGE.
BPT 77/98/74/95 0102
LCH 77/98/75/94 0102
LFT 77/97/75/94 0102
AEX 74/97/72/96 0001
8/21
.LCH...
TX...OZONE ACTION DAY FOR TXZ201-215-216.
LA...NONE.
FXUS64 KSHV 192006 la
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
915 PM EDT THU AUG 19 1999
TRICKY LTL CLOUD FCST TONIGHT. MAIN MASS OF MID/HIGH CLOUD IS
HEADING EAST OF THE CWA...AS THE UPR LOW EXITS THE SE CORNER OF MI.
LINGERING PATCHY LOW CLOUD IS IN MAINLY THE ERN CWA...ALONG WITH THE
LAST OF THE SPRINKLES. LAST USEFUL VSBL SAT IMAGES SHOWED SOME OF
THAT DIURNAL AND DISAPPEARING...SOME OF IT MORE STRATUS-LIKE AND
HOLDING ITS OWN. GENERAL CLEARING TREND SO FAR HAS BEEN WEST TO
EAST...AS OPPOSED TO THE EXPECTED NNW TO SSE. CLEARING HAS ALSO GONE
FASTER THAN PROGGED.
COMPLICATING FACTOR IS A MID CLOUD SWIRL IN NE LWR MI...SLOWLY
DRIFTING SOUTH...AND EVEN A LTL WEST OF SOUTH. OBVIOUSLY A S/WAVE
HERE...CENTERED IN THE 700-500MB LYR. 18Z MESOETA DID RESOLVE A VORT
LOBE AT 21Z...THEN RAPIDLY LOSES TRACK OF IT BY 03Z. DO NOT BELIEVE
THIS IS THE BEST SOLN. 21Z RUC AT LEAST MAINTAINS THIS S/WAVE
ENERGY...BUT PLACED IT TOO FAR WEST AT 00Z.
AMBIENT FLOW AROUND UPR LOW SHUD PRODUCE A GENERAL SOUTHWARD TRACK
ACROSS THE CWA TONIGHT...HEADING INTO NW OHIO AROUND 09Z. FEEL THAT
ASSOCIATED CLOUDS WL PERHAPS DIMINISH SLIGHTLY...BUT GENERALLY
MAINTAIN ITSELF. THUS...ALTHOUGH MOST THE CWA WL ACTUALLY GO
MO/CLEAR FOR LATE EVNG/EARLY OVERNIGHT...MOST PLACES WL ALSO SEE THE
CLOUDS RETURN NOT LONG AFTER. WL THUS NOT GO TOO OPTIMISTIC WITH
CLOUD CVR REST OF THE NIGHT.
HOWEVER...ENUF RAD COOLING WL OCCUR TO SUPPORT DROPPING MIN TEMPS
MOST PLACES.
.DTX...NONE.
ZOLTOWSKI
FXUS63 KDTX 191945 mi
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
830 PM CDT THU AUG 19 1999
FORECAST APPEARS TO BE IN GREAT SHAPE...WITH LITTLE MODIFICATION
NEEDED. FOG REMAINS THE MAIN CONCERN OVERNIGHT. CURRENTLY...DEWPOINT
DEPRESSIONS ARE LOWEST OVR E CNTRL MN/W CNTRL WI WHERE LEAST MIXING
OCCURED TODAY. IR IMAGERY SHOWING SOME CI/CS DIVING FROM MANITOBA
INTO WRN MN...ASSOCIATED WITH RIGHT ENTRANCE AREA OF 60KT JET STREAK
OVR MN/WI. 21Z RUC SHOWS THIS JET STREAK CIRRUS CONTINUING TO STREAM
INTO MN OVRNT...PSBLY LESSENING RADIATIONAL COOLING IN THE WEST. STILL
RETURN TO LGT SE/S FLOW WILL PROVIDE SOME UPSLOPE. OVERALL...EXPECT
DENSEST FOG FM STC TO RPD...WITH LIGHTER FOG AXN-RWF. WILL ONLY TOUCH
UP ZONES SLIGHTLY FOR WORDING. NOT YET CLEAR WHERE/IF A DENSE FOG
ADVISORY WOULD BE NEEDED...BUT WILL BE MONITORING SITUATION.
.MSP...NONE
DAVIS
FXUS63 KMPX 192030 mn
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
230 PM CDT THU AUG 19 1999
NOT A LOT OF SIG DIFF AMONG MODELS AT SFC AND 500 MB THRU 36 HRS.
SOME DISAGREEMENT ON WFNT COMING OUT OF PLAINS BY 48 HRS...BUT CAN
RESOLVE THAT LATER. IN THE MEANTIME...ST DECK HAS BROKEN UP OVR ALL
CWA XCP SRN TIER OF ZONES. CU IS POPPING ELSEWHERE AS ANTICIPATED.
LOOKING FOR CONTINUED THINNING/EROSION OF ST IN SOUTH AS MOIST LYR
QUITE THIN. XSCTNS INDICATING CONTD DRYING OF BLYR TONGT...SO PCLDY
TO MOCLR FCST SHOULD HOLD UP...ALTHO WTH LGT WNDS...LESS CLD CVR...
AND GRND STILL QUITE MOIST...WOULD XPCT PTCHY FG AGN OVRNGT. THIS
ALSO COVERED IN CURRENT ZFP PKG. NONE OF THE 12Z MODELS PICKED UP
THE VORT MAX MOVG ACRS CN TWD JAMES BAY VERY WELL...ALTHO RUC WAS
CLOSEST. XPCT TAIL OF MID/HIGH CLDS TO SWINGING ACRS NRN MN...BUT
VRY DRY UPR LVLS AND SUBSDC OVR RGN SHOULD NOT ALLOW FOR ANY PCPN.
INSTEAD...WILL USE PCLDY RATHER THAN MOCLR IN THE NORTH. LIKEWISE
WTH NXT IMPULSE APCHG ERLY SAT. NXT BEST CHC OF RAIN COMES LATE SUN
AND INTO MON AS MORE VIGOROUS S/WV COMES OVR THE RDG AND SFC FNTL
SYSTM APPCHS FROM THE PLAINS. NGM AND AVN MOS TEMPS QUITE CLOSE AND
SEEM RSNBL IN SHOWING A SLGT WRMG TREND OVR NXT 48 HRS AS MORE
SUNSHINE IS AVAIL AND PSG OF THE SFC RDG PUTS US BACK INTO A WAA
REGIME.
.DLH...NONE.
ERF
FXUS63 KMPX 191548 mn
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1030 AM CDT THU AUG 19 1999
FIRST PERIOD CONCERN FOCUSES ON CLOUD TRENDS. MOIST LOW LEVEL NELY
FLOW HAS PUSHED CLOUD EDGE INTO WESTERN ZONE FORECAST AREA...JUST
WEST OF AXN TO RWF...ALG WK SFC TROF. PER 12Z KMPX SOUNDING...LOW
LEVEL MOISTURE CENTERED NR 925 MB. RUC 925 MB RELATIVE HUMIDITY OF
80 TO 85 PERCENT LINING UP CLOSE TO CLOUD EDGE. WATER VAPOR IMAGERY
SHOWS VIGOROUS S/W OVR UPR OHIO VALLEY CONT TO SLIDE EWD WHICH WOULD
ALLOW A BIT MORE RIDGING/SUBSIDENCE TO DEVELOP OVER ZFA. LATEST
PIREP REPORT THICKNESS OF OVERCAST 2 TO 3K SO LOW LEVEL MOISTURE
FAIRLY DEEP. CLEAR AREA OF RPD HAS NOW FILLED IN WITH BKN/OVC MVFR
CLDS. PER VSBL IMAGERY SOME THIN SPOTS SHOWING UP SO WL CONT WITH
PARTIAL CLEARING WORDING THIS AFTN IN WI AND ERN CNTRL MN ZFA BUT
CONT WITH M/C WORDING IN HIGHER TERRAIN AREAS OF SOUTH AND WEST.
TEMPS LOWERED MOST AREAS DUE TO PERSISTANT CLOUDS AND ADDED FOG
MENTION FOR TNGT TO MOST AREAS.
.MSP...NONE
KAVINSKY
FXUS63 KMPX 190840 mn
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
925 PM CDT THU AUG 19 1999
THIS EVENING'S 850MB ANALYSIS SHOWED A N-S ORIENTED WARM FRONT
BETWEEN LBF AND OMA. THE 20/00Z RUN OF THE RUC INDICATES THAT THIS
WARM FRONT WILL SHIFT EWD OVERNIGHT AS THE 850MB FLOW VEERS TO THE
SW. THE MERRIMAN PROFILER IS ALREADY SHOWING AN INCREASING
LOW-LEVEL WARM ADVECTION SIGNATURE...WITH THE RUC PROGGING THE
STRONGEST WARM ADVECTION OVER S-CNTRL/SERN SD AND NERN NEB BY
09-12Z. ALTHOUGH WE DO NOT EXPECT ANY PRECIPITATION...CLOUDS COULD
INCREASE OVERNIGHT ACROSS THE FAR NWRN ZONES. THEREFORE...WE HAVE
MADE ADJUSTMENTS TO THE CLOUD WORDING IN THE FAR NW AND MINOR TWEAKS
TO THE WINDS ACROSS THE CWFA...PER 00Z RUC FORECASTS.
.OMA...NONE
MEAD
FXUS63 KLBF 191948 ne
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
900 PM EDT THU AUG 19 1999
SCATTERED SHOWERS DEVELOPED LATE THIS AFT AND EVENING ACROSS NORTHERN
PA AND HAVE MOVED INTO SOUTHERN TIER OF NYS. DID A QUICK UPDATE EARLIER
TO ACCOUNT FOR THIS PRECIP. SHOWERS ARE QUITE PERSISTENT AND SLOW MOVING
ALTHOUGH LIGHT. ETA SHOWS ELONGATED TYPE VORT MAX ACROSS SOUTHERN TIER
IN REGION WHERE THESE SHOWERS SEEM TO BE MEANDERING. ALSO NOTED ON RUC
AREA OF 850MB MOIST FLUX CONV OVER THE WHOLE CWA SO NOT QUITE SURE WHY
SHOWERS ARE PRETTY MUCH STATIONARY OVER A SMALL AREA. MORE SHOWERS
ACROSS CENTRAL PA ARE MOVING TWD THE NORTHEAST AND SHOULD REACH OUR
WESTERN ZONES BEFORE 10 PM. AREA OF RAIN OVER LAKE ERIE IS ALSO MAKING
SLOW EWD PROGRESS.
MAIN CHG TO FORECAST WILL BE TO REMOVE TWD MORNING TIMING OF PRECIP AND
LEAVE CHC POP. WILL KEEP LOW CHC POP ACROSS FINGER LAKES THAT WAS ADDED
IN LAST UPDATE.
.BGM...NONE.
JML
FXUS61 KOKX 200040 ny
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
840 PM EDT THU AUG 19 1999
LATEST SFC PLOT PUTS LOW PRES OVR KY. AVN LOOKS LIKE IT DID THE
BEST JOB WITH IT/S 12 HR SFC FCST POSITIONING. OTHERWISE...SATELLITE
LOOPS SHOW PLENTY OF CLOUDS MOVING EWD ACRS FA ATTM. UPSTREAM RADARS
INDICATE SCT SHRA WELL TO OUR WEST.
OVERNIGHT FCST MINS LOOK GOOD WITH 12 HR FWC TEMP FCST DOING A
PRETTY GOOD JOB COMPARED TO 00Z OBS...WITH THE EXCEPTION OF INLAND
STATIONS WHERE FWC/S RUNNING TOO COLD. WL GO WITH MCLDY OVERNIGHT.
MARINE: WINDS E/SE SHOULD SHIFT TO THE NE AS THE NIGHT PROGRESSES.
21Z RUC SHOWS THIS AS WELL.
NO CHANGES PLANNED. HOPEFULLY BETTER AGREEMENT WITH MODELS ON 00Z
RUN.
PRODUCTS OUT BY 0130Z.
.NYC/OKX...NONE.
WICHROWSKI
FXUS61 KBUF 192209 ny
AREA FORECAST DISCUSSION UPDATED
NATIONAL WEATHER SERVICE BUFFALO NY
606 PM EDT THU AUG 19 1999
RADAR SHOWING PRECIP APPROACHING SW NY FROM THE WESTERN HALF OF LK
ERIE...NE OHIO NW PA AND SW ONTARIO PROVINCE. LATEST RUC HANDLING
THIS PRECIP AREA FAIRLY WELL ATTM AND IT SPREADS IT NE BY 06Z INTO
IAG FRONTIER. HAVE UPDATED 8 WNY CNTYS TO MAKE IT SHWRS LKLY IN
WESTERN SOUTHERN TIER AND CHC POPS BY MIDNGT FOR BUF-IAG REGION.
WILL HOLD ON ANY CHANGES FOR AREAS FURTHER TO THE EAST FOR NOW.
.BUF...NONE
JJP
FXUS61 KBUF 191909 ny
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
938 AM EDT THU AUG 19 1999
CURRENT FORECAST IN GOOD SHAPE WITH NO CHANGES PLANNED.
SATELLITE SHOWS WIDESPREAD AREA OF BKN-OVC MID DECK UPSTREAM OVER
SRN ONT AND MICH. DEEPEST AND MOST WIDESPRAD MOISTURE EXPECTED
ACROSS SRN ZONES AND LATEST RUC/META AGREE. BUF 12Z SOUNDING SHOWS
SOME CAPE WITH WEAK CAP AT 750MB. IF LONG DURATION BREAKS DO OCCUR
EXPECT CU FIELD TO POP BUT ANY CONVECTION WILL STAY WELL SOUTH OF
FA. TEMPS LOOK GOOD.
.BGM...NONE.
RRM
ny
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
845 PM EDT THU AUG 19 1999
WILL ISSUE ZFP CLOSE TO WATCH EXPIRATION 9 PM. TSTM ACTION IS
DECREASING ...BUT ETA AND RUC CONTINUE TO DEVELOP AND PROGRESS THE
TROUGH FROM GREAT LAKES LOW TO THE APPALACHIANS BY SUNRISE
FRI...INCREASING MOISTURE FEED AND DYNAMICS ACROSS THE
CAROLINAS...SO WILL KEEP SCATTERED TSTMS IN AREA ESPECIALLY TOWARD
MORNING.
DROUGHT WAS REDUCED BY RAINS...UP TO 3-4 INCHES UNDER SOME OF THE
SLOW MOVING TSTMS THIS AFTN AND EVENING.
CWF...LOOKS FINE...NO CHANGES.
.ILM...NONE.
MATHESON
FXUS62 KMHX 200009 nc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC
1010 AM EDT THU AUG 19 1999
LTST SFC ANAL SHOWG BNDRY SUMWHR BTWN HAT AND CLKOUT THIS AM. FPSN7
BLOWG AT 28 KT THIS HR...IN VCNTY OF CNVCTN. OTHR BUOYS 5 TO 10 KT
AS GRAD RMNS WK. TEMPS IN THE MID 70S TO LWR 80S AT 10 AM. TEMPS
SHUD BE A LTL LWR THAN YSTRDY WI INCRSD CLD CVR ALNG THE CST. HWVR
MID 90S INLND STL GUD. UPR AIR ANAL SHOWG CPL S/WVS TO OUR W AND UPR
JET POISED TO ROTATE THRU THE TROF.
LTST RUC SHOWG S/WV TO RMN TO OUR W THRU TDY. HWVR WE WL BE IN RR OF
3H JET THIS AFTN. FNT APPRS TO MEANDR ARND ITS CRRNT POSN THRU THE
DAY. E/W ORIENTED FNTS TEND TO BE WX MKRS FOR US. THIS COMBND WI UPR
JET XPCT TO SEE ACTVTY THIS AFTN. MA UP POPS FOR TDY. HWVR BLV CHCS
WL BE AFT THIS FRST PD AS MAIN S/WV ROTATES THRU.
HT INDCS BRDR LN IN INLND CTS. WL MNTN HI HT INDEX IN ZONES BUT WONT
PUT A SPECIAL OUT FOR IT.
.MHX...NONE
FXUS62 KILM 191410 nc
FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS
900 PM CDT THU AUG 19 1999
...CLOUDS/FOG FORECAST CONCERNS TONIGHT...
S/W RIDING THRU ERN MONTANA PROVIDING ARC OF CI INTO ERN ND AS CLOUD
RIDES UP AND OVER RIDGE. MODELS SERIOUSLY UNDERDONE ON
EXTENT/PLACEMENT OF THIS MOISTURE INCLUDING LATEST RUC. SMALL AREA
OF TSRA EARLIER TONIGHT IN SE MT PUSHED INTO SW ND AND WEAKENED WITH
BLOWOFF CLOUDS PUSHING NOW TOWARDS KBIS. SFC ANALYSIS INDICATES
HI PRES EDGING INTO WRN WI WITH BROAD LOW PRES WITH A FEW CENTERS
ACROSS NORTHERN ROCKIES.
LAYERED RH INCREASES OVERNIGHT AS U/L FLOW BECOMES MORE ZONAL IN
WAKE OF S/W TO OUR NW. BULK OF MOISTURE ABOVE H7 SO WILL CHANGE MOST
SETS RRV AND WEST TO PCLDY TO ACCOUNT FOR THIS EXCEPT BCMG MCLDY DVL
SET WHERE 90% H5 RH PROGGED BY 12Z. ALSO TOYED WITH ADDING WDLY SCT
MENTION FOR PRECIP NW CWA AS 00Z RUC SPITS OUT FEW HUNDREDTHS BY 12Z
AS S/W TROF NEARS AND PROGGED SOUNDING GOES TO -2 LI.
HOWEVER...SOUNDINGS INDICATING ONLY MARGINAL MOISTURE BLO H6 AND
SHOWALTERS STILL ABOVE ZERO. BEST H85-H7 WAA HOLDS INTO CNTRL SD AND
THETA-RIDGE REMAINS PARKED IN WRN DAKOTAS IN ADVANCE OF NEARLY
STATIONARY SFC LO CENTERS. GOOD PVA ALSO STILL IN NW ND BY 12Z SO
WILL LEAVE IT AT BCMG MCLDY ATTM.
TD/S HAVE BEEN ON THE RISE THRU EVE AS LIGHT S FLO SETS UP BEHIND
SFC HI PRES. COMBINATION OF HI CLOUD/LIGHT S GRAD AND INFLUX OF
HIGHER TD/S LEAD ME TO NUDGE OVERNIGHT TEMPS UP A BIT FROM CURRENT
VALUES. SOME CREDENCE LEAD TO THIS DECISION BASED UPON VIEWING BOTH
LAMP AND LATE RUC MODEL GUIDANCE WHICH KEEPS RRV STATIONS ONLY NEAR
60 FOR LOWS BY 12Z FRI BUT WONT RAISE THEM THAT MUCH ATTM.
FOG CHANCES APPEAR LESS THAN RECENT NIGHTS WITH THE ADDITION OF HI
CLOUDS AND MOVEMENT OF SFC RIDGE AXIS TO THE EAST. BEST CHANCES
SHOULD BE IN ERN CWA WHERE LESSER CLOUD EXPECTED. HOWEVER...ANY
AREAS THAT DO CLEAR FOR AT TIME WILL STILL HAVE CHANCE WITH RELATIVELY
HIGH MOISTURE CONTENT IN LOW LEVELS AND LIGHT WIND. WILL THEREFORE
LEAVE MENTION OF PATCHY FOG IN ZONES EXCEPT FAR NW CWA.
UPDATE OUT BY 920 PM CDT.
.FGF...NONE.
SOROKA
FXUS63 KBIS 192030 nd
FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
940 AM CDT THU AUG 19 1999
.CURRENT SYNOPTIC OVERVIEW...
COOL CRISP FALL-LIKE MORNING YIELDING TO STRONG INSOLATION CURRENTLY
ACROSS REGION. LATEST SURFACE OBSERVATION AND SATELLITE TRENDS DEPICTED
CLOUD-FREE ENVIRONMENT WITH SURFACE RIDGE AXIS SITUATED ALONG NORTHERN
HALF OF RED RIVER VALLEY.
.SHORT TERM...
12Z RUC SHIFTS AFOREMENTIONED RIDGE AXIS SLOWLY EAST THIS AFTERNOON AS
UPSTREAM 5H RIDGE REMAINS PARKED OVER EASTERN FOOTHILLS OF THE ROCKIES.
STEEP 85H-7H LAPSE RATES NEARING ADIABATIC CONDITIONS COUPLED WITH
MARGINAL LOW-LEVEL MOISTURE ESPECIALLY EAST SHOULD RESULT IN SOME CU
FORMATION DURING PEAK HEATING THIS AFTERNOON. NO MAJOR CHANGES EXPECTED
WITH LATE MORNING UPDATE.
.FGF...NONE.
BERG
FXUS63 KFGF 190846 nd
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
807 PM EDT THU AUG 19 1999
A RATHER COMPLICATED FORECAST FOR THE OVERNIGHT HOURS AS THE RT
ENTRANCE REGION OF A STRONG H25 JET BECOMES MORE FAVORABLY ORIENTED
OVER THE CWA. THE 18Z ETA HAS STRONG UPPER LEVEL DIVERGENCE BY 03Z
ACROSS MOST OF THE AREA...AND THERE IS A CORRESPONDING RESPONSE IN
THE VVEL/S AND LAYER RH/S. HOWEVER...THE 1000-850 LAYER IS MARKED
BY DIVERGENCE...WITH LLVL CONVERGENCE CONFINED TO THE FRONTAL BNDRY
W OF THE MTNS. ALSO...THE 21Z RUC HAS MUCH WEAKER UPPER LEVEL
DIVERGENCE AND LOWER LAYER RELH/S. I THINK THE 18Z ETA MAKES A
LITTLE MORE SENSE AS CONVECTION IN ERN TN IS ABOUT WHERE THE ENTRANCE
REGION WAS PROGGED TO BE. THUS...DRY LLVLS SHOULD RECOVER SOME AS
FLOW BACKS TO SERLY...THOUGH NOT ENOUGH FOR WIDESPREAD OR SEVERE
CONVECTION. W/LACK OF SIG SFC CONVERGENCE...WL DROP POPS BACK TO 30
FOR ALL NON-MTNS COUNTIES AND KEEP 40S UP FOR THE HIGH COUNTRY.
I THINK WE STAND A PRETTY GOOD CHANCE OF DEVELOPING LOW CLOUDS
OVERNIGHT W/SE FLOW...THOUGH WE ARE FAIRLY CLEAR ATTM. THUS WILL GO
BECOMING MOSTLY IN ZONES.
MCAVOY
FXUS62 KCAE 192354 sc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
940 AM CDT THU AUG 19 1999
A FEW SMALL CHANGES WILL BE MADE TO THE FORECAST THIS MORNING.
ON THE SURFACE MAP...A SURFACE LOW WAS NORTHEAST OF KPAH WITH A COLD
FRONT TRAILING ACROSS THE MO BOOTHEEL TO WEST CENTRAL AR.
THUNDERSTORM CHANCES WILL BE REMOVED FROM BOOTHEEL AND NORTHEAST AR.
REST OF OUR FORECAST AREA WILL KEEP SMALL POPS. LOOKS LIKE GREATEST
CHANCE WILL BE AREAS EAST OF KMKL...AS NOTED IN DAY1 SEVERE OUTLOOK.
1200 UTC RUC MODEL INDICATES INCREASING BOUNDARY LAYER CONVERGENCE
AHEAD OF FRONT THIS AFTERNOON AND EVENING. UPPER AIR MAPS INDICATE
MORE WEAK ENERGY WILL SWING ACROSS THE REGION TODAY. CAPES WILL BE
IN THE 1500-3000 J/KG RANGE AND LAPSE RATES WILL STEEPEN. MAJOR
LIMITING FACTOR FOR CONVECTION IS LACK OF DEEP MOISTURE. ALSO...
AREAS SOUTHWEST OF KMEM WILL LIKELY REMAIN CAPPED.
ZONES WILL BE SLIGHTLY REALIGNED INCLUDING ADJUSTMENT TO INCLUDE A
LARGER CHUNK OF MS AND PART OF AR IN THE 95 TO 100 TEMPERATURE
RANGE.
.MEM...NONE.
SH
FXUS64 KOHX 191427 tn
COASTAL BEND FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
300 PM CDT THU AUG 19 1999
SHORT TERM...HAVE NOTICED A NICE FLARE-UP OF CONVECTION OVER THE
NORTHWEST GULF TODAY JUST TO THE EAST OF AN UPPER TROUGH. TD3
PROVIDING GOOD MOISTURE/INSTABILTY INTO THIS AREA AND THIS IS NOT
BEING HANDLED WELL BY THE MODELS. ACTIVITY ALREADY RAPIDLY SPREADING
OVER BRO COASTAL WATERS AND EXPECT ACTIVITY TO AFFECT CWA COASTAL
WATERS AND POSSIBLY COASTAL COUNTIES TONIGHT. ETA/AVN/RUC MOVING
TROUGH INLAND OVER SOUTH TX TONIGHT SO FOR NOW WILL INCLUDE LOW POPS
OVER THE COASTAL COUNTIES.
LONG TERM...UPPER RIDGE OVER CENTRAL U.S. WILL SHIFT WEST THROUGH
SATURDAY ALLOWING FOR TROUGH TO MOVE FURTHER INLAND. 1000-850 MB
FLOW CONTINUES TO HINT AT SEABREZE DEVELOPMENT FRIDAY AND SATURDAY.
THIS SHOULD PROVIDE PROVIDE FOCUS FOR WIDELY SCATTERED TO SCATTERED
SHOWERS/STORMS. WILL HAVE 20/30 POPS OVER AREA WITH UPPER TROUGH IN
VICINITY.
EXTENDED...WITH THE UNCERTAINTY OF TRACK WITH TD3...WILL HAVE CHC
POPS IN EXTENDED.
MARINE...WILL HAVE SCATTERED SHOWERS AND THUNDERSTORMS IN THE CWF
BEGINNING TONIGHT. OTHERWISE...WEAK GRADIENT TO CONTINUE. NO
FLAGS.
CRP BB 075/095 076/093 076 72233
VCT BB 073/096 074/093 074 72133
LRD BB 077/100 077/097 076 72111=
AP...72 (SYN)
TH...71 (MESO)
.CRP...NONE.
FXUS64 KHGX 191948 tx
TEXAS/OKLAHOMA PANHANDLES AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AMARILLO TX
145 PM CDT THU AUG 19 1999
UPR HIGH OVR W TX FCSTD TO BUILD WWD OVR THE SRN RCKYS BY TNGT AND
FRI AND THEN OVR THE SWRN STATES/FOUR CRNRS RGN BY SAT. THIS WL
SET UP A NWLY UPR FLOW REGIME ACRS THE PNHDLS. SFC FLOW OUT OF E
AND SE...UPSLP...AND PROVIDING LO LVL MSTR FOR PSBL CNVTN ACRS
THE PNHDLS. LTST RUC SHOWING ANOTHER SHRTWV DROPPING SEWD OUT OF
CO BY 03Z FRI WHICH SHOULD SET THE STAGE FOR CNVTN ONCE AGAIN
TNGT. VSBL STLT IMAGERY SHOWING A CNVCTVLY-INDUCED SHRTWV OVR THE
NRN TX PNDL ATTM DRIFTING SEWD. WL NEED TO SEE HOW THIS FEATURE
PLAYS OUT...BUT WL MAINTAIN SLGT CHC TO CHC POPS TNGT. MID AND UPR
LVL MSTR BAND ON WATER VAPOR IMAGERY ORIENTED NW TO SE FM CO DOWN
INTO THE PNHDLS. FEEL ANY CNVTN THAT DVLPS ACRS NRN NM OR SRN CO WL
PUSH SEWD INTO THE NWRN SXNS OF THE FA TNGT. STILL BEST FAVORED AREA
TNGT WL BE NWRN SXNS. ATMS MAY TAKE TIL LTR THIS AFTN TO RECOVER FM
LST NGT/S CNVTN...SO FEEL OVRNGT SHRA/S AND TSRA/S STILL LIKELY. WL
MENTION CNVTN MAINLY DURING OVRNGT HRS AS MOST OF THE ACTVTY WL DVLP
MID TO LT AFTN OVR HIER TRRN OF CO AND NM AND THEN MOV INTO THE FA BY
EVE HRS.
IN THE EXTENDED FCST PD SUN THRU TUE...NWLY FLOW REGIME CONTS ACRS
THE FA WITH SERIES OF SHRTWV/S DROPPING SEWD INTO THE PNHDLS THRU
THE PD. WL KEEP SLGT CHC TO CHC POPS GOING WITH PTLY CLDY SKIES
THRU THE FCST PD ALL SXNS.
PRELIM CCF:
AMA 063/091 064/089 064 2-2
GUY 063/090 064/088 063 3-3
DHT 061/089 062/087 062 3-4
.AMA...
TX...NONE.
OK...NONE.
SCHNEIDER
FXUS64 KEPZ 191809 tx
AREA FORECAST DISCUSSION...UPDATED FOR AVIATION DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
1027 AM CDT THU AUG 19 1999
AVIATION DISCUSSION...
SURFACE ANALYSIS SHOWS THE COLD FRONT STILL JUST NORTH OF THE RED
RIVER...BUT PRE-FRONTAL TROUGH HAS ALREADY PUSHED WINDS OUT OF THE
NORTH AND NORTHWEST THROUGH THE METROPLEX AND A MORE WESTERLY
DIRECTION IN KACT AND KCLL. MOST WINDS REMAINING BELOW 10KTS
THROUGH 18Z FRIDAY BUT NORTH TO NORTHEAST WINDS SHOULD STAY. NGM
TRIES TO PICK UP WINDS TOMORROW TO 10-15KT RANGE...BUT AVN AND ETA
KEEP WINDS BELOW 10KTS AND WILL GO CLOSER TO THAT GUIDANCE. OTHER
THAT SCATTERED CUMULUS...WHICH IS DEVELOPING TO THE WEST/SOUTHWEST
OF METROPLEX...CLOUD COVER SHOULD BE SIMILAR TO THE PAST FEW DAYS.
84
1030 AM PUBLIC DISCUSSION....
CURRENT FORECAST IN PRETTY GOOD SHAPE THIS MORNING BUT WILL MAKE A
FEW TWEAKS. PRE-FRONTAL TROUGH HAS MOVED INTO METROPLEX LATE THIS
MORNING WHILE VISIBLE SATELLITE SHOWS WEAK COLD FRONT CLOSE TO THE
RED RIVER...JUST NORTH OF KADM AT 15Z. FRONT WILL CONTINUE TO PUSH
SOUTH INTO THE FORECAST AREA THIS AFTERNOON. PRE-FRONTAL TROUGH
WILL LIMIT CONVERGENCE ALONG THE FRONT ITSELF BUT WITH SOME MOISTURE
CONVERGENCE INDICATED BY LAPS...NEW ETA...AND RUC...WILL ADD SOME
ISOLATED POPS ACROSS NORTHERN SECTIONS AND LEAVE SLIGHT CHANCE POPS
FOR SOUTHERN SECTIONS. WINDS HAVE SHIFTED MORE WESTERLY ACROSS THE
SOUTHERN ZONES AND WILL ADJUST WINDS THERE FOR THIS AFTERNOON.
TEMPS LOOK PRETTY GOOD AT THIS TIME. (80)
.FTW....NONE.
FXUS64 KCRP 191502 tx
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
911 PM EDT THU AUG 19 1999
WATCH CONTS ACROSS THE FAR SW PART OF THE CWA THIS EVE AS CLUSTERS
OF TSRA ASSOCD WITH UVM/PVA IN ADVANCE OF KY S/W ROLL EWD ALONG OLD
OUTFLOW BNDRY. INIT MESO TYPE FTR THAT PRODUCED WIND DAMAGE (PER INVERTED
V TYPE RAOB) IN SE WVA NOW PULLING NE OF THE AREA...HOWEVER REG
RADAR LOOPS INDICATE ADNTL CVRG OFF TO THE WEST. BIGGEST QUEST WITH
AMT OF CVRG OVRNGT AS SCENARIO BEGINS TO SHIFT FROM A CONVECT SITU
EARLY ON TO MORE OF AN OVERRNG/WAA PTRN FRI MORN. EVEN WITH LOSS OF
HEATING...THINK ENOUGH UPR SUPPORT/DIFFLUENCE AND EVOLVING LOW LEVEL
CNVRGNC GIVEN INCRSG PWATS TO CONT DECENT POPS AS BOTH RUC/MESO-ETA
SHOW DEEP RH LATER INTO FRI. THIS PARTICULARLY TRUE OVER THE WEST
AND NORTH WHERE PLAN TO HANG ON TO GOOD CHC/LKLYS OVRNGT...BUT MAY
TWEAK SERN ZONES TWD CHCY GIVEN LACK OF GOOD LIFT TIL LATE. OTRW
GOING FCST APRS GNRLY ON TRACK WITH ANY ADTNL CHANGES MAINLY TO
TEMPS JUST BEFORE RELEASE.
.RNK
VA...NONE.
NC...NONE.
WV...NONE.
JH
FXUS61 KRNK 192233 va
EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
150 AM PDT FRI AUG 20 1999
WEAK HIGH PRESSURE WILL KEEP THE WEATHER FAIR AND WARM THROUGH
SATURDAY. ONSHORE FLOW AND A SHALLOW MARINE LAYER WILL CONTINUE
NIGHT AND MORNING LOW CLOUDS AND FOG NEAR THE COAST. MOISTURE IN
SOUTHEAST FLOW ALOFT WILL BRING A FEW SHOWERS AND THUNDERSTORMS TO
THE MOUNTAINS AND SOUTHERN DESERTS MAINLY DURING THE AFTERNOONS.
PM MIRAMAR SOUNDING HAD MODERATE MARINE INVERSION WARMING 10 DEG IN
700 FT FROM 56 DEG AT 1300 FT TO 66 DEG AT 2000 FT. THIN MOISTURE
LAYER AT 12000 FT YIELDS A STABLE SOUNDING WITH K-INDEX OF -6.
MODERATE 5 MB ONSHORE FLOW HAS ALREADY DRAGGED THE MARINE LAYER INTO
THE COASTAL PLAINS AND VALLEYS...AND MAY PUT FOG IN THE WESTERN
INLAND EMPIRE BY SUNRISE.
PAST COUPLE OF DAYS...MODELS SHOWED A DRYING TREND IN UPPER FLOW DUE
TO WEAK TROF APRCHNG NCALIF. BUT AS EVIDENCED TODAY...THAT TROF
BARELY MOVED SOUTH...AND WAS NOT ABLE TO PUSH THE MONSOON FLOW EAST.
THUS MOIST SOUTHERLY FLOW GENERATED BAJA TSTRMS WHICH PROPIGATED UP
THE MTS INTO SAN DIEGO COUNTY THU PM. JULIAN GOT 7/10 OF AN INCH.
A BIT OF A SURPRISE!
RUC SHOWS A SIMILAR PATTERN FOR TODAY. IS ALSO SHOWS CYCLONIC SHEAR
VORTICITY OVER SCALIF DUE TO THE PROXIMITY OF THE WESTERN EDGE OF
THE BRISK MONSSON FLOW. SO WILL CONTINUE CHANCES OF MT TSTRMS TODAY
AND SAT. SOME DRYING OUT AND LESS VORTICITY OVER SAN DIEGO MTS
INDICATED FOR SUN AND EARLY NEXT WEEK...WHICH WOULD BE A COMPLETE
REVERSAL OF EARLIER SCENARIOS. MONSOON SEEMS TO BE HERE...SO MIGHT
AS WELL KEEP MT/DES TSTRM CHANCES GOING DURING NEXT WEEKS HEAT WAVE.
SAN 000
.SAN...NONE.
MACKECHNIE
FXUS66 KLOX 200424 ca
WESTERN COLORADO & EASTERN UTAH AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
249 AM MDT FRI AUG 20 1999
WELL ESTABLISHED MONSOON FLOW ONGOING TONIGHT APPEARS WILL CONTINUE
THROUGH THE WEEKEND. MOISTURE PLUME SHOWS A FEW THIN SPOTS IN BETWEEN
EMBEDDED VORT MAXES...MOST OF WHICH ARE HANDLED WELL BY THE 3 PRIMARY
MODELS...WITH A FEW NOTABLE EXCEPTIONS. VORT CIRCULATION NE OF TUCSON
TRAVELING NNW ALONG AZ/NM BORDER RESOLVED ONLY BY RUC WHICH CARRIES
THIS FEATURE AND ITS PCPN N INTO CO 15Z. VORT NE OF DELTA TRAVELING
SLOWER THAN 00Z MODELS PROGGED THUS THE LINGERING MAS OF PCPN
CURRENTLY OVER MUCH OF THE FORECAST AREA. APPEARS THERE WILL BE
PARTIAL CLEARING OVER WRN CO AT SUNRISE WILL LITTLE PCPN THIS MORNING
...BUT THEN SE AZ VORT CENTER SHOULD HELP CONVECTION AND PCPN TO
BEGIN EARLIER TODAY THAN YESTERDAY. ALL PROGS SHOW UNRELENTING
MONSOON RELATED CLOUDS AND PCPN CONTINUING THRU SAT AND THRU THE
WEEKEND ON THE PART OF THE AVN AND MRF. MODELS SHOW THAT SATURDAY
NIGHT...ESPECIALLY...COULD BE VERY WET. WITH SATELLITE SHOWING
ANOTHER EASTERLY WAVE MOVING OUR OF THE WESTERN GULF OF MEXICO AND A
TROPICAL DISTURBANCE NEAR THE YUCATAN TO SUPPLY MORE MOISTURE...WILL
BE ABLE TO KEEP HIGHER POPS OVER MUCH OF CWA...ESPECIALLY THE
SOUTHERN 2/3RD...THROUGH THE EXTENDED. CUOCO
WESTERN COLORADO AND EASTERN UTAH EMERGENCY MANAGERS SHOULD MAINTAIN
A NORMAL LEVEL OF WEATHER AWARENESS TODAY.
.GJT...NONE.
FXUS65 KBOU 192049 co
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
845 PM EDT THU AUG 19 1999
WILL ISSUE ZFP CLOSE TO WATCH EXPIRATION 9 PM. TSTM ACTION IS
DECREASING ...BUT ETA AND RUC CONTINUE TO DEVELOP AND PROGRESS THE
TROUGH FROM GREAT LAKES LOW TO THE APPALACHIANS BY SUNRISE
FRI...INCREASING MOISTURE FEED AND DYNAMICS ACROSS THE
CAROLINAS...SO WILL KEEP SCATTERED TSTMS IN AREA ESPECIALLY TOWARD
MORNING.
DROUGHT WAS REDUCED BY RAINS...UP TO 3-4 INCHES UNDER SOME OF THE
SLOW MOVING TSTMS THIS AFTN AND EVENING.
CWF...LOOKS FINE...NO CHANGES.
.ILM...NONE.
MATHESON
FXUS62 KMHX 200009 nc
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
320 AM CDT FRI AUG 20 1999
FORECAST CONCERNS INCLUDE DURATION OF FOG/LOW CLOUDS IN THE EAST THIS
MORNING...AND TSRA CHANCES IN LATER PERIODS.
IN THE NEAR TERM...FOG HAS AGAIN DEVELOPED IN EASTERN COUNTIES...
WHICH ARE STILL UNDER SLIGHT INFLUENCE OF SURFACE RIDGE JUST TO THE
EAST. 06Z RUC HANGS ON TO SIGNIFICANT LOW LEVEL MOISTURE MUCH OF
THE MORNING...AND WITH WEAKER SUNSHINE AND LIMITED MIXING DUE TO
CLOSE PROXIMITY TO RIDGE AXIS...WILL KEEP MENTION OF AREAS OF FOG
THROUGH MID MORNING FOR EASTERN TWO TIERS OF COUNTIES.
ATTENTION THEN TURNS TO APPROACHING SHORTWAVE...CURRENTLY OVER NERN
MT/ADJACENT AREA OF CANADA PER WATER VAPOR LOOP. MORE CLOSELY
FOLLOWED ETA/AVN SOLUTION WITH THIS WAVE...DROPPING IT SEWD ACROSS
ERN SD OVERNIGHT. CURRENTLY DEALING WITH PRETTY LIMITED MOISTURE...
AND BROAD HIGH OVER CENTRAL PART OF US WILL PREVENT TAPPING OF
DEEPER GULF MOISTURE...BUT MODELS AGREE IN SHOWING GRADUAL INCREASE
IN MID LEVEL MOISTURE...AND PRECIPITABLE WATER VALUES NEARING 1.5
INCHES BY 06Z/21. LATEST SURFACE ANALYSIS ALSO SHOWS BOUNDARY/WIND
SHIFT LINE ACROSS SW/SCNTRL SD INTO NERN NEBRASKA. MODELS HINT AT
SLIDING THIS NEWD INTO CWA...WHICH COULD SERVE AS LO LEVEL FOCUS FOR
DEVELOPMENT AS WAVE DROPS SEWD INTO AREA. AM A LITTLE UNCERTAIN
ABOUT EASTWARD SHIFT OF SLIGHT RISK AREA...NOW COVERING MUCH OF
CWA...ESP SINCE LATEST ETA NOW SHOWING LOWER CAPES/GREATER CIN FOR
TONIGHT THAN 12Z/19 RUN...BUT ENOUGH SUPPORT FOR AT LEAST CHANCE
TSRA POPS ALL AREAS IN TONIGHT PERIOD. WILL KEEP SLIGHT CHC TSRA
IN FAR SOUTHEASTERN COUNTIES INTO EARLY SATURDAY...AS WAVE CONTINUES
TO SLIDE SOUTHEAST OVER AREA...BUT FOR THE MOST PART A DRY SATURDAY
SEEMS REASONABLE.
.FSD...NONE.
HAMEN
FXUS63 KUNR 200208 sd
SOUTHEAST TEXAS...SOUTHWEST/CENTRAL LOUISIANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
813 PM CDT THU AUG 19 1999
THE RUC GUIDANCE SHOWS A CESSATION OF RAIN FOR THE REMAINDER OF
TONIGHT. THE RUC HIGHLIGHTS THE TUTT (TROPICAL UPPER TROPOSPHERIC
TROUGH) EDDY OVER THE LOWER WATERS OF TEXAS MOVING WEST. WITH THIS IN
MIND...I SEE NO REASON TO CHANGE THE CURRENT FORECAST PACKAGE.
BPT 77/98/74/95 0102
LCH 77/98/75/94 0102
LFT 77/97/75/94 0102
AEX 74/97/72/96 0001
8/21
.LCH...
TX...OZONE ACTION DAY FOR TXZ201-215-216.
LA...NONE.
la
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
1050 AM EDT FRI AUG 20 1999
...UPDATE FOCUSES ON CLOUDS...
MSAS SFC ANALYSIS AT 14Z SHOWING 1022MB SFC HI PRESSURE CENTERED
OVER CWA. VIS IMAGERY SHOWING FOG/STRATUS IN UPR LAKES BURING OFF
RAPIDLY...FASTER THAN YESTERDAY MORNING. 12Z GRB AND MSP RAOBS
CONTINUE TO DEPICT SUBSIDENCE INVERSION...STRONGEST AT MSP. EXPECT
INVERSION WILL RETARD CU DEVELOPMENT ALMOST COMPLETELY THIS
AFTERNOON. OTHERWISE WK SHORTWV ALOFT WILL CONTINUE TO DRIFT SE
ACROSS CWA THIS AFTERNOON...WITH LITTLE OR NO EFFECT ON SENSIBLE WX.
12Z RUC SUPPORTS THIS IDEA WITH WEAK QVECTOR DIV DISSIPATING OVR CWA
BY 18Z. BASED ON IR IMAGERY EXTRAPOLATION...SOME SCT HI CIRRUS WILL
LIKELY STREAM INTO W CWA THIS AFTERNOON IN ADVANCE OF NEXT SHORWV
DROPPING SE THRU NORTH DAKOTA.
UPSHOT IS THAT I WILL UPDATE FROM PARTLY TO MOSTLY SUNNY FOR MOST
ZONES. TEMPS/WINDS LOOK GOOD...WITH SUPPORT FROM LAMP GUIDANCE.
.MQT...NONE.
WOLF
FXUS63 KGRR 201432 mi
SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
913 AM MDT FRI AUG 20 1999
AM PLANNING TO UPDATE SOME OF THE WESTERN ZONES FOR ISOLATED
THUNDERSTORMS LATE THIS AFTERNOON.
A LOOK AT THE RUC RUN FOR 20/12Z INDICATES SOME POSITIVE VORTICITY
MOVING UP INTO THE MOUNTAINOUS AREAS THIS AFTERNOON. WATER VAPOR
IMAGERY ALSO SUGGESTS THIS. MOST OF THIS ENERGY SHOULD STAY WEST OF THE
COUNTY WARNING AREA...BUT ENOUGH IS THERE TO WARRANT A MENTION OF
ISOLATED THUNDERSTORMS BEGINNING LATE THIS AFTERNOON.
UPPER LEVEL ANALYSIS INDICATED A WEAK TROUGH AT THE 500 MB LEVEL OVER
CENTRAL MONTANA. THE TROUGH IS STRONGER AT THE 700 MB LEVEL. ACCORDING
TO THE RUC RUN...THIS FEATURE SHOULD CONTINUE TO MOVE EAST AND BE CLEAR
OF THE EASTERN ZONES EARLY THIS AFTERNOON. THUS LEAVING THE EASTERN
ZONES DRY UNTIL SATURDAY LOOKS GOOD.
HAVE NO ARGUMENT WITH THE TEMPERATURES. THEY ARE IN THE BALLPARK FROM
WHAT THE 20/12Z SOUNDINGS REVEAL. CHB
BIL BB 093/062 094/063 094 52023
LVM .. 091/056 091/... ... 52223
HDN .. 095/061 096/... ... 52023
MLS .. 095/064 095/064 ... 52002
4BQ .. 095/055 095/... ... 52002
BHK .. 091/054 091/... ... 52002
SHR BB 094/054 094/055 094 52023
FXUS65 KMSO 201503 mt
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
330 AM CDT FRI AUG 20 1999
...FORECAST CHALLENGES...AM FOG/TEMPS/CHC AND LOCATION OF PRECIP
...SYNOPSIS...LATEST IR SHOWING TWO AREAS OF INTEREST...THE FIRST IS
A STG SHRTWV OVR MT...PRODUCING CLDS IN THE DAKOTAS AND A FEW STORMS
NEAR THE MT/ND BORDER. THE SECOND IS AN MCS OVR NW KS WITH A STG
SHRTWV IN ERN CO. THE LATEST SFC CHART HAD SFC LO PRES OVR NE WY
WITH A WRMFNT IN SW SD. THE MRR PROFILER HAD STG 40KT H85 WNDS AND
WILL KEEP A CLOSE WATCH ON THE POTENTIAL FOR TSRA DVLPMNT NR THIS
FNT. THE RUCII GRAPHICS SHOWED STG WAA/STEEP LAPSE RATES/WK UVV AND
CAPES AROUND 1500 J/KG. FOG WISE...OMA WAS DOWN TO 11/2SM WITH 2-4SM
VSBYS IN WRN IA.
...FORECAST...WITH LGT SFC WNDS OVR THE ENTIRE CWA AND LGT H85 WNDS
ESP IN THE SE HALF OF THE CWA AND 0 TO 1 DEG C DEWPOINT
SPREADS...WILL MENTION PATCHY DENSE FOG EARLY IN THE THE ZONES.
THE MODELS ARE SIMILAR (ETA APPEARS THE BEST) WITH THE SLOW EWD
PROGRESSION OF THE UPR RIDGE INTO THE PLNS STATES...AND THE SERIES
OF SHRTWVS THAT TOP THE RIDGE AND MOV THRU THE DAKOTAS INTO ERN NEB
AND IA THRU THE PD. PARTS OF ERN NEB AND WRN IA MOST AT RISK FOR
PRECIP THIS EVE THRU MIDDAY SAT. THE ETA/NGM GENERATE PRECIP IN NE
NEB BY 06Z AND CONTINUES WITH LIGHT PRECIP THRU MIDDAY (ETA) AND SAT
EVE (NGM). UPR LVL DIV/UVV IS STGEST AT 06Z ON BOTH THE NGM/ETA AND
WAA/Q-VECTOR FORCING CONT FOR PARTS OF THE FCST AREA MOST OF THE PD
AT 18Z TOD. H85 DEWPOINTS RMN HIGHEST OVR THE NRN PORTION OF THE CWA.
FOCUS FOR INITIAL TSRA DVLPMTN WOULD BE ALONG AN E-W WRMFNT OVR SRN
SD WITH SFC LO PRES OVR NW NEB. CORFIDI VECTORS INDICATE PROP TO BE
SSE. THE THETA-E RIDGE/CAPE AXIS RMNS TO THE W AND THIS IS WHY THE
AREA IS UNDER WAA FOR SO LONG. ETA FCST SNDINGS SHOW BOTH OMA/LNK
MOST UNSTABLE AT 12Z...WITH OFK AND SUX MOST UNSTABLE FROM 00Z ON.
WITH THE ABOVE DISCUSSION...WILL INCREASE THE POPS IN THE N AND
INCLUDE THE CHC FOR TSRA FOR THE NRN ZONES THRU THE FCST PD. OMA
SWD...BEST CHC WILL BE AFT MIDNIGHT AND INTO SAT AM.
WOULD EXPECT SOME CLDS TO WORK THEIR WAY E WITH THE STORMS IN THE
WEST FOR P/C MOST CWA...AND BEC P/S N WITH APPROACH OF THE NRN
STREAM SHRTWV. CWA TO INCR CLDCOVER NW TO SE. TEMPS SEASONALLY
COOL THU...SHOULD BE CLOSER TO NORMAL TOD. CLDS TO HOLD TEMPS DOWN
NRN AND CNTRL CWFA SAT AND CLOSE TO GUID.
NO SIG CHGS TO THE EXTENDED.
.OMA...NONE
ZAPOTOCNY
FXUS63 KGID 200754 ne
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1020 AM EDT FRI AUG 20 1999
RUC 250MB WIND PROG SHOWS RRQ OF JET SLIPPING THROUGH CAROLINAS WITH
BEST DIVERGENCE REGION ALOFT OVER UPSTATE THIS MORNING AND DRIFTING
TOWARD THE EAST THIS AFTERNOON. UPPER AIR VERIFIES THIS.
CONVECTION ALONG NC FOOTHILLS/PIEDMONT AND UPSTATE FIRING ALONG WHAT
APPEARS TO BE FRONTAL BOUNDARY. CAPES AROUND 1500-2000J IN UPSTATES
WHERE MOISTURE POOLING HAS DEWPOINTS IN LOWER 70S. EXPECT THAT AS
MAIN VORT MAX ROTATES AROUND TROUGH BY THIS AFTERNOON...CONVECTION
POTENTIAL WILL DIMINISH. ANOTHER SPOKE OF VORTICITY MOVING TOWARD
CAROLINAS LATER TODAY BUT STRONG DRYING THROUGH DEEP LAYER OF AIR
MASS WILL PRECLUDE MUCH CHANCE OF PRECIP. WILL ADJUST ZONES TO
REFLECT THIS TREND.
TEMPERATURES WILL NEED TO BE ADJUSTED DOWNWARD BECAUSE OF EXTENSIVE
CLOUD COVER...ALTHOUGH SOME CLEARING THIS AFTERNOON WILL WARM THINGS
RATHER QUICKLY. DELGADO
.GSP...NONE.
FXUS62 KCAE 201405 sc
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1001 AM EDT FRI AUG 20 1999
MORNING SOUNDINGS INDICATE SLIGHT COOLING ALOFT. SOME SAT PROBLEMS THIS
MORN...BUT VAPOR CONTINUES TO INDICATE VORT ENERGY IN E TENN WITH
LEADING EDGE OF DRYING ALOFT MOVG INTO UPSTATE AND N GA. LATEST RUC
CONTINUES VORT ENERGY SE ACROSS AREA THROUGHOUT THE DAY...WITH SOME
DRYING ALOFT. FCST INSTABILITIES NOT AS HIGH AS YESTERDAY DUE TO LOW
LEVEL COOLING FROM CLDS/CONVECTION. HOWEVER...DUE TO SOME DYNAMICS FROM
VORT...UPPER WIND FIELDS...AND ANY LIFT ALONG LOW LEVEL CONVERGENCE
BOUNDARIES...TSRA DEVELOPMENT STILL EXPECTED. THIS ECHOES LATEST SPC DAY
1 OUTLOOK. RADAR CURRENTLY INDICATES A BAND OF TSRA DEVELOPING ALONG
APPARENT BOUNDARY STRETCHING ACROSS CENT SC INTO CSRA. WILL UP
POPS/INCREASE CLD CVR AND LOWER MAX TEMPS SLIGHTLY ALONG AND SOUTH OF
BOUNDARY. ANOTHER BAND TSRA FORMING ALONG MOISTURE CONVG BOUNDARY AND
REGION OF -6 LI UPSTATE/NE GA...INDICATED BY BOTH RUC/MESO ETA. CLD CVR
DIFFICULT DUE TO SAT PROBLEMS...OBS INDICATE FOG/LOW CLDS UPSTATE/N
GA/TENN WHICH MAY MIX OUT. WILL GO VRBL CLDS AND INCREASE POP/LWR MAX
TEMP NORTH.
.CAE...NONE.
MILLER
FXUS62 KGSP 200723 sc
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
950 AM MDT FRI AUG 20 1999
THE 15Z SURFACE ANALYSIS SHOWED A LOW NEAR KPHP WITH WEAK WARM FRONT
INTO NORTHEAST SD. SYSTEM BEING SUPPORTED BY SHORTWAVE ZIPPING
ACROSS ND PER 12Z UPPER AIR ANALYSIS AND WATER VAPOUR LOOP. ANOTHER
WEAK SHORTWAVE NOTED OVER MT. THE EFFECT OF THIS WAVE AND
TEMPERATURES ARE THE MAIN CONCERN THIS MORNING.
THE 12Z RUC INITIALIZED ALRIGHT AND AT 15Z IT REPRESENTED REALITY.
ND SHORTWAVE WILL LOSE IT/S INFLUENCE QUICKLY THIS MORNING AS
SUBSIDENCE AND DRYING ALLOWS SKIES TO BRIGHTEN AND TEMPERATURES TO
SOAR. 12Z KUNR SOUNDING SUPPORTS LOWER 90S FOR HIGHS. AFTERNOON
MODIFICATION INDICATES 2KJ/KG CAPE AVAILABLE...BUT 1-2C CAP WILL BE
IN PLACE. MT SHORTWAVE MAY BE ENOUGH FOR ISOLATED TSRA IN THE
HILLS...AND THEN ROLLING INTO PARTS OF THE PLAINS. THIS IS GENERALLY
COVERED IN THE FORECAST AND WILL NOT CHANGE. PRECIPITATION CURRENTLY
DEVELOPING OVER SOUTHWEST SD IN RESPONSE TO TRAILING SURFACE TROUGH
INTO THE NE PANHANDLE. WILL NEED TO ACCOUNT FOR THIS.
GIVEN PROJECTED AFTERNOON HIGHS...WILL BUMP UP FORECAST FOR
NORTHEAST WY AND THE BLACK HILLS. WILL BROADEN NORTHWEST SD HIGHS
SOMEWHAT.
.UNR...NONE.
HELGESON
FXUS63 KFSD 201515 sd
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1035 AM CDT FRI AUG 20 1999
FOG HAS DISSIPATED NICELY ACROSS WRN ZONE FORECAST AREA IN REGION OF
INCREASED BUT STILL WEAK WARM AIR ADVECTION. FEW AREAS OF FOG/LOW
CLOUDS HANGING ON THROUGH MID MORNING IN CENTRAL AND EASTERN AREAS
SHOULD CONT TO THIN THROUGH EARLY AFTERNOON. COOL POOL REMAINS OVR
ERN AREAS FAVORING BKN CU REDEVELOPMENT FOR AFTN HOURS. MID/HIGH
LVL MOISTURE INCREASES OVER WRN AREAS AHEAD OF NORTHERN PLAINS S/W.
IN FACT...APPEARED TO BE A BIT AHEAD OF SCHEDULE PER LATEST WATER
VAPOR IMAGERY AT 15Z...NR ND/SASK/MAN INTERSECTION. BROAD AREA OF
7H MOISTURE CONVERGENCE ACROSS NORTH DAKOTA WITH 8H DEWPTS AROUND 10
DEGREES AT BIS THIS MORNING. WK 250H JET OF 50 KTS AIDING WARM AIR
ADVECTION DYNAMICS IN PRODUCING CONT -SHRA/-TSRA ACRSS CNTRL ND.
PER LATEST RUC GUIDANCE...MAIN WAA FORCING REMAINS JUST TO THE WEST
THIS AFTN IN ERN DAKOTAS BUT SOME AFFECTS FM LEFT EXIT RGN PUSHING
INTO WEST CNTRL MN. HENCE WL INTRODUCE SML POPS FOR PRECIP IN AXN
AREA. LITTLE IF ANY ADJUSTMENTS TO TEMPS.
.MSP...NONE
KAVINSKY
FXUS63 KMPX 200845 mn
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
315 PM CDT FRI AUG 20 1999
FCST CHALLENGE...CHC TSRA FIRST PD.
MIDDAY SFC ANALYSIS SHOWS LOW PRES OVR WRN SD...MOVG SLWLY
EWD...WITH E-W WRMFNT EXTENDING THRU SERN SD. SFC RDG AXIS EXTENDS
INTO WRN OK. MORNING UPPER AIR CONTS TO DEPICT 500MB RDG OVR SRN
ROCKIES...WITH NWLY MID TROP FLOW OVR CWFA. EMBEDDED PAC NW SHORT
WAVE TROF HAS TOPPED THIS RDG...WITH CURRENT LOCATION OVR ND. THE
OVERNIGHT MCS THAT DEVELOPED IN WRN KS HAS HAD WARMING TOPS MOST OF
THE DAY...AND CONTS TO WEAKEN AND MOVE SEWD.
MAIN FCST FOCUS WL BE ON THE INTERACTION OF THE SD WRMFNT AND 500MB
WAVE. THO MOISTURE HAS REMAINED RELATIVELY LIMITED...THANKS TO SFC
RDG INTO WRN OK...A POOL OF HIER DEWPOINTS REMAINS OVR ERN NEBR INTO
SERN SD. RETURN 850MB MOISTURE AROUND PERIPHERY OF HI TRYING TO
WORK BACK INTO WRN NEBR...THO SLOW. WITH VEERING WND PROFILE...RUC
HAS PLUME OF CONDITIONALLY UNSTABLE 700-500MB LAPSE RATES OVR
ROCKIES AND WRN SD FCST TO ADVECT AHEAD OF 500MB WAVE...AND IN VCNTY
OF SFC WRMFNT BY 06Z. WAA /AND 850-700 Q CONVERGENCE /INCREASES AT
850MB OVR ERN SD...COINCIDENT WITH DEEPER LIFT INVOF 500MB SHORT
WAVE.
CHALLENGE OVERNIGHT IS HOW FAR S TSRA WL EXTEND. PREVIOUS MODELS
AGREED ON DEVELOPING TSRA OVR SERN SD...THEN MOVG PRECIP SEWD INTO
WRN IA AND NERN NEBR. OLD ETA RUN SEEMED TO BULLS-EYE THE BEST THREAT
WITH A SLUG OF 300MB DIV ACRS SD...THEN INTO NWRN IA. CURRENT
EVOLUTION AND 12Z RUNS INDICATE THAT INITIATION MAY BE FARTHER
N...AFFECTING MAINLY SD AND SWRN MN AT NOSE OF WEAK LLJ. HPC AND
SPC ALSO PINPOINT THIS AREA. WL GENERALLY FOLLOW ETA/RUC SOLUTION OF
PRECIP...AND KEEP SLIGHT CHANCE N...WITH SOME LINGERING CHC TSRA
DURING THE MORNING.
THIS WEEKEND...SFC TROF TO REMAIN ANCHORED TO LEE SLOPES...WITH
WEAK SLY SFC FLOW PREVAILING. SUBTROPICAL PLUME STAYS OVR SRN AND
CNTRL ROCKIES...WITH MODELS INDICATING ANOTHER WAVE MOVG INTO WRN KS
LATE SAT OR SUN. WL HAVE TO WATCH EVOLUTION OF THIS FEATURE FOR CHC
OF PRECIP LATER PERIODS.
FOR TEMPS...GOOD CONTINUITY BETWEEN RUNS...SO DID NOT MAKE MAJOR
CHANGE FM PREV FCST.
.OMA...NONE
BZ
FXUS63 KGID 201944 ne
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1223 PM CDT FRI AUG 20 1999
...CHALLENGE IS POPS EACH DAY...
STABLE PNA PATTERN CONTINUES ACROSS CONUS...WITH RIDGE OVER WEST AND
TROF OVER THE EAST. IMPRESSIVE SUBTROPICAL MOISTURE PLUME FEEDING INTO
THE CENTRAL ROCKIES MAKING FOR HIGH PRECIPITABLE WATER VALUES
THERE. SURFACE LOW OVER SOUTH DAKOTA PROGGED TO RETROGRADE BACK TO SE
WY/NE CO BY 00Z SAT. GOING FORECAST LOOKS OK...BUT AM TEMPTED TO TAKE
OUT POPS IN SOUTHERN ZONES ALTOGETHER.
MODELS...ETA SEEMS TO HAVE SLIGHTLY BETTER HANDLE THAN NGM AT LEAST ON
SHORT TERM SHORT WAVE FEATURES. MESOETA AND RUC SIMILAR IN BRINGING IN
A LOBE OF THE SHORT WAVE TO SHERIDAN AND CHERRY COUNTY THIS AFTERNOON.
MESOETA ALSO INCLUDE PORTIONS OF NORTH CENTRAL. EITHER THE MESOETA AND
RUC ARE ABOUT 8 HOURS TOO LATE IN THEIR FORECAST...OR WE HAVE YET TO
SEE MORE LITTLE SHOWERS. AVN SIMILAR TO ETA THROUGH FORECAST
PERIOD...WITH USUAL BIASES OF OVERDONE PRECIP FIELDS. AVN ALSO KEEPS
SFC LOW A LITTLE FARTHER WEST THAN ETA WITH REGARD TO NORTHEAST
NEBRASKA. PREFER ETA SOLN OVERALL.
AGREE WITH PREVIOUS DISCUSSION IN THAT THERE ARE SEVERAL SMALL...HARD
TO RESOLVE SHORTWAVES THAT WILL MOVE OUT OF THE ROCKIES INTO THE PLAINS
OVER THE NEXT COUPLE DAYS. ANOTHER ROUND COULD BE COMING FOR EXTREME
SOUTHWEST NEB SATURDAY NIGHT UNLESS IT IS HELD FAR ENOUGH TO THE WEST.
SINCE MEAN RIDGE AXIS IS SHIFTING TO LEE SLOPES OF ROCKIES
SATURDAY...DON'T FEEL PRECIP CHANCES ARE WARRANTED FOR SAT NIGHT.
THINGS SEEM TO COME TOGETHER BETTER FOR SUNDAY NIGHT. WILL GO WITH LOW
POPS THEN PROBABLY.
EXTENDED...MRF HAS GREAT BASIN HIGH AMPLIFIED WITH TIME. SHORTWAVE
STILL FORECAST TO TOP THE RIDGE SUNDAY INTO MONDAY. LOOKS LIKE ANOTHER
POSSIBLE REPEAT OF LAST NIGHT'S MCS OVER NORTHWEST KS ON SUNDAY
NIGHT...WITH SLIGHTLY BETTER CHANCES OF IT STARTING OUT IN NEB
PANHANDLE AND MIGRATING SOUTHEAST. NO LONGER SEE ANYTHING TO SUGGEST
MONDAY WILL BE ANYTHING BUT DRY AT THIS TIME. WEDNESDAY LOOKS PRETTY
DRY ALSO DESPITE SFC TROF BECAUSE MOISTURE IS LACKING.
.LBF...NONE.
$$
SLM
FXUS63 KLBF 201551 ne